JPH0153367B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing polyester fibers, and particularly to a method for producing polyester fibers having high strength, low elongation, and low heat shrinkage. (Prior Art) Polyester fibers, particularly polyethylene terephthalate fibers, have many excellent properties and are therefore widely used in various applications. However, for sewing threads, industrial fabrics, and even clothing fabrics, polyester fibers with higher strength, lower elongation, and lower heat shrinkage are required.
However, there is no known method for efficiently producing polyester fibers that fully satisfy all of these required performances. Conventionally, methods for producing polyester fibers with high strength, low elongation, and low heat shrinkage include (1)
The undrawn polyester yarn is first-stage stretched to 4 times or more at a high temperature of 120 to 180°C, followed by second-stage stretching to 1.1 to 1.6 times at a high temperature (150 to 220°C) higher than the first stage drawing temperature, Further, a method of limited shrinkage heat treatment at 130 to 200°C (Japanese Patent Publication No. 1972-21298) (2) The polyester drawn yarn is subjected to tension heat treatment at 150 to 250°C, and then 160 to 260°C.
and a method of relaxing heat treatment at a high temperature higher than the tension heat treatment temperature (Japanese Patent Application Laid-open No. 52-63425), (3) 60-100
A method in which stretching is started with wet heat using steam or warm water at 110°C to 150°C, and one-stage stretching heat treatment is performed with saturated steam at 110 to 150°C before the end of stretching (Japanese Patent Application Laid-Open No. 48-73513
(4) Liquid bath stretching is carried out to a density of 1.350 to 1.365 in the first stage, and then the density is adjusted in the second stage.
A method has been proposed in which the film is stretched in a steam bath to obtain a film thickness of 1.365 or higher (Japanese Patent Publication No. 1983-2060). However, none of these methods can efficiently produce polyester fibers with high strength, low elongation, and low heat shrinkage. Can not. That is, in the method (1) above, since the undrawn polyester yarn is stretched in the first step by a factor of 4 or more at a high temperature of 120 to 180°C, there is a problem that the stretching temperature becomes too high and yarn breakage occurs frequently. Method (2) involves two high-temperature heat treatment steps, and although it has the effect of lowering the heat shrinkage rate, it is impractical because it uses a large amount of energy, and the elongation of the high-temperature relaxation heat treatment increases. There is a drawback that it does. (3)
In the method described above, stretching is performed in one stage, so not only is it difficult to achieve a high strength of 8.0 g/d or more, but even if high strength is achieved, there is a lot of roller wrapping, resulting in poor workability. Furthermore, since the heat treatment is performed at the same time as the stretching, fibers with low heat shrinkage cannot be obtained. In method (4), liquid bath stretching is performed, but the density is 1.350~1.350 in the first stage.
1.365, and in order to obtain high strength due to insufficient increase in density, it is necessary to further increase the drawing ratio in the second stage, which causes deterioration of the drawing condition due to the yarn being wound around the rollers. The present inventors have already developed a method for easily producing polyester fibers with high strength, low elongation, and low heat shrinkage by solving the drawbacks of the conventional methods.
This was proposed in Publication No. 59-150109. This method works when the temperature of the feed roller group is between 35 and 55.
°C, 65 at the bottom of the final roller in feed roller county
Set up a ~80℃ hot water bath and place the tow 5~40mm below the warm water surface.
However, since the temperature of the feed roller group is low, stretching unevenness is likely to occur, and this tendency becomes particularly pronounced when the denier of the tow becomes large, resulting in frequent yarn breakage. (Problems to be Solved by the Invention) The present invention eliminates the various drawbacks of such conventional methods, allows high-strength stretching to be carried out under good stretching conditions, and achieves high strength, low elongation, and low heat shrinkage. The technical problem is to provide a method for easily producing polyester fibers. (Means for Solving the Problems) That is, the present invention provides unstretched polyester tow to a feed roller group, a first draw roller group, and a second draw roller group.
