JPH0350004B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to fibers that exhibit significantly high stress due to heat shrinkage under constant length (hereinafter referred to as high shrinkage stress fibers). Polyester fiber has traditionally been used as a covering tightening material that utilizes heat shrinkage stress, but as disclosed in JP-A-56-9443, etc., the heat shrinkage stress is low, so it provides sufficient tightening force. In this case, a large amount of fiber is required, especially when used as a fastening material for the insulation coating of a motor, making it impossible to reduce the weight and increasing the cost. This increases the cost. In order to solve the above-mentioned drawbacks, the present inventors have conducted intensive studies to obtain a high shrinkage stress yarn with higher tightening stress, and as a result, by drawing an oriented crystallized yarn at a high magnification near the crystallization temperature, The present invention was achieved based on the finding that thermal shrinkage stress increases. That is, the present invention is a polyester fiber with an intrinsic viscosity of 0.7 or more, which is obtained by drawing an undrawn polyester fiber with an oriented crystallization of Δn of 0.08 or more and a dry heat shrinkage rate of 20% or less at 160°C, and a heating rate of 20°C/min. A high shrinkage stress polyester fiber characterized by having a heat shrinkage stress of 0.8 g/denier or more and a melting temperature of 255°C or more in a temperature range of 100°C or more until melting in the dry heat process during heating. The heat shrinkage stress referred to in the present invention is 0.05g/
When a denier is held at a certain length under tension and the temperature is increased, the fiber tries to shrink due to heat, but since both ends are fixed, no actual shrinkage occurs; instead, the fiber does not shrink. An internal stress is generated. This stress is called heat shrinkage stress. Thermal shrinkage stress is measured using a commercially available non-adhesive metal resistance wire strain meter, which is increased in intensity and linked to an automatic X-Y recorder to record and measure changes in stress over time. The sample is made into a loop of a certain length, one end of which is hooked to a hook directly connected to the strain meter, and the other end of the loop is hooked, and the length between the sample and the hook is adjusted and fixed so that the initial tension is 0.05 g/denier at 20°C. (At this time, apply tension while being careful not to sag.) The thus fixed sample is placed in a cylindrical quartz glass tube with an inner diameter of 8 mm and a heater with a nichrome wire wrapped around the outside. Place the sample in the heater so that the sample is located in the center of a double-tube heater (length 20 cm) surrounded by a double-tube heater (length 20 cm). The shrinkage force due to thermal shrinkage was measured by directly connecting the fiber to a temperature controller and heating the heater at a heating rate of 20℃/min to continuously raise the temperature of the atmosphere until it melted. Let the value be the heat shrinkage stress. In conventionally known JP-B No. 48-17212, JP-A-56-9443, etc., unoriented crystallized undrawn yarns are drawn in multiple stages until the atmospheric temperature reaches 100°C or higher and the fibers are fused. 0.7 in the temperature range of
Although no fibers have been obtained that exhibit a heat shrinkage stress exceeding g/d, the fibers of the present invention obtained by multi-stage drawing of oriented crystallized undrawn yarns exhibit high thermal contraction stress in the temperature range of 100°C or higher before melting. It is a high shrinkage stress yarn that exhibits a heat shrinkage stress of 0.8 g/denier or more. The preferred fiber of the present invention has a temperature of 1.0 in the temperature range during the heating process.
The yarn exhibits a heat shrinkage stress of more than g/denier, and such a publicly shrinkable stress yarn has never been expected.
Note that the present invention also includes those whose heat shrinkage stress value (peak value) showing a maximum in the above temperature range during the heating process exceeds 0.8 g/d. The component constituting the fiber of the present invention is preferably polyester, and polyethylene terephthalate is particularly preferred. Intrinsic viscosity of the fiber of the present invention (measured in a 6/4 mixed solvent of phenol/tetrachloroethane at 30°C)
When it is 0.7 or more, the heat shrinkage stress becomes high, so it is preferable, and when it is 0.9 or more, it exceeds 1.0 g/denier, so it is particularly preferable. The fiber of the present invention has a shrinkage rate (JIS-L-1073-
According to the method shown in 6-12. Hereinafter abbreviated as SHD. ) is preferably 20% or less, especially 10% or less. For those using undrawn yarn with SHD of 40% or more, the heat shrinkage stress is 0.8
g/denier, which is not preferable. The undrawn yarn is then drawn to obtain the fiber of the present invention,
Two-step stretching is preferred as the stretching condition. Note that an appropriate stretching temperature may be selected depending on the desired maximum heat shrinkage stress temperature. Particularly preferably, the temperature is near the exothermic peak temperature due to crystallization during the temperature increase process (temperature increase rate 20° C./min) measured by DSC. For example, from polyethylene terephthalate ([η]: 0.7 or more)
For undrawn yarn obtained at a spinning speed of 3000 to 4000 m/min, the spinning speed is usually 110 to
The temperature is 115℃. As shown in Figure 1, the fiber of the present invention thus obtained exhibits a high thermal shrinkage stress of 0.8 g/denier or more in the temperature range of 100°C or higher. It is a high shrinkage stress fiber. The reason for this is still not fully understood, but the molecular chains of the oriented amorphous region, which is highly elongated and strained, are frozen in a network structure connected by crystals produced by oriented crystallization. It is assumed that this structure absorbs thermal energy and causes molecular movement, which results in extremely high contraction stress. Depending on the application, the fibers of the present invention may be used directly as a tightening material in the form of multifilaments or staples, or may be used in the form of strings, or may be used as strings, tapes, fabrics, etc. composited with other useful fibers. Good too. In particular, it is preferable to use a fabric in which the warp is a yarn made of the high shrinkage stress fiber of the present invention and a low shrinkage yarn or a naturally elongated yarn is a weft. Such publicly shrinkable stress fibers are of great industrial significance because they are used in a variety of applications as tightening materials and enable weight and cost savings. The present invention will be specifically explained below with reference to Examples. The heat shrinkage stress values used in the examples were measured using the strain meter manufactured by Toyo Baldwin Co., Ltd.
TI-550-360 type, preamplifier manufactured by Toyo Baldwin, PRE-AMPLIFIER SS-PR type, automatic X-Y recorder manufactured by Yokogawa Electric Industries, TYPE
PRO-11A type. The temperature controller is AGNE manufactured by Shinku Riko Co., Ltd.
Measured using HPC-1500 and AGNE SCR-BOX. Example Polyethylene terephthalate with an intrinsic viscosity of 1.0
Spun at 310℃ from a nozzle with 16 φ0.3 orifice holes at a rate of 1.5g/min per single hole.
Table 1 shows the properties of the undrawn yarn taken up at a take-up speed of 4000 m/min. The obtained undrawn yarn was then drawn at a drawing speed of 100 m/min at a temperature of 25° C. in the first stage and 110° C. in the second stage. The properties of the drawn yarn are shown in Table 1. The fiber of the present invention obtained using the oriented crystallized undrawn yarn was a high shrinkage stress yarn as shown in FIG. 1-1. Comparative Example Table 1 shows the properties of undrawn yarn and drawn yarn obtained under the same conditions as in Example except that the take-up speed was 1300 m/min and the stretching ratio was changed. Fibers obtained using undrawn yarns that were not oriented and crystallized had only low heat shrinkage stress, as shown in Figure 1-2.

