JP2002088607A - Method for producing synthetic staple fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensively and efficiently producing a synthetic staple fiber by producing a drawn tow by direct spinning and drawing and crimping the tow by a method different from a conventional method for storing an undrawn yarn, then drawing and crimping. SOLUTION: This method for a synthetic staple fiber comprises subjecting a thermoplastic polymer to melt spinning, providing the fiber with a finish, taking off an undrawn tow as it is or after doubling plural undrawn tows by a first hot roller group, preheating the tows, then drawing the preheated tows between the first not roller group and a second hot roller group, heat-treating the tows on the second hot roller group and continuously crimping and cutting the heat-treated tows.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic short fiber inexpensively and efficiently by producing a drawn tow by direct spinning drawing and applying a crimp.

[0002]

2. Description of the Related Art An industrial process for producing synthetic staple fibers, which is usually carried out, is to collect a large number of undrawn yarns obtained by spinning into a subtow of several thousand to several tens of thousands of decitex, and to form a subtow with a large number of rollers. A step of shaking down and collecting in a tow can while guiding, and then collecting a large number of the subtows to form hundreds of thousands to several million decitex tows, and stretching the tow with a number of stretching roller groups and a heat treatment device In the process, stretching heat treatment is performed, subsequently mechanical crimping is applied, heat setting is performed if necessary, and then cutting is performed to an appropriate length.
The spinning speed is usually 800 to 1000 (m / min), and the drawing speed is 80 to 250 (m / min).

[0003] On the other hand, the rationalization of the process by adopting a direct spinning drawing method in which a melt spinning process and a drawing process are directly connected has been applied to the production of multifilaments, but is extremely large compared to multifilaments. In the case of a tow having a fineness, it is extremely difficult to make the spinning step and the drawing step continuous, and thus there has been no industrial study on the direct spinning and drawing method. In addition, when the tow is drawn and heat-treated by direct spinning and drawing, the fineness and the number of filaments are too large, so that insufficient heat treatment is likely to occur due to the moisture content or oily agent contained in the tow, and the dry heat shrinkage increases. was there. Furthermore, when heat treatment is performed non-uniformly, there is a drawback that, in particular, spots are significantly deteriorated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to produce a drawn tow by direct spinning drawing without storing the tow, and to produce a synthetic short fiber at low cost and efficiently by applying a crimp. It provides a method.

[0005]

Means for Solving the Problems The present inventors have found and studied a method for producing a synthetic short fiber at low cost and efficiently by producing a drawn tow by direct spinning drawing and applying a crimp. As a result, the present invention has been achieved.

That is, according to the method of the present invention for producing synthetic short fibers, a thermoplastic polymer is melt-spun and an oil agent is applied.
The undrawn tow or a plurality of untwisted tows are taken up by a first hot roller group and preheated, and then drawn between the first hot roller group and the second hot roller group to form a second hot roller. After heat treatment on the roller group,
This is a method for producing synthetic short fibers in which crimping and cutting are continuously performed.

Further, after the thermoplastic polymer is melt-spun and an oil agent is applied, the undrawn tow or a plurality of unstretched tows are combined and taken up by a first hot roller group, preheated, and then the first hot roller is heated. Stretched between the group and the second hot roller group, heat-treated on the second hot roller group, and then subjected to crimping, then temporarily stored in a storage can, and then cut. It is a manufacturing method.

Further, after the thermoplastic polymer is melt-spun and an oil is applied, undrawn tow or a plurality of undrawn tows are combined and taken up by a first hot roller group to perform preheating. A method for producing a synthetic short fiber comprising stretching between a group and a second hot roller group, performing heat treatment on the second hot roller group, temporarily storing in a storage can, and then crimping and cutting. It is.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

According to the present invention, the thermoplastic polymer is melt-spun, an oil agent is applied, and the undrawn tow or a plurality of the undrawn tows are combined and taken up by a first hot roller group to perform preheating. Stretching between a hot roller group and a second hot roller group, applying heat treatment on the second hot roller group, and subsequently performing crimping and cutting continuously to produce a synthetic short fiber. Is the law.

Hereinafter, a method for producing a synthetic short fiber according to the present invention will be described with reference to the drawings.

