JPH02210033A - Low-shrinkable polyester staple fiber - Google Patents

Abstract

PURPOSE:To obtain the title staple fibers giving shirts or the like free from shrinkage and puckering even after repeated washing and ironing by using polyester fibers of polyethylene terephthalate so that they satisfy specific conditions. CONSTITUTION:The subject staple fibers are made from a polyester having major repeating units of ethylene terephthalate and satisfy simultaneously the following conditions: dry heat shrinkage (180 deg.C) <=2%, thermal shrinkage stress (200 deg.C) <=20mg/de, change rate of thermal shrinkage stress (160 to 200 deg.C) <=0.5mg /de deg.C, fiber strength <=4.0g/de, stress at 10% elongation (room temperature) >=2.0g/de, percentage crimp = 8.0 to 20%, and 2.0 >= percentage crimp/crimp number (number/inch) >=0.7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to low shrinkage polyester staple fibers used in spun yarns for shirting and the like.

[Prior Art] Traditionally, fabrics made of spun yarn using polyester staple fibers, regardless of whether the spun yarn is a blended yarn with cotton fiber or a spun yarn made of 100% polyester, have been subject to extreme damage due to repeated washing and ironing. ■As a result, shirts and the like have had problems such as shrinkage of the fabric due to dimensional changes and puckering of seams.

As a solution to these problems of fabric shrinkage, (b) after hot stretching and tension heat treatment with a first hot plate at a temperature of 60 to 260°C,
A method of relaxation heat treatment with a second hot plate at a temperature in the range of ~250°C (Japanese Patent Publication No. 41-4817), ■Birefringence is 0.1
4 or more polyester drawn yarn at 150-250℃
A method of carrying out tension heat treatment at a temperature of When stretching is performed by a method, the stretching ratio is stretched so that it satisfies 1.6≦DR1/DR2≦2.6, and then heat treatment is performed using a group of heating rollers at 190 to 220°C (Japanese Patent Application Laid-open No. 59-125905). Public bulletins) etc. have been proposed. However, with these methods, the reduction in the thermal shrinkage stress and shrinkage rate of the fibers is small, and the present situation is that these methods are not sufficiently effective means for suppressing the shrinkage of fabrics.

[Object of the Invention] The object of the present invention is to improve the conventional problems and to provide a polyester short fiber that can suppress the shrinkage of the fabric during washing and ironing to an extremely low level and exhibits extremely excellent spinnability. .

[Structure of the Invention] To achieve the above object, the present inventors conducted a detailed analysis of the shrinkage behavior of fibers, and found that in order to reduce the shrinkage of fabrics, in addition to reducing the thermal shrinkage rate and shrinkage stress, The present invention was developed based on the discovery that it is very effective to reduce the gradient of shrinkage stress of the fiber at a temperature corresponding to the finishing setting temperature in the manufacturing process and the ironing temperature after washing. .

That is, the present invention is a polyester fiber whose main repeating unit is an ethylene terephthalate unit, and is a low-shrink polyester short fiber characterized by simultaneously satisfying the following conditions.

(a) Dry heat shrinkage rate (180°C) ≦2% (b) Heat shrinkage stress (200°C) ≦20q/de (c) Heat shrinkage stress change rate, (160-200°C) ≦0.5
mg/de℃) Fiber strength≧4.0g/de Cutting stress at 10% elongation (room temperature)≧2.0g/de
f) 20% ≧ crimp degree ≧ 8.0% (g) 2.0 ≧ crimp degree / number of crimps (pcs/inch) ≧ 0
．． 7 The polyester fiber of the present invention has a main repeating unit composed of ethylene terephthalate units, and preferably contains 98% by weight or more of ethylene terephthalate. If 98% by weight of ethylene terephthalate is not swirled, the thermal shrinkage stress of the fibers will not be sufficiently reduced, and the shrinkage suppressing effect of the fabric will not be sufficiently exerted, making it impossible to fully achieve the object of the present invention.

Furthermore, the dry heat shrinkage rate of the polyester fiber of the present invention is 2
% or less, more preferably 1% or less.

When the dry heat shrinkage rate of the polyester fiber exceeds 2%, the shrinkage rate of the spun yarn increases, making it impossible to suppress the shrinkage of the fabric.

In addition, various analyzes have shown that the heat shrinkage stress of the polyester fibers is directly involved in the shrinkage of the fabric, and in order to suppress the shrinkage of the fabric, it is necessary to control not only the dry heat shrinkage rate of MitH but also the heat shrinkage stress of the fibers. It was also found that it was necessary to reduce the

That is, in the case of normal cleaning, the iron temperature is around 200°C, so the heat shrinkage stress of the polyester fiber needs to be 20η/de or less at 200°C, and more preferably 10It
g/de or less is preferable. If the heat shrinkage stress exceeds 20#19/de, the shrinkage rate of the fabric will increase when ironed at 200° C. after washing, and the various problems associated with the shrinkage mentioned above will appear, which is not preferable.

