JP2002308969A - Process for producing polyester with high degree of polymerization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a polyester with a high degree of polymerization in a shorter time than in the previously known production process, wherein a cyclic polyester oligomer is used for ring-opening polymerization. SOLUTION: This process for producing the polyester with the high degree of polymerization comprises blending the cyclic polyester oligomer with a polyester at a weight ratio of (0.01 to 0.9):1 and heating the blend at 200-320 deg.C for the ring-opening polymerization of the cyclic polyester oligomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ring-opening polymerization of a cyclic polyester oligomer, and more particularly to a method for producing a polyester having a high degree of polymerization in a short time by optimizing the ratio of the cyclic polyester oligomer to the polyester.

[0002]

2. Description of the Related Art Due to its excellent properties, polyesters are widely used in various fields such as fibers, films, and bottles. Among them, polyalkylene terephthalate is excellent in mechanical strength, chemical properties, dimensional stability and the like, and is preferably used. Among them, for example, fibers for industrial materials are required to have high strength, and a method for improving fiber strength by increasing the molecular weight of polyalkylene terephthalate has been proposed.

Generally, polyalkylene terephthalate is
Manufactured from terephthalic acid or its ester-forming derivative and alkylene glycol.In the commercial process for producing high molecular weight polymers, a method of increasing the degree of polymerization by solid phase polymerization after melt polymerization is widely used. Have been. However, the method of increasing the degree of polymerization by solid-state polymerization has some undesirable problems as described below.

For example, in order to obtain polyethylene terephthalate having a high degree of polymerization, it is produced from terephthalic acid or an ester-forming derivative thereof and ethylene glycol. However, due to cost advantages, a direct weight method using terephthalic acid is used. Further, a continuous polymerization method is employed. In order to further increase the degree of polymerization, a method based on solid-phase polymerization is known. The solid-state polymerization method also has an advantage of suppressing oligomers and acetaldehyde contained in the polymer. However, the solid-state polymerization requires a large increase in equipment cost such as a drying step for the polyester chips, and a long residence time of the chips. Therefore, it is required to greatly improve the productivity.

In order to solve such a problem, for example, WO96
/ 22319 discloses a polymerization degree of 5 to 3 in a molten state.
5 polyethylene terephthalate prepolymer was added to 12
It is cooled at 0 to 210 ° C. and crystallized at the same time as pelletization, or amorphous polyethylene terephthalate prepolymer in the form of pellets having a degree of polymerization of 5 to 35 is used for 120 to 21.
A method has been proposed in which a polyethylene terephthalate prepolymer crystallized by rapidly heating to 0 ° C. is subjected to solid-state polymerization at 230 to 240 ° C. According to this method, since the melt polycondensation step can be omitted, the equipment cost is reduced, but the solid-state polymerization equipment and a long reaction time for increasing the degree of polymerization of polyethylene terephthalate are indispensable. However, productivity is still insufficient.

On the other hand, in recent years, a ring-opening polymerization reaction using a cyclic polyester oligomer has attracted attention. JP-A-8-
53474, JP-A-8-253573, JP-A-9-31
No. 78 reports ring-opening polymerization of a cyclic polyester oligomer, and reports that a polymer having a high degree of polymerization can be obtained in a very short time by heating the cyclic polyester oligomer. However, the cyclic polyester oligomer has a higher melting point than the linear polyester oligomer, and thus has a higher temperature for melting the polyester oligomer than the conventional polyester production method.

Therefore, in order to solve the above problems,
Macromolecules (Birch, 33 (5053), 20
00) (Macromolecules (Robert R. Burch, 33 (5053),
2000)) describes that a cyclic polyethylene oligomer and a polyester are mixed and heated at a weight ratio of 1.0 in a ratio of 50:50, and ring-opening polymerization is performed at a temperature lower than the melting point.
In this report, the reaction proceeds at a relatively low temperature of 280 ° C. as compared with the ring-opening polymerization of a cyclic trimer alone by using a polymer in combination, but a polyester having sufficient strength cannot be obtained.

