KR20010017987A - Manufacturing method of high shrinkage copolyester - Google Patents

Abstract

PURPOSE: Provided is a process for producing a high shrinkable copolymerized polyester which can improve spinning property and work efficiency for a melt spinning. CONSTITUTION: The copolymerized polyester having an intrinsic viscosity of 0.60 dl/g or more and a shrinkage rate of 20-25 % or more is prepared by melting, blending, and copolymerizing 80-95 mol% of the initial polymer of polyethylene terephthalate having the intrinsic viscosity of 0.4-0.9 dl/g and 5-20 mol% of the initial polymer of polyethylene isophthalate having the intrinsic viscosity of 0.4-0.9 dl/g at 265-300 °C for 5-30 minutes.

Description

Manufacturing Method of High Shrinkage Copolyester {Manufacturing method of high shrinkage copolyester}

The present invention relates to a method for producing a highly shrinkable copolyester with high production cost and high productivity by producing polyethylene terephthalate (PET) and polyethylene isophthalate (PEI) separately and melt kneading at a high temperature. will be.

Conventional polyesters, especially PET, have excellent chemical resistance, heat resistance, weather resistance, high strength, high elastic modulus, and are used in large quantities in industrial fibers, films, containers, and general molded articles, but do not impair the excellent performance of polyester. Many attempts have been made to copolymerize a third component in the range to obtain a copolyester having new performance such as high shrinkage.

Although there are many known techniques for producing highly shrinkable PET fibers, industrially useful methods and the most widely used methods are carboxylic acids such as adipic acid and sebacic acid, which are used in the polymerization process of polymers, or alcohol. Instead of ethylene glycol, higher copolymers such as diethylene glycol, 2,2-dimethyl-1,3 propanediol, and 2,2-diethyl-1,3 propanediol or substituted glycols are used. .

This method is a method of forming a large number of amorphous portions in the fiber structure, the use of adipic acid, sebacic acid or the above-mentioned diol has a disadvantage that the low temperature shrinkage phenomenon that the glass transition temperature is lowered and shrinkage occurs at low temperatures.

In addition, when isophthalic acid or its derivatives are used, molecular chain breakage is imparted in the polymer, the crystallization temperature is increased, the crystallization rate is lowered, and a large number of amorphous regions are generated, thereby making high shrinkage yarns possible.

However, the existing methods including this method are all produced by batch polymerization method, which has disadvantages in terms of cost due to low productivity and high manufacturing cost.

It is an object of the present invention to provide a method for producing a highly shrinkable copolyester with high productivity at low cost.

The present invention relates to a method for producing a highly shrinkable copolyester characterized in that the PET and PEI are prepared separately and then melted, kneaded and copolymerized at a high temperature using a single or twin screw kneader.

PET and PEI are separately prepared and melted and kneaded to produce a highly shrinkable copolyester with higher productivity than a batch polymerization method in which isophthalic acid is copolymerized, and at low cost.

In particular, the present invention melt blended a mixture of about 80 to 95 mol% of PET initial polymer and 5 to 20 mol% of PEI initial polymer in a single or twin screw kneader to yield an ultimate viscosity (IV) of at least 0.60 dl / g and a shrinkage of 20 to 25 At least% copolyester can be prepared.

PET and PEI initial polymers used in the present invention can be prepared by conventional melt polymerization.

For example, PEI can be prepared by reacting isophthalic acid or diesters (dimethyl isophthalate or diethylisophthalate) with conventional methods EG, usually all reactants are esterified or trans esterified followed by a condensation polymerization step. Add to step to prepare PEI initial polymer.

PET initial polymers can also be prepared in a similar manner.

PET and PEI initial polymers used in the process of the present invention have an ultimate viscosity (IV) of at least 0.4 dl / g, preferably each initial polymer has an ultimate viscosity (IV) of 0.4 to 0.9 dl / g, and even better. The furnace usually has an intrinsic viscosity of 0.55 to 0.70 dl / g.

The process was carried out in a single screw or twin screw extruder to produce a mixture of PET and PEI initial polymer melt blended at high temperature.

In this case, the chips of PEI and PET prepared separately are mixed together.

