JPH03124876A - Polyester sewing machine thread - Google Patents

Abstract

PURPOSE:To provide the subject sewing machine thread reduced in the generation of oligomers when dyed, by subjecting a polyester containing ethylene terephthalate groups as main repeat units to a high speed melt-spinning process, drawing, heating and subsequently treating the prepared filaments having specific fiber characteristics to a hot water treatment. CONSTITUTION:A polyester polymer containing ethylene terephthalate groups as main repeat units and preferably having an intrinsic viscosity (in o- chloroform) of >=0.8 is melt-spun at a high speed of >=2000m/min, drawn and subsequently heated to provide multifilaments having (i) an intrinsic viscosity [eta]f of >=0.75, (ii) a birefringence ( n) of 0.16-0.19, (iii) a tenacity of 6.0-8.0g/de and (N) a dry thermal shrinkage degree of 1.5-6.0% at 150 deg.C. The filaments are twisted and treated is hot water of >=80 deg.C to a polyester thread satisfied with a reduction rate of <=1.5% when treated with xylene.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an improved polyester sewing thread. More specifically, the present invention relates to a polyester sewing thread in which the amount of oligomer generated during dyeing is extremely reduced.

(Prior Art) Sewing threads made of polyester filament yarns have many excellent properties, and are used for a wide variety of applications, and are being used in a wide range of applications.

In the process of industrially manufacturing sewing thread, the generation of oligomers during dyeing has been a problem, and various methods have been studied to reduce this. As a general method for reducing oligomers, a method of reducing oligomers by solid-phase polymerization of fibers has been disclosed, but this method has not been sufficient.

In addition, methods of removing with various solvents result in deterioration of the physical properties of the fibers, and are therefore not preferred for use in sewing threads that require high-speed sewing performance.

Improvements in the dyeing process were also considered, and since the solubility of oligomers in water increases as the temperature rises, a method was adopted in which the dye solution was discharged at a high temperature when dyeing was completed, but this method had the drawback of high equipment costs.

A method of using a dye dispersant with good oligomer dispersibility has also been adopted, but this method has the problem that dyeing properties are lowered due to increased dye dispersibility, and dyeing costs are increased.

(Object of the Invention) An object of the present invention is to solve the problems of the prior art, to provide a polyester sewing thread in which the amount of oligomers generated during dyeing is reduced, and which can be easily packed and dyed.

(Structure of the Invention) As a result of intensive studies to achieve the above object, the present inventors discovered that the amount of oligomers generated during dyeing can be significantly reduced by treating polyester fibers with specific fiber characteristics with hot water. Don't reach invention.

That is, according to the present invention, 2000 m of polyester having ethylene terephthalate as the main repeating unit
An undyed polyester sewing machine that is melt-spun at a spinning speed of /min or more, then subjected to drawing heat treatment to obtain a multifilament that satisfies the following (1) to 0 at the same time, and then twisted and treated with hot water of 80°C or more. There is provided a polyester sewing thread characterized in that the weight loss rate (L) of the sewing thread satisfies the following (Vl).

(i) 0.75≦[η]f 00 0.16≦Δn≦0.19 (iii) 6.0≦ST≦8.0 (iv) 1.5≦SH≦6.0 (V)LSI, 5 The present invention will be explained in more detail below.

The polyester used in the present invention is mainly polyethylene terephthalate, but other components may be copolymerized in an amount of 5 mol % or less, preferably 3 mol % or less based on the total repeating units. Such other components include isophthalic acid component, phthalic acid component, p-hydroxybenzoic acid component, benzoic acid component, 4,4'-diphenyldicarboxylic acid component, naphthalene dicarboxylic acid component, diethylene glycol component, tetramethylene glycol component, etc. I can give it to you.

The polyester may contain a matting agent, a coloring agent, an antistatic agent, a modifier, etc.

The multifilament of the present invention made of such polyester is obtained by melting a polymer having an intrinsic viscosity of preferably 0.80 or more, particularly preferably 0.90 or more and 1.30 or less, as determined from an orthochlorophenol solution at 35°C. After spinning, the intrinsic viscosity [η]f of the multifilament is determined by [
η]f≧0.75. If this condition is not satisfied, not only will it not be possible to achieve the objective of the present invention of reducing oligomers, but it will also be difficult to obtain sufficient strength as a sewing thread.

Further, the degree of orientation Δn of the multifilament of the present invention is 8
It is necessary to set 0.19≧80 as a condition for easy extraction of oligomers when treated with hot water of 0°C or higher, and on the other hand,
In order to maintain the strength of sewing thread, 80≧0□1
6 is required.

Furthermore, the breaking strength must be 6.0 to 8.0 g/d to facilitate oligomer extraction when treated with hot water of 80° C. or higher and to maintain the performance of the sewing thread.

In addition, the dry heat shrinkage rate at 150°C needs to be 6.0% or less from the viewpoint of dimensional stability in the processing process, but if the shrinkage is too low, the crystal structure will become extremely tight and 8.
A hot water treatment at 0° C. or higher will result in insufficient oligomer extraction and increase the generation of oligomers during dyeing, so it is not preferable to keep the amount below 1.5%.

