JPH08301996A - Method for polymerizing polyester - Google Patents

Abstract

PURPOSE: To prepare a polymer having a good color tone by reducing the occurrence of a sublimate in the polymn. of a polyester contg. an adipic acid component or a 1,4-butanediol component as a main component or a comonomer. CONSTITUTION: Polymn. is conducted in the presence of potassium titanium oxalate as a polymn. catalyst. The amt. of the potassium titanium oxalate added is pref. 1 to 200ppm in terms of titanium atom based on the total amt. of the polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polymerizing a polyester containing an adipic acid component and a 1,4-butanediol component as a main component or a copolymerization component.

[0002]

The polybutylene adipate resin obtained by the polycondensation reaction of adipic acid and 1,4-butanediol has a low melting point and is crystalline, so that it is used alone or mixed with other resins such as polyvinyl alkyl ether. Then, it can be used as a moldable cast material. Further, a modified resin obtained by copolymerizing a polybutylene terephthalate (hereinafter referred to as PBT) resin with adipic acid has a low glass transition temperature, and thus is excellent in flexibility and can be suitably used for various films and molding applications.

As a method for polymerizing polybutylene adipate, similar to the method for polymerizing PBT, a method using an organic titanium catalyst such as tetra-n-butyl titanate is used, as well as an organic titanium catalyst and a metal salt of a saturated aliphatic carboxylic acid. A method for carrying out a polycondensation reaction is known (Japanese Patent Laid-Open No. Sho 63-63).
-251424). In addition, a method of using an organic titanium catalyst is known in the polymerization of polyesters containing succinic acid and adipic acid as acid components and 1,4-butanediol as a diol component (Japanese Patent Laid-Open No. 5-70666).

[0004]

However, when the polymerization is carried out by the above-mentioned method, a large amount of sublimate is generated as a by-product, so that the piping is clogged and the polymerization is hindered. In addition, the generation of by-products leads to a decrease in yield. The sublimate is a cyclic diester compound produced by reacting one molecule of adipic acid and one molecule of 1,4-butanediol,
Since the mechanism of its formation is very similar to the polycondensation reaction, it was extremely difficult to suppress it only by changing the reaction conditions.

Further, a resin having a butylene adipate component as a constitutional unit has a poor color tone when an organic titanium catalyst is used, and is often reddish or yellowish, which is a problem in appearance.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have found that the above-mentioned problem is to use potassium titanium oxalate instead of tetra-n-butyl titanate which is generally used as an organotitanium catalyst used in the polycondensation reaction of polyester. The present invention has been accomplished and the present invention has been achieved. That is, the present invention is a polymerization method characterized by using potassium titanium oxalate as a polymerization catalyst in a polymerization reaction of a polyester containing an adipic acid component and a 1,4-butanediol component in all or part of the main chain. .

The addition amount of potassium titanium oxalate in the present invention is preferably equal to the addition amount of ordinary tetra-n-butyl titanate, that is, 1 ppm or more and 200 ppm or less by weight ratio in terms of titanium atom based on the total amount of the polymer.
When the addition amount of the titanium compound is less than 1 ppm, the polymerization reaction rate is extremely slow, so that a polymer having a sufficient viscosity cannot be obtained, and when it is more than 200 ppm, the decomposition reaction rate of the polymer is also extremely high. It is not preferable because the speed becomes faster and the color tone deteriorates, and the generation of sublimates is promoted. Titanium catalyst is 20
Since the effect is sufficiently exhibited at 0 ppm or less, there is no need to use a large amount at all.

As the polymerization method in the present invention, either a direct polymerization method using a dicarboxylic acid as a raw material or a transesterification method using a lower alkyl ester of dicarboxylic acid as a raw material may be used. Further, in order to carry out the reaction promptly, a metal salt of an aliphatic monocarboxylic acid may be appropriately added.
As the metal compound of the aliphatic carboxylic acid to be added, calcium salt is particularly preferable, and calcium acetate, calcium propionate, calcium stearate and the like are preferably used.

The reaction temperature of the polymerization reaction varies depending on the composition, but is preferably 220 ° C. or higher and 250 ° C. or lower. 220 ° C
If it is less than, it is not preferable from the viewpoint of reaction rate,
If the temperature is higher than 250 ° C., the thermal decomposition reaction of the polymer becomes faster, which is not preferable.

It is also possible to use a compound such as a hindered phenol together in order to suppress the decrease in the degree of polymerization during storage and use of the polymer.

Further, in the present invention, other components may be contained as a copolymerization component as long as it is a polymerization of a polyester having a butylene adipate constituent unit in the main chain. Also, 1,4-
Butanediol and adipic acid may be used as a copolymerization component in the main chain of another polyester resin. Specific examples of other copolymerization components include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid, malonic acid, succinic acid, pimelic acid, and suberic acid. Aliphatic dicarboxylic acids such as azelaic acid, sebacic acid, nonamethylenedicarboxylic acid, lauric acid, and dimer acid, and diol components include aliphatic diols such as ethylene glycol, diethylene glycol, polyethylene glycol, neopentyl glycol, and polytetramethylene glycol. It can be preferably used.

[0012]

The present invention will be described in more detail with reference to the following examples.