FIG. 1 is an example of a schematic diagram for explaining the present invention.
1 shows a process for producing synthetic short fibers in one step by direct spinning and drawing.

In FIG. 1, 1 is a spinneret, 2 is a spinning hole, 3 is a spun undrawn yarn, 4 is an oiling roller, 5 is a guide or roller, 6 is a convergence guide, 7 is a first hot roller group (Nelson Roller) and 8 are a second hot roller group (Nelson roller).

In the present invention, the first and second hot roller groups 7 and 8 are preferably Nelson type rollers, but are not particularly limited. With a Nelson-type roller, the speed can be increased, and when heating uniformly with a hot roller, the number of turns on the roller can be set appropriately, and as a result, the length of the yarn attached to the hot roller can be adjusted longer It is preferable because it can be performed. In the case of heat-treating the tow, it is more preferable to heat-treat both sides of the tow.

The first hot roller group (7A, 7A)
B) is provided for the purpose of uniformly heating the spun undrawn yarn to a temperature equal to or higher than the glass transition temperature, and a second hot roller group (8A, 8
B) is set for the purpose of heat setting the drawn yarn to adjust the shrinkage level and eliminate dye spots. for that reason,
The first hot roller group (7A, 7B) and the second hot roller group (8A, 8B) each preferably have 1 to 3 pairs for the purpose of extending the length and time of the yarn attached to the yarn. FIG. 1 shows a case where there are two pairs of a first hot roller group and a second hot roller group. The yarn uniformly heated by the first hot roller group is stretched one step between the first hot roller group and the second hot roller group (between 7B and 8A), or further drawn into the second hot roller group (8
(A-8B), two-stage stretching may be performed. Further, a relaxing roller may be provided after the second hot roller group for the purpose of relaxing.

In FIG. 1, 9 is a stretched uncrimped yarn, 10 is a crimper, 11 is a stretched crimped yarn, 12 is a high-speed cutter,
13 is a packing machine.

Further, it is preferable that after the crimping is applied to the drawn tow by direct spinning drawing, the drawn tow is once stored in a storage can and then cut.

FIG. 2 is an example of a schematic diagram for explaining the present invention. After the direct spinning and drawing, a crimp is applied, and the drawn crimped yarn is once stored in a storage can. After that, the stretched tow is set up from the storage can and cut.
This is a step of producing synthetic short fibers at the stage. In FIG. 2, reference numeral 14 denotes a storage can.

Although a crimper is used to crimp the stretched tow, the crimping slows down the tow speed and facilitates storage in a storage can.

Further, the method of the present invention has extremely high productivity as compared with the conventional method. That is, the conventional undrawn tow is temporarily stored in a storage can, and then the method of performing drawing and crimping is directly spun and drawn in the method of the present invention.
Since the stretched tow is obtained at a stretch, crimped and stored in a storage can, the cutting process is not performed.Therefore, there is no stretching process, so the cutting speed can be greatly increased and the productivity is higher than that of the conventional method. Is extremely high.

After the heat treatment, it is preferable to temporarily store in a storage can and then perform crimping and cutting.

FIG. 3 is an example of a schematic diagram for explaining the present invention.
The drawing shows a process in which a drawn tow which has been directly spun and drawn is once stored in a storage can, and thereafter crimping and cutting are performed to produce a synthetic short fiber in two stages.

As a method for storing the stretched tow in the storage can, a method disclosed in Japanese Patent Application Laid-Open No. 53-103401 or the like can be used.

The method of the present invention has extremely high productivity as compared with the conventional method. That is, in contrast to the conventional method of temporarily storing an undrawn tow in a storage can, and thereafter performing drawing and crimping, the method of the present invention performs direct spinning drawing, stores the drawn tow in the storage can, and then setstle. When shrinking and cutting are performed, since there is no stretching step, these speeds can be greatly increased, and the productivity is extremely high as compared with the conventional method.

In the present invention, the tow moisture content immediately before entering the first hot roller group is preferably 10% or less.

