JPS6036488B2 - Manufacturing method of high strength polyester sliver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a sliver made of polyester staple for use in high-strength spun yarn, which is uniform and has a high total single fiber strength.

Conventionally, in fields that require particularly high strength, such as industrial applications and sewing thread applications, spun yarns made of polyester and polyamide fiber filaments and polyvinyl alcohol fibers have been used, and polyester spun yarns have not been used much.

The reason for this is that to make polyester high-strength spun yarn, it is usually necessary to carry out two-stage drawing, and in conventional wet drawing systems, it is easy to cause wrapping around the roller due to single yarn breakage and uneven drawing due to nip defects. This is because in order to avoid troubles, only thin undrawn yarns can be used as raw materials, resulting in extremely low productivity and extremely high production costs. Furthermore, the conventional tow manufacturing process itself is a wet method using steam or hot water to achieve uniform stretching, and it takes a lot of effort to reduce the moisture content to 1 to 2% or less, which is enough to eliminate process troubles in later processes. Large-scale drying equipment was required.

This not only required a huge investment in equipment but also required a lot of energy as a heat source, so unless it was possible to produce thick tow, it would not be cost-effective and would not be suitable for manufacturing high-strength staples, so it has not been realized. . On the other hand, although it is possible to produce high-strength spun yarn using high-viscosity chips, multi-hole spinning, such as in staple production, frequently causes problems such as nozzle clogging, dripping, and increased furnace pressure, making stable production difficult. Very difficult.

Dry stretching using a hot plate in normal two-stage stretching cannot uniformly stretch thick unstretched tows of tens of thousands of deniers or more, and therefore it is not possible to obtain high-strength staples, and the cut rate is often uneven. However, it is difficult to obtain a uniform sliver, and furthermore, single yarn breakage tends to cause winding around the rollers, resulting in very poor operability.

As a result of extensive research into this stretching mechanism, the inventors of the present invention discovered that a uniform, high-strength tow can be stably obtained by applying a special dry heat stretching process, and this tow can be continuously produced. It was discovered that by carrying out drafting, it is possible to obtain a uniform high-strength sliver that maintains the uniformity and high strength of the tow, which has not been seen in the past. That is, in the dry heat stretching using a general hot plate, as shown in FIG.
It is pulled out and stretched by the stretching roller 8, and the netting line, which is a collection of stretching points (netking points) on the hot plate 5, forms an arc shape AE'A in the direction of travel.
becomes.

This is because the fiber layer is thicker at the center, and it takes more time for heat to be transmitted to the inner core of the fiber layer than to the thinner end portions. Such an arcuate necking line causes a difference in the thermal history experienced by the tow at the ends and the center.
In other words, the woven part is stretched at A or A', and at the same time the stretched tow receives a sufficient setting action between AB or A'B', but the central part is not stretched because the stretching point is E'. In the tow state, it undergoes thermal history between EE'. This unstretched state has extremely low orientation and is extremely unstable to heat, so once it is subjected to thermal history, its physical properties change significantly. Therefore, the toe physical properties after stretching will be significantly different between the center part and the end parts. Especially in the center, the tow has low elongation and tends to deteriorate. As a result of such non-uniform stretching, the tow not only has dyed spots and strong spots, but also has stress concentrated in areas with low elongation during stretch-cutting, causing stress in these areas. The cutting points tend to be concentrated in one place, resulting in group breaks, and the resulting sliver has large spots.
Furthermore, if this group breakage is significant, even continuous tension cutting becomes impossible, making it impossible to obtain a high-strength sliver. In addition, single yarn breakage in the tow state and overlong fibers are likely to occur due to uneven stretch cutting, leading to problems such as excessive winding around rollers. The present inventors have eliminated this phenomenon in conventional dry-heat stretching, and have achieved uniform rate cutting by supplying a high-strength and uniform stretched tow to the tension-cutting zone. In order to obtain the best sliver, as a result of intensive research on the stretching mechanism and stretching method, as mentioned above, by selecting a special dry heat stretching mechanism and stretching conditions, we were able to achieve an improvement that could not be achieved using the conventional two-stage dry heat stretching method. This made it possible to produce a uniform and highly strong sliver under stable conditions, which had previously been impossible to obtain. The method for producing sliver of the present invention involves stretching an unstretched tow made of polyethylene terephthalate fibers in two stages by bringing them into contact with a heating element, and then stretching the sliver in the first stage using heating pins or the like. Using a shaped heating element, the temperature is 80 to 10,000, and the maximum stretching ratio is 95 to 95.
Stretching is performed under conditions in the range of 99%, and then the second stage of stretching is performed using a heating pin or a heating element of the same shape, at a temperature of 150 to 23,000, and at a stretching ratio of 150 to 23,000, and at a stretching ratio of Stretching is carried out so that the total stretching ratio, which is the product of the second-stage stretching ratio, is in the range of 85 to 95% of the maximum total stretching ratio, and then tension cutting is performed without substantially stopping the fiber flow. This is a method for producing a high-strength polyester sliver.