It should be noted that the polyester multifilament having such characteristics needs to be produced by drawing and heat-treating a highly oriented undrawn yarn drawn at a spinning speed of 2000 m/min or more. If a low-oriented undrawn yarn taken at a normal spinning speed is subjected to drawing heat treatment, even if it has the above-mentioned properties, the high-speed sewability as a sewing thread will be insufficient. A harsh hot water treatment at 80° C. or higher is not preferable because it becomes difficult to efficiently extract oligomers and the amount of oligomers generated during dyeing cannot be sufficiently reduced.

The sewing thread of the present invention is obtained by twisting the polyester multifilament and then treating it with hot water of 80° C. or higher. If the treatment temperature is less than 80'C, the generation of oligomers during dyeing will increase, which is not preferable.

The polyester sewing thread subjected to the hot water treatment of the present invention has a weight loss rate of 1.5 when treated with xylene, which will be described later.
Must be less than % by weight. If L exceeds 1.5% by weight, the amount of oligomers generated during dyeing will increase, and cleaning to remove oligomers will be required after dyeing, which is not preferable.

The polyester sewing thread of the present invention explained above can be obtained, for example, by the following method.

That is, the intrinsic viscosity is 0.80 or more, preferably 0.90 to
1.30 polyester is spun in a molten state into a cooling zone, immediately cooled and solidified, and then an oil agent is applied and then taken off at a take-up speed of 2000 m/min or more, resulting in a highly oriented birefringent index of 2500 to 5000 x 10-5. By obtaining an undrawn yarn, stretching this undrawn yarn at a stretching ratio of 1.5 times or more and no more than 3.5 times, and then applying heat treatment at 160 to 250 ° C. at a constant length or a relaxation ratio of 10% or less. Polyester multifilament for sewing thread is produced. This stretching may be performed continuously following spinning, or may be performed after spinning and then winding.

The heating temperature during stretching is preferably less than 85°C.

Next, the polyester multifilament is twisted by a known method, and then heated to 80°C or higher, preferably 90°C or higher.
The treatment is carried out using hot water of 0 to 130° C. in a bath ratio of 1:10 or more, preferably in a container where hot water is constantly supplied and drained for 10 minutes or more. If the temperature, bath ratio, and time are below the above lower limits, the weight loss rate due to xylene treatment will exceed 1.5% by weight, which is not good.

The rate of weight loss due to xylene treatment in the present invention is measured by the following method.

That is, the weight measured after drying the sample at 150°C is defined as Wlg, and then the weight measured after being immersed in boiling xylene and treated for 18 hours and then dried at 150°C is defined as W2g. %
).

(Effects of the Invention) According to the present invention, since oligomers are extracted during hot water treatment, it is possible to reduce the amount of oligomers generated in the dyeing process, suppress the cost increase due to washing after dyeing, and can be manufactured without impairing its physical properties.

(Example) The present invention will be further explained below with reference to Examples.

Examples 1 to 2, Comparative Examples 1 to 6 Polynisder polymers were melted at about 300°C, and pore sizes of 0 and 3
330 mm after being discharged from a spinneret with 24 holes.
Cooling air at 25°C is passed through a heating tube heated to 4°C.
．． Cool and solidify while spraying at 0 Nm3/min, then apply oil with an oiling roller and roll up. The obtained undrawn yarn was subjected to drawing heat treatment to obtain a 70 denier 24 filament polyester yarn.

Furthermore, after first twisting the obtained polyester yarn, three yarns were doubled and final twisted to make sewing thread (#50), which was then treated with a cheese dyeing machine in warm water at 100°C for 20 minutes, and after washing with water, '
The amount of oligomers generated was compared by staining with C.

At this time, the polymer intrinsic viscosity, spinning speed, stretching ratio, and heat treatment temperature conditions were changed as shown in Table 1.

Physical properties of the obtained polyester yarn (breaking strength, Δn, 1
50°C dry heat shrinkage rate) and weight loss rate by xylene treatment (
L), the results of the amount of oligomers generated during staining are also shown in Table-1.

As is clear from Table 1, the sewing threads of Examples 1 and 2 within the scope of the present invention were of high quality with a small amount of oligomer generation during dyeing.

Claims (1)

[Claims] Polyester containing ethylene terephthalate as a main repeating unit is melt-spun at a spinning speed of 2000 m/min or more,
Next, a multifilament that simultaneously satisfies the following (i) to (iv) is obtained by drawing heat treatment, and then twisted to obtain 8
1. An undyed polyester sewing thread treated with warm water at 0° C. or higher, characterized in that the weight loss rate (L) of the sewing thread satisfies the following (v). (i) 0.75≦[η]_f (ii) 0.16≦Δn≦0.19 (iii) 6.0≦ST≦8.0 (iv) 1.5≦SH≦6.0 (v) L≦1.5 [However, [η]_f: Intrinsic viscosity of polyester constituting the multifilament Δn: Birefringence of the multifilament ST: Strength of the multifilament (g/de) SH: Dry heat of the multifilament at 150°C Shrinkage rate (%) L: Weight loss rate (%) of polyester sewing thread due to xylene treatment]