JPH08120064A - Production of polyester - Google Patents

Abstract

PURPOSE: To provide a process for producing a polyester which is excellent in impact resistance, mechanical strengths at a higher temp. than 150 deg.C, and dimensional stability. CONSTITUTION: A diol mixture contg. a 2C or a 4C aliph. diol and a dimer diol as the essential components is polycondensed with an arom. dicarboxylic acid to produce a polyester comprising arom. dicarboxylic acid units and diol units mainly comprising units derived from the 2C or 4C aliph. diol and contg. 0.01-20wt.% units derived from the dimer diol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester which contains a specific amount of dimer diol residues in its constituent components, has a high crystallization rate and is excellent in impact resistance.

[0002]

BACKGROUND OF THE INVENTION Polyethylene terephthalate is widely used as a resin for fibers, sheets and films because of its excellent mechanical properties, heat resistance and chemical resistance. Further, in recent years, it has been used for carbonated beverage bottles, containers for cosmetic foods, etc. by taking advantage of its excellent chemical resistance and low gas permeability. In the case of a fiber or a film, a stretching treatment is usually performed, but in the case of an injection-molded article or the like, since the stretching treatment is generally not performed, the crystallinity is usually low as it is and exceeds 200 ° C. It cannot withstand high temperatures and is inferior in mechanical properties and dimensional stability.

In order to solve the above problems, the molded product is heat-treated at a higher temperature to increase its crystallinity, and the temperature is close to the melting point of polyester, that is, 20.
It is performed to impart heat resistance of 0 ° C. or higher. However, in the above method, since the heat treatment temperature is increased or the heating time is lengthened, the productivity is poor, and the molded product is likely to be deformed, which may lead to deterioration in quality. On the other hand, polyethylene terephthalate has the drawback of low impact strength, and its improvement is desired.

[0004]

The present invention is intended to solve the above problems in crystalline polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and an object of the present invention is to achieve crystallization at a lower temperature. Another object of the present invention is to provide a novel polyester which has an excellent crystallization rate and is excellent in impact resistance, which is possible and does not require addition of additives.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when synthesizing polyethylene terephthalate, a polyester obtained by copolymerizing a small amount of dimer diol with ethylene glycol The present inventors have found that the crystallization rate is high and the molded product obtained from it has excellent impact resistance, and reached the present invention. That is, the present invention is characterized by polycondensing an aromatic dicarboxylic acid with a diol mixture containing an aliphatic diol having 2 or 4 carbon atoms and a dimer diol as essential components, and the above aliphatic diol having 2 or 4 carbon atoms. A method for producing a polyester comprising a diol unit containing a residue as a main component and 0.01 to 20% by weight of a dimer diol residue based on the total amount of all diol residues and an aromatic dicarboxylic acid unit, Is 25 ° C measured in a mixed solvent of 1,1,2,2-tetrachloroethane and phenol
The method for producing the above polyester, wherein the intrinsic viscosity is 0.3 or more.

The present invention will be described in more detail below. Dimer diol Dimer diol is an aliphatic diol having 36 carbon atoms obtained by completely hydrogenating dimer acid, and is obtained as a mixture of geometric isomers of dimer diol having a branched structure or a cyclohexane ring. As a commercially available product, the product name PRIPOL-20 manufactured by Unichema International
There are 33 etc. Examples of the dimer acid used as a raw material of the dimer diol include unsaturated fatty acids such as linoleic acid, oleic acid and linolenic acid, and dry oil fatty acids or semi-dry oil fatty acids such as tall oil, cottonseed oil and soybean oil having 18 carbon atoms. There is a dicarboxylic acid having 36 carbon atoms, which is obtained by thermally polymerizing one carboxylic acid. It is also possible to use a commercially available product. The amount of the dimer diol used in the present invention is 0.01 to 20% by weight of all the diol residues constituting the polyester. When the amount of the dimer diol used is 20% by weight or more, the strength of the resin decreases, while when it is 0.01% by weight or less, the effect of improving the crystallization rate is not recognized. More preferably 0.1 to 12% by weight
Is.

Diol used in combination with dimer diol The main component of the diol used in combination with the above dimer diol is ethylene glycol or 1,4-butane diol, and the preferred amount thereof is based on the total amount of diol residues. And 80 to 99.99% by weight. In the present invention, in addition to the above diols, diols having 5 or more carbon atoms,
Specifically, a small amount of hexanediol or the like can be used.

Aromatic Dicarboxylic Acid The preferred aromatic dicarboxylic acid in the present invention is terephthalic acid. Further, as terephthalic acid as a raw material for synthesizing polyester, an ester-forming terephthalic acid derivative may be used instead. The aromatic dicarboxylic acid units constituting the polyester of the present invention are terephthalic acid units 1
It is preferably seed only. If necessary, other dicarboxylic acids can be used in combination with the terephthalic acid, and other dicarboxylic acids include isophthalic acid,
Examples thereof include alkyl-substituted phthalic acids such as phthalic acid and methylterephthalic acid, naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, and aliphatic or alicyclic dicarboxylic acids such as succinic acid, adipic acid, and cyclohexanedicarboxylic acid.

