JPH039205B2 - - Google Patents

Description

[Detailed description of the invention]

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. 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 low heat shrinkage are required.
However, there is no known method for efficiently producing polyester fibers that fully satisfy all of these requirements. Conventionally, as a method for producing polyester fibers with high strength, low elongation, and low heat shrinkage, for example, (1) undrawn polyester yarn is drawn at a high temperature of 120 to 180°C to a factor of 4 times or more, followed by a second drawing. 1. A method of second-stage stretching to 1.1 to 1.6 times at a high temperature (150 to 220 °C) higher than the stretching temperature and further heat treatment for limited shrinkage at 130 to 200 °C (Tokuko Showa)
(Refer to Publication No. 42-21298) (2) After the undrawn polyester yarn is stretched in multiple stages by 3.8 to 7.5 times, it is held in contact with a final stretching roller kept at 180 to 230°C for 0.03 to 2 seconds, and then taken off without heating. A method of rapidly cooling with rollers and limiting shrinkage to 10% or less on the final roller or between the final roller and the take-up roller (Japanese Patent Application Laid-Open No. 1977-
(Refer to Publication No. 11809) (3) A method in which polyester drawn yarn obtained by a solution system or a steam injection system is subjected to tension heat treatment at 150 to 250°C, and then string slow heat treatment at 160 to 260°C and at a high temperature higher than the tension heat treatment temperature ( Japanese Unexamined Patent Publication 1972-
(Refer to Publication No. 63425) (4) Stretching with heat using steam or hot water at 60 to 100°C and stretching to 110 to 100°C before finishing stretching.
A method of stretching heat treatment with saturated steam at 150°C (see JP-A-48-73513) (5) A liquid bath or a gas bath is used for the first stage of stretching, and a tension state is applied during the second stage of stretching. A method of heating to 130 to 230° C. (see Japanese Patent Laid-Open No. 111114/1983) has been proposed. However, none of these methods can efficiently produce polyester fibers with high strength, low elongation, and low heat shrinkage, and even if they have high strength, they cannot produce polyester fibers with a strength of 8.0 g/d or more. . In other words, in method (1) above, high strength can be obtained due to stretching at high temperature and high magnification, but on the other hand,
Thermal shrinkage rate increases, and fibers with sufficiently low shrinkage cannot be obtained even with limited shrinkage heat treatment. In method (2), since the contact time of the fibers on the final drawing roller must be strictly regulated, many products deviate from the contact time regulation at the start of operation, resulting in poor product yield and additional work. There are drawbacks such as bad sex. In addition, in methods (3), (4), and (5), when performing the first stage stretching at a high magnification, it must be carried out in a solution system or a steam injection system, and the distribution of the temperature etc. of the solution or steam must be controlled. Difficult to control uniformly,
Poor control often causes the roller to get stuck. The present invention eliminates the drawbacks of such conventional methods and provides a method for obtaining polyester fibers with good stretchability, high strength, low elongation, and low heat shrinkage by high-magnification stretching. That is, when stretching polyester tow, the first stage is drawn at a stretching ratio of DR1 between a plurality of feed roller groups heated to 60 to 90°C and a plurality of first draw roller groups heated to 35 to 55°C. The tow is stretched and heated in a steam box having a length of 100 to 400 mm in the running direction of the tow, which is provided between the plurality of first draw roller groups and the next plurality of second draw roller groups. However, a second stage of stretching was performed at a stretching ratio of DR2, and at that time, DR1 and
The ratio of DR2 satisfies the following formula (1), and the total drawing ratio (product of DR1 and DR2) is such that the residual elongation of the drawn yarn is 20% or less, and then it is heated with a group of heated rollers at 190 to 220°C. It is heat treated. 1.6≦DR1/DR2≦2.6 ...(1) The first feature of the present invention is that one
The stretching in the stages is carried out between a plurality of feed roller groups heated to 60 to 90°C and a first draw roller group. This stretching method has the disadvantage that the maximum stretching ratio is lower than the method of stretching using local heating using steam or warm water.
Since the polyester tow is heated by multiple rollers, the temperature distribution of the polyester tow is uniform, and there are almost no problems such as fuzzing or cutting of the polyester tow, and the stretching condition is good. The heating temperature of the roller is higher than the glass transition temperature of the polyester fiber and lower than the temperature at which super draw occurs, preferably 60 to 90°C. The second feature of the present invention is that the second stage of stretching is 35
A steam box is provided between a plurality of first draw roller groups and a plurality of second draw roller groups heated to ~55°C. The length of the steam box is required to be 100 to 400 mm in the direction of travel of the tow. If it is less than 100 mm, the tow temperature will not rise and may cause problems such as cutting. If the length exceeds 400 mm, uniform stretching will not be possible and fuzz will likely occur. In stretching using local heating, the tow temperature does not rise rapidly to the desired temperature, and non-uniform temperature distribution tends to occur. When the roller temperature of the first draw roller group is heated to 35 to 55° C. as an auxiliary heating means, troubles such as fluffing and cutting do not occur and the stretching condition becomes good. High strength, low elongation cotton is produced with a normal strength of 6 to 7.
g/d and elongation of 30-35%, it must be drawn at a high draw ratio. Furthermore, since the stretching means in the first stage and the second stage are different, the distribution of the stretching ratios in the first stage and the second stage is important. DR1/DR2
must be 1.6 or higher and 2.6 or lower. When it is less than 1.6, the stretching is mainly done by local heating in the second stage, so the deterioration of the stretching condition due to uneven temperature distribution of the polyester tow becomes noticeable. Moreover, if it exceeds 2.6, the first stage stretching becomes the main one, and the stretching condition deteriorates. The total stretching ratio (product of DR1 and DR2) varies depending on the degree of orientation of the undrawn yarn, but it needs to be selected within a range such that the residual elongation is 20% or less. If the residual elongation exceeds 20%, it is not preferable because when used as sewing thread or industrial fabric, it will elongate when high tension is applied, resulting in a decrease in dimensional stability. Next, in order to stabilize physical properties such as strength and elongation, and to reduce heat shrinkage during heating, heat treatment is performed using a group of heating rollers at 190 to 220°C.
Heat treatment at temperatures below 190°C will result in poor dimensional stability during heating, especially during dyeing and finishing, while heat treatment at temperatures above 220°C will result in increased elongation of the fibers obtained by drawing. This results in high strength. A polyester fiber with low elongation and low heat shrinkage is produced. It is particularly advantageous for obtaining high-strength polyester fibers of 8.0 g/d or more. The polyester constituting the polyester fiber of the present invention is mainly polyethylene terephthalate, and its intrinsic viscosity (phenol/tetrachloroethane=1/1, 25°C) [η] is preferably 0.6 or more. Further, it may be copolymerized with a third component within a range (for example, 15 mol % or less) that does not essentially change its properties. Examples of the third component include isophthalic acid, 5-sodium-sulfoisophthalic acid, paraoxybenzoic acid, diethylene glycol, and 1,4-butanediol. These polyesters may contain small amounts of additives such as matting agents, colorants, stabilizers, flame retardants, moisture absorbers, and the like. The present invention makes it possible to obtain polyester fibers with high strength and low heat shrinkage, which could not be produced by conventionally known methods.
In particular, when this is blended with cotton fiber as a staple fiber, spun yarn can be obtained with high efficiency with little yarn breakage even if the spinning spindle rotation speed is increased. Furthermore, even if the spun yarn obtained in this way is used to weave, for example, taffeta and finished by a normal method, the shrinkage of the spun yarn on the fabric is small and the heat shrinkage rate of polyester staple fiber is low. Since there is no localized unevenness of shrinkage, it has the advantage that extremely high quality products can be obtained. The present invention will be explained in more detail with reference to Examples below. In addition, the measuring method of strength, elongation, and heat shrinkage rate in Examples is as follows. Strength (g/d)/Elongation (%): Strength when the sample is fixed in a constant speed loading type tensile tester/Matsukenji so that the sample length is 20 mm, and is pulled and cut at a loading rate of 20 g/min.・Find elongation. The strength is a value determined by the fineness of the single yarn determined by a conventional method. Heat shrinkage rate (%): Shrinkage rate when left in air at 170°C for 20 minutes. Example 1 Polyethylene terephthalate with an intrinsic viscosity of 0.65 was spun at a take-up speed of 1000 m/min using a conventional method.
An undrawn yarn tow of approximately 2.5 million denier was obtained. Next, the undrawn yarn tow was drawn under the drawing conditions shown in Table 1, using a local heating device with a steam box having a width of 300 mm between the first draw roller and the second draw roller, and the fiber length was adjusted using a cutter.
It was cut into 38mm pieces to make staple fibers. The resulting yarn breakage during drawing and raw cotton properties are also shown in Table 1. There is no deterioration in drawing condition due to thread breakage, and the raw cotton properties are also satisfactory.

