JPS5860022A - Production of discontinuous filament bundle of acrylic synthetic fiber - Google Patents

Abstract

PURPOSE:A bundle of crimped continuous filaments of acrylic fiber is brought into contact with a cooling medium, as the crimp is kept, to give drawing and shearing forces to break each filament in the bundle, thus producing the titled discontinuous filament yarn through a simple process. CONSTITUTION:A bundle 31 of continuous filaments of crimped acrylic fiber is adjusted in its thickness as it is separated into filaments uniformly with a certain width is overfed with the back roller 36 to reform the original crimps 32 and fed into the low-temperature tank 33. The bundle is brought into contact with a cooling medium of a temperature lower than -20 deg.C in the tank 33 to increase the toughness and make its elongation almost zero as well as fix its crimps. Then, break draft is given between the middle rollers 37 and the break roller 38 to generate concentrated stress or shear stress on the fixed crimps and break filaments, thus giving a bundle of discontinuous filaments 34. The bundle is drafted with the front rollers 39 and contained in to the can 35.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing zero bundles of discontinuous fibers, which are intermediate products for producing spun yarn from continuous IsO bundles of acrylic synthetic fibers, such as toku and multifilament. In more detail, a bundle of continuous fibers made from acrylic synthetic fibers is heated in a medium K at -20°C or less while maintaining crimping.
II! The present invention relates to a method for manufacturing a bundle of discontinuous fibers by applying a drawing force and/or a shearing force to a bundle of continuous fibers and cutting each single fiber by applying a drawing force and/or a shearing force to a bundle of continuous fibers while touching the fibers.

BACKGROUND ART Conventionally, as a method for producing spun yarn, a method is known in which the following steps are followed: short fiber group carding process → gill process or filament process → roving process → spinning process. However, this method requires 1 card step, so productivity is low.

■ Shrinkage cannot be imparted to the spun yarn during the spinning process.

■ Raw cotton manufacturing worker 1! In this process, a step is required to produce short fibers by cutting the fibers into the following fiber lengths depending on the purpose of spinning.

■ In the carding process, NEP (tC between single fibers),
There are problems such as the occurrence of hooks (curved ends of single fibers) and the need to take countermeasures such as lengthening the gill process due to poor parallelism.

On the other hand, after converting a bundle of continuous fibers such as tow or filament into a bundle of discontinuous fibers, the method of producing a spun yarn is to convert the continuous fibers into a bundle of discontinuous fibers at a temperature around room temperature by using the lock method, turbo method, etc. Methods are known for producing bundles of.

The Purlock method is a method in which a bundle of continuous fibers is stretched using a roller and each single fiber is cut to obtain a bundle of highly parallel discontinuous fibers at high speed. When cutting, the strength and elongation of the acrylic synthetic fiber in Figure 7 - [11(C) K
As shown, the fibers are stretched through an elastic deformation region with an elongation of O to about S-, and then stretched to a breaking elongation in a plastic deformation region of 5- or more before being cut. There is a limit to the low shrinkage rate spun yarn om*wc due to the presence of a large residual strain in the fibers during stretching.

(■) Since the strength and elongation, especially the loop strength and elongation, are greatly reduced, fibers are often cut and fried during the manufacturing process of spun yarn.

(l) When stretching and cutting highly elongated fibers, after pre-stretching, stretching and cutting is performed using the Parlock method, so (1)
The disadvantages of

翰 The cut fiber tips become jittery, which causes unevenness in the spun yarn.

There is a problem.

The turbo method is a method in which a bundle of continuous fibers is stretched and cut by applying shearing force. In this method.

It is not necessary to stretch the fibers to the elongation at break! Not though.

The staple diagram for cut fibers looks bad.

In other words, the content ratio of long fibers and short fibers increases.

The present invention solves the drawbacks of the conventional method, can be performed with less energy, and can freely produce spun yarns made of acrylic synthetic fibers with low to high shrinkage rates.
A fourth object of the present invention is to provide a method for producing a discontinuous fiber bundle, which can produce spun yarn of extremely excellent quality at high speed with extremely little occurrence of fiber breakage or fly.

