JPH01207437A - Method for drawing synthetic fiber - Google Patents

Abstract

PURPOSE:To enable drawing at a high draw ratio and simultaneously obtain a remarkably high strength, by applying gradients within a specific range of conditions to steam temperature and pressure in streaming treatment in a roller drawing process. CONSTITUTION:An undrawn yarn (Y), passing through a take-off roller 11 having a separate roller 12 and emerging from a feed roller 13 having a separate roller 14 is drawn between the feed roller and a draw roller 15. In the process, in order to continuously and substantially divide a necking point fixing zone and a molecular chain orienting and highly crystallizing zone with a steam chamber 16 in the first stage and a steam chamber 16' in the second stay, gradients satisfying the relations T1>=200 deg.C, T2>=T1+20 deg.C, P1>1.1P2 and T1XP1>T2XP2 are applied to steam temperature (T1) and pressure (P1) in the first stage and steam temperature (T2) and pressure (P2) in the second stage.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for drawing synthetic fibers, particularly reinforcing materials, lobes, and sheets for the rubber industry such as industrial belts, conveyor belts, and tire cords. The present invention relates to a drawing method for producing island strength yarns of industrial polyester fibers used in various fields such as belts.

[Prior Art] Conventionally, industrial polyester [1] has the quality characteristics of high strength and low shrinkage, and is widely used in a wide range of industrial fields, and its manufacturing method has also been developed to achieve high strength. A method that aims to improve the degree of orientation sequentially by one-stage stretching or multi-stage stretching such as two or three stages, and ultimately achieves the maximum degree of orientation, or by high-temperature heating using steam. Various production methods have been adopted, such as a method of obtaining highly oriented and high strength yarns at once under high tension. Among these manufacturing methods, No. 0883216187 has been proposed as a method with particularly high potential. According to the invention, it is possible to stretch the film at once due to the generation of a neck due to uniform heating of steam and tensile force, and to align the molecular chains to a high degree. With this method, conventional 8
Although we have been able to obtain high-strength yarns of ~9 g/de, we discovered that this method naturally has its limits when trying to obtain high-strength yarns due to even higher orientation and crystallinity. This led to the invention.

In other words, it is necessary to instantaneously raise the yarn temperature to 120°C or more, so it is necessary to expose the yarn to an extremely high temperature of 350 to 400°C, and as in industrial fiber manufacturing, the total temperature of 11 degrees is 1000 deniers or more. If the temperature is high, a huge amount of heat is required at 550℃ and 7 to 9/ci high temperature and high pressure, resulting in the atmospheric temperature in the steam chamber being high and causing parts of the yarn to rise to near the melting point. However, there was a drawback that high tension could not be applied to align the molecular chains, and it was virtually impossible to set the desired high stretching ratio.

For this reason, efforts have been made to obtain high-strength yarns with stronger crystals and penetrating molecular chains by orienting the molecular chains as highly as possible in the fiber axis direction, but it has not been possible to obtain sufficient high-strength yarns. is the reality.

[Object of the Invention] As a result of intensive studies on these drawbacks, the present invention has resulted in the achievement of a high degree of molecular orientation, that is, a high-strength yarn that could not be obtained by conventional methods.

In other words, the drawbacks of conventional stretching methods are that as the degree of orientation increases, crystallization tends to occur, making it difficult to align the molecular chains in subsequent stretching; Although the stretching neck point fixing method is the most suitable for improving this drawback, as mentioned above, the temperature of the heat-applied area is locally too high due to the stretching at a high magnification all at once. Considering that yarn breakage may occur due to yarn breakage such as fuzz generation, the amount of heat of steam applied to the yarn is adjusted to the neck point fixing zone, molecular chain orientation,
The most excellent method for manufacturing high-strength yarn is to continuously and substantially divide the high crystallization zone, and it is extremely effective to inject steam in two stages to create a gradient in temperature and pressure. It was discovered that this method is effective and led to the present invention.

[Structure of the Invention] That is, the present invention provides a method for stretching an undrawn yarn of thermoplastic synthetic fiber between a supply roller rotating at a predetermined speed and a drawing roller rotating at a surface speed several times faster than the supply roller. , heated steam is injected between the supply roller and the stretching roller in two stages, and the steam temperature (T1) and pressure (
P1), the second stage steam temperature (T2), and pressure (P1) are given a gradient, and the following relationship is established: TI≧200℃ T2≧T, +20℃ P+ > 1.1P2 T+ ×PI >T2 ×P2 This is a method for drawing synthetic fibers that is characterized by:

Hereinafter, the present invention will be explained with reference to the drawings while comparing it with a conventional method. FIGS. 1 and 2 are schematic diagrams of a straight extending device and a conventional device, respectively, suitable for carrying out the present invention.