PET and PEI initial polymer fed to the melt kneader are melt kneaded at a temperature of 265 to 300 ° C. for 5 to 30 minutes to cause a copolymerization reaction to produce a copolyester.

If the kneading temperature is less than 265 ° C., the difference in melting point with the polymer is small, so that the kneading and reaction are insufficient, so that a homogeneous copolyester is hardly obtained, and if it exceeds 300 ° C., thermal decomposition occurs, which is undesirable.

In addition, when the kneading time is less than 5 minutes, sufficient kneading with the reaction is not performed, and uniform copolyester is hardly obtained, and when the kneading time is more than 30 minutes, thermal decomposition occurs, which is not preferable.

The ratio of the two polymers to be melted and kneaded uses 80 to 95 mol% of PET and 5 to 20 mol% of PEI.

Preferably 85 to 90 mol% PET and 10 to 15 mol% PEI is used.

The copolyester of the mixture obtained after melt kneading may be prepared in a chip or pellet state after solidification and then spun, stretched and crimped using a conventional PET fiber manufacturing apparatus.

The measurement of the evaluation item shown in the Example is as follows.

Test Methods

1. Measurement of mole% of isophthalic acid

The mole% of isophthalic acid of the copolyester was measured using a DRX-300 proton nuclear magnetic resonance apparatus ( ¹ H NMR) manufactured by Bruker by dissolving the copolyester in trichloroacetic acid.

2. Glass transition temperature and melting point measurement

The glass transition temperature and melting point were measured using a differential differential scanning calorimeter (PerkinElmer DSC-7).

3. Intrinsic Viscosity (IV)

The chip was dissolved in phenol / tetrachloroethane (weight ratio 50/50) to make a 0.5wt% solution and measured at 25 ° C. with a Uberod viscometer.

4. Shrinkage rate measurement

Shrinkage was measured as the ratio of the contracted length to the initial length under tension in water at 100 ° C.

Examples 1-5

PET initial polymer and PEI initial polymer were kneaded with a biaxial kneader while changing the kneading conditions with mol%.

The molten mixture of these two initial polymers showed different properties depending on the conditions.

The fact that the two initial polymers form a uniform copolyester was confirmed using a nuclear magnetic resonance scanner ( ¹ H NMR).

After melt-spun spinning the prepared co-polyester at a rate of 1,000 m / min at 280 ℃ and stretched under the conditions of stretching temperature 75 ~ 85 ℃, stretching magnification 3.4 ~ 3.7 times, heat fixing temperature 190 ~ 230 ℃ 80 denier / 24 A high shrinkable copolyester fiber, which is a filament, was prepared.

〈Table 1〉

* Radioactive and workability ◎: Very good, ○: Good, △: Normal, ×: Poor

Comparative Examples 1-2

It manufactured similarly to the conditions of Examples 1-5 except having made the viscosity of an initial polymer low or changing kneading conditions.

When the kneading time was short, it was not possible to obtain a uniform copolyester, resulting in low shrinkage. When the kneading time was too long, the pyrolysis effect was low, resulting in low intrinsic viscosity and poor radioactivity and workability.

Comparative Example 3

It carried out similarly to the conditions of Examples 1-5 except changing PET / PEI mol% and kneading conditions.

When the mole% of PEI was high, shrinkage was remarkably reduced.

Comparative Example 4

Co-polyester was prepared according to the conventional batch polymerization process using isophthalic acid, and the conditions of spinning and stretching were the same as in Examples 1 to 5.

In the case of the conventional batch method, the shrinkage rate was lower than that of the present invention.

The copolyester prepared by the present invention exhibited a higher shrinkage rate and improved radioactivity and workability as compared with the conventional batch method.

Claims (1)

80 to 95 mol% of polyethylene terephthalate prepolymer having an intrinsic viscosity of 0.4 to 0.9 dl / g and 5 to 20 mol% of polyethylene isophthalate initial polymer having an intrinsic viscosity of 0.4 to 0.9 dl / g. A method for producing a highly shrinkable copolyester characterized by melting, kneading and copolymerizing at a temperature for 5 to 30 minutes.