(However, under the maximum total stretching ratio = given first-stage stretching conditions and second-stage stretching temperature conditions, the first and second stages are Product of stretching ratio.

) Hereinafter, the method for manufacturing a high-strength polyester sliver according to the present invention will first be explained based on the drawings.

FIG. 2 is a process schematic diagram showing one embodiment of the manufacturing method of the present invention.

In the figure, the unstretched tow 2 pulled out from the unstretched tow can passes through the towing device 3 and is towed into a sheet with a uniform thickness. It is guided to a first stage stretching zone consisting of rollers 8.

Younger brother--The stretching pin 6 contacts the unstretched toe, which is stretched by the first stretching roller 81 with the stretching point fixed in line on the hot pin. At this time, the drawing pin temperature is higher than the glass transition point, preferably 80 to 10,000. Subsequently, the toe is supplied to a second stage stretching zone consisting of a second stretching pin 9 and a second stretching roller 0, and is
The paper is brought into contact with the second drawing pin 9 which is heated to 0, and is fixed with the drawing points aligned in a straight line, and then taken up by the second drawing roller 105 and subjected to secondary drawing, without receiving any relaxation effect. It is continuously supplied to the tension cutting zone, and is 1.5 to 9. The cutting is carried out by a tension cutting roller 11 which rotates at the speed of a sharp sound. Textile East, which has been cut off, has cut its revised rate. - A sliver 1 which has been subjected to correction drafting and drafting by rollers 12 and 13 and has a predetermined fiber length and thickness.
4, which is picked up by the calendar roller 15 and stored in the sliver can 16. In the method according to the present invention, it is particularly important to carry out the stretching in such a way that the stretching points are aligned in a straight line in each of the two stages of stretching. That is, a stretching process that produces an arc-shaped necking line as shown in FIG. 1 is not adopted in the present invention. In the present invention, stretching is carried out such that the variation width 1 of the necking line is fixed to 1=3 or less as shown in FIG. In other words, if the fluctuation width 1 is 3 degrees or less, the difference in thermal history is minute considering the running speed of the tow and the contact length with the heating pin, and it is considered that the tow is substantially fixed in a straight line. Become. That is, in the present invention, "straight line" refers to a narrow band having a width of 3 willows or less. Such stretching can of course be called uniform stretching. Such stretching is performed by appropriately selecting the shape of the heating body disposed in the stretching castle.

According to the findings of the present inventors, if the heating body is a cylindrical (pin-shaped) or hot plate with an arcuate end, the stretching as described below can be particularly effectively achieved, and generally, as shown in FIG. As shown in the figure, it seems that the heating body may have a curved surface with a diameter D of 5 to 15 mm, preferably 40 to 100 mm, at the portion in contact with the tow. In the method for producing a high-strength polyester sliver according to the present invention, a particularly important point is the set value of the stretching ratio in each of the two stages of stretching treatment.

