JP6807960B2 - A method for producing non-crimped short fibers and a wet non-woven fabric containing the obtained non-crimped short fibers. - Google Patents

Description

The present invention relates to a method for producing non-crimped short fibers, and more particularly to a method for producing non-crimped short fibers having excellent dispersibility in water.

Patent Document 1 discloses a manufacturing method in which a drawn tow is manufactured by a direct spinning and stretching method to impart crimping, and as a preferred method thereof, a method of collecting cans after crimping treatment and then cutting, or collecting cans. A method of crimping and cutting after the treatment is adopted. However, in such a can collecting process, in addition to the process being temporarily stopped and the production efficiency being lowered, the thread guiding is complicated by guides and rollers in the middle, and quality defects are likely to occur. In addition, residual yarn at the end of production due to variations in yarn length and tow treated as waste are likely to occur, and there is a problem in terms of yield. Further, in the can collecting process in which the spun fibers are temporarily stored in a tow or the like, it is required to impart convergence to the fibers for process stability, and it is possible to use a spinning oil having high convergence in the spinning stage. is necessary. However, such a highly convergent oil agent may hinder the dispersibility of the final product, short fibers, in water. In particular, short fibers for papermaking need to have an excellent reinforcing effect and excellent dispersibility in water, and the conventional manufacturing method has not been able to obtain sufficiently satisfactory quality short fibers.

According to Patent Document 2, the traveling speed of the drawn fiber tow is 130 to 6,000 m / min, and immediately after the heat treatment, a finishing oil is sprayed onto the synthetic fiber tow to impart crimp to the synthetic fiber tow. A method for producing a synthetic fiber tow, which is characterized by the above, is disclosed. Further, in short fibers for papermaking, it is known that it is effective to have a high water retention rate in addition to adding a hydrophilic oil agent to the fibers in order to improve the dispersibility in water in the papermaking process. Has been done. However, with the high-speed traveling technique disclosed in Patent Document 2, it is difficult to impart a high adhesion rate of water, oil, etc., which is necessary for maintaining the performance of dispersibility in water.

Japanese Unexamined Patent Publication No. 2002-08607 JP-A-2002-155422

The present invention has been made based on the above background, and an object of the present invention is to provide a method for more efficiently producing non-crimped short fibers having excellent dispersibility in water.

The method for producing non-crimped short fibers according to the present invention is the following method for producing non-crimped short fibers, which spins at a spinning speed of 600 m / min or more and cuts the fiber toe to a length of 35 mm or less at a speed equal to or higher than the spinning speed. Requirements (I)-(III):
(I) The undrawn multifilament immediately after spinning is used as it is, or a plurality of fibers are bundled to form a fiber tow;
(II) Continuously cutting the bundled fiber tow without collecting cans; and (III) Applying one or more hydrophilic oils from the undrawn multifilament immediately after spinning to before cutting the fiber tow. It is characterized by having a step of performing.

Further, the cutting speed is preferably in the range of 600 to 4,000 m / min. Further, the above-mentioned cutting is preferably a method of cutting with a short fiber cutter having a plurality of cutter blades and having the same distance between the cutter blades from the cutting surface to the back surface of the cutter blades. Further, the fiber tow is preferably 1000 dtex or more. Further, the hydrophilic oil agent is preferably an oil agent containing a polyalkylene glycol derivative.

Further, in the step of applying the hydrophilic oil agent, a liquid applying device including a curved portion forming an arc shape in a cross-sectional view is used, and the curved portion is run while the fiber toe is in contact with the curved portion. It is preferable to include a step of discharging a liquid oil agent from the body to apply it to the fiber tow. Alternatively, in the step of applying the hydrophilic oil agent, a liquid applying device including a flat surface portion, a perforated region is provided in a part of the flat surface portion, and the perforated region has a perforated portion (liquid discharge hole). Including a step of applying the fiber toe to the fiber toe by discharging a liquid from the opening while running the fiber toe above and / or below the opening region so as not to contact the flat surface portion. Is preferable.

Further, it is preferable that the unrolled short fibers are undrawn. Further, it is preferable that the birefringence of the undrawn short fibers is in the range of 0.001 to 0.100. Further, it is preferable that the tension of the fiber toe in each step before cutting the fiber toe is less than the yield tension.
The present invention also obtains an aqueous dispersion obtained by mixing unstretched unrolled short fibers obtained by the above method and stretched short fibers as a main raw material by papermaking with a wet non-woven fabric manufacturing apparatus and hot pressure processing. To provide a non-woven fabric to be used.

According to the present invention, non-crimped short fibers having excellent dispersibility in water can be produced more efficiently.

Conceptual diagram of yield stress (σy) in the load-elongation curve of undrawn yarn Schematic diagram of liquid application device Schematic diagram of the liquid application process showing the thread path and the holding angle α when the lower side of the fiber toe is run along the upward curved portion. Schematic diagram of the liquid application process showing the thread path and the holding angle α when the upper side of the fiber toe is run along the downward curved portion. Schematic diagram of a liquid applying device according to another aspect Schematic diagram of a process example in which the upper and lower sides of the fiber tow are sandwiched between the flat surfaces of the liquid applying device according to another aspect. Schematic diagram of a process example in which spinning, drawing / overfeeding, liquid application, and cutting are continuous.

The method for producing non-crimped short fibers according to the present invention is the following method for producing non-crimped short fibers, which spins at a spinning speed of 600 m / min or more and cuts the fiber toe to a length of 35 mm or less at a speed equal to or higher than the spinning speed. Requirements (I)-(III):
(I) The undrawn multifilament immediately after spinning is used as it is, or a plurality of fibers are bundled to form a fiber tow;
(II) Continuously cutting the bundled fiber tow without collecting cans; and (III) Applying one or more hydrophilic oils from the undrawn multifilament immediately after spinning to before cutting the fiber tow. It is characterized by having a step of performing.

The polymer used for producing the non-crimped short fibers may be a polymer made of a synthetic resin that is discharged from a spinneret to form fibers. Specifically, aromatic polyesters such as polyethylene terephthalate and polyethylene naphthalate, aliphatic polyesters such as polylactic acid, aliphatic polyamides such as polyamide 6 and polyamide 66, polyparaphenylene terephthalamide and polymetaphenylene iso. Aromatic polyamide-based such as phthalamide, polyolefin-based such as polyethylene and polypropylene, polyacrylonitrile-based, vinylon, polyphenylene sulfide, and the like can be selected according to the purpose of use. In particular, in order to ensure water dispersibility and thermal adhesiveness suitable for papermaking, it is preferable to use a polyester resin as such a fiber-moldable polymer.

As a preferable example of the polyester-based resin, a polyester composed of polyalkylene terephthalate such as polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate, and aromatic dicarboxylic acid and aliphatic diol such as polyalkylene naphthalate such as polyethylene naphthalate. , Polyester composed of alicyclic carboxylic acid and aliphatic diol such as polyalkylenecyclohexanedicarboxylate, polyester composed of aromatic carboxylic acid and alicyclic diol such as polycyclohexanedimethanol terephthalate, polyethylene succinate, Examples thereof include polybutylene succinate, polyester composed of an aliphatic carboxylic acid such as polyethylene adipate and an aliphatic diol, and the like. Polyesters made of polyhydroxycarboxylic acids such as polylactic acid and polyhydroxybenzoic acid may be used. Further, depending on the specific purpose, isophthalic acid, phthalic acid, adipic acid, sebacic acid, α, β- (4-carboxyphenoxy) ester, 4,4-dicarboxyphenyl, 5-sodium sulfoisophthalic acid as acid components Acids, 2,6-naphthalenedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids or esters thereof, and diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol as diol components. , Neopentyl glycol, 1,4-cyclohexanedimethanol, polyalkylene glycol, etc. may be copolymerized with one or more components. Further, a polymer structure may be branched by copolymerizing three or more carboxylic acid components such as pentaerythritol, trimethylolpropane, trimellitic acid, and trimesic acid or components having a hydroxyl group. Moreover, you may use the mixture which combined 2 or more kinds of the said polyester resin. In particular, it is preferable that 85 mol% or more, preferably 95 mol% or more of all repeating units is a polyester composed of ethylene terephthalate. At that time, as the copolymerization component other than the terephthalic acid component and the ethylene glycol component, it is preferable to use a small amount of the copolymerization component of 15 mol% or less with respect to the terephthalic acid component.

When a polyester polymer is used, the intrinsic viscosity of the raw material polyester is preferably in the range of 0.30 to 1.50 dL / g, more preferably 0.40 to 1.20 dL / g. For example, the intrinsic viscosity can be adjusted by a method such as solid-phase polymerization of a polymer once formed into a chip shape by a drying step. Further, to the fiber-formable polymer used in the present invention, known additives such as pigments, dyes, matting agents, antifouling agents, antibacterial agents, deodorants, fluorescent whitening agents, flame retardants and stabilizers are added. , Ultraviolet absorber, lubricant and the like may be contained.

In the method for producing non-crimped short fibers of the present invention, a spinning liquid in which a fiber-moldable polymer as described above is melted or dissolved is discharged from a spinneret having a plurality of discharge holes, coagulated and spun, and undrawn. Multifilament. At that time, it is necessary to spin at a high speed of 600 m / min or more. The upper limit of the spinning speed is preferably 3000 m / min or less, and more preferably 800 to 2700 m / min, particularly high speed spinning in the range of 900 to 2500 m / min. Further, as the spinning device, it is preferable to use a melt spinning device equipped with a screw type extruder.

If the spinning speed is too low, the molecular orientation in the undrawn yarn after spinning tends to be small, and as a result, embrittlement due to crystallization over time tends to occur, and the physical properties of the obtained short fibers may deteriorate. When such low-physical short fibers are used in the papermaking field, they become a drawback and the strength of the papermaking is reduced, or it causes variations in various physical characteristics. On the contrary, when the spinning speed is too high, the physical characteristics of the fiber are improved, but the orientation crystallization on the spinning line is promoted, and the amorphous portion tends to be reduced. When short fibers having few amorphous portions are adopted in the papermaking field, the adhesive performance of the wet non-woven fabric after papermaking tends to deteriorate.

In the method for producing unrolled short fibers of the present invention, it is necessary to apply a hydrophilic oil agent in one or more steps from the undrawn multifilament immediately after spinning to before cutting the fiber tow. Preferably, one or more places are applied from immediately after spinning until the multifilament converges and from the draw heat treatment to before the fiber toe is cut.
The hydrophilic oil agent is preferably a polyalkylene glycol derivative, and particularly preferably a polyether / polyester copolymer. More specifically, it is preferably a polyether-polyester copolymer composed of terephthalic acid and / or isophthalic acid, lower alkylene glycol and polyalkylene glycol and / or monoether thereof.

Examples of the lower alkylene glycol preferably used include ethylene glycol, propylene glycol, and tetramethylene glycol. On the other hand, examples of the polyalkylene glycol include polyethylene glycol having an average molecular weight of 600 to 6000, a polyethylene glycol / polypropylene glycol copolymer, and polypropylene glycol. Further, examples of the monoether of polyalkylene glycol include monomethyl ethers such as polyethylene glycol and polypropylene glycol, monoethyl ethers and monophenyl ethers. The copolymer preferably has a molar ratio of terephthalate unit to isophthalate unit in the range of 95: 5 to 40:60 from the viewpoint of dispersibility in water, but alkali metal salts sulfoisophthalic acid, adipic acid, sebacic acid and the like. May be copolymerized in a small amount. The average molecular weight of the polyether-polyester copolymer composed of the above components is usually 1000 to 20000, preferably 3000 to 15000, although it depends on the molecular weight of the polyalkylene glycol used. If the average molecular weight is too low, the effect of improving the dispersibility in water is lowered, while if the average molecular weight is too high, the emulsifying component of the polymer is lowered.

In the method for producing non-crimped short fibers of the present invention, it is preferable to attach a hydrophilic oil such as a polyalkylene glycol derivative to the fiber surface as an aqueous dispersion. The hydrophilic oil agent can usually be easily dispersed in water by a stirring step or the like. In addition, in order to further improve the stability of the obtained aqueous dispersion, a small amount of a surfactant or an organic solvent may be added, and it is also preferable to mix and use various treatment agents such as other oils. is there. As a method for adhering the hydrophilic oil agent, it is preferable to adopt a method such as spraying, roller touch (kiss roll), metering oil (a method of applying a certain amount of oil agent to a ceramic guide having holes with a gear pump or the like).

