KR960005797B1 - Process for preparing polyester - Google Patents

Abstract

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Description

Manufacturing method of polyester for extrusion molding

The present invention relates to a method for producing polyester for extrusion molding, and more particularly, to produce a highly viscous polyester by adding a side chain forming compound to increase the melt strength of the resin, by adding a new carbonate compound The present invention relates to a new process for producing polyester that not only prevents gelation of polymers occurring at the end of the polymerization but also makes it possible to easily control the degree of polymerization.

In general, polyester resins are excellent in mechanical and chemical properties, and are widely used in fibers, bottles, engineering plastics, films, sheets, and the like. In particular, high molecular weight polyester resins having an intrinsic viscosity of more than 0.7 dl / gr have been widely used in various carbonated beverages, cosmetics, and medicine bottles through injection blow molding processes. After making the parison as a molded article, the secondary parison is heated and blown, which is mainly used as a pressurized container containing carbonated drinks due to the rigidity of the molded article.

However, there is a disadvantage that cannot be formed by extrusion blow molding suitable for non-pressurized container molding, that is, by direct blow without making a parison, which is sufficient to allow the polymer to be extrusion blow molded. It does not have a melt strength.

In order to increase the melt strength of the polymer, a method of simply increasing the intrinsic viscosity of the polymer through solid phase polymerization, such as IV 1. ⁵ dl / gr or more, may be used. It is not practical because it does not show sufficient melt strength.

Therefore, in order to increase the melt viscosity and strength of the polymer in the molten state, it is advantageous to use an appropriate amount of modifier. For this purpose, a method of increasing the viscosity and melt strength of the polymer by adding a side chain forming agent having three or more reactive functional groups Many studies have been conducted.

However, this method also increases the melt strength of the polymer to the extent that extrusion hollow molding is possible, but there is a high risk of gelation at the end of the polycondensation reaction and it is difficult to control the degree of polymerization. . The gelled part of the polymer may cause a fatal damage such as a fish eye to the appearance of the final molded container. Meanwhile, the degree of polymerization is difficult to control and a polymer having a uniform physical property cannot be obtained.

In addition, US Pat. No. 4,234,708 discloses a method of polycondensation using a side chain forming agent and a chain terminator at the same time, but is not effective in controlling the degree of polymerization.

In the present invention, in order to solve such a conventional problem, a chain forming agent is added to increase the melt strength of the polymer during polyester production, and at the same time, one ester forming derivative is added to improve the transparency of the molded product, The purpose of the present invention is to provide a new polyester production method that can stably produce high-viscosity polyester capable of extruded hollow molding, tube, and sheet extrusion molding by adding a specific carbonate compound and providing excellent transparency and thermal stability. There is this.

Hereinafter, the present invention will be described in detail.

The present invention provides a catalyst and a thermal stabilizer for a polymer obtained by esterification or transesterification using terephthalic acid or its ester-forming derivative and isophthalic acid or its ester-forming derivative using a diol compound mainly composed of a side chain forming agent and ethylene glycol. In preparing the polyester through the polycondensation reaction, the polyfunctional to 100 mol% selected from polyethylene terephthalate homopolyester or ethylene terephthalate / isophthalate high polyester having 20 mol% or less of ethylene isophthalate units, 0.05 to 1.5 mol% of a side chain forming agent having a functional group and one carbonate compound selected from the compounds represented by the following structural formulas (I) or (II) are added in an amount of 0.5 to 20 equivalents relative to the amount of the side chain additive It is characterized by.

Wherein R ₁ and R ₂ are hydrogen or an alkyl or aryl compound having 1 to 10 carbon atoms, respectively.

Referring to the present invention in more detail as follows.

In the present invention, the terephthalic acid component is 80 mol% or more of the total acid component, the isophthalic acid component is preferably 20 mol% or less of the total acid component, when it exceeds 20 mol% to reduce the heat resistance of the molding or lower the mechanical strength This is undesirable.

In addition, as the side chain forming agent, polycarboxylic compounds such as trimellitic acid, pyromellitic acid or anhydrides thereof, trimeric acid, 1,2,3-propyltricarboxylic acid and carboxyl or hydroxyl group-containing compounds may be used. , It is preferable to add 0.05 ~ 1.5 mol% of the total acid component, wherein if the side chain forming agent component is less than 0.05 mol%, it is difficult to expect the polymer melt strength of the extrusion hollow molding possible, and if it is 1.5 mol% or more, polycondensation The gelation tends to be clear during the process, making the reaction difficult.

On the other hand, the carbonate compound added in the polycondensation process is used as the compound of the formula (I) or (II), for example ethylene carbonate, diphenyl carbonate, etc., the amount of the carbonate compound is 0.1 to 10 relative to the equivalent ratio of the side chain forming agent component It is preferable to add the equivalent, if less than 0.1 equivalent does not effectively inhibit the gelation of the end of the reaction, if more than 10 equivalent will reduce the polycondensation reaction rate.