In the present invention, after the thermoplastic polymer is melt-spun and an oil agent is applied, undrawn yarns or a plurality of undrawn yarns are combined and taken up by the first hot roller group to perform preheating. At this time, it is preferable to regulate the moisture content when applying the oil solution to the unstretched tow for the purpose of efficiently performing uniform stretching, and the moisture content of the unstretched tow immediately before entering the first hot roller group is 10% or less. It is preferred that If the moisture content in the unstretched tow exceeds 10%, preheating on the first hot roller group is not sufficiently performed, resulting in non-uniform preheating. As a result, it is difficult to perform uniform stretching, which is not preferable.

Next, stretching is performed between the first hot roller group and the second hot roller group, and heat treatment is performed on the second hot roller group. At this time, if the unstretched tow moisture content immediately before entering the first hot roller group exceeds 10%, it is difficult to sufficiently perform heat treatment even on the second hot roller group, and dye spots are likely to occur. Also, the dry heat shrinkage tends to be high, and it is difficult to obtain raw cotton having low shrinkage, which is not preferable.

Furthermore, in the present invention, it is preferable that the amount of oil attached to the synthetic staple fiber is 0.12% or more and 0.5% or less. It is more preferably 0.12% or more and 0.25% or less, and further preferably 0.15% or more and 0.20% or less.

If the amount of the oil agent is 0.12% or more and 0.5% or less, the unstretched tow does not vary on the hot roller group even when the moisture content in the unstretched tow is 10% or less. This is preferable because stretching and heat treatment can be performed subsequent to preheating while maintaining a certain convergence. When the amount of the oil agent is more than 0.5%, the convergence of the undrawn tow is improved, but the roller stains with the oil agent are remarkably deteriorated with time on the second hot roller group, and thread breakage frequently occurs. This is not preferred because of the tendency. In addition, the card passability in the high-order processing step is deteriorated, and the detachment and adhesion between the spinning steps after the drawing are increased, so that the process passability is remarkably reduced, such as an increase in roller winding and a decrease in the can capacity. This is not preferred because of the tendency.

If the amount of the oil agent is less than 0.12%, it is not preferable because static electricity is generated when passing the sample roller card and the passing property is deteriorated.

Further, it is preferable that the thermoplastic polymer is polyethylene terephthalate.

The present invention is not particularly limited as long as it is a thermoplastic synthetic polymer that can be melt-spun, such as polyester, polyamide and polyolefin, but the effect is remarkable if polyester, especially polyethylene terephthalate.

In the present invention, when the heat treatment is performed on the second hot roller after the direct spinning and drawing, the following formulas (1) to (3)
Is preferably satisfied at the same time.

D / W ≦ 2.2 (1) 160 ≦ Temp ≦ 240 (2) 0.1 ≦ Time ≦ 0.5 (3) (However, D is the total decitex of tow (10,000 Dtex), W
Represents a tow width (cm), Temp represents a heat treatment temperature (° C.) of at least one pair of hot rollers of the second hot roller group, and Time represents a heat treatment time (sec) of the hot roller heated at the temperature of the formula (2). In the present invention, it is preferable that D / W is 2.2 or less.
When D / W is larger than 2.2, it means that the contact area is small with respect to the fineness of the drawn yarn in contact with the heat treatment roller, and it is difficult to perform uniform heat treatment.
The obtained drawn yarn is not preferable because the dyeing spots are significantly deteriorated. If D / W is 2.2 or less, the drawing area of the drawn yarn in contact with the heat treatment roller is sufficiently large,
It is possible to perform a uniform heat treatment. The smaller D / W is, the more uniform heat treatment can be performed.
Preferably it is 1.0 or less.

In the present invention, for example, in the case of producing polyester short fibers, a large number of subtows are collected and drawn.
Although heat treatment is performed, the total decitex ranges from several hundred thousand to several million decitex, so that heat cannot be smoothly transmitted to the drawn yarn on the heat treatment roller. As a result, uneven heat treatment occurs in the portion that is in contact with the heat treatment roller and the portion that is not in contact with the heat treatment roller, and as a result, the dyeing spots are significantly deteriorated.

In the present invention, the amount of heat required for uniform stretching is given to the unstretched tow in the step of passing through the first hot roller group, and the shrinkage of the obtained raw cotton is determined in the step of passing through the second hot roller group. Therefore, it is preferable to prescribe the heat treatment temperature and the heat treatment time.

