KR940007321B1 - Process for preparation of polyester copolymer - Google Patents

Abstract

This invention relates to the manufacturing of polyester copolymer of good transparency, impact resistance and heat resistance. The ethylene terephthalate base polyester manufacturing method comprises esterification or ester exchange reaction and polycondensation. In esterification or ester exchange reaction, dimethylterephthalate and dimethyl 2,6-naphthalenedicarboxylate are added in the weight ratio of 94:6-58:42; and in polycondensation, trimelitic acid anhydride 0.2-0.8 wt.% and dimeric acid 9-36 wt.% are added.

Description

Process for producing polyester copolymer

The present invention relates to a method for producing a polyester copolymer excellent in transparency and excellent in impact resistance and heat resistance and its use.

Polyester, in particular polyethylene terephthalate, has excellent mechanical and chemical properties and is widely used in fibers, films, resins, and plastic containers.

Among them, the use of plastic containers has been widely used in recent years because of the excellent mechanical properties, transparency and harmlessness of polyethylene terephthalate, such as beverage containers, reagent containers, mineral water, and liquor. .

The first plastic name started with acrylic from Monsanto, but after being discontinued by the US Food and Drug Administration (FDA), DuPont developed a polyethylene terephthalate name (trade name: Dalar). It has been growing rapidly and is growing rapidly.

General polyester synthesizes bis-hydroxyethyl terephthalate (BHT) by transesterification (esterification) of dimethyl terephthalic acid (terephthalic acid) and ethylene glycol at 240 ° C, and then increases the temperature to 285 ° C or less. Polycondensation while removing ethylene glycol to obtain a conventional polyester, the pressure-resistant container is a high-polymerization bottle resin produced through a solid-phase polymerization in order to have transparency and strength, the resin is mainly carbonated drinks It is often used as a container for containers, cosmetics, and alcoholic beverages. Patents relating to polyester bottles have been published in US 3,733,309 for the preparation of biaxially stretched polyester bottles. In addition to homopolymers, the present invention also discloses copolymerization of terephthalic acid with diols such as diethylene glycol, propane-1,3-diol, butane-1,4-diol, 1,4-hydroxymethylcyclohexane, and US 3,890,256. Discloses a patent for neopentylglycol copolymerized polyester. These copolymers lacked impact resistance, and the homopolymer had a disadvantage in that the cooling time was long for the manufacture of thick bottles due to the rapid crystallization rate.

In order to improve pressure resistance and moldability, the above resins are required to have a resin having a high molecular weight of a predetermined amount or more, and after melt polymerization, the viscosity is increased by solid phase polymerization to form a bottle using a blow molding machine.

In addition, PET homopolymers are difficult to use because of low heat resistance in beverages that require sterilization. In addition, in some cases, such as orange juice is injected into the bottle in a hot state is required to improve the heat resistance of the bottle.

Accordingly, the present invention has excellent heat resistance to withstand sterilization temperature (70 ℃) or orange juice import temperature (85 ℃), and has a trifunctional carboxyl terminal which can induce chemical crosslinking in the molecular structure during polymerization. It is an object of the present invention to provide a method for producing a polyester copolymer having excellent strength, transparency, and impact resistance, as well as enhancing the polymerization rate by adding a substance.

Dimethyl terephthalate, dimethyl 2,6-naphthalene-dicarboxylate and ethylene glycol are added to a conventional polyester reaction tube, a transesterification catalyst and a complementing agent are added, and the temperature is raised to a temperature of 240-250 ° C. (ester Exchange reaction) to remove methanol by stirring for 1-2 hours, trimellitic anhydride and dimer acid were added in this order, and then a polycondensation catalyst and a heat-resistant material were added to increase the temperature to 280-290 ° C (polymerization shaft temperature). It is a method of synthesizing a polyester copolymer by reducing the pressure to 1.0 L or less over 1 hour and then reacting for 1 hour using nitrogen to reduce the pressure to normal pressure. In this case, dimethyl terephthalate and dimethyl 2,6-naphthalene-dicarboxylate are added in a weight ratio of 94: 6 to 58: 42, and the heat resistance required when the dimethyl 2,6-naphthalene-dicarboxylate is 6 or less It is difficult to have, and when it is 42 or more, it is unnecessary and disadvantageous in terms of price. And the trimellitic anhydride is suitable 0.2 to 0.8% by weight compared to the polymer and below this range there is no effect of viscosity increase and the strength of the bottle state is not good. Is impossible.

In addition, the amount of dimer acid is suitable in the range of 9.0 to 36% by weight compared to the polymer, and less than that, the impact strength is insignificant, and above that, the heat resistance is lowered, the strength is lowered, and the color is worsened. .

Here, the transesterification catalyst is preferably magnesium acetate, zinc acetate, manganese acetate, and the content thereof is suitably 200 to 400 PPM relative to the polymer.