That is, the stretching ratio in the first stage is set to a value of 95 to 99% of the maximum stretching ratio that allows uniform stretching in the first stage, and
The draw ratio of each step is set so that the total draw ratio, which is the product of the draw ratio of the first step and the draw ratio of the second step, is 8 of the maximum total draw ratio.
It is necessary to stretch the film to a value of 5 to 95%.

Outside this range, it will not be possible to obtain a polyester sliver that is uniform and has high short fiber strength under stable operability.

The polyester sliver obtained by the method of the invention generally has a sliver uniformity factor of sliver 1
The coefficient is 4.0 or less, and the short fiber strength is 7.0/d or more.

In the conventional tow drawing/dial cutting method, it has not been possible to obtain a sliver with excellent properties in both the sliver 1 coefficient and the short fiber strength. That is, in the conventional tow drawing/drainage cutting technique, it has not been possible to obtain the uniformity of the sliver of the present invention due to the above-mentioned problems such as moisture content and necking lines. Even if a product with high strength could be obtained, in most cases, the uniformity was further impaired due to the unreasonable stretching conditions. Hereinafter, the first and second stage stretching ratios in the method of the present invention will be explained in more detail.

According to the findings of the present inventors, the first stretching ratio and the second stretching ratio are the limits at which uniform stretching can be performed under a given stretching pin temperature in the first stretching, that is, the necking line fluctuation range is the same as described above. The maximum stretching ratio that allows stretching to be less than or equal to 3 Yanagi is the primary maximum stretching ratio d, max), and the primary stretching ratio is d. Furthermore, in the second drawing zone, under the given primary drawing conditions and second drawing temperature conditions, the product of the first and second draw ratios immediately before single filament breakage begins to occur in the drawn tow due to drawing is calculated. Maximum total stretching ratio dt (max
), if the product of the primary and secondary draw ratios is the total draw ratio dt, the strength of the obtained sliver, the uniformity of the sliver,
Surprisingly, the number of rolls due to roller winding and uneven tension cutting is d, /d, (max), dt/dt (max
).

According to the studies of the present inventors, firstly, the short fiber strength of the obtained sliver was found to be 5.0 to 6.5 tanodenier, which is the general value of conventional polyester sliver.
d) of the sliver of the invention which is significantly greater than 7.
In order to make it 0 evening/d or more, it needs to be within the following conditions.

o. 95≦d, /d, (max>...
...(1'o.85≦dt/dt(max)
......{2} Also, the sliver symmetry is
It is mainly influenced by dt/dt(max), and in order to make 1 coefficient = 4.0 or less, it is necessary to satisfy the following conditions.

0.83≦dt/dt(max)mi0.95 ・
...t3'Next, the number of fences due to roller wrapping and uneven punching is d, /d, (max), dt/dt (m
ax), and in order to reduce the number of machines to the same level as the currently widely used polyacronitrile (acrylic) turbo stapler and Parlock tension-cut spinning, the following conditions must be met: It must be in

o. 80≦d,/d, (max)<0.99 ・
・・・・・・【4}0.65≦dt/dt(max)SO
．． 95 ・・・・・・{5} Therefore, in order to stably bottle a highly strong and uniform sliver,
d, /d, (max), dt/dt (max) (1}
~The following equation (6) and [7] that simultaneously satisfy equation {5)
It must fall within the range expressed by .

o. 95≦d,/d, (max)<0.99 ・
・・・・・・(6}o.85≦dt/dt(max) SO
．． 95 ...{7} Table 1 shows that the present inventors set the primary stretching temperature at 9000 and the secondary stretching temperature at 1800.
The results were experimentally confirmed by supplying 15 undrawn polyester yarns with a 7-way denier of 0 and varying the primary draw ratio and secondary draw ratio as undrawn yarn tows. Table 1 To further explain the polyester sliver according to the present invention, it has an extremely low elongation of 9.5% or less, and this low elongation also greatly contributes to the uniformity.