Polyester synthesis method As a polyester synthesis method, a method of polycondensing each diol and dicarboxylic acid using a catalyst, a method of depolymerizing polyethylene terephthalate or polybutylene terephthalate using a dimer diol and then polycondensing However, either method may be adopted. In the former case, a catalyst is added to each diol and dicarboxylic acid, an esterification reaction is performed at high temperature and normal pressure, and then ethylene glycol is distilled off under reduced pressure to perform a condensation reaction. In the latter method, polyethylene terephthalate and dimer diol are heated, and if necessary, a depolymerization catalyst is used to depolymerize, and then decompression is carried out to carry out polycondensation. Even during polycondensation,
A catalyst is used if necessary. Specific examples of the catalyst include zinc acetate dihydrate for transesterification, antimony pentoxide for condensation polymerization, and manganese acetate for depolymerization.
Examples include tetrahydrate and the like.

Intrinsic viscosity The intrinsic viscosity of the polyester in the present invention is 1,1,
2,2-tetrachloroethane, phenol (weight ratio 1:
1) 0.3 when measured at 25 ° C. using a mixed solvent
The above is desirable. When the intrinsic viscosity is less than 0.3, the strength of the obtained molded product is low and it is not practical.

[0011]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. ○ Example Dimethyl terephthalate (hereinafter referred to as DMT), ethylene glycol, dimer diol (PRIPOL-2033 manufactured by Unichema International), zinc acetate-2
Charge the hydrate and in a nitrogen atmosphere at 210 ° C for 3 hours
The temperature was raised to 40 ° C., and the reaction was continued for 40 minutes to distill off the produced methanol. Then, after adding antimony oxide,
The temperature was raised to 280 ° C over 3.5 hours, and the degree of vacuum was gradually increased over 1.5 hours until finally reaching 0.2
mmHg. Further condensation was carried out for 1 hour to distill off ethylene glycol. The reaction was terminated when the reaction liquid became highly viscous.

In the polyester synthesized by the above operation, since the dimer diol and the dicarboxylic acid have high boiling points, almost all of the charged weight is a constituent component of the polyester. On the other hand, the low-boiling diol is distilled during polycondensation, so that the diol having a low boiling point is drastically reduced relative to the charged weight and incorporated into the polyester. With respect to the obtained polyester, the crystallization temperature when the temperature was raised and the solidification temperature when the temperature was once raised to the melting temperature or higher and then cooled were measured using DSC. The rate of temperature increase / decrease during measurement was 20 ° C./min, and the measurement was performed under a nitrogen atmosphere. The measurement results are as shown in the table.

The intrinsic viscosity of polyester was measured by the following procedure. That is, 0.25 g of dried polymer
Accurately weighed and placed in a 50 mL volumetric flask. Further, a mixed solution of 1,1,2,2-tetrachloroethane and phenol (weight ratio 1: 1) was added, and the mixture was heated to 70 ° C. and well dissolved. The solution was placed in a water bath maintained at 25 ° C. to a constant temperature, filled with the solvent up to the marked line of the volumetric flask, and allowed to stand for 1 hour or more. Add this solution to a viscometer (Cannon Fenceke SO
-90366) was used to measure the viscosity, and the intrinsic viscosity was determined by the following formula.

Η = ln {(T / Tb) / C} η: Intrinsic viscosity T: Flow time of solution Tb: Flow time of mixed solvent C: Concentration 0.5 g / dL

Comparative Example Polyethylene glycol terephthalate containing no dimer diol was synthesized in the same manner as in the examples using the diols and dicarboxylic acids described in the table, and the intrinsic viscosity, crystallization temperature and solidification temperature thereof were calculated. Was measured.

[0016]

【table】

[0017]

INDUSTRIAL APPLICABILITY The polyester containing a specific amount of dimer diol units in the present invention can be crystallized at a lower temperature and has a higher impact resistance than polyethylene glycol terephthalate or polybutylene glycol terephthalate, which have similar components. It has excellent properties. According to the polyester having the above characteristics, impact resistance as well as 150 ° C.
A polyester molded product having excellent mechanical strength and dimensional stability at a temperature exceeding 100 ° C. can be easily obtained.

Claims (2)

[Claims] 1. A diol mixture containing an aliphatic diol having 2 or 4 carbon atoms and a dimer diol as essential components and an aromatic dicarboxylic acid are polycondensed.
A diol unit and an aromatic dicarboxylic acid unit containing the above-mentioned aliphatic diol residue having 2 or 4 carbon atoms as a main component and containing 0.01 to 20% by weight of a dimer diol residue based on the total amount of all diol residues. A method for producing a polyester. 2. The method for producing a polyester according to claim 1, wherein the intrinsic viscosity at 25 ° C. measured in a mixed solvent of 1,1,2,2-tetrachloroethane and phenol is 0.3 or more.