In addition, the heat-resistant agent is triethyl phosphate, trimethyl phosphate, triphenyl phosphate triphenyl phosphite, phosphoric acid and the like is good content of 200 to 300PPM compared to the polymer, and the complementary agent is high baltic acetate, the content is 50 to 50 100PPM is suitable. In addition, the polycondensation catalyst is good antimony trioxide, antimontriacetate, antimony glycolate, the content of 300 to 400PPM is suitable for the polymer. The resin thus synthesized is not only suitable for use as carbonated beverages, juice containers, medicines, and cosmetic containers, which are heat and pressure resistant containers, but also for food contact packaging materials requiring heat resistance, particularly as herbal medicine bags.

The dimer acid used herein is commercially available under the trade names UNIICHEMA, PRIPOL 1009, and the chemical formula is dicarboxylic acid having 36 carbons and molecular weight of 573. In addition, the trimellitic anhydride used was the product of AMOCO.

Copolymerization with dimethyl 2,6-naphthalenedicarboxylate improves the glass transition temperature to above 85 ° C, increases the intrinsic viscosity rise rate by adding trimellitic anhydride, and withstands pressure without solid phase polymerization. Tensile strength of 900 ~ 1100Kg / cm, tensile elasticity modulus 30,000 ~ 35,000Kg / cm, which can be used as a bottle, is enhanced, which is due to the small amount of crosslinking, and impact strength of 4.0Kg / The impact resistance is increased to more than cm, and at the same time, a bottle having excellent transparency can be manufactured even during a short cooling time during the bottle forming process. This is because dimer acid acts as an impact agent and also acts as a crystallization retarder, thereby decreasing the crystallization rate.

Unlike other resins, bottle resins have a slower crystallization rate, which reduces bottle cooling and median cooling time, resulting in shorter molding time and improved productivity. Good bottle formability here means excellent transparency even at short cooling times.

The polyester copolymer thus prepared can be used for food and non-food containers. For food, it is used for juice bottles requiring heat and pressure resistance, carbonated beverage bottles for pressure resistance, and pharmaceutical and cosmetic containers for non-food items and bottles requiring heat resistance and transparency.

The present invention will be described in more detail based on examples.

Example 1

5.16 Kg of dimethyl terephthalate, 0.33 Kg of dimethyl 2,6-naphthalene-dicarboxylate, 2.7 l of ethylene glycol, 1.2 g of magnesium acetate hydrate and 0.4 g of cobalt acetate hydrate were added to a polyester reaction tube, and the temperature was increased. After stirring for 1.5 hours at 245 ° C. (ester exchange reaction) to remove methanol, 21 g of trimellitic anhydride and 1 Kg of dimer acid were added, 1.8 g of antimony trioxide and 2 g of triethyl phosphate were added thereto, followed by 285 ° C. The reaction was carried out for 1 hour after the pressure was reduced to 0.5 Torr over 1 hour while the temperature was raised to), reduced to normal pressure using nitrogen, and discharged to obtain a polyester. The resin thus prepared was obtained by obtaining an intrinsic viscosity at a concentration of 0.5 weight fraction at 30 ° C. with a phenol / tetrachloroethane solvent, and measuring the glass transition temperature at a temperature rising rate of 20 ° C./min using a thermal analyzer. The 3Kg sample was crystallized and dried at 170 ° C. for 2 hours using a vacuum dryer, then dried at 200 ° C. for 4 hours, and the acetaldehyde content was measured. The remainder was 1.51 using a blow molding machine (Japan ASB Machinery Co., Ltd.). After preparing a bottle of l (45g) size by 2 stages (1st stage: Preform, 2nd stage: Blowing) method, transparency was measured at 6 seconds of cooling time. After injection, the lid was closed and left for 24 hours, and then the degree of deformation (shrinkage) was visually observed.

In addition, the sample of 3Kg was made of an ASTM standard mold using an injection molding machine (FANUC) to measure the heat deformation temperature and impact strength.

[Examples 2 to 6 and 1 to 10 in comparison]

The polymerization was changed only to the following composition, and the polymerization method was carried out in the same manner as described above, and the composition, intrinsic viscosity, glass transition temperature, and acetaldehyde content are shown in Table-1. The heat deflection temperature, impact strength, tensile strength and elongation of the synthetic resin are shown in Table 2 below.

The heat deflection temperature and impact strength were measured in a 1/4 ”bar specimen after drying the resin at 170 ° C. for 4 hours using an injection molding machine to make an ASTM standard mold. The tensile strength, elongation and elastic modulus were measured in bottles. After making, cut to a constant size, tensile steel, elongation and tensile modulus were measured by Instron.

TABLE 1

TABLE 2

* Transparency: ◎: Very good, ○: Good, △: Poor

Heat resistance: A: No deformation, B: Slight deformation, C: Many deformation

Claims (1)

In preparing a polyester copolymer containing ethylene terephthalate as a main component, the weight ratio of dimethyl terephthalate and dimethyl 2,6-naphthalene-dicarboxylate participating in the transesterification reaction is added at 94: 6 to 58: 42. And 0.2 to 0.8% by weight of trimellitic anhydride and 9 to 36% by weight of dimer acid during the polycondensation reaction.