Another condition for the heat shrinkage stress of the polyester fiber of the present invention is the rate of change of the heat shrinkage stress depending on temperature. Specifically, the average slope ( That is, the average rate of change in thermal shrinkage stress must be 0.55 NF/de'c or less. If the value of the rate of change of thermal stress at 160°C and 200°C deviates significantly from this (the slope is large),
-The fabric was finished and set at a temperature of 160℃ for 200℃.
When ironing at a temperature of ℃, new shrinkage stress is generated and the material shrinks significantly. Therefore 160℃ and 200℃
The rate of change in heat shrinkage stress at the temperature is 0.5■/de℃
The following is good.

On the other hand, from the viewpoint of spinnability, it is preferable that the strength of the fibers (breaking strength) is high, since this can reduce yarn breakage during the spinning process. In order to maintain normal spinning and spinning properties, the strength of the m-thread is 4.
0g/de or more is required, preferably 4.59/d
It is more than e. If the strength of the fiber is less than 4.097 de, yarn breakage during the spinning process will increase, impairing the productivity of the spinning process, which is not good. In addition to the fiber strength (breaking strength), when used for blending with cotton, the elongation stress of the polyester fiber at an elongation equivalent to the breaking elongation of cotton (approximately 10%) has an effect on spinnability. The impact is large;
In order to maintain normal spinnability, the elongation stress is 2.09
/de or more is required, preferably 2.597de or more. When the elongation stress is less than 2.0 g/de, the yarn strength of the yarn blended with cotton is significantly reduced,
This is undesirable because thread breakage increases during the spinning and weaving processes.

Another important factor that affects spinnability is the crimp performance of the fibers. Regarding crimp performance, the degree of crimp should be 8.0% or more in order to maintain normal spinnability.20.
It is necessary that the content be in the range of 0% or less, and more preferably 10.0% or more and 18.0% or less. If the degree of crimp is less than 8.0%, the intertwining between the fibers will be weak and the passability of the card will be poor, and if it exceeds 20.0%, neps will occur in the card sliver, adversely affecting the quality of the spun yarn. This is not good because it gives In addition to this, the balance between the degree of crimp and the number of crimp (pieces/inch) is also important, and it is necessary that the degree of crimp/number of crimp is 0.7 or more and less than 2.0. If the degree of crimp/number of crimp is less than 0.1, the number of crimp must be increased in order to obtain the above degree of crimp, which is likely to cause neps; If the number of crimp is low, but the degree of crimp is high, the raw cotton and sliver become bulky and difficult to handle.

The manufacturing conditions for obtaining the polyester fiber described in this patent include the following steps: (1) low-magnification stretching, (2) high-temperature tension setting, (2) crimping at high temperature, and (2) high-temperature relaxation heat treatment. Among these, high-temperature relaxation heat treatment is a method that has traditionally been used to produce low-shrinkage polyester fibers, but this alone is only effective in reducing the heat shrinkage rate of fibers. This treatment alone is insufficient to suppress the shrinkage of the fabric in the final product; furthermore, this treatment alone results in a decrease in strength and stress at 10% elongation; If the degree of crimp is significantly reduced, it is not suitable for the purpose of the present invention.

That is, in order to completely achieve the purpose of the present invention, low-magnification stretching and high-temperature tension setting are used to bring about the center orientation and high crystallization of the polymer molecules constituting the fibers, and this is then subjected to a relaxation heat treatment. It is possible to obtain fibers with extremely low distortion while maintaining fiber strength and stress at 10% elongation at a high level.Furthermore, high crystallization makes it difficult to apply crimp, and hot air treatment reduces the degree of crimp. In order to prevent the degree of crimp from decreasing to the required level, it is necessary to reduce the decrease in the degree of crimp by applying crimp at a high temperature.

As specific manufacturing conditions for the polyester fibers used in the present invention, for example, the following conditions are preferable from the viewpoint of practicality. The stretching ratio is 0.90 to 1 of the natural stretching ratio of the undrawn yarn.
．． One-stage stretching or two-stage stretching at 10 times may be used, and the tension heat setting temperature is preferably 200 to 230°C. The crimp density is 13
If the temperature is 0 to 140°C, the effect of relaxation heat treatment can be obtained at the same time as crimping, but relaxation heat treatment with hot air may be performed if necessary.

Note that the present invention is not limited in any way by the above-mentioned manufacturing conditions regarding the manufacturing conditions for the polyester fiber of the present invention.

The polyester fiber of the present invention may be used at 100%, or may be used in a blend with other spinning fibers (particularly preferred is blending with cotton) (the proportion of the blend is known in the art). For blending with cotton, fineness of 0.5 to 2.0 denier and fiber length of 20 to 2.0 denier can be used.
A 40M one is used. Further, the spinning method may be any generally known method (for example, ring spinning method or open-end spinning method).

In addition, the number of crimp and degree of crimp of the II fiber described in the present invention.

The dry heat shrinkage rate, thermal stress and washing shrinkage rate are measured by the following method.

Number of crimps: Fix one end of the polyester single fiber, apply a load of 2q per denier to the other end, measure the number of crimps and fiber length, and convert to the number of crimps per 2581.