As the continuous fiber bundle of the present invention, tow or multifilament is generally used.

For fiber bundle skipping, single fiber diameter is 0.1 d to 60 d.
Filaments with a total denier of 30 d to 2,000,000 d, consisting of large filaments and.

Applicable to tow etc.

Furthermore, it can also be applied to a mixture of the above-mentioned continuous fibers and a fiber bundle made of short fibers, or a mixture with other types of fibers.

One aspect of the present invention is a medium in which a bundle of continuous fibers made of acrylic synthetic fibers having crimps is kept crimped in a cooling region at -20°C or lower.

K while contacting with a medium preferably at -40°C or lower, more preferably -80°C or lower, or immediately after contact.

This is a method for cutting single fibers.

Another invention is to overfeed a bundle of continuous fibers made of acrylic synthetic fibers having crimps into a cooling zone, while keeping the crimps in contact with a cooling medium at the above temperature, or This method produces a bundle of discontinuous fibers by cutting the single fibers immediately after contact.

Figure 1 (A) shows acrylic fiber (product name: Cashmilon [
(B) is the strength and elongation curve when a single fiber of the same company (Co., Ltd.) with crimps is stretched in a state where it is in contact with liquid I1 at -100°C for 45 seconds. This is the strength and elongation curve when stretched in contact with a similar medium.

The curve in Figure S shows the breaking strength after being left at each temperature for 1 minute with the crimp maintained, and ■ shows the breaking strength after the same treatment with the crimp fully stretched. Compared to cooling and cutting with the crimp stretched out, it is about 10-
The tension force acting on the cut is reduced. Furthermore, it can be cut with the same tension as the conventional stretch breaking method.

By contacting with a medium at -40°C or lower, continuous fibers have less fiber damage, less fly and shrinkage, and excellent physical performance and quality such as parallelism, unevenness, and neps. A bundle of nine discontinuous edge fibers is obtained. -go
By touching the medium Km at a temperature of 0.degree.

To explain the crimp state using Figure 4, the single fibers constituting a bundle of continuous fibers = 1! 2 Longitudinal crimp XS
may exist continuously like 0), but (b)
The cutting zone may have at least one crimp 23 within the length L of the cutting zone. When viewed as a continuous fiber bundle 21, it is desirable that the continuous fibers exist in two strands in the length direction. Then, it is preferable to uniformly split the bundle of crimped continuous fibers into single fibers with a constant width and adjust the thickness before supplying the bundle to the cooling zone.

The original V! At A, KW! supplies a bundle of continuous fibers to the cooling zone! A, it is more preferable to carry out the process while overfeeding in order to reduce the breaking energy.

That is, the fibers are cut by overfeeding and brought into contact with a medium at -to DEG C. or lower in a cooling zone while maintaining the crimp of the original fibers as much as possible, or are cut immediately after contact with this medium.

Figure 10 shows the results when a continuous fiber bundle consisting of crimped acrylic synthetic fibers (single fiber denier 34 x 100 fibers) was fed to a -100°C cooling zone for 45 seconds at various overfeed rates. It is well understood that the breaking strength decreases as the overfeed rate increases.

In the trap of the present invention, the single fiber is crimped when fed to the cooling zone, within the length L of the cutting zone, at least one crimp O angle (0<θ≦120 as shown in Figure #E5). It is preferable that there be.

Note that the angle gc <e> was measured with a load of 211 F/d applied.

As a cooling medium, anything below -H°C can be used; however, ammonia, carbon dioxide, air, oxygen, vaporized gases such as G1 element, or liquids, alcohol, solid carbonic anhydride, and ether can be used as cooling agents. In addition, chlorides of ice and zinc chloride, sodium chloride, sodium nitrate, sulfuric acid, etc.
A mixture of nitric acid and a sulfuric acid compound, a vaporized gas thereof, etc. can be used.

The time of contact with this cooling medium varies depending on the type of fiber, feeding method, type of medium, degree of medium, etc. 4, but generally about 1 to 100 seconds is used.