In the method of performing two-stage stretching between draw roller groups and then heat treatment with a heating roller group, the feed roller group is heated to 60 to 90°C and the first draw roller group is heated to 35 to 55°C. A nip roller is placed below the last roller to grip the tow, a hot water bath of 60 to 95°C is provided near the contact point between the final roller of the feed roller group and the nip roller, the tow is passed under the hot water surface, and the immersion length is Z ₁ . (mm) satisfies the following formula (1), the first stage is stretched between the feed roller group and the first draw roller group at the first stage stretching ratio DR, and then immediately after the first draw roller group The second stage of stretching is carried out at a second stage stretching ratio of DR ₂ between the first draw roller group and the second draw roller group through a steam box with a box length Z ₂ (mm) that satisfies the following formula (2), which is installed in In this case, DR ₁ /DR ₂
The ratio of 190
This is a method for producing high-strength polyester fiber, which is characterized by heat treatment using a group of heating rollers at ~220°C. 5√ ₁・y ₁ ≦Z ₁ ≦700 (1) 2√ ₂・y ₂ ≦Z ₂ ≦600 (2) 2.0≦DR ₁ /DR ₂ ≦2.9 (3) (Here, X ₁ and X ₂ are The width of the tow passing through each feed roller group and first draw roller group is 1 mm.
The value obtained by multiplying the number of denier per hit by 10 ^-4 [However,
X ₁ ≦5, X ₂ ≦2.5], y ₁ and y ₂ respectively indicate the speed (m/min) of the tow passing through the feed roller group and the first draw roller group. ) Figure 1 is a schematic diagram of the stretching and heat treatment equipment used in the present invention, and as described later,
7 is stretched in two stages between the feed roller groups 1 to 7 and the first draw roller group 9 to 15 and between the first draw roller group and the second draw roller group 16 to 22, and then stretched to the heating roller group 23 to 26. It is heat set and sent to the next process. 8 in the figure is the Nitsu Pro roller,
It is installed below the final roller 7 of the feed roller group. This nip roller 8 is very effective in fixing the stretching point. The first stage drawing of the present invention is carried out between the heated feed roller group and the heated first draw roller group via a hot water bath 28 in which the exit tow of the final roller 7 of the feed roller group is immersed. The exit tow of the last roller 7 of the feed roller group is immersed in a warm water bath in order to fix the drawing point of the polyester tow at the bottom of said last roller. Hot water or hot oil can be used as the heating medium in the hot water bath, and these heating mediums are used as a thermal stimulus to initiate the drawing. Hot water bath temperature is 60~
It is 95℃. At a low temperature of less than 60°C, there are many stretching points that are not fixed, resulting in unstretched parts being mixed in and yarn breakage occurring frequently. Furthermore, if the temperature exceeds 95°C, a super draw phenomenon occurs and high strength fibers cannot be obtained. Immersion length of polyester tow in hot water bath Z ₁ (mm)
The optimum range is determined by the value X ₁ obtained by multiplying the denier number per 1 mm width of the tow passing through the first draw roller group by 10 ^-4 and the tow speed (m/min). That is, the immersion length may be determined within the range expressed by the following formula. 5√ ₁・y ₁ ≦Z ₁ ≦700 (however, X ₁ ≦5) If the immersion length is less than 5√ ₁・y ₁ (mm), undrawn yarn will be mixed in or yarn breakage will occur frequently. On the other hand, if it exceeds 700 mm, the drawing point of the tow will not be fixed at the final roller exit section, causing frequent yarn breakage. When X ₁ >5, the thickness of the tow is too large, and uniform heating cannot be achieved, resulting in frequent yarn breakage. This phenomenon becomes noticeable when drawing at a high magnification in order to obtain high-strength fibers. By the way, when applying only thermal stimulation with hot water, the tow temperature does not rise rapidly to the target temperature, and uneven temperature distribution tends to occur. However, heating the rollers of the feed roller group to 60 to 90°C has the effect of eliminating the temperature unevenness, preventing fuzz, yarn breakage, etc., and improving the stretching condition. When the roller temperature is less than 60°C, the effect of heating on the stretching condition is small. Furthermore, if the temperature exceeds 90°C, the stretching point of the tow moves in the direction opposite to the running direction of the tow from the gripping point between the final roller of the feed roller and the nip roller and becomes unstable, resulting in poor stretching performance. Further, the present invention is characterized in that a nip roller is disposed below the last roller of the feed roller group to grip the tow, and the gripping force of the nip roller makes it easier to fix the stretching point, so that Coupled with heating, the stretching point is aligned immediately after the gripping point of the nip roller, preventing the occurrence of stretching unevenness and reducing yarn breakage. The second stage stretching in the present invention is carried out using a steam box 29 provided immediately after the first draw roller group between the first draw roller group and the second draw roller group.
