JPH11236441A - Production of polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester with favorable color tone, mainly from adipic acid and 1,4-butanediol. SOLUTION: This method for producing a polyester mainly from adipic acid and 1,4-butanediol comprises performing a polycondensation reaction in the presence of a polycondensation catalyst, i.e., a titanium compound (e.g. tetra-n-butyl titanate) in 1-50 ppm calculated as titanium atom, a cobalt compound (e.g. cobalt acetate) in 3-70 ppm calculated as cobalt atom, and a sulfonic acid compound (e.g. ethanesulfonic acid) in 40-200 ppm calculated as sulfonic acid group, based on the final polyester, respectively.

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 mainly composed of adipic acid and 1,4-butanediol and having a good color tone.

[0002]

2. Description of the Related Art A polyester comprising adipic acid and 1,4-butanediol (abbreviated as AD / BD polyester) is a crystalline polyester having a low melting point and can be used in a high-temperature atmosphere. Hot melt binder fiber, moldable cast material, various films,
It is used as a molding material.

As a polycondensation catalyst for producing an AD / BD polyester, a polycondensation reaction is preferably carried out at a relatively low temperature of 260 ° C. or lower in order to prevent thermal decomposition of 1,4-butanediol. Titanium compounds such as tetra-n-butyl titanate, which is necessary and exhibit sufficient catalytic activity even at such a temperature, are used. However, the polyester obtained by the above method has a strong reddish or yellowish color and has a problem that it cannot be used for applications requiring good color tone.

As a method for solving such a problem, a method in which a polycondensation reaction is carried out in the presence of a titanium compound and a metal salt of a saturated aliphatic carboxylic acid (JP-A-63-251424), (JP-A-8-169945), a method using potassium titanium oxalate as a polycondensation catalyst (JP-A-8-30).
1996) has been proposed. However, even when using these methods, when the above-mentioned titanium compound is used in an amount necessary to obtain a practical polycondensation reaction rate, there is a problem that the obtained polyester has a reddish or yellowish tinge. Was.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a practical method for producing an AD / BD polyester having a good color tone.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the gist of the present invention is to provide a method for producing a polyester comprising adipic acid and 1,4-butanediol. As a catalyst, an amount of 1 to 50 ppm of a titanium compound as a titanium atom, 3 to 70 ppm of a cobalt compound as a cobalt atom, and 40 to 200 ppm of a sulfonic acid compound as a sulfonic acid group is added to the finally obtained polyester. And carrying out a polycondensation reaction.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The main components constituting the polyester in the present invention are adipic acid and 1,4-butanediol,
Other components may be contained as copolymer components as long as the object of the present invention is not hindered. Examples of such a copolymer component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid, malonic acid, succinic acid, pimelic acid, suberic acid, azelaic acid, and sebacine. Examples include aliphatic dicarboxylic acids such as acids and dimer acids, and aliphatic diols such as ethylene glycol, diethylene glycol, polyethylene glycol, neopentyl glycol, and polytetramethylene glycol.

As the polycondensation catalyst used in the present invention, it is necessary to use a titanium compound, a cobalt compound and a sulfonic acid compound in combination. For example, when a polyester having a practical degree of polymerization is produced by using a required amount of each of the above polycondensation catalysts alone, the polymer becomes reddish or yellowish in the case of a titanium compound, and in the case of a sulfonic acid compound. A large amount of sublimate is by-produced at the time of condensation, and a cobalt compound is not preferable because the polymer has a strong bluish tint or a thermal decomposition reaction is promoted.

The amount of each polycondensation catalyst used in the present invention may be 1 to 3 as titanium atoms.
50 ppm, cobalt compound is 3 to 7 as cobalt atom
0 ppm, sulfonic acid compound is 40 to 40
It needs to be 200 ppm. When the amount of the titanium compound is less than 1 ppm as a titanium atom, a practical polycondensation reaction rate cannot be obtained, and when the amount exceeds 50 ppm, the decomposition reaction of the polyester is accelerated and the color tone of the polyester is deteriorated. If the cobalt atom is less than 3 ppm, the effect of improving the color tone of the polyester cannot be obtained,
If it exceeds 70 ppm, the polymer will be strongly bluish,
The thermal decomposition reaction of the polyester is accelerated, and a polymer having a sufficient degree of polymerization cannot be obtained. If the sulfonic acid compound is less than 40 ppm as a sulfonic acid group, a polymer having a sufficient degree of polymerization cannot be obtained, and if it exceeds 200 ppm, the reaction system becomes acidic, and tetrahydrofuran is converted from the 1,4-butanediol component. The by-product reaction is promoted, and the acid /
The glycol composition ratio is changed, and a large amount of sublimate in which adipic acid and one molecule of 1,4-butanediol are bonded to each other is produced as a by-product.

