KR19990001321A - Method for producing a polyethylene naphthalate copolymer copolymer heat resistant container capable of high temperature filling - Google Patents

Abstract

The present invention relates to a method for producing a polyethylene naphthalate copolymer heat-resistant container capable of high temperature filling, and more particularly, a transparent polyethylene naphthalate system having excellent heat resistance that can be filled at high temperature and easily formed even at low temperature. It relates to a method for producing a copolymer heat-resistant container.

According to the method of the present invention, since the container can be molded at a low temperature by using a small amount of polyethylene naphthalate copolymer compared to the conventional technology, production cost can be reduced, and acetaldehyde, which may occur during high temperature molding, can be used. Since almost no by-products are generated, a polyethylene naphthalate copolymer heat resistant container having a stable storage property of the contents can be prepared.

Description

Method for producing a polyethylene naphthalate copolymer copolymer heat resistant container capable of high temperature filling

The present invention relates to a method for producing a polyethylene naphthalate copolymer heat-resistant container capable of high temperature filling, and more particularly, a transparent polyethylene naphthalate system having excellent heat resistance that can be filled at high temperature and easily formed even at low temperature. It relates to a method for producing a copolymer heat-resistant container.

Polyethylene terephthalate-based copolymer is widely used as a container for non-food containers such as carbonated beverages, bottled water, fruit juices and beverages as well as for foods such as carbonated beverages, bottled water and juice drinks because of its easy molding and transparency. In order to use, special processing such as primary blowing, heat-set process, and secondary blowing is required.

In Japanese Patent Publication No. 55-12031, it is necessary to prevent heat deformation by heat-processing and whitening (crystallizing) the neck of a polyethylene terephthalate container. In addition, Japanese Patent Publication No. 64-85732 has a high polyethylene naphthalate composition of 65 to 98.5 mol% and blows the product as it is without whitening and heat treatment to enable high temperature filling of 85 ° C or higher. However, 2, 6-naphthalene dicarboxylic acid, which is a raw material of polyethylene naphthalate, is expensive, and when the composition of polyethylene naphthalate is high, the processing temperature is relatively much higher than that of polyethylene terephthalate, which causes byproducts such as acetaldehyde.

The present inventors have studied the polyethylene naphthalate copolymer for use in the manufacture of a heat-resistant container that can be filled at a high temperature without forming by-products during molding without additional treatment.

It is an object of the present invention to provide a method for producing a polyethylene naphthalate copolymer heat-resistant container which can be easily molded even at a low temperature even using a small amount of polyethylene naphthalate copolymer, can be filled at a high temperature, and has excellent heat resistance.

The present invention is added to 8, 20 mol% of 2, 6-naphthalene dicarboxylic acid or lower alkyl ester thereof and 92-80 mol% of terephthalic acid or lower alkyl ester thereof to react in an ethylene glycol solution, to which a polycondensation catalyst is added. After the polymer was prepared by polycondensation under reduced pressure, the polymer obtained was subjected to solid phase polymerization at 190 to 210 ° C to prepare a polymer having an intrinsic viscosity of 0.75 to 0.80 dl / g and a number average molecular weight of 90,000 to 100,000, and drying the preform. After injection molding, it is a method for producing a polyethylene naphthalate copolymer heat-resistant container, which is blow molded at a mold temperature of 100 to 150 ° C.

Hereinafter, the present invention will be described in more detail.

Polyethylene naphthalate copolymer according to the present invention is 8 to 20 mol%, preferably 10 to 15 mol% of benzene dicarboxylic acid and 90 to 85 mol% of 2, 6-naphthalene dicarboxylic acid And polycondensation of excess ethylene glycol. The polyethylene naphthalate copolymer according to the present invention having the above-described composition has a reduced use amount of 2, 6-naphthalene dicarboxylic acid, which is an expensive raw material, compared with a conventional polyethylene naphthalate copolymer, but a melting point compared with polyethylene terephthalate. Since the temperature is about 20 ° C., it is possible to mold at a low temperature. Since the glass transition temperature is 5 to 10 ° C. or more, it exhibits excellent heat resistance, so that high temperature filling at 85 ° C. or more is possible.

Specifically, in the present invention, benzenedicarboxylic acid, preferably terephthalic acid or lower alkyl ester thereof and ethylene glycol as a reaction solvent are added to 2, 6-naphthalene dicarboxylic acid or lower alkyl ester thereof, and esterified by conventional methods. The transesterification reaction produces a oligomer. Next, using a polycondensation catalyst such as antimony trioxide and germanium oxide, the polycondensation reaction of the oligomer obtained above is carried out at 260 to 270 ° C. under reduced pressure to produce a polymer having a desired viscosity. This polymer was subjected to solid phase polymerization at 190 to 210 ° C to prepare a polymer having an intrinsic viscosity of 0.75 to 0.80 dl / g and a number average molecular weight of 90,000 to 100,000, and the obtained polymer was 0.01% by weight, preferably 0.005% by weight or less. After drying by injection molding the preform at a barrel temperature of 265 to 280 ℃, blow molding in the form of a container to prepare a heat-resistant container.