It is done through. In this case, the number of denier per 1 mm width of the tow passing through the first draw roller group is
The value multiplied by 10 ^-4 is X ₂ , and the tow speed is y ₂ (m/min)
Then, the length Z ₂ (mm) of the steam box is 2√ ₂・ in the strike direction of the polyester tow.
It is necessary to satisfy y ₂ ≦Z ₂ ≦600 (however, X ₂ ≦2.5). If Z ₂ is less than 2√ ₂ ·y, the tow temperature will not rise, causing thread breakage, etc. On the other hand, if it exceeds 600 mm, uniform stretching will not be possible.
Fuzz, etc. is likely to occur. When X ₂ > 2.5, the tow is too thick and cannot be heated uniformly, resulting in frequent yarn breakage. Also, the roller temperature of the first draw roller group is 35~
It needs to be at 55℃. If the temperature is less than 35°C, the tow temperature will not rise quickly to the desired temperature, and uneven temperature distribution will tend to occur. On the other hand, if the roller temperature exceeds 55°C, the drawing point of the tow moves from the inlet of the steam box in a direction opposite to the running direction of the tow, making it unstable, resulting in poor drawing performance. The steam supplied to the steam box is usually saturated steam at a pressure of 0.5 to 10 kg/cm ² . Even when heated with steam, the tow temperature does not rise rapidly to the desired temperature, and uneven temperature distribution tends to occur. When the first draw roller group is heated to 35 to 55° C. as an auxiliary heating means, fluff, thread breakage, etc. do not occur, and the stretching condition becomes good. In order to produce high-strength, low-elongation cotton, it is necessary to draw at a higher draw ratio than in the case of producing cotton with a normal strength of 6 to 7 g/d and elongation of 30 to 35%. Furthermore, since the stretching media used in the first stage and the second stage are different between hot water and steam, the distribution of the stretching ratios in the first stage and the second stage is important. In the present invention,
The ratio of DR ₁ /DR ₂ is preferably 1.5 or more and 2.9 or less.
If the stretching ratio is less than 1.5, 1-stage stretching DR ₁
Since the tension is too low, the tension in the first stage is also small, making it difficult to fix the stretching point, and the stretching condition deteriorates significantly. Moreover, when it exceeds 2.9, the stretching in the first stage becomes the main one, and the stretching condition deteriorates. In the present invention, in order to stabilize the physical properties such as fiber strength and elongation, and to improve the fiber dimensional stability during heating, that is, to reduce the thermal shrinkage rate, heating at 190 to 220 ° C. Heat treatment is performed using a group of rollers. Heat treatment at temperatures below 190°C will result in poor dimensional stability during heating, especially during dyeing and finishing of fibers.