Japanese Patent Application Laid-Open No. Hei 6-228291 describes the use of a cyclic polyester oligomer as a starting material to provide a molded polyester article having excellent flexural strength, resistant to cracking and having solvent resistance. During the ring-opening polymerization of the cyclic polyester oligomer, the heat of fusion of the
To reduce the amount to less than J / g, 8 to 30 mol% of a cyclic or linear polyester is combined with the cyclic polyester oligomer, and the polyester is obtained by heating at 190 ° C. for 10 minutes in the examples. However, in this publication, a polyester having a high degree of polymerization and high strength cannot be obtained simply by mixing and heating the polyester with the cyclic polyester oligomer. The publication also reports that it is not preferable to use a linear polyester as a mixture for the cyclic polyester oligomer because the viscosity of the cyclic polyester oligomer becomes unduly high.

[0009] From the above background, there is a demand for economically obtaining a high-polymerized polyester.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks in the process for producing a highly polymerized polyester,
An object of the present invention is to provide a method for producing a high polymerization degree polyester by ring-opening polymerization.

[0011]

The object of the present invention is to provide a cyclic polyester oligomer having an intrinsic viscosity of 0.5 to 0.5.
In mixing and heating a polyester of 1.5 and obtaining a polyester having an intrinsic viscosity of 0.65 or more, a cyclic polyester oligomer is blended with the polyester in a weight ratio of 0.01 to 0.9, This is achieved by a manufacturing method in which heating is performed in the range of 320 ° C.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester of the present invention is a polymer synthesized from dicarboxylic acid or its ester-forming derivative, and diol or its ester-forming derivative, and is used as a molded article such as a fiber, a film, and a bottle. There is no particular limitation as long as is possible.

Specific examples of such polyesters include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene 2,6-naphthalenedicarboxylate, and polyethylene-1,2-. Bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate and the like can be mentioned. The present invention is particularly suitable for polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, or a polyester copolymer mainly composed of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, which are widely used.

These polyesters include, as copolymerization components, dicarboxylic acids such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, and ester-forming derivatives thereof, polyethylene glycol, diethylene glycol. And dioxy compounds such as hexamethylene glycol, neopentyl glycol, and polypropylene glycol; oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid and lactic acid; and ester-forming derivatives thereof, and the like.

In the present invention, the cyclic polyester oligomer comprises the above-mentioned polyester as a constituent, and its production method may be a conventionally known method, and is not particularly limited. For example, Polymer Letters (Humb, 5 (1057), 1967) (PolymerL
etters (F. Lynn Hamb, 5 (1057), 1967)) discloses a method for synthesizing a cyclic polyester oligomer, which comprises using 1 as a solvent.
-It has been reported that methyl naphthalene is used as a cyclization catalyst using tetraisopropyl titanate. Also,
JP-A-8-225633 discloses a solvent such as a hydrocarbon such as ortho-, meta- or para-terphenyl, an organic tin compound as a cyclization catalyst, and / or a tetraalkoxy titanate such as tetrabutyl titanate. It is proposed to use. Therefore, as the solvent used in the present invention, a hydrocarbon such as 1-methylnaphthalene, ortho-, meta- or para-terphenyl may be used, and as the cyclization catalyst, an organotin compound and / or An alkoxy titanate or the like may be used and is not particularly limited. Further, the addition amount of the cyclization catalyst is preferably from 100 to 20,000 ppm by weight of the metal based on the obtained cyclic polyester oligomer, from the viewpoint of the reaction rate and economical efficiency of the cyclization reaction,
More preferably, it is 1,000 to 10,000 ppm.

In the process for producing a polyester having a high degree of polymerization of the present invention, first, when the cyclic polyester oligomer (A) and the polyester (B) are mixed and heated, the weight ratio A / B is adjusted to 0.01 to 0.9. Need to be mixed. Preferably it is 0.2-0.7, more preferably 0.3-0.0.
5 When the weight ratio A / B is less than 0.01, a high degree of polymerization degree polyester cannot be obtained because the number of cyclic oligomers connecting the polyester chains is small, while the weight ratio A / B is 0.1.
If it exceeds 9, it is not preferable because it takes a long reaction time for the cyclic oligomer to react to open the ring. In the present invention, the intrinsic viscosity of the polyester mixed with the cyclic polyester oligomer is 0.50 to 1.50, preferably 0.55 to 1.00, more preferably 0.65 to 1.00.
0.85. The polyester used in the present invention may be produced by a conventionally known method, and is not particularly limited.