Degree of crimp: fix one end of the polyester single fiber and apply a load of 2Rg per denier to the other end to measure the fiber length (Ll), then apply a load of 50Rg per denier and measure the fiber length L2) again. . The degree of crimp is calculated from these measured values using the following formula.

Crimp degree = 100 (L2-11)/L2 machine"1! 1500 total by bundling 1 barley m-2 polyester short 1
A denier short fiber bundle is hung with an initial load of 100 g, marks are made at two locations, and the distance between them is measured. Said I
After subjecting the fiber bundle to free heat treatment at 180° C. for 20 minutes, the initial load is suspended again, the distance between the two marks is measured, and the shrinkage rate is calculated.

Heat-shrinkable polyester short fibers were bundled to form a fiber bundle with a total denier of 250 denier, and a KE-II heat-shrinkage stress measuring device manufactured by Kanebo Engineering was used (paper length approximately 2cm!). R), apply an initial load of 15g for 120 seconds/30
The temperature is increased at a temperature increase rate of 0° C. until lIN melts, and the relationship between temperature and thermal stress is determined.

at m*: 1.36 kg of fabric sample in a regular washing machine
and 0.1% monogen (detergent) solution at 60°C in a bath ratio of 1:3.
0, stirred for 30 minutes, rinsed with 40°C warm water for 5 minutes, and then rinsed with hot water for 10 minutes. (Bath ratio 1:30) After dehydrating the fabric sample for about 1 minute, it was pressed with a surface pressure of 2 kg/ci at a specified temperature for a specified time with a surface pressure of 2 kg/ci, and after conditioning the shrinkage rate. Measure. This operation is repeated and the shrinkage rate is measured each time.

[Operations and Effects of the Invention] The polyester fiber thus obtained could be spun without any problem under normal high-productivity spinning conditions, and a high-quality spun yarn could be obtained.

Fabrics made from this spun yarn show extremely small shrinkage compared to fabrics made from conventional polyester fibers, and shirts made from this fabric show virtually no shrinkage or puckering even after repeated washing and ironing. A significant difference from conventional products was observed.

[Example code] The present invention will be explained in more detail with reference to Examples below.

Examples 1-2 Intrinsic viscosity measured in ornechlorophenol is 0.6
1 polyethylene terephthalate is melt-spun and the thickness is
An undrawn yarn having a denier of 3.8 and a natural draw ratio (NDR) of 3.2 times was prepared. Next, this undrawn yarn was drawn in a hot water bath at 70°C at a drawing ratio (DR>) of 3.4 times (1.06 times the natural drawing ratio), followed by tension heat treatment under the conditions listed in Table 1. After steam preheating, buckling crimp application, and relaxation heat treatment,
Two types of polyester 11Alt! (1.2 denier, 38.41 min. length) was obtained.

These polyesters [[T blended with cotton (polyester/cotton = 65/35) L, cotton count 45
A plain woven fabric with a warp density of 105 threads/inch and a light density of 87 threads/inch was prepared, and the washing shrinkage rate of the fabric was measured. As a result, as listed in Table 1, the polyester short film of the present invention! ! The fiber exhibits excellent spinnability, and the fabric woven with the spun yarn has an extremely low washing shrinkage rate and can withstand repeated washing.
There were no problems with shrinkage due to heat setting.

±1''L Ent≦T In Comparative Example 1, the crimping temperature was changed to 95°C and the hot air treatment temperature was changed to 136°C under the manufacturing conditions of Example 1, and polyester short fibers with a low degree of crimp were used. In Comparative Example 3, the crimping temperature was increased to 160"C to produce short polyester fibers with a high degree of crimping, and in Comparative Example 3, the hot air treatment temperature was increased to 160"C.
Polyester short fibers with a low degree of crimp were produced at 70°C. When these were subjected to a spinning process, the card passability was poor and further spinning was not possible, so evaluation was abandoned.

Comparative Examples 4 to 7 The same undrawn yarn as used in Example 1.2 was drawn in a 70″c hot water bath under the conditions listed in Table 1, and subjected to tension heat treatment,
Steam preheating, frustation and crimp application, and hot air treatment were performed to obtain four types of polyester short and thick materials. these polyester short 4
! The fabric was spun and woven in the same manner as in Example 1.2, and the shrinkage of the fabric was measured. As a result, as shown in Table 1, the washing shrinkage rate of the fabric was high, and especially the shrinkage due to repeated washing and heat setting increased significantly.

Claims (1)

[Claims] (1) A low-shrinkage polyester staple fiber, which is a polyester fiber whose main repeating unit is an ethylene terephthalate unit, and which satisfies the following conditions at the same time. (a) Dry heat shrinkage rate (180℃)≦2% (b) Heat shrinkage stress (200℃)≦20mg/de (c) Heat shrinkage stress change rate (160-200℃)≦0.5
mg/de℃ (d) Fiber strength ≧4.0g/de (e) Stress at 10% elongation (room temperature) ≧2.0g/de (f) 20%≧degree of crimp ≧8.0% (g) 2.0≧Crimp degree/Number of crimps (pcs/inch)≧0.7