The method of contact with the cooling medium is not limited to *, but includes a method of passing the bundle of continuous fibers through a gas atmosphere or a liquid, a method of dropping the cooling medium onto the bundle of continuous fibers, and the like.

The continuous fiber bundle may be cut while being brought into contact with a medium at −w° C. or lower, or may be cut immediately after contact.

In cutting, each single fiber is cut by applying a drawing force and/or a shearing force to the bundle of continuous fibers. In addition to these, another cutting force can also be used. Thus, zero bundles of discontinuous fibers found will have a good staple diameter 2A. Specifically, the bundle of discontinuous fibers produced in this manner includes fiber bundles for direct spinning of slivers and rovings.

Figure 1 shows the relationship between the temperature of the cooling medium and the shrinkage rate of the single fibers that make up the bundle of discontinuous fibers when cutting acrylic fibers (product name: Kashijan ■) while maintaining crimping. This is a diagram showing the relationship, and as you will see, according to the method of the present invention, it is possible to achieve from a low shrinkage rate to a high shrinkage rate.In addition, when the required medium temperature is set during cutting, As shown in FIG. 1, the shrinkage rate of the single fiber corresponding to the temperature is determined. In that case, the provision of a shrinkage rate higher than the determined shrinkage rate is achieved only by carrying out stretching, preferably hot stretching, before contacting the medium at temperatures below 0°C. Figure 6 (C) shows acrylic fibers (product name: Kashishin@) that have been hot-stretched at -100°C.
It is a figure which shows the shrinkage rate change when cut while making it contact with the medium of degreeC. The shrinkage rate without hot stretching is 4 inches, but as the hot stretching ratio increases, the shrinkage rate increases.

On the other hand, (D) is the shrinkage rate when cutting at 20° C. using the Parlock method. In this case, the shrinkage rate can only be adjusted within the range of ZSS to 28-28. Since the present invention produces bundles of discontinuous fibers by bringing them into contact with a cooling medium of K, -C or less, ) If a bundle of discontinuous fibers is produced by cutting while maintaining crimping, the energy required for cutting is extremely small. It becomes possible to manufacture spun yarn with a shrinkage rate of .

(c) By carrying out the stretching process prior to cutting, it becomes possible to arbitrarily change the shrinkage rate.) The occurrence of fly and fiber breakage during the spinning process is extremely reduced.

(e) Nine spun yarns made from bundles of discontinuous fibers according to the method of the present invention have extremely little unevenness and high yarn strength.

It shows remarkable action and effect.

FIG. 1 is a process diagram showing an embodiment of a method for maintaining crimp and cutting in good condition. The original crimp 32 is recovered by overfeeding a continuous fiber bundle 31 made of single fibers having crimps with a uniform thickness while dividing the single fibers into a constant width using a back roller 36. ◇Then, by bringing the fibers into contact with a low-temperature medium at -20°C or lower in the cryostat 33, the stiffness of the fibers is increased and the elongation becomes almost non-existent, and the winding of the fibers is increased. Fix the contraction. Next, $5.
A slight break draft is applied between the roller 37 and the break roller north to generate shear stress or concentrated stress in the fixed and crimped portion, and the single fiber is cut into a bundle of discontinuous fibers U at the front.・After drafting with low 2-39, it is stored in can 35.

FIG. 2 shows that a crimp p:-40 is provided between the back four-sea 36 and the middle row 2-7, and a bundle 31 of continuous fibers without crimp or with weak crimp is crimped appropriately. 32 and supplied into the cryostat 33, the middle p-sea s7
It is a process diagram for producing a bundle 34 of discontinuous fibers by applying a break draft between the fibers and the break sealer and cutting the fibers.

FIG. 3 is a process diagram suitable for manufacturing a bundle 34 of discontinuous fibers with arbitrary shrinkage, in which a bundle 31 of continuous fibers is packed and
A pair of upper and lower heating plates is provided between the roller 36 and the stretching/p-sea 41, and the continuous fiber bundle 31 is heated and softened, and simultaneously stretched at a stretching ratio suitable for obtaining a predetermined shrinkage. do. Next, a crimp 32 is applied with a crimper 40 and the material is fed into a cryostat 33, and then a slight break draft is applied between a middle roller 37 and a break p-sea 38 to form a fixed crimping. A shearing stress or concentrated stress is generated in the constricted portion 32, and the single fibers are cut into a bundle U of discontinuous fibers, which is stored in the can 35.