In the present invention, the heat treatment temperature of at least one pair of hot rollers in the second hot roller group is 1
It is preferable that the temperature be 60 ° C or higher and 240 ° C or lower. The purpose of the heat treatment is to crystallize the drawn yarn to reduce the shrinkage. At this time, when the heat treatment is performed in the region of 160 to 240 ° C., the shrinkage is most easily reduced. If the temperature is lower than 160 ° C., it is not preferable because the shrinkage cannot be sufficiently reduced.
When the temperature exceeds 240 ° C., crystal melting inside the fiber starts to occur, and it becomes easy to fuse on the second hot roller group.
The obtained fibers also have a clear tendency to deep dye, and the strong elongation is remarkably reduced, which is not preferable.

The heat treatment time of the hot roller heated at the temperature of the formula (2) is preferably 0.1 second or more. The heat treatment time can be appropriately set according to the diameter and number of the hot rollers, the number of windings, and the like. If the heat treatment time is shorter than 0.1 second, the shrinkage rate becomes high similarly to the insufficient heat treatment temperature, which is not preferable.

The heat treatment time is preferably 0.5 seconds or less. The longer the heat treatment time, the lower the shrinkage ratio and the more the number of dyed spots is reduced, which is preferable. However, if the heat treatment time exceeds 0.5 seconds, the reduction in shrinkage rate and the occurrence of dye spots become saturated. Also, if the length of the hot roller is increased or the number of hot rollers is increased until the heat treatment time exceeds 0.5 seconds, the production cost increases, which is not preferable.

In the present invention, in order to obtain, for example, polyester short fibers, it is preferable to simultaneously satisfy these three conditions. If at least one of these formulas is not satisfied, the shrinkage rate becomes high and the dyeing spots tend to deteriorate, which is not preferable.

As described above, in order to obtain polyester short fibers, the total decitex on the heat treatment roller reaches hundreds of thousands of decitex or more. When heat treatment is performed in the second hot roller group, it is preferable to heat-treat both surfaces of the drawn yarn.

At this time, means for heating both sides can be considered as appropriate. However, heat treatment on both sides of the drawn yarn greatly improves the uniformity and the dyeing spots. A method of heat-treating both surfaces of the drawn yarn by increasing the number of pairs to three can be used. Further, a method of attaching a hot plate using radiant heat or a pressurized steam for the purpose of improving the thermal efficiency of the second hot roller group can also be used.

The method for producing synthetic short fibers according to the present invention comprises:
A method of stretching between the first and second hot roller groups is preferred. The hot roller group is preferably a Nelson roller from the viewpoint that heat treatment can be performed efficiently.

The peripheral speed of the first hot roller group is 100
It is preferred to be 0 m / min or less. Peripheral speed 1000
If it exceeds m / min, the yarn properties immediately after leaving the first hot roller group tend to be highly oriented, and the subsequent draw ratio must be low, and the yarn has satisfactory yarn physical properties in terms of strength. Is difficult to obtain. On the other hand, the lower the peripheral speed, the larger the draw ratio, which is preferable. However, the lower the peripheral speed, the more the discharge amount has to be reduced and the productivity is remarkably deteriorated. It is preferable to set the peripheral speed as follows.

Further, it is preferable that the final peripheral speed of the second hot roller group is 2500 m / min or less. When the feeding speed exceeds 2500 m / min, the degree of non-uniformity of the crimp increases, short fibers having poor crimp quality are obtained, and troubles are apt to occur in the process of passing through a card device during spinning. Therefore, it is not preferable. Therefore, the final peripheral speed of the second hot roller group is preferably set to 2500 m / min or less.

[0046]

The present invention will be described in more detail with reference to the following examples. In addition, each characteristic value in an Example was implemented by the following measuring methods. (1) Intrinsic viscosity (ηc) Measured at 25 ° C. using orthochlorophenol as a solvent. (2) Measurement of Moisture Content Using an infrared moisture meter (IR-M1100) manufactured by Chino Co., Ltd., after applying an oil agent with an oiling roller, the moisture content of the unstretched tow immediately before entering the first hot roller group was measured. . (3) Measurement of Attached Amount of Oil The raw cotton is put into a Soxhlet extractor, and the oil is extracted from the raw cotton for 3 hours using methanol as a solvent. The methanol is evaporated, and the residual oil content Wo (g) is measured. After the extracted raw cotton is sufficiently dried, the weight Ws (g) is measured.