On the other hand, according to the present invention, the addition time of the carbonate compound is preferably between 20 minutes after the start of the vacuum reaction during the polycondensation reaction and 10 minutes before the end of the reaction. If the carbonate compound is added 20 minutes after the start of the vacuum reaction, the polymerization reaction rate is lowered. If the compound is added within 10 minutes of the end of the reaction, the reaction time is insufficient and the effect of addition is small.

In addition, in the present invention, a known diol compound, a catalyst, and a heat stabilizer are used in a known method.

As described above, when the melt polycondensation is performed, a high viscosity polyester resin having a melt strength capable of extrusion hollow molding can be prepared, and the degree of polymerization can be stably controlled without gelation in the melt polycondensation process. Because of this, the polyester produced by the present invention is used as a container such as a bottle through the extrusion blow molding, and can be used as a container for various material parts by extrusion molding in a tube or sheet state.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to Examples.

Intrinsic viscosity is the value measured by the solution of 1.2% by weight with respect to the phenol / tetrachloroethane (volume ratio: 6: 4) mixed solvent, the melt index (melt index) is measured by the load of 325g at 270 ℃.

Example 1

92 parts by weight of dimethyl terephthalate, 5 parts by weight of dimethyl isophthalate, 64 parts by weight of ethylene glycol, 0.56 parts by weight of trimellitic hydride, and 0.06 parts by weight of manganese acetate were added to a reactor equipped with a distillator and a condenser. After the reaction, the amount of methanol was obtained, followed by 0.07 part by weight of trimethyl phosphate and 0.05 part by weight of antimony triacetate, followed by vacuum reaction for 50 minutes while extracting ethylene glycol, 0.4 part by weight of diphenyl carbonate, and then vacuum reaction for 30 minutes. The reaction was in good condition without gelation. The IV was 0.73 dl / g and the melt index was 3.6 g / 10 min.

Example 2

The reaction was carried out in the same manner as in Example 1, except that 1.0 part by weight of ethylene carbonate was added instead of 0.4 part by weight of diphenyl carbonate. The reaction was good and did not gel. IV was 0.70 dl / g and MI was 3.8 g / 10 min.

Comparative Example 1

The reaction was the same as in Example 1 except that diphenyl carbonate was not added in Example 1. From 70 minutes of vacuum reaction time, the reactants rapidly gelled and no further reaction was possible, and IV and MI could not be measured.

Comparative Example 2

The reaction was carried out in the same manner as in Comparative Example 1 except that the vacuum reaction time was changed to 65 minutes in Comparative Example 1. The reaction was good but the IV was 0.58 dl / g and the MI was 12.5g / 10min, which was not suitable for extrusion.

Example 3

In Example 1, 0.28 parts by weight was added without adding 0.56 parts by weight of trimellitic anhydride, and the reaction was carried out in the same manner as in Example 1 except that the reaction time was 40 minutes after the addition of diphenyl carbonate. The reaction was good and did not gel. IV was 0.74 dl / g and MI was 2.9 g / 10 min.

Example 4

The reaction was carried out in the same manner as in Example 3, except that 1.0 part by weight of ethylene carbonate was added instead of 0.4 part by weight of diphenyl carbonate. The reaction was in good condition and no gelation occurred. IV is 0.72 dl / g. MI was 3.4 g / 10 min.

Comparative Example 3

The reaction was performed in the same manner as in Example 3, except that diphenyl carbonate was not added in Example 3. After 80 minutes of vacuum reaction, gelation of the reactants occurred and the reaction could not proceed any further, and IV and MI could not be measured.

Comparative Example 4

The reaction was carried out in the same manner as in Comparative Example 3 except that the vacuum reaction time was changed to 75 minutes in Comparative Example 3. Although the reaction was good, the IV was 0.59 dl / g and the MI was 11.8 g / 10min, which was not suitable for extrusion blow molding.

In the above examples and comparative examples, when ethylene carbonate and diphenyl carbonate were not added but trimellitic anhydride, which is a multifunctional component, gelling easily occurred, and a sufficient melt viscosity was obtained when the reaction time was shorter than the time of gelation. Although it was difficult to prepare a polymer having ethylene carbonate or diphenyl carbonate, it can be seen that high viscosity polyester can be prepared to the extent that extrusion is possible without gelation.

Claims (1)

The oligomer obtained by esterification or transesterification of terephthalic acid or its ester-forming derivative and isophthalic acid or its ester-forming derivative using a side chain forming agent and a diol compound mainly composed of ethylene glycol is used as a catalyst and a heat stabilizer, In preparing a polyester through a polycondensation reaction with a compound, 100 mol% of a polyethylene terephthalate homopolyester or an ethylene terephthalate / isophthalate high polyester having 20 mol% or less of ethylene isophthalate units is multifunctional. 0.05 to 1.5 mol% of a side chain forming agent having a functional group and one carbonate compound selected from the compounds represented by the following structural formulas (I) or (II) are added in an amount of 0.1 to 10 equivalents based on the amount of the side chain additive added, Compound is polymerized Extrusion method for producing a molded polyester according to claim 10 minutes before the addition of between 20 minutes after the start of the vacuum reactor and the reaction was completed. Wherein R ₁ and R ₂ are hydrogen or an alkyl or aryl compound having 1 to 10 carbon atoms, respectively.