Example 1 A 500,000 denier tow composed of 3D polyacrylonitrile fibers was placed in the apparatus shown in Figure 1 and spun under the following conditions.

, one crimp state, the number of crimp is 1! (+/(7f) Crimp angle・O0≦−≦1200 Overfeed rate lo (%) Cooling medium Liquid nitrogen Low-temperature cypress indoor banquet air temperature -1o・(℃) Residence time 45 (EC) Break driver 7) 1.11 Spinning speed 1 (10 (m/sb) Next, the above tow was OM) Ureactor (OM Seisakusho Co., Ltd.)
Spinning was carried out under the following conditions and the results were compared.

Hot plate temperature 1zo (℃) Hot stretching ratio 1.281 Residence time 6 (Island ea
) Total Draft 6.51 (Break Drawer 7) ) (2,53) Driving Atmosphere Temperature 2G(u) Spinning Speed
degree ioo (tm/m) In addition, in the worsted spinning process, the same as rosy card (3d to 7
O-127 (proverbial) bias cut and nine stable
The process performance and physical properties of the sliver were compared using fibers supplied and spun under the following conditions.

Spinning speed 3・(泗/-') Result 1 In addition, ring spun yarn obtained from the above sliver (the tow reactor sliver was subjected to relaxation set) through a normal spinning process and We also compared these products and found that 3. Because tow with a total denier of 500,000 denier is brought into contact with the cooling medium at -106°C, conventional tow reactors could not be used to achieve full power with a break draft less than 11 times. On the other hand, in the present invention, even after overfeeding 1G-, the break rate is as low as ′i,xs times.
This cart can be cut using a draft, and there is less fly and cotton drop than the conventional method.

It was also good compared to other methods. The obtained sliver has a low shrinkage rate and maintains its original crimp.
It is no longer necessary to use a setter step to relax and fix the crimp applied after one tension cut as in the one-type tow reactor.

Furthermore, compared to card slivers that also do not exhibit shrinkage, slivers with superior quality in terms of parallelism, neps, and US can be produced at high speed7'j.

In terms of yarn physical properties, the method of the present invention has almost no fiber damage and better fiber strength than the conventional tow reactor method, and is superior in U% yarn defects and O quality compared to the card method. There is.

Similarly to the card method, the molded product had good repellency, and had good dyeability and hot polyurethane properties.

Example 2 In order to compare the tensile force required for cutting between the method of the present invention and the conventional method, a 300% polyacrylonitrile fiber 3D was
Denier fiber bundle (crimps number 100A7f).

The crimp angle goO≦θ≦two0) was stretched with Denjip under the following conditions, and the OS-S curves were compared. The results are shown in Figure 1.

Conventional method Stretch cutting was carried out at an ambient temperature of 20 (r). (Glass C) This method A bundle of single fibers is made to slack in the longitudinal direction by 10 (-) and crimped, and then cooled at 45 degrees with liquid 9 at 110°C (°C). After that, it was stretched and cut. (Gutsu 7m) In addition, the SS curve when the tension was increased to 4 and the winding was stretched was cooled for -ZGo (° C.) K 45 sec, and then stretched and cut. (Graph B) Example 3 In the same sump jL as in Example 2, the tensile tension required for cutting when the crimp was cooled and fixed with liquid nitrogen at -100°C and when the crimp was cooled with the crimp in between. We investigated the temperature dispersion alignment trap and the shrinkage rate depending on the temperature. (Fig. 8-9) Method of the Invention After cooling for 45 seconds in a state in which crimps were developed by twisting and loosening K 10 (*) in the length direction, they were stretched and cut. (Graph A) Comparative method After cooling at 45°C with the crimps stretched out, the crimps were stretched and cut.
(Graph B) In this way, it was found that by contacting the cooling medium, it became possible to cut with extremely low break draft, and the shrinkage rate C was also found to be almost negligible. Fix 1 crimp and break draft 4
It was found that if the material could be cut with a very small surface tension, the yield rate would also be much smaller.