The titanium compound used in the present invention includes, for example, tetra-n-butyl titanate, tetrapropyl titanate, potassium potassium oxalate and the like. The cobalt compound includes cobalt acetate, cobalt formate and the like. Examples of the sulfonic acid compound include ethanesulfonic acid, 5-sulfosalicylic acid, and o-sulfobenzoic anhydride.

Next, the manufacturing method of the present invention will be described. In producing the polyester of the present invention, for example, first, an oligomer is formed from a dicarboxylic acid or a lower alkyl ester thereof and a diol by an esterification or transesterification reaction, and then the oligomer is polycondensed. The temperature of the polycondensation reaction varies depending on the composition of the polyester, but is usually preferably from 220 to 260 ° C. If this temperature is lower than 220 ° C., a sufficient reaction rate cannot be obtained, and depending on the composition, the viscosity at the time of melting becomes too high, making the operation difficult. On the other hand, if the temperature is higher than 260 ° C., the decomposition reaction becomes remarkable, the reaction reaches an equilibrium, and a polyester having a high polymerization degree cannot be obtained, or the color tone of the polyester deteriorates.

In order to suppress a decrease in the degree of polymerization of the obtained polyester, it is preferable to add an antioxidant. As the antioxidant, hindered phenol-based antioxidants are preferable. For example, "ADK STAB" manufactured by Asahi Denka Co., Ltd.
AO-20-80, Sumitomo Chemical "Sumilyzer" GA
-80, BHT (2,6-di-t-butyl-4-methylpheninol), “Irganox” 1 manufactured by Ciba-Geigy
010 and the like. The addition amount of the antioxidant is suitably 1% by weight or less, and if it exceeds 1% by weight, the color tone of the polyester deteriorates.

Next, the production method of the present invention will be described more specifically. For example, in the case of producing polybutylene adipate (abbreviated as PBA) using each component of adipic acid and 1,4-butanediol, for example, dimethyl adipate and 1,4-butanediol are used as catalysts and titanium as a catalyst. The compound is added, and at a temperature of 200 to 220 ° C. under a nitrogen gas atmosphere, the formed methanol is distilled off,
A transesterification reaction is performed for a time to obtain a PBA oligomer. Next, the PBA oligomer is transferred to a polycondensation reaction vessel, a predetermined amount of a cobalt compound and a sulfonated compound are added, and the mixture is heated under reduced pressure to perform a polycondensation reaction until a predetermined degree of polymerization is obtained to obtain a polyester. .

Also, for example, adipic acid and terephthalic acid are used as acid components, and 1,4 and 4 are used as glycol components.
-When producing a copolymerized polyester using each component of butanediol and ethylene glycol, first, terephthalic acid and ethylene glycol are heated to a temperature of 230 to 260.
The esterification reaction is carried out at a temperature of 3 ° C. in a nitrogen gas atmosphere for 3 to 8 hours to obtain an ethylene terephthalate oligomer. Next, a predetermined amount of a slurry of adipic acid and 1,4-butanediol was added thereto, and the temperature was further increased to 240 to 260 ° C.
For 1 to 2 hours to obtain a copolymerized oligomer. Alternatively, a titanium compound is added as a catalyst to dimethyl terephthalate, dimethyl adipate, ethylene glycol and 1,4-butanediol, and the mixture is heated at a temperature of 210 to 210.
Transesterification is performed for 1 to 3 hours at 240 ° C. in a nitrogen gas atmosphere while distilling off generated methanol to obtain a copolymerized oligomer. Next, the above copolymerized oligomer is transferred to a polycondensation reaction vessel, a predetermined amount of a titanium compound, a cobalt compound, and a sulfonic acid compound are added, and the mixture is heated under reduced pressure until a polyester having a predetermined polymerization degree is obtained. Perform a condensation reaction. In addition, since a titanium compound not only functions as a polycondensation catalyst but also functions as a catalyst of a transesterification reaction or an esterification reaction, it is desirable to add the titanium compound at the time of the transesterification reaction or the esterification reaction.

[0015]

According to the production method of the present invention, an AD having a good color tone can be obtained.
/ BD polyester can be obtained because a titanium compound having high catalytic activity at a relatively low temperature as a polycondensation catalyst and a cobalt compound and a sulfonic acid compound having a catalytic activity and a color tone improving effect are used in combination. It is considered that an AD / BD polyester having a good color tone and a high degree of polymerization can be obtained because the addition amount may be smaller than the amount added when used alone and the color tone improving effect by the cobalt compound and the sulfonic acid compound is obtained. .

[0016]

Next, the present invention will be described in detail with reference to examples. In addition, the measuring method is as follows. (A) Intrinsic viscosity [η] Using an equal weight mixture of phenol and tetrachloroethane as a solvent, the viscosity was measured at a concentration of 0.5 g / dl and a temperature of 20 ° C. (B) Color Tone Measured using an ND- # 80 color difference meter manufactured by Nippon Denshoku Industries Co., Ltd. The a value indicates a red-green hue (red side is reddish, the-side is greenish), and the b value is yellow-blue hue (+ side is yellowish, and-side is bluish).