In the method for producing non-crimped short fibers of the present invention, it is preferable to add a hydrophilic oil agent in the spinning step immediately after discharging from the spinneret. In particular, undrawn unrolled short fibers are preferable and effective.
In the past, in the process of manufacturing short fibers, there was a process of collecting cans after spinning, so there was a problem that the multifilament was loosened, and it was necessary to use an oil agent with high convergence, resulting in a wet non-woven fabric. The required underwater dispersibility was not sufficient. However, by omitting the can collecting step and the like of the present invention and adopting a manufacturing method in which the process from spinning to cutting is continuous, the above-mentioned problem that the multifilament occurs at the time of collecting cans can be avoided, and the convergence is somewhat higher than before. Although inferior, production is possible due to the convergence of the hydrophilic oil agent used in the present invention, and the papermaking quality is greatly improved in combination with the improvement of the dispersibility in water at the time of papermaking provided by the hydrophilic oil agent. It was.
Normally, such a hydrophilic oil agent is often applied in the final process, but in the present invention, it can be adopted as a spinning oil agent by omitting intermediate processes such as winding and collecting cans during the production of short fibers. It has become possible. Further, it is preferable that the molten polymer discharged from the mouthpiece is cooled and solidified, and then the hydrophilic oil agent is quickly applied without bundling the fiber tow. It is possible to shorten the treatment time and uniformly apply the hydrophilic oil agent to the fiber surface.

Furthermore, in the present invention, when a hydrophilic oil agent such as a polyalkylene glycol derivative is applied to unstretched fibers before being focused, it is effective on the surface of each fiber as compared with the conventional case where the unstretched fibers are applied after being focused. The ingredients are easier to spread. Therefore, the component is sufficiently adhered to the fiber surface, and the effect of significantly suppressing undispersion in water can be obtained.

When a hydrophilic oil agent is used as a spinning oil agent, it is preferably an aqueous emulsion in the production method of the present invention. The emulsion concentration of the polyalkylene glycol derivative is preferably in the range of 0.5 to 3% by mass. Further, the amount of the emulsion adhered to the undrawn fibers immediately after spinning is preferably 5 to 50% by mass, particularly preferably in the range of 10 to 30% by mass.

The amount of the hydrophilic oil agent attached to the undrawn fibers or drawn fibers is preferably 0.1 to 3% by mass, more preferably 0.2 to 2.5% by mass, based on the mass of the undrawn fibers or the drawn fibers. , More preferably in the range of 0.5 to 1.5% by mass. If the amount of adhesion is too small, the fibers tend to be insufficiently dispersed in water in the subsequent papermaking process or the like. On the contrary, when the amount of adhesion is too large, the adhesiveness between fibers tends to be impaired. In addition, there is a tendency to increase the water quality load on the circulating water in the papermaking process. Here, the amount of the spinning oil adhered is a value defined by the following method.
Adhesion rate = oil emulsion concentration (mass%) x water content (mass%) / 100

In the method for producing non-crimped short fibers of the present invention, undrawn multifilaments to which a hydrophilic oil agent is applied after ejection of a spinneret as described above are used as they are or a plurality of undrawn multifilaments are bundled to obtain a fiber toe of 1000 dtex or more. It is preferable to discharge 1000 to 50,000 dtex, particularly 2000 to 20000 dtex multifilaments from one spinneret. More preferably, it is preferable to bundle 2 to 40 or more, particularly 3 to 30 multifilaments to form a fiber tow of 2000 to 100,000 dtex, particularly 3000 to 50,000 dtex after the yarn is combined. The total number of filaments of the final fiber tow in which such short fibers are aggregated is preferably in the range of 500,000 to 100,000, particularly 100,000 to 90,000 so as to have the above-mentioned total fineness.

If the total fineness of the undrawn fibers immediately after spinning is made too small, it becomes easier to adhere the oil component to the fiber surface more uniformly, but in order to obtain a high production capacity, a large number of caps are used. It is necessary to use, which is industrially disadvantageous. Further, if the total fineness is too large, it tends to be difficult to uniformly apply the oil agent containing the polyalkylene glycol derivative to the fiber surface.

The fineness of the single yarn constituting the non-crimped short fibers obtained in the present invention is preferably 0.001 to 100 dtex, preferably 0.1 to 30 dtex. In particular, when the non-crimped short fibers obtained by the production method of the present invention are used for papermaking, such a single yarn fineness enables more efficient production. If the single yarn fineness is too thin, the spinnability at the time of spinning tends to decrease, and if the single yarn fineness is too thick, cooling after spinning tends to be difficult. In particular, when the short fibers obtained by the production method of the present invention are used for papermaking, it is preferable to have such a fineness range.

Further, the cross-sectional shape of the non-crimped short fiber obtained in the present invention is not particularly limited, and in addition to the round cross section, an elliptical cross section, a multi-leaf cross section such as a 3 to 8 leaf cross section, and a deformed cross section such as a polygonal cross section of 3 to 8 angles are used. It is also preferable to have. Further, the fiber is not limited to the solid fiber, but is preferably a hollow fiber or a composite fiber. Examples of the composite form in the case of composite fibers include a core sheath type, an eccentric core sheath type, a side-by-side type, a sea island type, and a segment pie type.

In the production method of the present invention, unstretched multifilaments to which an oil containing a polyalkylene glycol derivative is applied immediately after spinning are directly or bundled to form a fiber tow, and the surface temperature is 80 ° C. or lower continuously without collecting cans. After preheat treatment with a dry heat roller of 70 ° C. or lower, the stretching treatment can be performed at a temperature of less than 240 ° C.
By performing preheat treatment at a low temperature with such a dry heat roller, it is possible to suppress thermal decomposition by the alkylene glycol derivative and perform stable production. This is because if the fibers are heated at a high temperature at this stage, the fibers tend to stick to each other and the dispersibility in water tends to deteriorate.

Stretching can then be performed between the plurality of heating rollers at different speeds. At this time, the temperature of the stretching treatment is preferably controlled to less than 240 ° C., more preferably in the range of 140 to 220 ° C. It is preferable that the undrawn fibers are wound around a pair of rollers for 2 to 10 turns and stretched in 2 to 10 steps between a plurality of Nelson type rollers at different speeds. The draw ratio is preferably greater than 1 time and less than 5 times between each roll pair, and is preferably 1.5 to 5.0 times as a whole. Further, after the stretching, it is preferable to perform heat treatment at 140 ° C. or higher and lower than 240 ° C., particularly preferably 160 ° C. or higher and lower than 220 ° C. By performing such a heat treatment, it is possible to appropriately suppress the heat shrinkage rate of the finally obtained fiber. However, if this temperature is too high, the fibers tend to stick to each other, and particularly when used for papermaking, the dispersibility in water tends to be insufficient.

In the method for producing non-crimped short fibers of the present invention, the fiber tow is cut at a speed equal to or higher than the spinning speed. Conventionally, in the case of producing unstretched or stretched short fibers, the unstretched fiber tow made of unstretched multifilament is temporarily stored in a toe can or the like, or manufactured by a crimping step. After reducing the speed, it is subjected to a low-speed cutting process. However, the present invention is a method for producing non-crimped short fibers, which comprises eliminating extra steps such as can collection and crimping and continuously cutting fiber tow.

When the non-crimped short fibers obtained in the present invention are used for papermaking, a hydrophilic oil agent such as a polyalkylene glycol derivative required for dispersibility in water, specifically an aqueous emulsion of a polyether / polyester copolymer can be added. Although necessary, in the production method of the present invention, when a hydrophilic oil agent is applied in the spinning process, the application of the oil agent in the drawing step and other steps can be omitted, and continuous process formation is easy.
Normally, when a winding process or a can collecting process is included in an intermediate process, it is difficult to use a hydrophilic oil as a spinning oil due to low friction and insufficient convergence. However, in the production method of the present invention, the winding process and the winding process By omitting the can collecting step, it became possible to use a hydrophilic oil agent as the spinning oil agent.

Further, in the method for producing non-crimped short fibers of the present invention, since the obtained short fibers are non-crimped, entanglement in water is prevented. Further, the continuous process is easy because the crimper process for crimping is omitted.

In the method for producing non-crimped short fibers of the present invention, an undrawn tow that has been liquid-applied immediately after spinning is put into a cutter (high-speed cutter) from a spinning machine through a drawing step if necessary. By continuous processing, the process can be shortened, and single yarn breakage due to scratches on the yarn guides in the guides and rollers in the middle, and poor convergence in single yarn or subtow units occur. As a result, it has become possible to reduce the occurrence of overlong fibers (fiber length is longer than the set value). In the normal process, when the fiber tow is collected, the fiber toe may bend (gearly), or even if the fiber tow does not bend, single yarn sabbing or loops may occur (ejector). In addition, when collecting cans, fiber tow (raw yarn) may be entangled, twitched, or single yarn disintegration (sabake) may occur.

By the way, in the method for producing non-curly short fibers of the present invention, continuous cutting is performed, and at that time, the fibers are cut to a length of 35 mm or less at a speed higher than the spinning speed.

That is, in the present invention, the cutting speed of the fiber tow in the cutting step is preferably equal to or higher than the spinning speed and higher than the spinning speed. Specifically, the cutting speed of the fiber tow in the cutting step is faster than the spinning speed of 600 m / min or more, preferably 800 m / min or more, more preferably 900 m / min or more, and preferably 4. The range is 000 m / min or less, more preferably 3,500 m / min or less, still more preferably 3,000 m / min or less, and particularly preferably 2700 m / min or less.

In the method for producing non-crimped short fibers of the present invention, for example, in the case of producing drawn short fibers, it is preferable to add water to the drawn and heat-treated drawn fiber tow as needed. By adding water, it is possible to prevent the fibers from scattering after cutting, and it is possible to reduce the bulk at the time of packing. In addition, it is possible to promote the permeation of water between fibers during papermaking and improve the dispersibility in water. The water content at this time is preferably 0.5 to 35%, more preferably 0.5 to 20%, and further 2 to 15%, particularly less than 15%, based on the fiber mass. preferable.

Further, at this time, in order to complement the effect of the alkylene glycol derivative applied at the time of spinning, it is preferable to add the alkylene glycol derivative after the drawing treatment and before cutting the fiber tow. In addition, a functional agent such as a surfactant may be added as needed. The alkylene glycol derivative to be imparted may be the same as or different from that used at the time of spinning.

Then, in the manufacturing method of the present invention, the fiber is supplied to a high-speed cutter without crimping and cut to a predetermined fiber length. When supplying to this high-speed cutter, it is preferable to control the tow tension in order to prevent the generation of excessively long fibers due to slack or the like. To control tow tension, known techniques such as auto control by dancer rollers and load cells, and balancers used in high-speed winders can be applied.

The cut length of the manufacturing method of the present invention is 35 mm or less, but when the short fibers obtained by the manufacturing method of the present invention are used for papermaking, the fiber length is 1 to 30 mm or less, and further. The range is preferably 1 to 20 mm, particularly 2 to 10 mm.

When the fiber length is long, the cutting frequency is low even when the processing speed is high, so that the processing is easy, but the problem that the fibers are easily entangled with each other tends to occur. Especially when used in the papermaking field, the fiber length is preferably 30 mm or less. When the cut length is long, the dispersibility of the fibers in water tends to deteriorate during papermaking. If the fiber length is too long, the fibers tend to be entangled with each other in water, so it is preferable that the upper limit fiber length is short. The fiber length is preferably 20 mm or less, particularly preferably 10 mm or less. On the other hand, if the fiber length is too short, the distance between the cutter blades becomes small and the cutting resistance during manufacturing in the space formed by the blades becomes large, so that the fibers are stretched or the single fibers are separated from each other. It becomes easy to get entangled and tends to lead to deterioration of quality. For example, interfiber sticking tends to occur, making stable cutting difficult. In addition, the resulting fibers tend to have a large number of fiber lumps, and particularly when used for papermaking, the dispersibility in water tends to deteriorate.

And in order to obtain such a high-speed and short drawn short fiber, the cut has a plurality of cutter blades, and the distance between the cutter blades is the same or more from the cut surface of the cutter blade to the back surface. The method of cutting with a fiber cutter is preferable.

Although a normal rotary cutter has a plurality of cutter blades, the distance between the cutter blades is gradually narrowed from the cutting surface of the cutter blade to the back surface. This is because the blade is arranged toward the outside of the rotary in which the cutter blade is arranged, the fiber toe is wound around the outside of the rotary, and the cut fiber is discharged from the center of the rotary. With such an apparatus, it is very difficult to secure a processing speed of 600 m / min or more.

For example, a general-purpose rotary cutter as described in Utility Model Registration No. 3103190 is the most commonly used in the industry for cutting fiber tow (long fiber bundle) into short fibers. .. In this method, in the fan-shaped space formed between the cutter blades, the distance between the blades gradually narrows toward discharge after cutting, and the discharge resistance of the cut fibers increases. Therefore, the rotor rotation speed, that is, the cutter speed If (= toe speed) is increased, problems such as the cutter blade breaking due to poor discharge will occur. Normally, it is said that the limit speed of this type of cutter needs to be used at 300 m / min or less.

In the present invention, as described above, it is preferable to use a cutter for short fibers in which the distance between the cutter blades is the same or more from the cut surface to the back surface of the cutter blade (hereinafter, may be referred to as a high-speed cutter). .. More specifically, for example, it is preferable to use a cutter for short fibers having the mechanism described in US Pat. No. 4,577,537 and US Pat. No. 4,528,880. It becomes easy to cut the fiber tow even at a speed exceeding 600 m / min without an increase in discharge resistance unlike a normal rotary cutter. The mechanism is to arrange the cutter blades in a radial pattern, but with the cutting side facing upward, and while winding the fiber toe around the rotating rotor placed above it, to push off the fiber toe installed further above. It is a method of gradually pushing through with the tilt ring of. Since the distance between the blades is constant from the cut surface of the cutter blade to the back surface (cut fiber discharge side), it is possible to suppress an increase in discharge resistance, even when the fiber toe is cut at a high speed of 3000 m / min or more. However, it is possible to prevent the occurrence of blade breakage.