In FIG. 2, the yarn Y, which has been cooled in a spinning cylinder (not shown) and has been treated with an oil agent, is wound around a take-up roller 1 having a separate roller 2 to adjust the tension, and then passed through a supply roller 3 having a separate roller 4. After the turn winding and tension irregularities have been repaired, the material enters a steam chamber 6 arranged between the drawing roller 5 and the supply roller 3 on the entry side of the next drawing roller pair 5.5'. Here, it is heated to a predetermined temperature and stretched at a predetermined stretching tension-stretching ratio while fixing the stretching point, and then heat-set between stretching rollers 5.5'. Subsequently, the tension between the inlet roller 7 and the stretching roller 5 is relaxed by the next pair of rollers 7 and 7' in order to maintain the target shrinkage rate, and the sheet is sent to a winder (not shown).

In contrast, in the present invention, the yarn Y is stretched between a drawing roller 15 after passing through a take-up roller 11 having a separate roller 12 and exiting a supply roller 13 having a separate roller 14, as shown in FIG. In the conventional method shown in FIG. 2, the supply roller 3 and the stretching roller 5 are heated to a predetermined temperature in a single stage steam chamber 6 at once, whereas the first stage steam chamber 16 and the The two-stage steam chamber 16' distributes the amount of heat so that the neck point fixation zone and the molecular chain orientation/high crystallization zone are continuously and substantially divided.

The temperature conditions of the steam chamber 16 according to the present invention are such that the temperature of the yarn Y is higher than the secondary transition point, and the temperature condition of the steam chamber 16' is TI = 20Q℃ or higher for the purpose of making the yarn Y a temperature of the neck point fixing zone. The temperature is 220° C., which is higher than the steam chamber 16, for the purpose of high-magnification stretching to improve the orientation of molecular chains and high crystallization.
In addition to the above, the relationship between the temperature T+ of the steam chamber 16 and the temperature T2 of the steam chamber 16' must be T2≧T++20°C.

Here, if TI and Tz are lower than the above-mentioned temperature, the yarn temperature cannot be heated all at once to a temperature sufficient to perform the targeted high-magnification drawing, and the temperature T1 of the steam chamber 16 and the steam chamber 16' temperature T2
If T2 < TI +20° C., the amount of heat cannot be greater than that in the case where the steam chamber has one stage, and the object of the present invention cannot be satisfied. In addition, if the temperature of TI and T2 is too high, the yarn temperature will rise to near the melting point, which may cause single yarn breakage and fluff, and the original effect may not be obtained.
It is preferable that T2 be within a range not exceeding 600°C.

Furthermore, the pressure conditions of the steam chamber in the present invention are as follows:
If the pressure P1 of the steam chamber 16 and the pressure P2 of the steam chamber 16' are P1≧1. It needs to be set to IP2. When Pl is made to have a higher pressure than Pl, it passes through the steam chamber 16 and the yarn Y, which has already started drawing, is disturbed and single yarn breaks.

This causes fluffing, making it impossible to stretch at a sufficiently high magnification.

Furthermore, the relationship between the temperature and pressure of the steam chamber 16, 16' must be P+ XT1>Pl XT2. P+ XTI <Pl XT
In the case of 2, as described above, even if the relationship P1≧1.1P2 is satisfied, the excessive steam heat in the second stage causes the single yarns of the yarn to fuse and break, resulting in the present invention. It is not possible to stretch at the intended high magnification.

[Example] Polyethylene terephthalate with an intrinsic viscosity of 0.90 measured with an O-chlorophenol solution at 35°C was melted at 300°C, spun using a 0.4φ x 250H spinneret, cooled and oiled by a conventional method, and then , Figures 1 and 2
Using the device shown in the figure, the take-up speed is 400 m/min (take-up roller 1
1500De/2504i1
A drawn yarn was obtained.

[Effects] As shown in Table 1, compared to the conventional method, the drawing method according to the present invention enables high-stretching ratio, and provides significantly higher strength than the conventional yarn.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams of a straight extending device and a conventional device, respectively, suitable for carrying out the present invention. 13... Supply roller, 15... Stretching roller. 16...1st stage steam chamber. 16'...Second stage steam chamber Figure 1 Figure 2

Claims (1)

[Claims] When stretching an undrawn yarn of thermoplastic synthetic fiber between a supply roller rotating at a predetermined speed and a stretching roller rotating at a surface speed several times that of the supply roller, the supply roller and the stretching roller Heated steam is injected in two stages between A method for drawing synthetic fibers, characterized in that the following relationships are established: T_1≧200°C, T_2≧T_1+20°C, P_1≧1.1P_2, T_1×P_1>T_2×P_2.