The adhered amount of the oil agent is measured by the following equation.

The amount of oil agent attached = Wo / Ws × 100 (%) (4) Heat treatment time (Time) The heat treatment time is determined by the following equation. Time = (the yarn length of the hot roller heated at a temperature of 160 to 240 ° C.) / (The peripheral speed of the hot roller heated at a temperature of 160 to 240 ° C.) The yarn length is calculated from the diameter of the hot roller. It can be determined from the perimeter, the thread angle and the like. (5) D / W Measure the toe width W (cm) on the second hot roller group,
Relational expression (D) with the total decitex of tow D (10,000 Dtex)
÷ W). (6) Dry heat shrinkage Grasp both ends of the sample with clips, and a total of 300 mg / d
The original length L ₀ (cm) is obtained by applying an initial load of tex. Loosen the gaps between the clips sufficiently and treat them in an oven at 180 ° C. for 15 minutes under no load.
An initial load of 00 mg / dtex is applied, and the length L ₁ (cm) after the treatment is measured. The dry heat shrinkage is determined by the following equation. The number of tests is 15 times, and the average value is obtained.

Dry heat shrinkage = {(L ₀ −L ₁ ) / L ₀ } × 100 (%) (7) Evaluation of Dye Spots 10 panelists ranked dye spots very well (10 points) Good (8 points), normal (5 points), poor (0 points)
Points), and when the average point is more than 8 points, the texture of the cushioning material is very good. ◎, 7 points or more and 8 points or less are good. Less than "poor" was evaluated. Examples 1 to 7 A polyethylene terephthalate polymer having an intrinsic viscosity of 0.65 was melted, and a spinneret (930 H holes, pore diameter 0.3) was melted.
mmφ), spinning temperature 285 ° C, polymer discharge 550
Spin at g / min. The spun yarn was cooled in a cylindrical spinning tube between the spinneret and the oiling roller.

The spun yarn was cooled in a cylindrical spinning cylinder between the spinneret and the oiling device at 25 ° C. and a wind speed of 80 m / min. The undrawn yarn to which the oil agent was adhered passed through a free roller and was bundled with a yarn of another spindle by a bundle guide. The number of weights at this time was 10 weights.

Next, it is heated to 60 ° C. and guided to a Nelson-type roller (7A of the first roller group in FIG. 1) which rotates at a peripheral speed of 485 m / min. A Nelson-type roller heated at a peripheral speed of 500 m / min (the first roller group 7 in FIG. 1)
B) and 6 turns on the roller. Then 11
It was guided to a Nelson-type roller (8A of the second roller group in FIG. 1) which was heated to 0 ° C. and rotated at a peripheral speed of 2000 m / min. It is further heated to 210 ° C. and guided to a Nelson-type roller (8B of the second roller group in FIG. 1) rotating at a peripheral speed of 2425 m / min.
There were 10 turns on the roller. At this time, a confounding air guide is installed between 8A and 8B, and the air pressure is adjusted to change the width (D) of the drawn yarn to be heat-treated on the second roller group; Was changed as shown in Tables 1 and 2. The total stretching ratio at this time was 5.0 times,
The unstretched tow moisture content just before entering the hot roller group is 7%
Met.

The stretched tow that has exited the second hot roller group is
After being guided to a dimensional crimper and subjected to mechanical crimping, it was cut to obtain polyester short fibers of 2.3 dtex × 51 mm. The oil adhering amount of this polyester staple fiber is 0.18%
Met.

Dry heat shrinkage of the obtained polyester short fibers,
Table 1 shows the evaluation of dye spots.

In Examples 1 to 5, the D / W was 2.2 or less, and the heat treatment temperature of the second hot roller group;
0 ° C., the heat treatment time is also 0.16 sec.
Since the formula (3) was satisfied, a good raw cotton having a low dry heat shrinkage and no dyeing spots was obtained.