The non-crimped short fibers obtained by the production method of the present invention are hydrophilic non-crimped short fibers having an oil agent uniformly applied to the fiber surface and having excellent dispersibility in water, and are undispersed. It is difficult and becomes a short fiber particularly suitable for papermaking. Then, in the production method of the present invention, such non-crimped short fibers can be efficiently produced.

Further, this non-crimped short fiber can be suitably used for various living materials and industrial materials by processing it into a wet non-woven fabric or the like.
In the method for producing non-crimped short fibers of the present invention, short fibers can be obtained by unstretching or stretching after spinning, depending on the purpose.

The process of undrawn short fibers of the present invention will be described below.
In order to maintain the state of the undrawn yarn, it is necessary to suppress the process tension to the limit where the neck drawing of the undrawn yarn does not occur in all the processes. The tension of the fiber toe in each step before cutting is preferably less than the yield tension of the undrawn yarn.

Above all, the tension of the undrawn yarn (fiber toe) before and after the cutter process is important, and in particular, the tension of the undrawn yarn (fiber toe) before the cutter can be suppressed to the limit where the neck drawing of the undrawn yarn does not occur. is important. It is preferable to adjust the tension to 1% to 95% of the tension at which neck stretching occurs, and it is particularly preferable to adjust the tension to 2% to 90%. The tension at which neck stretching occurs can be determined by measuring the load-elongation curve of the undrawn yarn offline with a tensile strength tester, determining the yield stress before neck stretching, and comparing it with that tension. Is. A conceptual diagram of the yield stress (σy) of the undrawn yarn is shown in FIG.

If the tension before the cutter is too small, the fiber toe will loosen inside the high-speed cutter, and overlong fibers will be generated. On the contrary, if the tension before the cutter is too high, partial neck stretching starts due to a slight fluctuation in the process tension, and uniform short fibers cannot be obtained. Such non-uniform short fibers, especially when used in the papermaking field, cause fluctuations in binder performance and fiber diameter, resulting in deterioration of adhesive performance and dimensional stability, and disturbance of papermaking texture. In order to control such pre-cutter tension (toe tension), known techniques such as auto control by dancer rollers and load cells, balancers used for high-speed winders, and making the cutter speed faster than the pre-cutter supply speed should be applied. Is preferable.

Further, in order to use the unstretched unrolled short fibers obtained by the method for producing unrolled short fibers of the present invention in the papermaking field, particularly as unstretched binder fibers, the birefringence of the unstretched short fibers is 0.001. It is preferably in the range of ~ 0.100. Further, the appropriate range varies depending on the resin, but for example, when a polyester resin is used, it is preferably in the range of 0.005 to 0.090, particularly preferably 0.010 to 0.080. The birefringence indicates the orientation of the molecules of the undrawn fibers, and particularly when the undrawn binder fibers are used for paper, it greatly affects the binder bonding performance and the paper strength, and greatly affects the bonding temperature and pressure conditions in the intermediate process. It is a physical property.

Further, the birefringence of the undrawn unrolled short fibers can be adjusted by the spinning speed and the spinning draft rate. When used as a binder fiber for papermaking, the spinning speed is preferably in the range of 700 to 3000 m / min in the case of undrawn short fibers in order to keep the refractive index within this range. When the spinning speed is low, the molecular orientation in the undrawn yarn is small, so that embrittlement due to crystallization over time tends to occur, which becomes a drawback, and the paper strength in the case of undrawn short fibers is reduced or varies. Can be seen. Further, if the spinning speed is too high, orientation crystallization occurs on the spinning wire, and the adhesive performance of the non-woven fabric after papermaking, which is dominated by the amorphous portion, is deteriorated.

Further, the unstretched unrolled short fibers obtained by the production method of the present invention preferably have a water retention rate of 3 to 40% by mass, particularly when used as a binder fiber for papermaking. Although it is not clear, if the water retention rate is too low, the hydrophilic oil film formed on the fiber surface is less likely to fall off from the fiber surface during the papermaking process, causing adhesion problems and reducing paper strength. It is in. On the other hand, if the water retention rate is too high, water will be scattered a lot in the cutting step, and it will be difficult to cut the fibers stably. In addition, the mass of the obtained undrawn fiber increases, which is uneconomical from the viewpoint of transportation cost.

The unstretched unrolled short fibers obtained by the production method of the present invention are unstretched short fibers having excellent dispersibility in water and thermal adhesiveness, and are particularly suitable for papermaking binders. It becomes. Then, in the production method of the present invention, such undrawn short fibers can be efficiently produced.

Next, an example of a method of applying a liquid to the traveling fiber tow will be described.
The portion where the fiber toe contacts is composed of a curved portion having an arc shape in a cross-sectional view. A liquid applying device is used in which an opening region is provided in a part of the curved portion and the opening region has an opening portion (liquid discharge hole), and a fiber toe is placed in the opening region with a holding angle larger than 20 °. The liquid is discharged from the perforated portion and applied to the fiber toe while being contacted and run so as to be smaller than 180 °.

As illustrated in FIGS. 2, 3, and 4, the arc-shaped curved portion has a curved portion with the apex (FIG. 2-g) facing upward (FIG. 3), that is, a pattern in the antigravity direction (curved portion). It does not matter whether the direction is such that the apex of the curved portion is directed downward (FIG. 4), that is, the pattern in the direction of gravity (the curved portion is brought into contact with the upper side of the fiber toe).
The effect of the present invention is exhibited even when the apex of the curved portion faces upward. When the apex of the curved portion is directed downward, the liquid application rate tends to increase, and the higher the fiber toe speed, the more remarkable the liquid application effect.

The curved portion may come into contact with the fiber toe while being tilted within a range that does not affect the effect of the present invention with respect to the tangent line of the apex (FIG. 3-g) of the curved portion. That is, the traveling direction of the fiber toe may be tilted (blurred) with respect to the tangent line of the curved portion within a range that does not affect the liquid application.
More specifically in FIGS. 2 and 3 (a pattern in which the curved portion faces upward), it is composed of a curved portion (FIG. 2-a) having a plurality of opened portions (FIG. 2-b), and a liquid is discharged from the opened portion. This is performed using the discharged liquid applying device (Fig. 2). The curved portion (FIG. 2-a) is composed of a curved surface having an arc shape in a cross-sectional view, and the holding angle adjusting portion (FIG. 3-α) has a predetermined holding angle (FIG. 3-α) along the curved surface. The fiber toe is adjusted and fixed in e), and the fiber toe is brought into surface contact with the perforated region (FIG. 2-c). At this time, by discharging the liquid from the opening (FIG. 2-b), the liquid can be permeated into the fiber toe.

The shape and forming method of the perforated portion (Fig. 2-b) are a punching plate shape by press punching, a wire winding by winding a wire with a hole, a mesh shape formed by weaving a wire, etc. Can be selected as appropriate. In particular, a wire rod wound by winding a wire with a hole is preferable.
The hole shape of the perforated portion (FIG. 2-b) is not particularly limited, and a circular, elliptical, semicircular, triangular, quadrangular, polygonal, linear slit, or the like can be appropriately selected, and there are a plurality of perforated portions. It is formed by the holes of.

As the material of the curved portion (Fig. 2-a), a material that can withstand corrosion and wear due to the oil emulsion may be appropriately selected, and an alumite-treated aluminum material and stainless steel material (SUS-304, SUS-316, etc.) are exemplified. be able to. The material constituting the curved portion may be treated so that the liquid film is uniformly formed on the surface of the curved portion by the discharged liquid. Further, in order to prevent the fibers from being taken into the opening region (FIG. 2-c) at the time of contact, friction reduction treatment such as satin finish may be performed.
The radius of curvature of the arc shape (FIG. 3-f) is preferably 30 to 300 mm, more preferably 50 to 200 mm, although it depends on the traveling speed of the fiber toe. If it is smaller than 30 mm, a sufficient contact time cannot be obtained even if the holding angle (FIG. 3-α) is increased. If it is larger than 300 mm, the area of the perforated region becomes too large with respect to the contact area of the fiber toe, so that the efficiency decreases and the running cost increases.

The opening ratio is preferably defined as a value obtained by dividing the total area of the opening portion by the area of the opening region and multiplying by 100, preferably 10% or less, more preferably 5% or less, still more preferably 3% or less. Most preferably, it is 1% or less. If it is larger than 10%, the discharge pressure cannot be secured and adhesion spots are likely to occur.
The lower limit of the opening ratio is preferably 0.01%, more preferably 0.03%, and even more preferably 0.05%. When the aperture ratio is smaller than 0.01%, it becomes difficult for the liquid to adhere uniformly.

Further, the liquid applying device (FIG. 2) has a curved shape that forms an arc shape in a cross-sectional view, so that the liquid tow can be brought into surface contact with the fiber toe to secure a contact time, and the fiber toe has a curved portion. By being pressed against the fiber at a predetermined holding angle, the fiber is spread thinly in the width direction, and at the same time, the liquid supplied from the opening easily penetrates into the fiber toe. The hugging angle when the fiber toe is brought into contact with the arcuate curved portion is greater than 20 ° and less than 180 °, preferably greater than 30 ° and less than 160 °, more preferably greater than 30 ° and less than 150 °. More preferably, it is larger than 50 ° and 150 ° or less, and most preferably, it is larger than 50 ° and smaller than 130 °. If it is smaller than 20 °, the fiber toe does not spread sufficiently in the width direction, the liquid cannot penetrate into the fiber toe, and the contact time is insufficient, so that a sufficient liquid adhesion rate cannot be obtained. When the temperature is 180 ° or more, the fibers are easily removed at the time of contact and single yarn breakage is likely to occur, and entanglement occurs when the fibers are dispersed in water.

Although the examples of FIGS. 2 and 3 have been described above, the same tendency can be said in FIG. 4, that is, in the pattern in which the curved portion is directed downward.
In addition, the flow velocity discharged from the opening is 0.2 m / sec or more, which is necessary for uniform penetration into the single yarn inside the fiber tow traveling at high speed. When the liquid discharge flow rate is less than 0.2 m / sec, it becomes difficult for the liquid (oil emulsion solution) to penetrate into the fiber tow where the single yarn is densely packed, and the dispersion of short fibers in water tends to be uneven. .. The preferred flow velocity range is 0.3 to 5.0 m / sec, more preferably 0.7 to 3.0 m / sec.
The contact time (seconds) when the fiber tow is brought into contact with the curved portion of the liquid applying device is 0.001 to 0.05 seconds, preferably 0.002 to 0.01 seconds. If it is shorter than 0.001 seconds, it is difficult to obtain a sufficient amount of oiling agent, and if it is longer than 0.05 seconds, the amount of adhesion becomes excessive and the liquid scatters greatly.

In the present invention, it is preferable to include a process of adjusting the amount of the liquid adhering to the fiber toe by partially dropping the liquid held by the fiber toe after applying the liquid. The means for adjusting is not particularly limited, but a nip roller that grips the fiber toe with a constant gripping pressure with a pair of rollers can be exemplified. By adjusting the pressure gripped by the nip roller, the adhesion rate of the liquid to the fiber tow can be controlled.

Next, another method of applying the liquid to the running fiber tow will be described.
The portion through which the fiber toe passes is composed of a flat surface portion, and a liquid applying device having a hole portion (liquid discharge hole) in the flat surface portion is used, and the fiber toe is run in the open hole region so as not to contact. While discharging the liquid from the opening, the liquid is applied to the fiber toe.

The above-mentioned flat surface portion comprises a plurality of the perforated portions (liquid discharge holes) (FIG. 5-aa) having in the perforated region, and a liquid applying device (FIG. 5) for discharging liquid from the perforated portions. Do using. This is done by passing the fiber toe through the upper and / or lower sides of the perforated region (region with liquid discharge hole FIG. 5-aa) without contact. At this time, by positively discharging the liquid from the opening (FIG. 5-aa), the liquid can be applied to the fiber toe without damaging the fibers. The shape and forming method of the perforated portion (Fig. 5-aa) are a punching plate shape by press punching, a wire winding by winding a wire with a hole, and a mesh shape formed by weaving a wire. Alternatively, a non-woven fabric or the like can be appropriately selected.

The hole shape of the hole is not particularly limited, and a circle, an ellipse, a semicircle, a triangle, a quadrangle, a polygon, a linear slit or the like can be appropriately selected, and the hole is formed by a plurality of holes. .. As the material of the perforated region (Fig. 5-aa), a material that can withstand corrosion and wear due to the oil emulsion may be appropriately selected, and anodized aluminum material and stainless steel material (SUS-304, SUS-316, etc.) are exemplified. can do.

