KR840002346B1 - A method for manufacting the polyester monofilament - Google Patents

Abstract

A process for the prepn. of polyester monofilaments comprises spinning thermoplastic polyester resins contg. a 0.05-3.0 wt.% compd. of formula (1) at 60 m/min from a melt-extruder, and drawing and heat-treating them in an ordinary method. In the formula, X is H or - OC(=O)R; R is C6H5, C6H4COOCH3, C6H4COOH, or C4-12 alkyl; A is H or CH3; B is H or CH3; m is 2-4; and n is 10-120.

Description

How to make polyester monofilament

The present invention relates to a method for producing a monofilament with thermoplastic polyester as a material and having particularly excellent properties for use as a pastener. Here monofilament refers to a continuum having a constant cross-sectional shape of 0.1 to 2 millimeters in diameter.

The conventional method for producing monofilament is to solidify the dried polyester resin after extrusion through the melt extrusion apparatus attached to the metering pump and the mold having a certain diameter at the front end, and then apply tension to both ends above the secondary transition temperature. After stretching to a certain magnification, it is composed of several processes such as imparting stability of the form through loss and heat treatment. The properties of the monofilament produced in this way are determined by the processing conditions such as the temperature rise and fall of the polymer in each process, the thermal history over time, the magnitude of stress, the degree of crystallization, the degree of orientation, etc. The properties required for use vary somewhat in the manufacturing process, but in general, the physical properties should be high strength, high elongation, thermal properties at low temperatures, low thermal shrinkage, and moldability. In the case of smooth deformability and dyeing property, there is an easy penetration and dispersibility of the disperse dye, and it is most ideal to satisfy these properties simultaneously.

The reason is that in case of fasteners such as fascias or zippers, the manufacturing method has to go through several steps precisely. This is because there is a big probability. However, it is impossible to simultaneously satisfy all the physical properties required by the filament monofilament using a conventional thermoplastic polyester resin.

For example, in order to manufacture high-strength monofilament, when the stretching ratio is increased in the stretching process after extrusion, the elongation must be lowered and become stiff and the moldability is weakened. Initial tensile resistance is weakened, so there is no stability and weak strength.

As another example, in order to reduce the heat shrink in the dyeing process during fastener manufacturing, if the relaxation and heat treatment in the monofilament manufacturing process is too strong, the crystallization is severe, poor moldability and poor staining. In fact, some zipper manufacturers use an external lubricant to compensate for molding processability, but in this case, the effect is minimal due to the low contribution to internal lubrication.

As a result, in the conventional monofilament manufacturing method, the conditions are compromised in the compromised physical properties within a range that does not significantly damage each of the required characteristics.

As a result of intensive studies to solve the above problems, the inventors have invented a method for producing a monofilament that satisfies all the incompatibilities required for the following fasteners.

After stretching the thermoplastic polyester resin having a molecular weight of 20,000 or more, which will contain 0.05% to 3% by weight of the resin of the general formula (1) at a speed of 60 / m / min or more through a cross section in a melt extruder, drawing and Heat treatment to produce a monofilament for the thickness of the thinner.

next

In the present invention, thermoplastic polyester is a main component of which divalent acid component is at least 90% of terephthalic acid, isophthalic acid and methyl ester derivatives thereof, and as the divalent alcohol component, ethylene glycol, propylene glycol, butanediol and the like. The polymer or copolymer manufactured by this polycondensation reaction as said 90% or more is said.

The theoretical background of the present invention will be described in detail as follows. The compound of formula (1) is mainly composed of polyoxyalkylene, which has a lower melting point than the polyester resin, has good fluidity in the molten state, has excellent affinity for disperse dyes, and one to the other end thereof as an ester derivative. It has good characteristics of compatibility with polyester resin. When a small amount of a compound having such a property is contained in a polyester resin and spun at a high speed, the following changes occur.

First: It increases the fluidity in the molten state of the resin, so that the melt behavior is not exerted even if the speed is hard even when extruding the molten resin through the detention of the extruder tip. The purpose of speeding up the spinning speed is to increase the degree of orientation by increasing the radiation draft, thereby realizing the strength improvement of the monopolar.