On the other hand, in Examples 6 and 7, the heat treatment temperature of the second hot roller group: 8B was 210 ° C. and the heat treatment time was 0.1.
Although it was 6 sec, the D / W exceeded 2.2, and the dyeing spots tended to be slightly bad. Examples 8 to 13 Second hot roller group: spinning, stretching, crimping, and the like as in Example 1 except that the temperature of 8B was changed as shown in Table 1.
A cut was performed.

In Examples 9 to 12, since the 2DR temperature was within the specified range and the drawing was performed, the obtained polyester staple fiber had a low dry heat shrinkage and was a good polyester fiber having no spots. there were.

On the other hand, in Example 8, since the heat treatment temperature was low,
The dry heat shrinkage was high, and the dyeing spots were not good. Further, in Example 13, the heat treatment temperature of 8B was too high, and the drawn yarn was liable to frequently fuse on 8B during the yarn production. In addition, the obtained raw cotton also showed a relatively large number of dyeing spots due to fusion, and the quality was not sufficient. Examples 14 to 198 Spinning, stretching, crimping, and cutting were performed in the same manner as in Example 1 except that the number of turns on 198B was changed and the heat treatment time was changed as shown in Table 1.

In Examples 16 to 19, since the heat treatment time was sufficiently long, a good polyester short fiber having a low dry heat shrinkage and having no spots was obtained.

On the other hand, in Comparative Examples 14 and 15, since the heat treatment time was short, the dry heat shrinkage was high, and only polyester short fibers with slightly deteriorated spots were obtained. Examples 20 to 22 Based on the conditions of Examples 5, 9, and 16, the drawn yarns were 8A and 8
B was heat-treated on both sides. However, the number of turns on 8B in Examples 5, 6, and 10 and Example 1
The number of turns on 8B in 4, 15, and 16 was set to the same number of turns, and the same time such as the heat treatment time was used.

Table 1 shows the dry heat shrinkage and the evaluation of spots on the polyester short fibers obtained at this time. By performing the double-sided heat treatment, polyester short fibers having a lower dry heat shrinkage ratio and further improved dyeing spots were obtained as compared with the polyester short fibers obtained in Examples 5, 9, and 16.

From the above results, when the D / W, the heat treatment temperature and the heat treatment time of the second hot roller group are within the ranges, it is possible to obtain a polyester short fiber having a low dry heat shrinkage and a good quality without spotting. It is understood that it can be done. Examples 23 and 24 Polyester short fibers were obtained in the same manner as in Example 1 except that the unstretched tow moisture content immediately before entering the first hot roller group was respectively 10 and 13%. Table 1 shows the dry heat shrinkage and the evaluation of spots on the obtained polyester short fibers. In Examples 23 and 24, since the unstretched tow moisture content immediately before entering the first hot roller group exceeds 10%, uniform preheating on the first hot roller group and heat treatment on the second hot roller group It is found that it is difficult to sufficiently perform the process, dyeing spots are easily generated, and the dry heat shrinkage ratio is also a high value, and it is difficult to obtain raw cotton having low shrinkage. Examples 25 to 29 Polyester short fibers were obtained in the same manner as in Example 1 except that the amount of the oil agent adhering to the obtained polyester short fibers was changed. Table 2 shows the dry heat shrinkage, the evaluation of dye spots, and the card passability of the obtained polyester short fibers.

In Example 25, the amount of the oil agent adhered was less than 0.12, static electricity was generated when the card passed, and the winding was severe, and the card passing property was likely to be poor.

In Examples 26, 27, and 28, the amount of oil applied was in the range of 0.12 to 0.5, and no particular problem occurred. In particular, the raw cotton having the oil agent adhesion amount of 0.18% level had a good passage property.

In Example 29, since the amount of the oil agent adhering exceeded 0.5%, the deterioration of the card passability in the high-order processing step increased, and the process passability tended to decrease, such as an increase in roller winding. became. Further, in Example 29, during the running test, roller stains due to the oil agent occurred and deteriorated with time, particularly on the second hot roller group, and thread breakage occurred frequently. Example 30 The spinning and drawing steps were carried out in the same manner as in Example 1, and the resulting product was led to a two-dimensional crimper to obtain a crimped tow. Next, 30 crimped and drawn tows housed in the can were pulled out, and 30 were collected, passed through a tow guide and a convergence roller, guided to a known cutter and cut, and then packed as polyester short fibers by a packing machine. The obtained polyester staple fiber had almost the same quality as that of Example 1. Example 31 The spinning and stretching steps were performed in the same manner as in Example 1, and the uncrimped stretched tow was stored in a can using an ejector. Next, the uncrimped stretched tow stored in the can was pulled out, 30 pieces were collected, and a crimp was applied by a known two-dimensional crimper through a tow guide and a collecting roller. Further, the crimped and drawn tow was guided by a cutter and cut, and then packed as a polyester short fiber by a packing machine.