The opening ratio is preferably defined as a value obtained by dividing the total area of the opening portion by the area of the opening region and multiplying by 100, preferably 10% or less, more preferably 5% or less, still more preferably 3% or less. Most preferably, it is 1% or less. If it is larger than 10%, the discharge pressure cannot be secured and adhesion spots are likely to occur. The lower limit of the opening ratio is preferably 0.01%, more preferably 0.03%, and even more preferably 0.05%. When the aperture ratio is smaller than 0.01%, it becomes difficult for the liquid to adhere uniformly.

Further, in the present invention, the liquid can be applied to the fiber toe without contacting the liquid application device (FIG. 5) with the fiber toe. Good quality fibers can be obtained with less fiber damage and thread breakage.
The opening region and the opening portion of the liquid applying device may be upward or downward. Either the upward (Fig. 6-ff) or downward (Fig. 6-gg) liquid application device may be installed, or the upward and downward liquid application devices may be used in combination, and the fiber toe may be placed on a flat surface from above and below. It may be installed so as to be sandwiched (Fig. 6).

When the liquid applying device is installed so as to be sandwiched between the upper and lower sides, the liquid can be applied more uniformly by discharging the liquid from both sides of the fiber toe.
The distance (h) between the perforated portion and the traveling fiber toe is preferably in the range of 5 to 200 mm, more preferably 10 to 100 mm. If the distance between the perforated portion and the fiber toe is closer than 5 mm, workability deteriorates. If the distance is more than 200 mm, it becomes difficult for the discharged liquid to be applied to the fiber toe, and the liquid adhesion efficiency deteriorates.

In addition, the flow velocity discharged from the opening is 0.2 m / sec or more, which is necessary for uniform penetration into the single yarn inside the fiber tow traveling at high speed. When the liquid discharge flow rate is less than 0.2 m / sec, it becomes difficult for the liquid (oil emulsion solution) to permeate into the fiber tow where the single yarn is densely packed, and the dispersion of the short fibers in water tends to be non-uniform. The preferred flow velocity range is 0.3 to 5.0 m / sec, more preferably 0.7 to 3.0 m / sec.
The transit time for the fiber tow to travel in the open region (FIG. 5-aa) of the liquid applying device is 0.001 to 0.05 seconds, preferably 0.002 to 0.01 seconds. If it is shorter than 0.001 seconds, it is difficult to obtain a sufficient amount of oiling agent, and if it is longer than 0.05 seconds, the amount of adhesion becomes excessive and the liquid scatters greatly.

The area of the flat surface portion can be appropriately selected depending on conditions such as the traveling speed of the fiber toe and the width of the fiber toe. The length of the fiber toe in the opening region (FIG. 5-aa) in the traveling direction (FIG. 5-bb) needs to be set so as to secure the above-mentioned transit time (seconds). A plurality of the above liquid applying devices may be installed in the traveling direction of the fiber toe. The transit time in that case is the time obtained by adding the transit times of the respective liquid applying devices.
The width of the perforated region (Fig. 5-cc) needs to be wider than the width of the fiber toe (Fig. 5-ee). If the perforated region is narrower than the width of the fiber toe, liquid adhesion spots are likely to occur in the width direction of the fiber toe, which is not preferable.

In the present invention, it is preferable to include a process of adjusting the amount of the liquid adhering to the fiber toe by partially dropping the liquid held by the fiber toe after applying the liquid. The means for adjusting is not particularly limited, but a nip roller that grips the fiber toe with a constant gripping pressure with a pair of rollers can be exemplified. By adjusting the pressure gripped by the nip roller, the adhesion rate of the liquid to the fiber tow can be controlled.

It is preferable that the short fiber moisture content and the oil agent adhesion ratio are high. The short fiber moisture content is preferably 3 to 40% based on the short fiber mass, and more preferably 5 to 35%. The oil agent adhesion rate is preferably 0.05 to 1.0%, more preferably 0.1 to 0.8%, based on the fiber mass. Within this range, a functional liquid such as an oil can be permeated into the fiber tow.

When the short fibers are used for papermaking, it is preferable to pack the fibers after applying the water or oil emulsion as they are without drying. By doing so, it is possible to prevent the fibers from scattering after cutting, and it is possible to reduce the bulk at the time of packing. In addition, it promotes the penetration of water between fibers during papermaking and improves the dispersibility in water.

In general, examples of the method of applying the liquid to the fiber tow include a method of immersing the fiber tow in a liquid bath, a method of applying the fiber tow with an oiling roller, a method of applying the liquid with a shower or a spray, and the like. The method of immersing the fiber tow in a liquid bath is difficult to apply because the liquid scatters remarkably under the condition that the fiber tow runs at high speed.

In the method of picking up the liquid on the surface of the rotating roller from the liquid bath installed under the roller like the oiling roller and then applying it by contacting the fibers, the amount of liquid film formed on the roller surface is limited. Will be done. In particular, when the fiber tow is thick and the traveling speed is high, sufficient liquid cannot be applied. In addition, in the method of applying by spraying or showering, when the running speed of the fiber toe is high, the amount of liquid applied is limited, and the liquid adheres only to the surface layer of the fiber toe, so that the fiber toe is applied to the nip roller. An additional step such as permeating the liquid on the surface layer into the inside of the fiber toe is required by means such as gripping with. Further, when a liquid is sprayed by a spray, there are problems that a highly viscous liquid cannot be applied and that the spray holes are blocked when the use time is long.

Since the liquid applying method in the method for producing short fibers of the present invention can sufficiently apply liquid even when the fiber tow runs at high speed, the above-mentioned problems of the general liquid applying method can be solved. , It becomes possible to obtain short fibers having good dispersibility in water in the papermaking process.

The method for producing non-crimped short fibers of the present invention is a production method in which spinning, liquid application, and cutting are carried out in a continuous process. Short fibers can be obtained by unstretching or stretching between spinning and cutting, depending on the purpose.
When stretched (see FIG. 7), it is preferable in terms of physical properties and is useful as a main fiber, and when it is not stretched, it is useful as an unstretched binder fiber. It is also possible to produce a wet nonwoven fabric by using the main fiber of the present invention and the unstretched binder.

In the present invention, one or a plurality of undrawn multifilaments after spinning are continuously drawn without being collected, and a functional agent such as an oil agent is continuously applied as necessary. This is a method for producing short fibers, which is carried out by a process of continuously cutting with a high-speed cutter. In such a process, it is necessary to uniformly apply the oil emulsion to the fiber tow that runs at high speed and has a high fineness. However, the above liquid application device (FIGS. 2 and 5) is used. It becomes possible.

Normally, when producing short fibers, they are stored in tow cans, etc., or the production speed is reduced in a crimping process, and then a low-speed cutting process is performed. Often offered. By continuously processing according to the present invention, it is possible to shorten the process, and single yarn breakage due to scratches on the yarn guides in the guides and rollers in the middle, and poor convergence in the single yarn or sub tow unit. It is possible to reduce the generation of overlong fibers (fiber length is longer than the set value) due to the generation.

In the conventional manufacturing method, the fiber tow may be bent (gearly) when the fiber toe is collected, or even if the fiber tow is not bent, single yarn sabbing or loops may occur (ejector). In addition, when collecting cans, fiber tow (raw yarn) may be entangled, twitched, or single yarn disintegration (sabake) may occur. In the continuous manufacturing method according to the present invention, such defects can be reduced, and the obtained short fibers have a uniform single yarn length.

The short fiber obtained by the production method of the present invention is a short fiber in which a liquid such as an oil emulsion is uniformly applied to the fiber, and a functional component is uniformly applied to the fiber, and the non-crimped short fiber. In the case of, the short fiber has excellent dispersibility in water and is particularly suitable for papermaking.
In the case of crimped short fibers, the functional component is uniformly applied to the fibers to reduce the spots, and the quality is excellent. The production method of the present invention makes it possible to efficiently produce such short fibers.
These short fibers can be suitably used for various living materials and industrial materials by processing them into wet non-woven fabrics, dry non-woven fabrics and the like.

Hereinafter, another stretching process of the present invention will be described.
In the method for producing unrolled short fibers of the present invention, a fiber toe in which one or a plurality of undrawn multifilaments after spinning is converged is continuously stretched without collecting cans, and at the time of stretching. After the surface temperature of at least one of the rollers is 120 ° C. or less and the total stretching ratio is 1.5 to 5.5 times, overfeeding is performed, and at least one of the rollers at the time of overfeeding is performed. The surface temperature of the fiber is 140 to 240 ° C., and the total draft ratio is 0.88 to 0.98, and the stretched tow can be continuously cut to a length of 1 to 35 mm.

More specifically, one or more undrawn multifilaments are converged to form a fiber tow, and in the subsequent drawing process, the surface temperature of the drawing roller is 120 ° C. or lower, preferably 100 ° C. or lower. be able to. The lower limit of the stretching roller is preferably room temperature or higher (15 ° C. or higher), more preferably 30 ° C. or higher, and even more preferably 50 ° C. or higher. Then, overfeed can be continuously performed. When the surface temperature of the drawing roller is higher than 120 ° C., the fibers stick to each other or the fibers are blown during drawing. On the other hand, when the stretching temperature is low, sufficient magnification and uniform stretching may not be possible.

Stretching can be performed between a plurality of heating rollers at different speeds. It can be wound around a pair of rollers for 2 to 10 turns and stretched in any range of 2 to 10 steps between a plurality of Nelson type rollers at varying speeds.
The draw ratio of the stretching process is preferably greater than 1 time and less than 5.5 times between each roll pair, and the total draw ratio is preferably 1.5 to 5.5 times.
In the drawing process, it is preferable that the fiber tow formed by converging one or a plurality of undrawn multifilaments after spinning is continuously supplied to the drawing process without collecting cans.

Further, after stretching, overfeeding can be performed, and the roller surface temperature thereof is 140 ° C. or higher and 240 ° C. or lower, preferably 160 ° C. or higher and 220 ° C. or lower. Under such conditions of the roller surface temperature, it is possible to appropriately suppress the heat shrinkage rate of the finally obtained fiber. However, if this temperature is too high, the fibers tend to stick to each other, and especially when used for papermaking, the dispersibility in water tends to be insufficient.

Similar to stretching, overfeeding can be done by winding a pair of rollers for 2-10 turns. Further, it is necessary to overfeed between the rollers at the same time as the heat treatment at this time. By overfeeding, the molecular orientation can be relaxed, the thermal shrinkage of the fiber can be suppressed, and the initial elastic modulus of the fiber can be reduced. Overfeeding can be performed by setting the speed of the Nelson type roller on the upstream side to be higher than the speed of the roller on the downstream side. That is, assuming that the peripheral speed of the roller pair on the upstream side (spinning side) is V1 m / min and the peripheral speed of the roller pair on the downstream side is V2 m / min, V1 is set to be larger than V2. At this time, if V2 / V1 is defined as a "draft ratio", overfeed can be rephrased as making the draft ratio smaller than 1.00. Here, the overfeed may be performed in one step or in multiple steps, and the product of the draft ratios of each step is defined as the total draft ratio. The total draft ratio is 0.88 to 0.98, preferably 0.90 to 0.96. If the total draft ratio is larger than 0.98, the heat shrinkage rate and elastic modulus become high, and satisfactory paper physical characteristics cannot be obtained at the time of papermaking. If the total draft ratio is less than 0.88, slack occurs between the rollers, and the fibers are wound on the upstream roller, and the slack fibers are introduced into the cutter process, resulting in the generation of excessive fibers. Is a problem.

The fiber tow after stretching and overfeeding is preferably cooled before being cut. If the fiber tow is cut while the temperature is high, undispersed fibers are generated when the fibers are dispersed in water by fusing the fiber ends or crimping the fiber side surfaces. The means for cooling is not particularly limited, but means such as applying water or an aqueous emulsion to the fiber tow wound on a roller having a surface temperature of 100 ° C. or less, and securing a distance for air cooling before introducing into the cutter. Can be considered.

Then, in the method for producing non-crimped short fibers of the present invention, the fiber tow subjected to such a drawing treatment is continuously cut (see FIG. 7). Normally, when producing short fibers, they are stored in tow cans, etc., or the production speed is reduced in a crimping process, and then a low-speed cutting process is performed. Often offered. However, the method for producing non-crimped short fibers of the present invention is characterized in that extra steps such as can collection and crimping are eliminated and continuous processing is performed.
Further, in the method for producing non-crimped short fibers of the present invention, entanglement of the obtained short fibers in water is prevented. Further, the continuous process has become easy because the crimper process for crimping is omitted.

The outline of the manufacturing method of the wet non-woven fabric will be described.
A wet non-woven fabric (synthetic fiber paper) made of synthetic fibers can be obtained by mixing and thermocompression-bonding the unstretched unrolled short fibers and the stretched unrolled short fibers of the present invention.
In the composition of the wet non-woven fabric of the present invention, stretched non-curly short fibers are used as the main fibers, and unstretched unrolled short fibers are applied as the binder fibers. The ratio (mass%) of the main fiber to the binder fiber is 30/70 to 80/20. If it deviates from each of these fiber ratios, the physical properties (strength, adhesiveness) of the non-woven fabric will decrease.