In the case of spinning at high speed without additives, the melting behavior is unreasonable, and thus the monofilament obtained is uneven or flawed. By adding the compound of the formula (1) to the polyester resin, it is possible to speed up the spinning speed, thereby enabling the first step in the production of high strength monofilament.

Second: In the monofilament hot drawing process, easy drawing is possible under low tension.

This is because, due to the low melting point of the compound of the formula (1), it melts under the monofilament drawing temperature, thereby lowering the frictional stress between the polyester polymer and the polymer. In the absence of such additives, the stretching tension should be increased, and after stretching, the residual stress inside the monofilament becomes excessive, causing heat shrinkage. In the case of high-speed spinning, the temperature difference between the outside and inside of the monofilament is severe and only the surface is stretched. Skinning phenomenon occurs that is a problem that the stretching effect is reduced.

Third: Since the monofilament oriented by easy stretching earlier has less residual stress inside, it is more easily thermally stabilized by soft heat treatment compared to the case where no additives are added. Stability can be achieved.

Fourth: In the molding process for manufacturing a fastener, the additive is easily melted at the molding process temperature and serves as a lubricant between crystal groups composed of polymer molecules, thereby improving molding processability.

Fifth: The additive has excellent affinity with the disperse dye, which is a dye of polyester resin, to enable easy dyeing.

The amount of the compound represented by the general formula (1) of the present invention to the resin should be adjusted according to the molecular weight of the polyester, but in general, 0.05% to 3% by weight is appropriate. If the molecular weight is small, the principle is to go to a low content and to a high content if the molecular weight is high.

However, when it is 0.05% by weight or less, the effect is insignificant, and when it is 3% by weight or more, it is difficult to excessively damage the basic physical properties of the polyester. In addition, in the method of adding the compound, a method of adding in a polyester polycondensation reaction step, a method of making a chip after mixing with a molten polymer, a method of mixing with a resin chip, and the like may be used. It doesn't matter.

The specific embodiments described above are as follows.

Example 1

In the case of resin polycondensation, a polyethylene terephthalate resin having a number average molecular weight of 30,000 is a derivative of polyoxypropylene glycol having a molecular weight of 2,000, in which the terminal is substituted with an ester group by benzoic acid as a compound of the general formula (1). The obtained resin chips were melted at 280 degrees in a conventional filament extruder, cooled after spinning at a rate of 80 meters / minute, drawn four times in hot water at 95 degrees Celsius, and heat-treated to give a monofilament with a 0.8 mm diameter cross section. Filament was prepared.

Comparative Example 1

In the same manner as in Example 1, monofilaments of the same thickness were prepared using a resin to which the compound of Formula (1) was not added.

Comparative Example 2

In Comparative Example 1, the diameter of the hole of the extruder cap was reduced, and the monofilament of the same thickness was prepared with a spinning speed of 35 meters per minute and a draw ratio of 4.2.

Comparing the physical properties of the monofilaments obtained in the above test as follows.

Example 2

0.4 wt% of a derivative of polytetramethylene glycol having a molecular weight of 1,000, in which one end is substituted with an ester group as a dimethyl terephthalate as a compound of the formula (1) in a polyethylene terephthalate resin having a number average molecular weight of 45,000. The mixture was added to the resin chip for 30 minutes using a rotary mixer under the following conditions, and then spun at a speed of 120 meters per minute while melt extruding to 285 degrees Celsius through a conventional monofilament extrusion apparatus, followed by stretching under the same conditions as in Example 1. As a result, a monofilament having a diameter of 0.8 mm in diameter was produced, and the physical properties thereof were 54 kg / mm ² , elongation 75%, specific number 0.25%, density 1.3822, and the uniformity, formability, and dyeability of Example 1 The same level as if obtained.

Claims (1)

Polyester mono-stretched and heat treated by a conventional method in which a thermoplastic polyester resin having a molecular weight of 20,000 or more, which will contain 0.05% to 3.0% by weight of the resin, is spun at a speed of 60 m / min in a melt extruder. Method of manufacturing filament next