The obtained polyester staple fiber had almost the same quality as that of Example 1.

As described above, according to the method for producing polyester short fibers of the present invention, drawn crimped polyester short fibers having excellent yarn physical properties can be produced with high productivity, which is extremely industrially advantageous.

[0067]

[Table 1]

[0068]

[Table 2]

[0069]

According to the present invention, there is provided a method for producing a stretched tow by direct spinning stretching, which cannot be achieved by the prior art, and producing a synthetic short fiber at low cost and efficiently by crimping. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of producing a synthetic short fiber in one step according to the present invention.

FIG. 2 is a schematic view showing an example of producing a synthetic short fiber in two steps according to the present invention.

FIG. 3 is a schematic view showing an example of producing a synthetic short fiber in two steps according to the present invention.

[Explanation of symbols]

 1: spinneret 2: spinning hole 3: spun undrawn yarn 4: oiling roller 5: guide or roller 6: focusing guide 7: first hot roller group (Nelson roller) 8: second hot roller group (Nelson roller) 9: Stretched uncrimped tow 10: Crimper 11: Crimped tow 12: High speed cutter 13: Packing machine 14: Storage can

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D01D 10/00 D01D 10/00 Z D01F 6/62 301 D01F 6/62 301E 301P F-term (Reference) 4L035 BB36 BB61 BB89 DD19 EE04 4L036 MA05 MA25 MA35 PA12 PA18 PA26 PA36 PA46 RA03 RA04 UA16 UA21 4L045 AA05 BA03 BA06 BA36 BA56 BA60 CA25 CA29 CB09 CB13 DA14 DA40 DA42 DA52 DC02

Claims (7)

[Claims] 1. A thermoplastic polymer is melt-spun and an oil agent is applied. Then, an undrawn tow or a plurality of undrawn tows are combined and taken up by a first hot roller group to perform preheating. A method for producing a synthetic short fiber, comprising: stretching between a group and a second hot roller group, performing heat treatment on the second hot roller group, and then continuously performing crimping and cutting. 2. After the thermoplastic polymer is melt-spun and an oil is applied, undrawn tow or a plurality of undrawn tows are combined and taken up by a first hot roller group to perform preheating. After stretching between the group and the second hot roller group, heat-treated on the second hot roller group, and then subjected to crimping, once stored in a storage can,
A method for producing synthetic staple fibers, characterized in that cutting is performed thereafter. 3. After the thermoplastic polymer is melt-spun and an oil agent is applied, undrawn tow or a plurality of undrawn tows are combined and taken up by a first hot roller group to perform preheating. Stretching between the group and the second hot roller group, performing heat treatment on the second hot roller group, temporarily storing in a storage can, and then performing crimping and cutting. A method for producing short fibers. 4. The method according to claim 1, wherein the moisture content of the undrawn tow immediately before entering the first hot roller group is 10% or less. 5. The amount of oil agent attached to synthetic short fibers is 0.12.
% Or more and 0.5% or less.
5. The method for producing a synthetic short fiber according to any one of 4. 6. The method according to claim 1, wherein the thermoplastic polymer is polyethylene terephthalate. 7. The method according to claim 6, wherein the following formulas (1) to (3) are simultaneously satisfied when the heat treatment is performed on the second hot roller group. D / W ≦ 2.2 (1) 160 ≦ Temp ≦ 240 (2) 0.1 ≦ Time ≦ 0.5 (3) (However, , D is the total decitex of the tow (10,000 Dtex), W
Represents a tow width (cm), Temp represents a heat treatment temperature (° C.) of at least one pair of hot rollers of the second hot roller group, and Time represents a heat treatment time (sec) of the hot roller heated at the temperature of the formula (2). Indicates)