Unstretched unrolled short fibers and stretched unrolled short fibers are dispersed in water at a mixing ratio that can achieve the desired physical properties such as strong elongation and air permeability to obtain a dispersion liquid (slurry) before papermaking. If necessary, natural short fibers (wood pulp, abaca, sisal hemp, kenaf, etc.) and synthetic fibers (vinylon short fibers, acrylic fibers, polyolefin fibers such as polyethylene and polypropylene) other than the short fibers of the present invention are used. Fibers, core-sheath composite short fibers such as polyester / copolymer polyester and polypropylene / modified polyolefin, etc.) Fibers such as inorganic fibers (glass fibers, etc.), additives, functional materials, etc. are added to the aqueous dispersion according to the purpose. Mixed abstracts may be used.

The industrial continuous papermaking method is to use a known short net paper machine, long net paper machine, circular knitting paper machine, or a combination thereof to make a dispersion liquid on a paper making net, and to obtain a short fiber wet web with a Yankee dryer. Alternatively, it is heated and dried at 80 to 160 ° C. with a device such as a hot air type perforated cylinder dryer, and at the same time, temporary melt bonding is performed. Further, in order to obtain sufficient strength of the non-woven fabric, at least a part between the fibers is thermocompression bonded by performing thermocompression bonding with a calendar roller having a flat surface or an embossing roller having an uneven surface. The temperature and pressure of the thermal pressure may be selected according to the desired physical properties, but in general, a temperature of 180 to 250 ° C. is selected.
A small batch-type papermaking machine is sufficient to obtain test pieces. A square sheet machine manufactured by Kumagai Riki Kogyo Co., Ltd. is filled with an aqueous dispersion, mixed, stirred, and dehydrated to create a wet web. The web may be heated and dried with a hot roller, a hot plate, or a hot air dryer, and then the same thermal pressure processing as described above may be performed.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the invention is not limited by the present description. Each item in the examples was measured by the following method.

(1) Intrinsic viscosity ([η])
The polymer was weighed in a certain amount, dissolved in o-chlorophenol at 35 ° C. at a concentration of 0.012 g / ml, and then determined according to a conventional method.

(2) Fineness (single yarn fineness)
Unrolled short fibers cut to 50 mm by changing the number of blades of the high-speed cutter were sampled and measured by the method described in JIS L 1015: 2005 8.5.1 A method.

(3) Total fineness The total fineness was calculated from the following formula.
Total fineness (dtex) = {Discharge amount per weight (g / min) x number of spinning weights (weight) x 10000} / {spinning speed (m / min) x total draw ratio (times)}

(4) Birefringence index (Δn)
A commercially available polarizing microscope was used to obtain a retardation from the Berek compensator method while the sample was immersed in α-bromnaphthalene using a sodium lamp as a light source.

(5) Moisture content (short fiber moisture content, moisture content after cutting)
Approximately 100 g of undrawn yarn immediately after spinning, yarn collected in the middle of the process, or cut cotton is dried in a hot air circulation type dryer at 120 ° C. until it is completely dried. It was calculated by the following formula from the mass W0 of the sample before drying and the mass W1 of the sample after drying.
Moisture content (%) = [(W0-W1) / W1] x 100

(6) Oil Adhesion Rate It is shown as mass% as a calculated value obtained by multiplying the oil agent water-based emulsion concentration by the water content of (5) above.
Adhesion rate = oil emulsion concentration (%) x water content (%) / 100

(7) Dispersibility in water Put 500 mL of tap water in a 1000 mL graduated cylinder, and put 0.1 g of short fibers in it. When the fibers reach the bottom of the graduated cylinder, cover the opening of the graduated cylinder, hold the top and bottom with both hands, invert the graduated cylinder once to disperse the fibers, and determine the quality of dispersibility in water according to the following criteria. To judge.
◯: There is no undispersed fiber bundle, and each single fiber is spread cleanly in water. Δ: There is almost no undispersed fiber bundle. Some entanglement between single fibers is observed, but acceptable range ×: There are several or more undispersed fiber bundles, and there are many entanglements between single fibers.

(8) Overlong fiber Place 150 g of short fiber on a black velvet plate, take a small amount of cotton, and spread it with tweezers, one fiber longer than the set fiber length (shorter in some cases; ± 2 mm or more), or one by one. The fiber length was measured by sampling in a group (bundle).

(9) Yield stress (σy) of undrawn yarn
The unrolled short fibers cut to 50 mm by changing the number of blades of the high-speed cutter are sampled, and the load elongation curve (Stress-Strain Curve) of the undrawn yarn of the single fiber is measured using a FAVIMAT + machine manufactured by TEXTECHNO, and the neck. The maximum strength until the start of stretching was defined as the yield stress (unit: cN / dtex).

(10) Tear length (paper strength)
The strength of the paper using the unstretched fiber was measured as the tensile strength according to JIS P8113, and the tear length thereof was determined.

(11) Melting point (Tm), glass transition point (Tg)
The temperature was measured at a heating rate of 20 ° C./min using a thermal analyst 2200 manufactured by TA Instruments Japan Co., Ltd.

(12) Strength / Elongation The number of blades of the high-speed cutter was changed, and unrolled short fibers cut to 50 mm were sampled and measured by the method described in JIS L 1015: 2005 8.7.1 method.

(13) Stress during 10% elongation Change the number of blades of the high-speed cutter to sample unrolled short fibers cut to 50 mm, and use a FAVIMAT + machine manufactured by TEXTECHNO to stretch the load-stretch curve (Stress) of undrawn yarn of single fibers. (Strine Curve) was measured, and the strength at 10% elongation was read and used as the stress at 10% elongation (unit: cN / dtex).

(14) 180 ° C. Dry Heat Shrinkage Heat treatment when unrolled short fibers cut to 50 mm by changing the number of blades of a high-speed cutter are sampled and left in a static dryer at 180 ° C. for 20 minutes without tension. The rate of change in fiber length before and after was defined as the dry heat shrinkage rate. That is, it is determined as (L1-L0) / L0 × 100% (L0: fiber length before heat treatment, L1: fiber length after heat treatment).

[Example 1]
A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 is dried, melted at 300 ° C., discharged at 492 g / min through a spinneret having 3000 holes, and picked up at a speed of 1230 m / min. An undrawn multifilament (subtow) having a fineness of 1.3 dtex and Δn 0.0150 was used. Immediately after the spinneret was discharged, a hydrophilic oil was applied by an oiling roller. The hydrophilic oil used was a poly having an average molecular weight of about 12,000, consisting of 80 mol% of terephthalic acid, 20 mol% of isophthalic acid, 70% by mass of polyethylene glycol having an average molecular weight of 3000 (copolymerization mass standard), and a component of ethylene glycol. The aqueous dispersion of the ether-polyester copolymer was used as an emulsion and adjusted to a concentration of 21% by mass (hereinafter, also referred to as "polyethylene-polyester copolymer aqueous solution").

Then, the obtained unstretched multifilament (sub-tow) was bundled by 12 weights without winding to obtain a fiber toe of 48,000 dtex. Subsequently, a high-speed cutter was used to cut the undrawn short fibers of 5 mm at the process speeds shown in the table without crimping. The fiber toe tension before the cutter was 0.1 cN / dtex (28.6% of σy). The moisture content of the undrawn short fibers after cutting was 15% by mass.
The high-speed cutter used here was such that the cutting side of the cutter blades faced upward, and each cutter blade was arranged radially. Then, a fiber toe composed of undrawn multifilaments is wound around a rotating rotor arranged further above the cutting side of the cutter blade, and the fiber toe is gradually pushed off by an inclined ring installed further above to cut the fiber toe. It was cut to shorten the fiber. In addition, the distance between the blades was constant from the cut surface of the cutter blade to the back surface (cut fiber discharge side), the fiber discharge resistance did not increase even during cutting, and the blade did not break.
The obtained undrawn short fibers were made into a mixed paper with unrolled drawn short fibers. That is, first, using a square sheet machine manufactured by Kumagai Riki Kogyo Co., Ltd., 40% of the above-mentioned undrawn short fibers of the present invention are stretch-heat-treated with a fineness of 1.7 dtex and a fiber length of 5 mm without crimping. 60% of the drawn short fibers of the above were mixed well in water and dispersed to obtain a sheet having a size of about 25 cm × about 25 cm and a texture of about 50 g / m ² . Furthermore, the sheet is sandwiched between filter papers, and the surface temperature of the drum is set to 140 ° C., the contact time with the drum is set to 2 minutes, and the drum is dried using a KRK high-temperature rotary dryer manufactured by Kumagai Riki Kogyo Co., Ltd. And adhesive heat treatment was performed. The paper strength (tear length) of this heat-treated sheet was measured according to JIS P8113 to obtain a mixed paper containing the undrawn short fibers of the present invention.

[Comparative Example 1]
Similar to Example 1, a polyethylene terephthalate (PET) tip having an intrinsic viscosity of 0.64 is dried, melted at 300 ° C., and discharged at 492 g / min through a spinneret having 3000 holes, at a speed of 1230 m / min. An undrawn multifilament (subtow) having a single fiber fineness of 1.3 dtex and Δn 0.0160 was obtained. However, in order to temporarily collect the cans thereafter, as a spinning oil agent, a mixed aqueous emulsion of 90% by mass of lauryl phosphate potassium salt and 10% by mass of terminal alkyl-sealed polyethylene glucol was adjusted to 21% by mass with an oiling roller. .. By the way, when the spinning oil used in Example 1 was used, the convergence in the next can collecting step was too low, and poor convergence occurred in units of single yarn or subtow, resulting in the final non-crimped short fiber. Even when it was used, it contained a large amount of excess fibers.

Twelve weights of sub-tows made of fibers to which a spinning oil was applied were bundled, and a total of 48,000 dtex of unstretched sub-tows was collected in a toe can. Further, 14 cans of this were combined to obtain a fiber tow of 672,000 dtex, and after washing with water, the aqueous solution of the polyether / polyester copolymer used as the spinning oil in Example 1 was dip in this step to obtain 100 mm. It was subjected to a test on a nip roller, squeezed, and applied as an emulsion at 22% by mass. Further, it was subjected to an EC cutter (drum type rotary cutter) and cut to a fiber length of 5 mm. The amount of emulsion adhered after cutting was 15% by mass.
Table 1 also shows the process conditions and the physical characteristics of the obtained undrawn short fibers and the like.

[Example 2, Comparative Example 2]
The unstretched short was the same as in Example 1 except that the spinning speed of 1230 m / min in Example 1 was changed to the speed shown in Table 1 and the subsequent process speed was changed to the speed shown in Table 1 accordingly. Fiber and mixed paper were obtained. However, in Comparative Example 2 in which the spinning speed was 300 m / min, it adhered to the dryer in the drying step at the time of papermaking, and mixed papermaking could not be obtained. Table 1 also shows the process conditions and the physical characteristics of the obtained undrawn short fibers and the like.

[Example 3]
The process speed of Example 1 was lowered, and the toe tension before the cutter was lowered to obtain Example 3. Table 1 also shows the process conditions and the physical characteristics of the obtained undrawn short fibers and the like.
When the process speed was further reduced to lower the toe tension before the cutter, a large amount of overlong fibers of 15 to 30 mm were generated, and when the undrawn short fibers were made into paper, it became a clear defect. Further, when the process speed was increased to increase the toe tension before the cutter and the tension was equal to or higher than the yield stress of the undrawn yarn, neck stretching occurred and the fiber had a large variation in birefringence. Further, when the undrawn short fibers were made into paper, only paper having low paper strength was obtained.

[Example 4]
Similar to Example 1, a polyethylene terephthalate (PET) tip having an intrinsic viscosity of 0.64 was used, but a spinneret whose number of holes was changed from 3000 to 1305 in Example 1 was used to further determine the fineness of the obtained short fibers. In order to match Example 1, the conditions were changed to discharge at 429 g / min and pick up at a speed of 2530 m / min. The fineness of the obtained single fiber was 1.3 dtex, and an undrawn multifilament (subtow) of Δn0.036 was obtained. As the spinning oil agent, an aqueous dispersion of a polyether / polyester copolymer having an average molecular weight of about 12000 used in Example 1 was used, and 21% by mass was added.
Then, the obtained unstretched multifilament (sub tow) was bundled by 12 weights to obtain a fiber tow of 20,000 dtex without winding up. Subsequently, the high-speed cutter used in Example 1 was used to cut into 5 mm undrawn short fibers. The moisture content of the undrawn short fibers after cutting was 15% by mass.
The obtained unstretched short fibers were made into a mixed paper with unrolled short fibers in the same manner as in Example 1. The process conditions and the physical characteristics of the obtained undrawn short fibers and the like are shown in Table 1.