Further, the lower limit of the sliver 1 coefficient is generally about 3.5, and in some cases, a sliver 1 coefficient of about 3.0 with extremely high uniformity can be obtained. As described above, the present invention is extremely useful industrially because it provides a polyester sliver produced by the toe-drawing-stretch-cut method, which is optimal for use in polyester high-strength spun yarns, and has uniformity and high single fiber strength.

In addition, in the description of the present invention, the sliver 1 coefficient is
It is a value obtained by dividing the actual Worcester mottling U% of the target sliver for which 1 coefficient is to be obtained by the ideal Worcester mottling U% of an ideal sliver that is considered to be completely uniform. Specifically, it is calculated by the following formula, Slur small - 1 coefficient = basic value lamp However, q is the number of fibers in the sliver cross section, and is a value determined by q = (total sliver denier) / (short fiber denier).

Examples are described below.

Example 1 Using 10 unstretched polyester tows of 110,000 denier,
The first stretching temperature is 9500, the first stretching ratio is 4.03 times, which corresponds to 96% of the primary maximum stretching ratio, and the second stretching ratio is set to 90% of the maximum total stretching ratio in the second stretching zone. Stretching ratio: 1.475 times, secondary stretching temperature: 170
Stretching was carried out at qo, followed by tension cutting and modified tension cutting to obtain a sliver with a thickness of 2.07mm/skin.

The short fiber strength of the sliver at this time was 7.50/d,
A sliver with a 1 coefficient of 3.71 and high strength and uniformity was obtained, and the number of thickness cutting machines was 0.5 times/10 hours, allowing stable spinning. On the other hand, if the secondary draw ratio is set to 1.362 times so that the maximum draw ratio becomes 98% of the maximum total draw ratio, and the other conditions are the same as above, the short fiber strength of the sliver is 8.04 ta'. A very high strength product was obtained, ie, sliver 1 coefficient = 4.6, but on the other hand, not only was the sliver 1 coefficient = 4.6, which was highly uneven, but the number of thicknesses was 3.0 times/10 hr, which was poor in operability.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the necking line of normal tow dry heat drawing, Fig. 2 is a process schematic diagram showing one embodiment of the method for producing high strength polyester sliver according to the present invention, and Fig. 3 is a diagram showing the present invention. FIG. 4 is an explanatory diagram showing the necking line of two-stage stretching in the method according to the present invention. 1: End drawn tow can, 2: Undrawn tow, 3: Adjusting tow device, 4: Supply roller, 5: Hot plate, 6: First drawing pin, 7
: Stretching toe, 8: First stretching roller, 9: Second stretching pin,
10: Second stretching. 11: Main tension cutting roller, 12, 13: Modified tension cutting roller, 14: Sliver, 15: Calendar roller, 1
6: Sliver Kens. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. When an undrawn tow made of polyethylene terephthalate fiber is brought into contact with a heating element and stretched in two stages, and then stretched, the first stage of stretching is first carried out using a heating pin or a heating element of the same shape. Stretching is carried out at a temperature of 80 to 100°C and within a range of 95 to 99% of the maximum stretching ratio, and then the second stage of stretching is carried out at a temperature of 150 to 230°C using a heating pin or a heating element of the same shape. and the stretching ratio is such that the total stretching ratio, which is the product of the first stage stretching ratio and the second stage stretching ratio, is in the range of 85 to 95% of the maximum total stretching ratio, and then A method for producing a high-strength polyester sliver, which is characterized by cutting the fiber flow substantially without stopping it. (However, under the maximum total stretching ratio = given first-stage stretching conditions and second-stage stretching temperature conditions, (Product of stretching ratio.)