Example 1 87 g (0.5 mol) of dimethyl adipate, 1,4-
63 g (0.7 mol) of butanediol and 22 mg of potassium titanium oxalate (30 ppm based on titanium metal based on the polymer) were placed in a 1 L glass reaction vessel (theoretical yield of polymer: 100 g). Under nitrogen atmosphere 23
A transesterification reaction was performed at 0 ° C. for 3 hours, and the produced methanol was removed to the outside of the reaction system to prepare a low polymerization degree butylene adipate. Then, in 45 minutes, the pressure was gradually reduced and the temperature was raised to 0.4 mmHg and 250 ° C. A polymer was obtained by carrying out a polycondensation reaction under these conditions for 2 hours, and the viscosity of this polymer was measured. During the reduced pressure reaction, a trap was placed between the vacuum pump and the reaction vessel to collect the distillate under reduced pressure. This distillate was filtered, only the solid component was taken, and the weight was measured.

Example 2 A polymerization reaction was carried out under exactly the same conditions as in Example 1 except that 44 mg of calcium acetate (100 ppm based on calcium metal) was added in addition to 22 mg of potassium titanium oxalate (30 ppm). Similarly, the viscosity and the weight of the sublimate were measured.

Example 3 The amount of potassium titanium oxalate added was 110 mg (15
Polymerization reaction was performed under exactly the same conditions as in Example 1 except that the concentration was set to 0 ppm), and the viscosity and the weight of the sublimate were measured in the same manner.

Comparative Example 1 The same as Example 1 except that 10 mg of tetra-n-butyl titanate (15 ppm based on titanium metal based on the polymer) was added in place of potassium potassium oxalate, using the same raw material as in Example 1. The polymerization reaction was performed under the conditions, and the viscosity and the weight of the sublimate were measured in the same manner.

Comparative Example 2 Exactly the same as Example 2 except that the same raw material as in Example 2 was used and 10 mg of tetra-n-butyl titanate was added instead of potassium potassium oxalate (15 ppm in terms of titanium metal based on the polymer). The polymerization reaction was performed under the conditions, and the viscosity and the weight of the sublimate were measured in the same manner.

Comparative Example 3 Exactly the same as Example 2 except that the same raw material as in Example 2 was used and 185 mg of tetra n-butyl titanate was added instead of potassium titanium oxalate (250 ppm in terms of titanium metal based on the polymer). The polymerization reaction was performed under the conditions, and the viscosity and the weight of the sublimate were measured in the same manner.
The above results are summarized in Table 1.

Example 4 73 g (0.42 mol) of dimethyl adipate, 190 g (0.98 mol) of dimethyl terephthalate, 1,4-
Butanediol 176 g (1.96 mol) Titanium potassium oxalate 66 mg (Titanium metal conversion, 30 ppm relative to polymer) and calcium acetate 132 mg
(100 pp for polymer in terms of calcium metal)
m) was taken in a 1 L glass container (theoretical yield of polymer 300 g). A transesterification reaction was carried out at 230 ° C. for 3 hours in a nitrogen atmosphere, and the produced methanol was removed outside the reaction system to prepare a low polymerization degree oligomer. Subsequently, the pressure is gradually reduced in 45 minutes to raise the temperature to 0.4 mmHg, 25
It was set to 0 ° C. A polymer was obtained by carrying out a polycondensation reaction for 2 hours and 30 minutes under these conditions, and the viscosity of this polymer was measured. During the reduced pressure reaction, a trap was placed between the vacuum pump and the reaction vessel to collect the distillate under reduced pressure. This distillate was filtered, only the solid component was taken, and the weight was measured.

Example 5 The polymerization reaction was carried out under the same conditions as in Example 4 except that 33 mg of potassium titanium oxalate (15 ppm in terms of titanium metal based on the polymer) was used.
The weight of the sublimate was measured.

Comparative Example 4 Except that the same raw material as in Example 4 was used, 30 mg of tetra-n-butylertitanate (15 ppm in terms of titanium metal based on the polymer) was added in place of potassium titanium oxalate. The polymerization reaction was performed under the same conditions, and the viscosity and the weight of the sublimate were measured in the same manner. The above results are summarized in Table 2.

The solid components obtained as by-products in each of the examples and comparative examples are gas chromatography, NMR,
From the mass spectrum, it was confirmed that adipic acid and 1,4-butanediol were cyclic diester compounds which reacted at a ratio of 1: 1.

[0023]

[Table 1]

(Description of abbreviations) K2TiOx potassium titanium oxalate TBTi tetra-n-butyl titanate

[0025]

[Table 2]

(Explanation of Abbreviations) K2TiOx Potassium Titanium Oxalate TBTi Tetra n-butyl titanate

In the examples, viscosity and color were measured by the following methods. (1) Relative viscosity: phenol / tetrachloroethane = 1
It was measured at 20 ° C. and a concentration of 1% in a mixed solvent of 1/1 (weight ratio). (2) Color: Measured using a SM color computer SM-4 manufactured by Suga Test Instruments Co., Ltd.

[0028]

According to the polymerization method of the present invention, a by-product generated during the polymerization of a polyester having butylene adipate as a constituent can be reduced, and a resin having an improved color tone can be obtained.

Claims (2)

[Claims] 1. A polymerization method comprising using potassium titanium oxalate as a polymerization catalyst in a polymerization reaction of a polyester containing an adipic acid component and a 1,4-butanediol component in all or part of the main chain. 2. The amount of potassium titanium oxalate added is 1 based on the total amount of the polymer in terms of titanium atom based on the polymer.
The method for polymerizing polyester according to claim 1, wherein the content is not less than ppm and not more than 200 ppm.