[Example 5]
Polyethylene naphthalate (PEN) was used instead of the polyethylene terephthalate of Example 1. That is, a polyethylene naphthalate tip having an intrinsic viscosity of 0.51 is dried and melted at 310 ° C., discharged at 310 g / min through a spinneret having 1305 holes, and picked up at a speed of 1000 m / min to achieve the fineness of a single fiber. An unstretched multifilament (subtow) having an intrinsic value of 1.1 dtex and Δn0.06 was obtained. As the spinning oil agent, an aqueous dispersion of a polyether / polyester copolymer having an average molecular weight of about 12000 used in Example 1 was used, and 21% by mass was added.
Then, the obtained unstretched multifilament (sub tow) was bundled by 12 weights without winding to obtain a fiber tow of 37,000 dtex. Subsequently, the high-speed cutter used in Example 1 was used to cut into 5 mm undrawn short fibers. The moisture content of the undrawn short fibers after cutting was 15% by mass. The obtained unstretched short fibers were made into a mixed paper with unrolled short fibers in the same manner as in Example 1. However, the drum surface temperature of the rotary dryer was set to 160 ° C. The process conditions and the physical characteristics of the obtained undrawn short fibers and the like are shown in Table 1.

[Example 6]
A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 was prepared.
Separately, an acid component of 80 mol% terephthalic acid and 20 mol% isophthalic acid, 70% by mass of polyethylene glycol having an average molecular weight of 3000 (copolymerization mass standard), and a polyether / polyester co-weight having an average molecular weight of about 12000 consisting of an ethylene glycol component. A combined aqueous dispersion (emulsion concentration 1% by mass) was prepared as an emulsion oil (spun oil).

The above PET tip is dried and melted at 300 ° C., and is discharged at 510 g / min through a spinneret having 1305 holes. The emulsion oil is not applied to the unstretched multifilament immediately after the mouthpiece is discharged by an oiling roller. After the yarn was applied so as to have a moisture content of 21%, the yarn was taken up with a Nelson type roller at a temperature of 55 ° C. at a speed of 750 m / min to obtain an undrawn multifilament (subtow).

This sub-tow is bundled by 12 weights to make about 82,000 dtex, and then wound around a Nelson type roller pair 2 with a surface temperature of 55 ° C. and a peripheral speed of 788 m / min for 6 turns to preheat, and then 100 ° C., a peripheral speed of 2, Nelson type rollers vs. 3 at 457 m / min were made to make 6 turns. Next, the Nelson type roller pair 4 having a surface temperature of 220 ° C. and a peripheral speed of 2,457 m / min was made to make 6 turns, and the Nelson type roller pair 5 having a surface temperature of 220 ° C. and a peripheral speed of 2.457 m / min was made to make 6 turns, and then. A Nelson-type roller pair having a surface temperature of 50 ° C. and a peripheral speed of 2,457 m / min was subjected to 6 turns to obtain a fiber toe composed of stretched fibers (total draw ratio 3.28 times).

The stretched fiber tow was continuously cut to a length of 5 mm with a tension before the cutter of 0.1 cN / dtex. Water was sprayed from above and below the fiber tow on the drawn fiber tow before the cutter to set the moisture content after cutting to 5% by mass. The process speed at this time was 2,482 m / min. In addition, the high-speed cutter used here was such that the cutting side of the cutter blades faced upward, and each cutter blade was arranged radially. Then, the fiber toe composed of the drawn multifilament is wound around the rotating rotor arranged further above the cutting side of the cutter blade, and the fiber toe is gradually pushed off by the inclined ring installed further above to cut the fiber toe. It was to shorten the fiber. In addition, the distance between the blades was constant from the cut surface of the cutter blade to the back surface (cut fiber discharge side), the fiber discharge resistance did not increase even during cutting, and the blade did not break.

The obtained non-crimped short fibers were excellent in water dispersibility and were particularly suitable for papermaking. Table 2 shows the process conditions and the evaluation results of the obtained non-crimped short fibers.
For evaluation of the wet non-woven fabric, a mixed paper made of the unrolled short fibers obtained in Example 6 and the unstretched short fibers obtained in Example 1 and Comparative Example 2 was prepared.
That is, first, using a square sheet machine manufactured by Kumagai Riki Kogyo Co., Ltd., 60% by mass of the unrolled short fibers and the unrolled short fibers obtained in Example 1 or Comparative Example 2 were used. 40% by mass of the fiber was well stirred and mixed in water and dispersed to obtain a sheet having a size of about 25 cm × about 25 cm and a basis weight of about 50 g / m ² . Furthermore, the sheet is sandwiched between filter papers, and the surface temperature of the drum is set to 140 ° C., the contact time with the drum is set to 2 minutes, and the drum is dried using a KRK high-temperature rotary dryer manufactured by Kumagai Riki Kogyo Co., Ltd. And adhesive heat treatment was performed. The tensile strength of this heat-treated sheet was measured according to JIS P8113 to obtain a mixed paper containing the short fibers of the present invention.

The paper strength of the mixed paper with the undrawn short fibers obtained in Example 1 was 0.45 km.
The mixed paper with the undrawn short fibers obtained in Comparative Example 2 adhered to the dryer in the drying step at the time of paper making, and the mixed paper could not be obtained.
The mixed sandpaper with Example 1 was able to obtain sufficient adhesiveness as a wet non-woven fabric.

In the same manner as above, however, when the concentration of the aqueous dispersion of the polyether-polyester copolymer as the spinning oil was reduced from 1% to 0.5%, the amount of the oil applied was reduced and the fibers were applied. Although the adhesion of the oil agent to the surface became uneven and the water dispersibility at the time of papermaking tended to decrease, it was barely possible to make paper.

On the contrary, when the concentration of the aqueous dispersion was increased from 1% to 5%, the adhesiveness to the metal roller tended to appear, and the single yarn breakage was likely to occur, but it was barely crimp-free and short. I was able to get the fiber.

[Example 7]
An aqueous dispersion (emulsion concentration 1% by mass) of a polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 and a polyether / polyester copolymer having an average molecular weight of about 12000, which is the same as in Example 6, is used as an emulsion oil (spun oil). ).

The above PET tip is dried and melted at 300 ° C., and is discharged at 330 g / min through a spinning spout having 2504 holes, and a spinning oil is not applied to the unstretched multifilament immediately after the spout is discharged by an oiling roller. After the yarn was applied so as to have a moisture content of 21%, the yarn was taken up with a Nelson-type roller at a temperature of 55 ° C. at a speed of 635 m / min to obtain an undrawn multifilament (subtow).

This sub-tow is bundled by 12 weights to make about 62,000 dtex, and then wound around a Nelson type roller pair 2 with a surface temperature of 55 ° C. and a peripheral speed of 667 m / min for 6 turns to preheat, and then 100 ° C., a peripheral speed of 2, Nelson type rollers vs. 3 at 234 m / min were made to make 6 turns. Next, the Nelson type roller pair 4 having a surface temperature of 220 ° C. and a peripheral speed of 2,234 m / min was made to make 6 turns, and the Nelson type roller pair 5 having a surface temperature of 220 ° C. and a peripheral speed of 2.234 m / min was made to make 6 turns. A Nelson-type roller pair having a surface temperature of 50 ° C. and a peripheral speed of 2.234 m / min was subjected to 6 turns to obtain a fiber toe composed of stretched fibers (total draw ratio 3.52 times).

The stretched fiber tow was cut with the same high-speed cutter as in Example 1 so that the tension before the cutter was 0.1 cN / dtex and the length was continuously 5 mm. Water was sprayed from above and below the fiber tow on the drawn fiber tow before the cutter, and the moisture content after cutting was set to 3% by mass. The process speed at this time was 2,256 m / min. Even during cutting, there was no increase in fiber discharge resistance and no blade breakage occurred.

The obtained non-crimped short fibers were excellent in water dispersibility and were particularly suitable for papermaking. Table 2 also shows the process conditions and the evaluation results of the obtained non-crimped short fibers.

[Comparative Example 3]
As an emulsion (spinning) oil agent, a mixed aqueous emulsion (emulsion concentration 1% by mass) of 90% by mass of lauryl phosphate potassium salt and 10% by mass of terminal alkyl-sealed polyethylene glucol was prepared.

Non-crimped short fibers were obtained in the same manner as in Example 6 except that this emulsion oil was used. It was inferior in dispersibility in water and was unsuitable for papermaking. Table 2 also shows the process conditions and the evaluation results of the obtained non-crimped short fibers.

[Comparative Example 4]
Similar to Comparative Example 1, a mixed aqueous emulsion (emulsion concentration 1% by mass) containing 90% by mass of lauryl phosphate potassium salt and 10% by mass of terminal alkyl-sealed polyethylene glucol was prepared as an emulsion (spun) oil agent.

Further, as a finishing oil, an aqueous dispersion of the polyether / polyester copolymer having an average molecular weight of about 12000 used in Example 1 was prepared, but an emulsion oil having an emulsion concentration changed from 1% by mass to 1.5% by mass was prepared. did.

Non-curly short fibers were obtained in the same manner as in Example 6 except that the above spinning oil was used and the above finishing oil was added after drawing. The finishing oil (emulsion concentration: 1.5% by mass) was stretched and then sprayed from above and below the fiber tow so as to have a water content of 5% by mass.

Although the dispersibility in water was improved as compared with Comparative Example 3, it could not be said that it was suitable for papermaking. Table 2 also shows the process conditions and the evaluation results of the obtained non-crimped short fibers.

[Example 8]
A polyethylene terephthalate (PET) tip having an intrinsic viscosity of 0.64 was dried at 170 ° C. for 4 hours, melted at 287 ° C., and discharged at 700 g / min through a spun cap having a pore size of 0.28 mm and a number of holes of 1701. Unstretched multifilaments (subtows) were obtained by taking up at a speed of 634 m / min with a Nelson type roller pair 1. The four weights of the sub tow were converged to 44,164 dtex, and the sub toe was continuously wound around a Nelson type roller pair 2 at 50 ° C. and a peripheral speed of 641 m / min for 6 turns without collecting cans, and then the surface was preheated. The first stage was stretched by making 6 turns on a Nelson type roller pair 3 having a temperature of 88 ° C. and a peripheral speed of 1,923 m / min. Next, a Nelson-type roller pair 4 having a surface temperature of 120 ° C. and a peripheral speed of 2,500 m / min was subjected to 6 turns to perform the second-stage stretching, and then Nelson having a surface temperature of 220 ° C. and a peripheral speed of 2,500 m / min. Heat treatment was performed on the mold roller pair 5 for 6 turns, and then on the Nelson mold roller pair 6 with a surface temperature of 80 ° C. and a peripheral speed of 2,500 m / min for 6 turns to obtain a drawn fiber tow having a total fineness of 11,200 dtex. (Total draw ratio 3.94 times).

The obtained fiber toes are continuously formed in a curved portion a having an upward semi-arc-shaped radius of curvature (FIG. 3-f) of 61 mm, which is shown in FIGS. 2 and 3, and has a width of 100 mm (FIG. 2-d). A liquid applying device consisting of an opening region (FIG. 2-c) (stainless wire wound) having a plurality of openings (FIG. 2-b) having a length of 126 mm (liquid discharge area 126 cm ² ) and an opening ratio of 0.5%. With the composition of an acid component composed of 80 mol% of terephthalic acid and 20 mol% of isophthalic acid, and a diol component composed of 70% by mass of polyethylene glycol having an average molecular weight of 3,000 and 30% by mass of ethylene glycol. Emulsion oil, which is an aqueous dispersion of 12,000 polyether / polyester copolymer (emulsion concentration 2% by mass), is discharged from a liquid imparting device at a liquid discharge rate of 5.0 kg / min (liquid discharge flow rate 1.3 m / sec). The lower side of the fiber toe is brought into contact with the arc-shaped curved surface discharged in step 1 so as to have a holding angle of 75 degrees (contact length 80 mm), and after applying an oil agent, it is cut with a high-speed cutter (NMC-H290 manufactured by Oerlikon Neumag). It was cut to a length of 5 mm. The cutting speed of the fiber tow at this time was 2,500 m / min. The high-speed cutter used here was such that the cutting side of the cutter blades faced upward, and each cutter blade was arranged radially. Then, the fiber toe composed of the drawn multifilament is wound around the rotating rotor arranged further above the cutting side of the cutter blade, and the fiber toe is gradually pushed off by the inclined ring installed further above to cut the fiber toe. It was to shorten the fiber. In addition, the distance between the blades was constant from the cut surface of the cutter blade to the back surface (cut fiber discharge side), the fiber discharge resistance did not increase even during cutting, and the blade did not break.
Despite the high cutting speed, the dispersibility in water was good. Table 3 shows the conditions and the evaluation results of the obtained short fibers.

For evaluation of the wet non-woven fabric, a mixed paper made of the unrolled short fibers obtained in Example 8 and the unstretched short fibers obtained in Example 1 and Comparative Example 2 is used in the procedure described in Example 6. Made in.
The paper strength of the mixed paper with the undrawn short fibers obtained in Example 1 was 0.48 km.
The mixed paper with the undrawn short fibers obtained in Comparative Example 2 adhered to the dryer in the drying step at the time of paper making, and the mixed paper could not be obtained.
The mixed sandpaper with Example 1 was able to obtain sufficient adhesiveness as a wet non-woven fabric.