Heat treatment at temperatures above 220°C increases the elongation of the fibers obtained by drawing. As described above, the polyester undrawn tow is subjected to the first stage of hot drawing between the heated feed roller group and the first draw roller group via a hot water bath, and then the first draw roller group and the second draw roller group are heated. A polyester fiber with high strength, low elongation, and low heat shrinkage is produced by a second stage of hot drawing in a steam box, followed by heat treatment with a group of heated rollers. The method of the present invention is advantageous for obtaining high strength polyester fibers, especially those of 8.0 g/d or more. In the present invention, the polyester constituting the polyester fiber is mainly polyethylene terephthalate, but it may be copolymerized with a third component within a range that does not essentially change the properties (for example, 15 mol% or less). Examples of the third component include isophthalic acid, 5-sodium sulfoisophthalic acid, paraoxybenzoic acid, diethylene glycol, and 1,4-butanediol. The intrinsic viscosity [η] of the polyester is preferably 0.60 or more. If it is less than 0.60, it is difficult to obtain high strength fibers. These polyesters are matting agents,
It may contain small amounts of additives such as colorants, stabilizers, flame retardants, moisture absorbers, etc. (Example) The present invention will be explained in further detail by giving examples below. In addition, the measuring method of strength, elongation, and heat shrinkage rate in Examples is as follows. Strength (g/d), elongation (%) Strength and elongation when the sample is fixed to a constant speed loading type tensile tester Matsukenji so that the sample length is 20 mm and is pulled and cut at a loading speed of 20 g/min. seek. The strength is the value obtained by dividing this tenacity value by the fineness of the single yarn determined by a conventional method. Heat shrinkage rate (%) This is the shrinkage rate when left in air at 170℃ for 20 minutes. Example 1 The intrinsic viscosity measured at 25°C using a mixed solution of phenol and tetrachloroethane (mixing ratio 1:1) as a solvent was
0.65 polyethylene terephthalate was spun in a conventional manner to obtain an undrawn yarn tow of approximately 150 denier consisting of six sub-tows of 250,000 denier. Next, the unstretched tow was stretched using a stretching apparatus shown in FIG. The immersion depth of the tow in hot water is 10 mm, the immersion length of the tow is 300 mm, the length of the steam box is 200 mm, and the temperature of the second draw roller group is
The temperature was 30° C., the stretching speed (speed of the tow passing through the second draw roller) was 150 m/min, and other stretching conditions were as shown in Table 1. After stretching, the fibers were crimped by the indentation method and cut into fibers of 38 mm in length using a cutter to obtain staple fibers (raw cotton). Table 2 shows the state of yarn breakage and raw cotton properties. There was no deterioration in drawing condition due to yarn breakage, and the raw cotton properties were also satisfactory. Comparative Example 1 Using the undrawn yarn tow and the drawing device used in Example 1, drawing was carried out under the drawing conditions shown in Table 3. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. A method in which an unstretched polyester tow is stretched in two stages between a feed roller group, a first draw roller group, and a second draw roller group, and then heat-treated with a heating roller group, in which the feed roller group is 90
℃ and the first draw roller group to 35~55℃.
℃, place a nip roller below the last roller in the feed roller group to grip the tow, set up a hot water bath at 60 to 95°C near the contact point between the last roller in the feed roller group and the nip roller, and place the tow on the hot water surface. The film was passed through the film, and the film was run so that the immersion length Z ₁ (mm) satisfied the following formula (1), and the film was stretched in the first stage at a first stage stretching ratio of DR ₁ between the feed roller group and the first draw roller group. Then, the second stage is heated between the first draw roller group and the second draw roller group through a steam box with a box length Z ₂ (mm) that satisfies the following formula (2), which is provided immediately after the first draw roller group. A second stage of stretching is performed at a stretching ratio of DR ₂ , at which time the ratio of DR ₁ /DR ₂ satisfies the following formula (3), and then heat treatment is performed using a group of heating rollers at 190 to 220°C. A method for producing high-strength polyester fiber. 5√ ₁・y ₁ ≦Z ₁ ≦700 (1) 2√ ₂・y ₂ ≦Z ₂ ≦600 (2) 2.0≦DR ₁ /DR ₂ ≦2.9 (3) (Here, X ₁ and X ₂ are The width of the tow passing through each feed roller group and first draw roller group is 1 mm.
The value obtained by multiplying the number of denier per hit by 10 ^-4 [However,
X ₁ ≦5, X ₂ ≦2.5], y ₁ and y ₂ respectively indicate the speed (m/min) of the tow passing through the feed roller group and the first draw roller group. )