[Table] Example 2 The filament obtained in Example 1 was twisted at 300T/m.
The two yarns were woven into a plain weave fabric with 280 vertical yarns and 120 horizontal yarns, and then subjected to shrinkage treatment in boiling water at 130° C. for 30 minutes. The number of fabrics after boiling water treatment was 352 vertically and 148 horizontally. This fabric was then treated to be water repellent. Table 2 shows the functionality of the water-repellent treated fabric. In the same way, using the filament of the comparative example,
280 pieces/120 pieces of plain woven fabric were treated with boiling water. The number of fabrics after boiling water treatment was 310 vertically and 132 horizontally. A similar water-repellent finish was applied to this fabric.
Table 2 shows the properties after water repellent finishing.

[Table] When the fiber of the present invention is used, it is possible to achieve high density through shrinkage treatment, and the fiber retains good modulus, so it maintains good "stiffness" even after shrinkage treatment. Fibers outside the scope of the present invention are not sufficiently densified, have a large decrease in modulus due to shrinkage treatment, and lack "stiffness."

[Brief explanation of drawings]

FIG. 1 shows the change in thermal shrinkage stress during the temperature rising process. 1 is the change in heat shrinkage stress exhibited by the fiber of the present invention, 2
is the change in heat shrinkage stress exhibited by the fiber of the comparative example.

Claims (1)

[Claims] 1 Polyester fibers with an intrinsic viscosity of 0.7 or more drawn from oriented crystallized polyester fibers with a dry heat shrinkage rate of 20% or less at 160°C with a Δn of 0.08 or more, heated at a heating rate of 20°C/min. A high shrinkage stress polyester fiber characterized by having a heat shrinkage stress of 0.8 g/denier or more and a melting temperature of 255°C or more in the dry heat temperature range of 100°C or more until melting in the heating process.