[Example 9]
Short fibers were obtained in the same manner as in Example 8 except that the holding angle of the liquid applying device was 150 degrees (contact length 160 mm, contact time 0.004 seconds). The dispersibility in water was good. Table 3 shows the conditions and the evaluation results of the obtained short fibers.

[Example 10]
Short fibers were obtained in the same manner as in Example 9 except that the liquid discharge area of the liquid applying device was changed from 126 cm ² (100 mm width × 126 mm length) to 290 cm ² (100 mm width × 290 mm length). The liquid discharge flow velocity at this time decreased to 0.6 m / min. Table 3 shows the conditions and the evaluation results of the obtained short fibers. Although both the water content of the short fibers and the adhesion rate of the oil agent were low, the dispersibility in water was good.

[Comparative Example 5]
The fibers were obtained in the same manner as in Example 8 except that the holding angle of the fiber toe was 10 °, the contact time was 0.0003 seconds, and the contact length was 11 mm. The short fiber moisture content and the oil agent adhesion rate (hereinafter, the short fiber moisture content and / or the oil agent adhesion rate may be referred to as the liquid addition rate) were low, and the dispersibility in water was insufficient. Table 3 shows the process conditions and the evaluation results of the obtained short fibers.

[Example 11]
Short fibers were obtained in the same manner as in Example 8 except that the holding angle of the fiber toe was 40 °, the contact time was 0.001 seconds, and the contact length was 43 mm. Although the hugging angle of the present invention was low, the dispersibility in water was good. Table 3 shows the conditions and the evaluation results of the obtained short fibers.

[Comparative Example 6]
The fibers were obtained in the same manner as in Example 8 except that the holding angle of the fiber toe was 180 °, the contact time was 0.005 seconds, and the contact length was 192 mm. Table 3 shows the process conditions and the evaluation results of the obtained short fibers. Many entanglements (defects) between single fibers were confirmed due to single thread breakage presumed to have occurred in the liquid application device.

[Example 12]
The liquid discharge area of the liquid feeder is changed from 126 cm ² (100 mm width x 126 mm length) to 290 cm ² (100 mm width x 290 mm length), and the liquid discharge rate from the liquid dispenser is 1.5 kg / min (liquid discharge flow velocity). It was the same as in Example 8 except that it was set to 0.2 m / sec), and short fibers were obtained. Although the liquid discharge flow rate was low, the dispersibility in water was within the permissible range. Table 3 shows the conditions and the evaluation results of the obtained short fibers.

[Comparative Example 7]
The same as in Example 12 except that the liquid discharge rate was 0.6 kg / min (liquid discharge flow velocity 0.07 m / sec). The liquid application rate was low, and the dispersibility in water was insufficient. Table 3 shows the conditions and the evaluation results of the obtained short fibers.

[Example 13]
A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 was dried at 170 ° C. for 4 hours, melted at 287 ° C., and discharged at 700 g / min through a spinneret having a pore size of 0.28 mm and a number of holes of 1701. After picking up the undrawn yarn at a speed of 1350 m / min with a Nelson type roller pair 1, the four weights of the sub tow are converged, and the sub tow is continuously brought to 50 ° C. and a peripheral speed of 1362 m / min without collecting cans. After preheating by winding around the mold roller pair 2 for 6 turns, the Nelson mold roller pair 3 having a surface temperature of 88 ° C. and a peripheral speed of 3,037 m / min was wound for 6 turns to perform the first-stage stretching. Next, a Nelson-type roller pair 4 having a surface temperature of 120 ° C. and a peripheral speed of 3,500 m / min was subjected to 6 turns to perform the second-stage stretching, and then Nelson having a surface temperature of 220 ° C. and a peripheral speed of 3,500 m / min. Heat treatment is performed by winding around the mold roller pair 5 for 6 turns, and then rolling the Nelson type roller pair 6 at a surface temperature of 80 ° C. and a peripheral speed of 3,500 m / min for 6 turns at a total draw ratio of 2.57 times. And heat treatment was carried out to obtain a drawn fiber tow having a total fineness of 8,000 dtex.

Using the liquid application device (liquid discharge area 290 cm ² ) used in Example 10 continuously, the obtained fiber tow was used, the holding angle of the oil agent application device was 150 degrees (contact length 160 mm), and the liquid discharge flow velocity was 1.3 m. The liquid discharge rate was set to 11.0 kg / min so as to be / sec, and the same oil emulsion as in claim 1 was applied, and then the liquid was cut with a high-speed cutter (NMC-H290 manufactured by Oerlikon Neumag) with a cut length of 5 mm. The cutting speed of the fiber tow at this time was 3,500 m / min. Despite the high cutting speed, the dispersibility in water was good. Table 4 shows the conditions and the evaluation results of the obtained short fibers.

[Example 14]
Nelson type rollers 1 to 6 are set to 1.01 times between each roller when the roller surface temperature is room temperature (20 to 40 ° C), the total draw ratio is 1.05 times, and the pre-cutter speed is 660 m. The conditions were the same as in Example 11 except that the temperature was changed to / minute. Both the water content of the short fibers and the adhesion rate of the oil agent were high, but the dispersibility in water was good. Table 4 shows the process conditions and the evaluation results of the obtained short fibers.

[Comparative Example 8]
Oiling was performed using the same fiber tow and emulsion oil as in Example 8 and using an oiling roller composed of a rubber roller having a diameter of 145 mm. The contact angle of the fiber toe with the oiling roller was set to 30 ° from the horizontal plane, and the holding angle was set to 100 °. The rotation direction of the rollers was the same as the traveling direction of the fiber toe (forward direction), and the roller rotation speed was set to 39 rotations / minute. Since the cutting speed was high, the liquid application rate was low and the dispersibility in water was insufficient. Table 4 shows the process conditions and the evaluation results of the obtained short fibers.

[Example 15]
In the curved portion a having a downward semicircular arc-shaped radius of curvature (FIG. 4-f) shown in FIGS. 2 and 4, the width is 100 mm (FIG. 2-d) and the length is 126 mm (liquid discharge area 126 cm ² ). A liquid applying device (hereinafter, a downward arc-shaped liquid applying device) composed of an opening region (Fig. 2-c) (stainless wire wound) having a plurality of openings (Fig. 2-b) having an opening rate of 0.5%. It was the same as in Example 8 except that it was changed to (may be called), and short fibers were obtained. Similar to Example 8, the dispersibility in water was good. However, the liquid application rate was higher than that of Example 8. Table 4 shows the conditions and the evaluation results of the obtained short fibers.

[Example 16]
Short fibers were obtained in the same manner as in Example 11 except that the liquid applying device was changed to a downward arc-shaped liquid applying device. Similar to Example 11, the dispersibility in water was good. However, the liquid application rate was higher than that of Example 11. Table 4 shows the conditions and the evaluation results of the obtained short fibers.

[Example 17]
The same as in Example 14 except that the liquid applying device was changed to a downward arc-shaped liquid applying device, and short fibers were obtained. Similar to Example 14, the dispersibility in water was good. However, the liquid application rate was higher than that of Example 14. Table 4 shows the conditions and the evaluation results of the obtained short fibers.

[Example 18]
The liquid application device was changed to a downward arc-shaped liquid application device, and the liquid discharge rate was changed from 5.0 kg / min to 11.0 kg / min (the liquid discharge flow velocity increased from 0.6 m / sec to 1.3 m / sec). Except for the above, the same as in Example 10 was used to obtain short fibers. The dispersibility in water was better than that of Example 10. The liquid application rate was higher than that of Example 10. Table 4 shows the conditions and the evaluation results of the obtained short fibers.

[Comparative Example 9]
Short fibers were obtained in the same manner as in Comparative Example 5 except that the liquid applying device was changed to a downward arc-shaped liquid applying device. Similar to Comparative Example 5, the liquid application rate was low and the dispersibility in water was insufficient. Table 4 shows the conditions and the evaluation results of the obtained short fibers.

[Comparative Example 10]
Short fibers were obtained in the same manner as in Comparative Example 6 except that the liquid applying device was changed to a downward arc-shaped liquid applying device. Similar to Comparative Example 6, a large number of entanglements (defects) between the single fibers were confirmed due to the single yarn breakage presumed to have occurred in the liquid applying device. Table 4 shows the conditions and the evaluation results of the obtained short fibers.

[Example 19]
A polyethylene terephthalate (PET) tip having an intrinsic viscosity of 0.64 was dried at 170 ° C. for 4 hours, melted at 287 ° C., and discharged at 700 g / min through a spun cap having a pore size of 0.28 mm and a number of holes of 1701. Unstretched multifilaments (subtows) were obtained by taking up at a speed of 634 m / min with a Nelson type roller pair 1. The four weights of the sub tow were converged to 44,164 dtex, and the sub toe was continuously wound around a Nelson type roller pair 2 at 50 ° C. and a peripheral speed of 641 m / min for 6 turns without collecting cans, and then the surface was preheated. The first stage was stretched by making 6 turns on a Nelson type roller pair 3 having a temperature of 88 ° C. and a peripheral speed of 1,923 m / min. Next, a Nelson-type roller pair 4 having a surface temperature of 120 ° C. and a peripheral speed of 2,500 m / min was subjected to 6 turns to perform the second-stage stretching, and then Nelson having a surface temperature of 220 ° C. and a peripheral speed of 2,500 m / min. Heat treatment was performed on the mold roller pair 5 for 6 turns, and then on the Nelson mold roller pair 6 with a surface temperature of 80 ° C. and a peripheral speed of 2,500 m / min for 6 turns to obtain a drawn fiber tow having a total fineness of 11,200 dtex. (Total draw ratio 3.94 times).

The obtained fiber toes were continuously subjected to a length of 200 mm (Fig. 5-bb) (passing time: 0.05 seconds) with respect to the traveling direction of the fiber toes in the perforated region (Fig. 5-aa) shown in FIG. ), Width 100 mm (Fig. 5-cc) (Liquid discharge area 200 cm ² ), and liquid application consisting of an open area (Fig. 5-aa) (triangular hole punching) having a plurality of openings with an aperture ratio of 0.5%. Using the device, as shown in FIG. 6, the traveling fiber tow was arranged so as to sandwich it up and down. The distance between the fiber toe and the opening was 20 mm. The average molecular weight obtained from the pores by the composition of an acid component composed of 80 mol% of terephthalic acid and 20 mol% of isophthalic acid and a diol component composed of 70% by mass of polyethylene glycol having an average molecular weight of 3,000 and 30% by mass of ethylene glycol. An emulsion oil, which is an aqueous dispersion of about 12,000 polyether-polyester copolymer (emulsion concentration 2% by mass), is discharged at a discharge rate of 16.0 kg / min (liquid discharge flow rate 1.3 m / sec). After applying an oil agent to the fiber tow, it was cut with a high-speed cutter (NMC-H290 manufactured by Oerlikon Neumag) to a cut length of 5 mm. At this time, the cutting speed of the fiber tow was 2,500 m / min, and the passing time of the liquid applying device was 0.005 seconds. The high-speed cutter used here was such that the cutting side of the cutter blades faced upward, and each cutter blade was arranged radially. Then, the fiber toe composed of the drawn multifilament is wound around the rotating rotor arranged further above the cutting side of the cutter blade, and the fiber toe is gradually pushed off by the inclined ring installed further above to cut the fiber toe. It was to shorten the fiber. In addition, the distance between the blades was constant from the cut surface of the cutter blade to the back surface (cut fiber discharge side), the fiber discharge resistance did not increase even during cutting, and the blade did not break.
Despite the high cutting speed, the dispersibility in water was good. Table 5 shows the conditions and the evaluation results of the obtained short fibers.

For the evaluation of the wet non-woven fabric, the mixed paper of the unrolled short fibers obtained in Example 19 and the unstretched short fibers obtained in Example 1 and Comparative Example 2 is used in the procedure described in Example 6. Made in.
The paper strength of the mixed paper with the undrawn short fibers obtained in Example 1 was 0.48 km.
The mixed paper with the undrawn short fibers obtained in Comparative Example 2 adhered to the dryer in the drying step at the time of paper making, and the mixed paper could not be obtained.
The mixed sandpaper with Example 1 was able to obtain sufficient adhesiveness as a wet non-woven fabric.

[Example 20]
Short fibers were obtained in the same manner as in Example 19 except that the liquid discharge rate was 4.0 kg / min (liquid discharge flow velocity 0.3 m / sec). Although the liquid discharge flow rate was low, the dispersibility in water was within the permissible range. Table 5 shows the conditions and the evaluation results of the obtained non-crimped short fibers.

[Example 21]
Except that the length of the perforated area in the traveling direction was 50 mm (liquid discharge area 50 cm ² , passing time 0.001 seconds) and the liquid discharge amount was 1.8 kg / min (liquid discharge flow velocity 0.6 m / sec). The same as in Example 19 was used to obtain short fibers. The dispersibility in water was good. Table 5 shows the conditions and the evaluation results of the obtained non-crimped short fibers.