Example 1 Dimethyl adipate and 1,4-butanediol were charged into a transesterification reactor at a molar ratio of 1 / 1.2.
Tetra-n is used as a catalyst for the resulting polyester.
-49 ppm of butyl titanate as a titanium atom and 0.1% by weight of Irganox 1010 as an antioxidant were added, and transesterification was carried out at 210 ° C. under normal pressure at a temperature of 210 ° C. while distilling off generated methanol for 2 hours. PBA
An oligomer was obtained. The PBA oligomer is transferred to a polycondensation reactor, and as a catalyst, 15 ppm of cobalt acetate as a cobalt atom and 40 ppm of 5-sulfosalicylic acid as a sulfonic acid group are added as a catalyst.
The temperature in the polycondensation reactor was raised to 250 ° C. in 30 minutes,
The pressure was gradually reduced to 1.2 hPa or less after 60 minutes.
Under these conditions, a polycondensation reaction is carried out for 2 hours while stirring,
Polyester was obtained. Table 1 shows the properties of the obtained polyester. In Table 1, TPA is terephthalic acid, AD is adipic acid, EG is ethylene glycol, B
D represents 1,4-butanediol.

Example 2, Comparative Example 1 A polyester was obtained in the same manner as in Example 1, except that the amount of the polycondensation catalyst was changed as shown in Table 1. Table 1 shows the properties of the obtained polyester.

Example 3 A slurry of terephthalic acid and ethylene glycol in a molar ratio of 1 / 1.6 was continuously supplied to an esterification reactor in which an ethylene terephthalate oligomer was present.
Esterification was carried out under the conditions of 0 ° C., a pressure of 0.1 MPaG, and a residence time of 8 hours to continuously obtain an ethylene terephthalate oligomer having an esterification reaction rate of 95%. The ethylene terephthalate oligomer was transferred to a polycondensation reactor, and a slurry of adipic acid and 1,4-butanediol in the molar ratio shown in Table 1 was charged. 25 ppm of butyl titanate as a titanium atom, 15 ppm of cobalt acetate as a cobalt atom, 40 ppm of 5-sulfosalicylic acid as a sulfonic acid group, and 0.1% by weight of Irganox 1010 as an antioxidant were added at a temperature of 240 ° C. and a pressure of 0%. The esterification reaction was carried out for 1 hour while stirring under a condition of 0.1 MPaG. Subsequently, the temperature in the polycondensation reactor was set to 3
The temperature was raised to 260 ° C. in 0 minutes, and the pressure was gradually reduced to 1.2 hPa or less after 60 minutes. Under these conditions, a polycondensation reaction was performed for 3 hours while stirring to obtain a polyester. Table 1 shows the properties of the obtained polyester.

Examples 4 to 9 and Comparative Examples 2 to 7 The same procedures as in Example 3 were carried out except that the ratio of adipic acid to 1,4-butanediol and the amount of the polycondensation catalyst added were changed as shown in Table 1. A polyester was obtained in the same manner. Table 1 shows the properties of the obtained polyester.

[0021]

[Table 1]

As is clear from Table 1, in Examples 1 to 9, polyesters having a degree of polymerization [η] which can be practically used and having a good color tone were obtained. On the other hand, in Comparative Examples 1 and 2, since the amount of the titanium compound was insufficient, a polyester having a sufficient degree of polymerization could not be obtained. In Comparative Example 3, the color tone of the polyester was poor because the amount of the titanium compound was too large. In Comparative Example 4, since the amount of the cobalt compound was too large, the thermal decomposition reaction proceeded, and a polyester having a sufficient degree of polymerization could not be obtained. In addition, the polyester had a strong bluish color and was not practically used. there were. In Comparative Example 5, the color tone improving effect was insufficient because the amount of the cobalt compound was too small. In Comparative Example 6, since the amount of the sulfonic acid compound was too small, the color tone of the polyester deteriorated, and a polyester having a sufficient degree of polymerization could not be obtained.
In Comparative Example 7, since the amount of the sulfonic acid compound was too large,
During the polycondensation reaction, a large amount of sublimate was produced as a by-product, causing a problem that the piping of the reduced pressure system was clogged, and the reaction could not proceed until a polyester having a sufficient degree of polymerization was obtained.

[0023]

According to the present invention, a practical production method for obtaining a high polymerization degree AD / BD polyester having a good color tone is provided, and its industrial value is extremely large.

Claims (1)

[Claims] 1. A method for producing a polyester mainly comprising adipic acid and 1,4-butanediol, wherein a titanium compound is used as a polycondensation catalyst in an amount of 1 to 50 pp as a titanium atom with respect to a finally obtained polyester.
m, 3 to 70 ppm of cobalt compound as cobalt atom
A sulfonic acid compound having a sulfonic acid group of 40 to 20;
A method for producing a polyester, wherein a polycondensation reaction is carried out by adding each amount of 0 ppm.