As described above, when the amount of 2, 6-naphthalene dicarboxylic acid or lower alkyl ester is decreased, the glass transition temperature of the polyethylene naphthalate-based copolymer is lowered. In the present invention, the mold temperature is 100 to 160 ° C. during blow molding. For example, it is possible to improve heat resistance and strength of the molded product by fixing at 140 to 150 ° C.

In the present invention, when the composition of 2, 6-naphthalene dicarboxylic acid is 8 mol% or less, the glass transition temperature is lowered to obtain desired heat resistance, and when 20 mol% or more, the melting temperature and the melt viscosity are increased, thereby relatively processing during injection molding. Due to the high temperature, pyrolysis may occur and it becomes difficult to manufacture high quality containers such as acetaldehyde production.

The polyethylene naphthalate-based copolymer according to the present invention prepared as described above can be molded at low temperatures because of its low melting point, thereby preventing the formation of acetaldehyde, improving storage properties as a container, and having a high glass transition temperature. It can exhibit heat resistance.

EXAMPLE

Hereinafter, the present invention will be described in more detail with reference to Examples.

Examples 1-6

The polymer chips obtained by melt polymerization and solid phase polymerization using the raw material composition shown in Table 1 were dried at 160 to 170 ° C. for at least 4 hours, and the preform was molded at an injection molding machine at a barrel temperature of 270 to 280 ° C., followed by heat resistance of 1.5 L and a weight of 55 g. The containers were molded to make Examples 1 to 6, respectively. At this time, the temperature of the mold was fixed at 140 to 160 ℃.

The molded container was randomly taken out 10 copies in all the examples, filled with high-temperature contents at 85 ° C. and 90 ° C., and then capped to stand for 1 day, 3 days, 5 days, 10 days, 30 days, and then inspected for appearance defects. The results are listed in Table 2 below.

TABLE 1

* 2, 6-NDC: 2, 6-naphthalene dicarboxylic acid

TPA: terephthalic acid

IPA: Isophthalic Acid

DMT: Dimethyl Terephthalic Acid

DMI: Dimethyl isophthalic acid

EG: ethylene glycol

* Intrinsic viscosity: The concentration was adjusted to 0.5 g / dl with a mixed solvent of phenol / tetrachloroethane and measured at 20 ° C. using an uberoid viscometer.

* Melting point and glass transition temperature: measured by heating at a rate of 20 ℃ / min using DSC (Differential Scanning Colorlimeter, manufactured by Perkin Elmer).

TABLE 2

Comparative Example 1

Except for using the raw material composition shown in Table 1, the heat-resistant container was molded in the same manner as in Example to investigate the appearance defects. The mold temperature was determined according to the raw materials used.

The results are shown in Table 3 below.

TABLE 3

Comparative Examples 2 to 3

Except having used the raw material composition of Table 1, the heat-resistant container was shape | molded by the same method as Example, and it was set as the comparative examples 2 and 3. The mold temperature was determined according to the raw materials used.

In Comparative Examples 2 and 3, appearance defects did not occur, but preform molding was possible only at a high temperature of 300 ° C. or higher, and thus, acetaldehyde of 3 μg or more was generated per 1 L of heat-resistant container.

According to the method of the present invention, since the container can be molded at a low temperature by using a small amount of polyethylene naphthalate copolymer compared to the conventional technology, production cost can be reduced, and acetaldehyde, which may occur during high temperature molding, can be used. Since almost no by-products are generated, a polyethylene naphthalate copolymer heat resistant container having a stable storage property of the contents can be prepared.

Claims (1)

92-80 mol% of terephthalic acid or its lower alkyl ester is added to 8-20 mol% of 2, 6- naphthalene dicarboxylic acid or its lower alkyl ester, and it reacts in an ethylene glycol solution, and polycondensation catalyst is added here and it polycondenses under reduced pressure. After the polymer was prepared by a polymerization reaction, the obtained polymer was solid-phase polymerized at 190 to 210 ° C. to prepare a polymer having an intrinsic viscosity of 0.75 to 0.80 dl / g and a number average molecular weight of 90,000 to 100,000, followed by injection molding. After that, blow molding is performed at a mold temperature of 100 to 150 ° C. A method for producing a polyethylene naphthalate copolymer heat-resistant container.