[Table] Comparative Example 1 The undrawn yarn tow used in Example 1 was drawn under the drawing conditions shown in Table 2. A local heating device using a steam box with a width of 300 mm was used between the first draw roller and the second draw roller.

[Table] Experiment No. In samples 1 to 3, 6, and 7, thread breakage occurred frequently and the stretching condition was poor. Experiment No. 4 has a high heat shrinkage rate,
When spun yarn was made using this raw cotton, taffeta was woven, and finished using the usual method, the quality deteriorated due to uneven shrinkage. Experiment No. In sample No. 5, raw cotton with high strength and low elongation could not be obtained. Comparative Example 2 Experiment No. of Example 1. 1, No.. Stretching was carried out using a local heating device with a steam box length of 50 mm and a steam box length of 500 mm using each roller temperature condition of 2. Table 3 shows the stretching results when the steam box length is 50 mm and 500 mm.
It is shown in Table 4. In all cases, yarn breakage occurred frequently and the stretching condition was poor.

【table】

【table】

Claims (1)

[Claims] 1. When stretching polyester tow, 60 to 90
A group of multiple feed rollers heated to 35 to 55 °C
A first stage of stretching is performed at a draw ratio of DR1 between a plurality of first draw roller groups heated to ℃.
While heating with a steam box having a length of 100 to 400 mm in the running direction of the tow, which is installed between the draw roller group, the tow is further stretched at a stretching ratio of DR2 to 2.
At that time, the ratio of DR1 and DR2 satisfies the following formula (1), and the total stretching ratio (DR1 and
A method for producing a high-strength polyester fiber, characterized in that the residual elongation of the drawn yarn is 20% or less (product of DR2), and then heat-treated with a group of heating rollers at 190 to 220°C. 1.6≦DR1／DR2≦2.6……(1)