[Comparative Example 11]
Except that the length of the perforated area in the traveling direction was 10 mm (liquid discharge area 10 cm ² , passing time 0.0002 seconds) and the liquid discharge amount was 0.8 kg / min (liquid discharge flow velocity 1.3 m / sec). The same as in Example 19 was used to obtain short fibers. Both the water content of the short fibers and the adhesion rate of the oil agent were low, and the dispersibility in water was poor. Table 5 shows the conditions and the evaluation results of the obtained non-crimped short fibers.

[Comparative Example 12]
Short fibers were obtained in the same manner as in Example 19 except that the liquid discharge rate was 0.8 kg / min (liquid discharge flow velocity 0.1 m / sec). Both the water content of the short fibers and the adhesion rate of the oil agent were low, and the dispersibility in water was poor. Table 5 shows the conditions and the evaluation results of the obtained non-crimped short fibers.

[Example 22]
A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 was dried at 170 ° C. for 4 hours, melted at 287 ° C., and discharged at 700 g / min through a spinneret having a pore size of 0.28 mm and a number of holes of 1701. After picking up the undrawn yarn at a speed of 1350 m / min with a Nelson type roller pair 1, the four weights of the sub tow are converged, and the sub tow is continuously brought to 50 ° C. and a peripheral speed of 1362 m / min without collecting cans. After preheating by winding around the mold roller pair 2 for 6 turns, the Nelson mold roller pair 3 having a surface temperature of 88 ° C. and a peripheral speed of 3,037 m / min was wound for 6 turns to perform the first-stage stretching. Next, a Nelson-type roller pair 4 having a surface temperature of 120 ° C. and a peripheral speed of 3,500 m / min was subjected to 6 turns to perform the second-stage stretching, and then Nelson having a surface temperature of 220 ° C. and a peripheral speed of 3,500 m / min. Heat treatment is performed by winding around the mold roller pair 5 for 6 turns, and then rolling the Nelson type roller pair 6 at a surface temperature of 80 ° C. and a peripheral speed of 3,500 m / min for 6 turns at a total draw ratio of 2.57 times. And heat treatment was carried out to obtain a drawn fiber tow having a total fineness of 40,400 dtex.

The obtained fiber tow was continuously used in the liquid application device of Example 19 (length 200 mm (passing time 0.003 seconds)) width 100 mm (liquid discharge area 200 cm ² ), opening ratio 0.5%. Short fibers were obtained in the same manner as in Example 19 except that the running toe speed was 3,500 m / min using the fiber toe to the opening distance of 20 mm). Despite the high cutting speed, the dispersibility in water was good. Table 5 shows the conditions and the evaluation results of the obtained short fibers.

[Example 23]
Nelson type rollers 1 to 6 are set to 1.01 times between each roller when the roller surface temperature is normal temperature (15 to 40 ° C), the total draw ratio is 1.05 times, and the pre-cutter speed is 660 m. The conditions were the same as in Example 19 except that the condition was changed to / minute. The number of seconds passed through the opening was 0.018 seconds, and the dispersibility in water was good. Table 5 shows the process conditions and the evaluation results of the obtained short fibers.

[Example 24]
In the liquid applying device shown in FIG. 5, the liquid was applied from only one side of the gg portion except for the ff portion in FIG. 6, and the liquid discharge amount was set to 8.0 kg / min (liquid discharge flow velocity 0.7 m / sec). Was the same as in Example 19 to obtain short fibers. The dispersibility in water was good. Table 5 shows the conditions and the evaluation results of the obtained non-crimped short fibers.

[Comparative Example 13]
Oiling was performed using the same fiber tow and emulsion oil as in Example 19 and using an oiling roller composed of a rubber roller having a diameter of 145 mm. The contact angle of the fiber toe with the oiling roller was set to 30 ° from the horizontal plane, and the holding angle was set to 100 °. The rotation direction of the rollers was the same as the traveling direction of the fiber toe (forward direction), and the roller rotation speed was set to 39 rotations / minute. Since the cutting speed was high, the liquid application rate was low and the dispersibility in water was insufficient. Table 5 shows the process conditions and the evaluation results of the obtained non-crimped short fibers.

[Example 25]
A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 is dried at 170 ° C. for 4 hours, melted at 300 ° C., and discharged at 450 g / min through a spinneret having 1305 holes. Emulsion oil was applied to the undrawn multifilament with an oiling roller so that the moisture content of the undrawn yarn was 21%, and then the undrawn multifilament was picked up with a Nelson type roller pair 1 at a speed of 635 m / min. Subtoe) was obtained.

12 weights of this sub-tow were converged to 85,000 dtex, and the sub-tow was continuously wound around a Nelson-type roller pair 2 having a surface temperature of 55 ° C. and a peripheral speed of 666 m / min for 6 turns without collecting cans, and then preheated. Nelson type rollers vs. 3 at 100 ° C. and a peripheral speed of 2,232 m / min were subjected to 6 turns. Next, the Nelson type roller pair 4 having a surface temperature of 220 ° C. and a peripheral speed of 2,188 m / min was made to make 6 turns, and the Nelson type roller pair 5 having a surface temperature of 220 ° C. and a peripheral speed of 2,100 m / min was made to make 6 turns, and then. A Nelson-type roller pair having a surface temperature of 80 ° C. and a peripheral speed of 2,100 m / min was subjected to 6 turns to obtain a fiber toe composed of stretched fibers (total draw ratio: 3.31 times).

The stretched fiber tow was continuously cut to a length of 5 mm with a tension before the cutter of 0.1 cN / dtex. With respect to the drawn fiber tow before the cutter, an acid component consisting of 80 mol% of terephthalic acid and 20 mol% of isophthalic acid, 70% by mass of polyethylene glycol having an average molecular weight of 3,000, and ethylene glycol were sprayed from above and below the fiber tow. An emulsion oil which is an aqueous dispersion (emulsion concentration 2% by mass) of a polyether / polyester copolymer having an average molecular weight of about 12,000, which is obtained by a composition of a diol component consisting of 30% by mass, is sprayed, and the water content after cutting. The rate was 15% by mass. The cutter speed at this time was 2,121 m / min. In addition, the high-speed cutter used here was such that the cutting side of the cutter blades faced upward, and each cutter blade was arranged radially. Then, the fiber toe composed of the drawn multifilament is wound around the rotating rotor arranged further above the cutting side of the cutter blade, and the fiber toe is gradually pushed off by the inclined ring installed further above to cut the fiber toe. It was to shorten the fiber. In addition, the distance between the blades was constant from the cut surface of the cutter blade to the back surface (cut fiber discharge side), the fiber discharge resistance did not increase even during cutting, and the blade did not break.
The obtained non-crimped short fibers did not have any binding defects and were excellent in water dispersibility, and were particularly suitable for papermaking. Table 6 shows the process conditions and the evaluation results of the obtained non-crimped short fibers.

For evaluation of the wet non-woven fabric, a mixed paper of the unrolled short fibers obtained in Example 25 and the unstretched short fibers obtained in Example 1 and Comparative Example 2 is used in the procedure described in Example 6. Made in.
The paper strength of the mixed paper with the undrawn short fibers obtained in Example 1 was 0.44 km.
The mixed paper with the undrawn short fibers obtained in Comparative Example 2 adhered to the dryer in the drying step at the time of paper making, and the mixed paper could not be obtained.
The mixed sandpaper with Example 1 was able to obtain sufficient adhesiveness as a wet non-woven fabric.

[Comparative Example 14]
A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 is dried at 170 ° C. for 4 hours, melted at 300 ° C., and discharged at 450 g / min through a spinneret having 1305 holes. After applying the emulsion oil to the drawn multifilament with an oiling roller so that the moisture content of the undrawn yarn is 21%, the undrawn multifilament (subtow) is taken up with a Nelson type roller pair 1 at a speed of 635 m / min. Obtained.

This sub-tow is converged by 12 weights to 85,000 dtex, and is continuously wound around a Nelson-type roller pair 2 having a surface temperature of 55 ° C. and a peripheral speed of 666 m / min for 6 turns without collecting cans, and then preheated to 100. Nelson type rollers vs. 3 at ° C. and a peripheral speed of 2,232 m / min were made to make 6 turns. Next, the Nelson type roller pair 4 having a surface temperature of 220 ° C. and a peripheral speed of 2,232 m / min was made to make 6 turns, and the Nelson type roller pair 5 having a surface temperature of 220 ° C. and a peripheral speed of 2,232 m / min was made to make 6 turns, and then. A Nelson-type roller pair 6 having a surface temperature of 220 ° C. and a peripheral speed of 2,232 m / min was subjected to 6 turns to obtain a fiber toe composed of stretched fibers (total draw ratio 3.51 times).

The stretched fiber tow was continuously cut to a length of 5 mm with a tension before the cutter of 0.1 cN / dtex. With respect to the drawn fiber tow before the cutter, the acid components of 80 mol% terephthalic acid and 20 mol% isophthalic acid and 70% by mass of polyethylene glycol having an average molecular weight of 3,000 (copolymerization) were sprayed from above and below the fiber tow. Spray an emulsion oil which is an aqueous dispersion (emulsion concentration 2% by mass) of a polyether / polyester copolymer having an average molecular weight of about 12,000, which is obtained by a composition of a diol component consisting of 30% by mass of ethylene glycol (based on mass). Then, the water content after cutting was set to 15% by mass. The cutter speed at this time was 2,254 m / min. In addition, the high-speed cutter used here was such that the cutting side of the cutter blades faced upward, and each cutter blade was arranged radially. Then, the fiber toe composed of the drawn multifilament is wound around the rotating rotor arranged further above the cutting side of the cutter blade, and the fiber toe is gradually pushed off by the inclined ring installed further above to cut the fiber toe. It was to shorten the fiber. In addition, the distance between the blades was constant from the cut surface of the cutter blade to the back surface (cut fiber discharge side), the fiber discharge resistance did not increase even during cutting, and the blade did not break.
The obtained non-crimped short fibers were found to have many binding defects and had a high heat shrinkage rate, and could not be said to be suitable for papermaking. Table 6 shows the process conditions and the evaluation results of the obtained non-crimped short fibers.

a. Curved part b. Opening part c. Opening area d. Width e. Hugging angle adjustment part f. Arc-shaped radius of curvature g. The apex of the curved part α. Hugging angle
aa. Opened part, open area (shaded part)
bb. Opening area length in the fiber toe running direction
cc. Opening area width
dd. Textile tow
ee. Fiber toe width
ff. Flat surface portion in the same direction as in FIG. 5 (opening portion facing upward, opposite to gravity)
gg. A flat surface portion in which FIG. 5 is vertically inverted by 180 ° (opening portion downward, gravity direction)
hh. Distance between flat surface and fiber toe
A. Spinning process
B. convergence
C. Processes such as stretching and overfeeding
D. Liquid application process
E. Cutting process

Claims (4)

In the method for producing non-curly short fibers, which spins at a spinning speed of 600 m / min or more and cuts the fiber toe to a length of 35 mm or less at a spinning speed or higher, the following requirements (I) to (IV):
(I) The unstretched multifilament immediately after spinning is used as it is, or a plurality of undrawn multifilaments are bundled to obtain a fiber toe of 20000-85000 dtex after combining.
(II) Continuously cutting the bundled fiber tow without collecting cans;
(III) To have a step of applying a hydrophilic oil containing one or more polyalkylene glycol derivatives from the undrawn multifilament immediately after spinning to before cutting the fiber tow; and (IV) the cutting speed is 1232 m. A method for producing non-crimped short fibers, which is a method comprising / min or more and satisfies any one of the following methods A to C :
A. Regarding the drawn yarn, the step of applying the hydrophilic oil agent uses a liquid applying device including a curved portion having an arc shape in a cross-sectional view, and the fiber toe is run while being in contact with the curved portion. Including the step of discharging the liquid oil agent from the curved portion and applying it to the fiber toe, the holding angle is made larger than 20 ° and smaller than 180 °, and the flow velocity of the liquid discharged from the opening portion is 0.2 to 3.0 m. A method in which the contact time of contacting the fiber toe with the curved portion of the liquid applying device is 0.001 to 0.05 seconds.
B. With respect to the drawn yarn, the step of applying the hydrophilic oil agent is to provide a liquid applying device including a flat surface portion, providing a perforated region in a part of the flat surface portion, and having a perforated portion (liquid discharge hole) in the perforated region. The flow velocity of the liquid discharged from the perforated portion is 0.2 to 3.0 m / sec, and the passing time of the fiber toe traveling in the perforated region of the liquid applying device is 0.001 to 0.05 second. Technique; and
C. For undrawn yarn, a method in which a hydrophilic oil agent is applied immediately after spinning using an oiling roller to adjust the concentration of the hydrophilic oil agent containing a polyalkylene glycol derivative to 1 to 5% by mass. The manufacturing method according to claim 1, wherein the cutting is a method of cutting with a short fiber cutter having a plurality of cutter blades and having the same distance between the cutter blades from the cutting surface to the back surface of the cutter blades. The production method according to claim 1 or 2, wherein the birefringence of the unstretched product is in the range of 0.001 to 0.100 . The production method according to any one of claims 1 to 3, wherein the tension of the fiber tow in each step before cutting is less than the yield tension with respect to the unstretched material .

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