Using the same sample as in Example 2, -10011:: crimps were overfed with liquid nitrogen and fixed by cooling for 4 seconds, and the relationship between the tensile strength required for cutting in 9 cases and the overfeed rate was shown. (Fig. 10) Example 5 An open denier tow composed of polyacrylonitrile edge line 3d was placed in the apparatus shown in Fig. 3 under the following conditions: 1, hot drawing ratio on a hot plate and shrinkage of the obtained sliver. The yield was compared with that of the conventional method, which was spun using a single tow reactor.

1) Invention conditions Hot plate temperature 12o (C) Residence time Approximately 15 (see) Tow crimping state Number of crimps 12 1 out of 9 inches crimping angle 60°≦0≦1200 Overfeed rate 1G (*) Low temperature Medium: Atmosphere inside liquid nitrogen cryostat 1! t -1oo (r,) Residence time 45 (see) Break draft 1.15 Spinning speed
100 (m/”) 2) Tow reactor one-side hot plate temperature 120 (U) Residence time Approx. 6 (Hatake ec) Daughterization/draft LSI (break draft) (z, sx) Spinning speed loo (m/-) The results are shown in Figure jI6. In the conventional method, the single fiber must be drawn to the breaking elongation K in order to perform tension cutting after hot drawing. is added.Therefore, the shrinkage rate is relatively higher than the hot stretching ratio^
Although there is a proportional relationship in the area where the hot stretching ratio is low, it was not possible to obtain a shrinkage rate below a certain value due to additional shrinkage due to tension cutting in the area where the hot stretching ratio was low. In other words, with the conventional method, the range of shrinkage obtained was extremely narrow. On the other hand, with the method of the present invention, it is possible to obtain a shrinkage curve that is linearly proportional to the heat frog stretching magnification up to the height shrinkage of the fiber. It is also found that it can be easily spun.

[BRIEF DESCRIPTION OF THE DRAWINGS] #441-3 are diagrams showing examples of steps for implementing the present invention, Figures 4 (a) and (b) are schematic diagrams showing the crimp state, and Figure 5 is a diagram showing an example of the process of carrying out the present invention. Figure 6 shows the relationship between the crimp angle and the shrinkage rate after boiling. Figure 7 shows the relationship between the tensile elongation and tensile strength of acrylic synthetic fiber (product name: Nikacimiron ■). Fig. 8 is a diagram showing the relationship between the temperature of the JFL fiber and the breaking strength during cutting. A diagram showing the relationship between the shrinkage rate and FIG. 10 is a diagram showing the relationship between the overfeed rate and the breaking strength. Patent applicant: Asahi Kasei Kogyo Co., Ltd. Figure 4 Figure 5 Figure 6 Hot drawing ratio 1 tensile elongation (%) → 1 hi (0C) 1 temperature (0C) Figure 1 o → Over-stretch ratio (%)

Claims (1)

[Scope of Claims] L A bundle of continuous fibers made of acrylic synthetic fibers having crimps is kept crimped in a cooling region and heated to -3G°C in the following state.
Immediately after contact with this cooling medium, the mahiki applies a drawing force to the east of the continuous fiber and/or Fi, m
A method for producing discontinuous fibers made of acrylic synthetic fibers by applying shear force and cutting six single fibers constituting a bundle of continuous fibers. * A bundle t of continuous fibers made of acrylic synthetic fibers having crimps is fed into the cooling zone with Og/C to maintain the crimps and in good condition while contacting the Og body at -10°C or below, Immediately after contact with this cooling medium, a drawing force and/or a shearing force is applied to the bundle of continuous fibers to cut each single fiber that makes up the bundle of continuous fibers, thereby creating a discontinuous strand of acrylic synthetic fibers. A method of manufacturing fiber bundles.