In the method for producing a polyester having a high degree of polymerization of the present invention, the heating temperature of the cyclic polyester oligomer and the polyester must be 200 to 320 ° C. Here, when the temperature is lower than 200 ° C., the mixture of the cyclic polyester oligomer and the polyester is difficult to melt, and the reaction speed is low even after the melting, which is not preferable from the viewpoint of economy. On the other hand, if the temperature is higher than 320 ° C., it is easily melted, but it is not preferable in that the polymer quality is deteriorated due to thermal decomposition of the produced polyester. Therefore, more preferably 220 to 310
° C, more preferably 240-300 ° C. Also,
The heating method may be carried out at a constant temperature, but a temperature control involving a temperature rise and / or a temperature fall may be carried out in order to obtain a polyester having a higher degree of polymerization.

The polymerization catalyst used in the present invention is Ti, S
b, Bi, Sn, Al, Ge, Zr, Hf, Y, Sc, lanthanoid compounds (La, C
e, Sm, Eu, Yb) are preferred compounds having at least one selected from the group consisting of: More preferably Ti, Sb, Bi, Sn, Al
Is a compound having As the polymerization catalyst, one or more of the above compounds may be used, and a method of adding a plurality of compounds or a method of adding a compound composed of a plurality of metals may be used.

Specific examples of the tin compound include dibutyltin oxide, stannous chloride, tin octylate, tin laurate, and monobutylhydroxytin oxide. These tin compounds may include those in which a plurality of tin compound molecules are associated or oligomerized with a slight change.

Examples of the titanium compound include titanium alkoxide compounds such as tetrabutyl titanate and tetraisopropyl titanate, ethylenediamine tetraacetic acid, hydroxyethyl imino diacetic acid, diethylene triamine pentaacetic acid, triethylene tetramine hexaacetic acid, citric acid, maleic acid and the like. And the like, but are not limited to, titanium compounds containing a chelating agent such as a mixture of the above, tetrastearyl titanate, potassium titanyl oxalate, lithium titanyl oxalate, and the like. The composite oxide containing a titanium compound as a main metal element is produced, for example, from a titanium alkoxide compound and an alkoxide compound such as silicon, aluminum, zirconium, and germanium by a coordination chemical sol-gel method.

Examples of the bismuth compound include bismuth alkoxides such as bismuth acetate and bismuth oxalate, examples of the aluminum compound include aluminum butoxide, aluminum isopropoxide and aluminum ethoxide, and examples of the antimony compound include antimony trioxide. .

Other than the compounds mentioned above, mention may be made of germanium ethoxide, zirconium ethoxide, zirconium propoxide, zirconium oxalate, hafnium butoxide, triphenylyttrium, yttrium trifluoromethanesulfonic acid, scandium trifluoromethanesulfonic acid. As the lanthanoid compound, lanthanum acetate, lanthanum isopropoxide, lanthanum benzoate, cerium isopropoxide, triphenyl samarium, samarium oxalate, samarium isopropoxide, europium acetate,
Ytterbium acetate and the like can be mentioned.

The polymerization catalyst is added in an amount of 1 to 10000 ppm by weight of the metal relative to the cyclic polyester oligomer.
Is preferred in view of the reaction rate of the ring-opening polymerization and the color tone of the finally obtained polyester. More preferably, the metal weight is 10 to 3000 ppm, still more preferably 2 to 3000 ppm.
0 to 1500 ppm.

In the present invention, the method of mixing the cyclic polyester oligomer and the polyester is preferably a method of continuously mixing using one or more extruders. The extruder includes a twin-screw extruder. The method of supplying the cyclic polyester oligomer and the polyester is not particularly limited, but a method of simultaneously supplying the cyclic polyester oligomer and the polyester from the supply port is preferable. The polyester used may be supplied in a molten state, or may be supplied in the form of chips. Here, the particle size of the chipped polyester is preferably as small as possible.

As a method for removing the water present in the polyester and the cyclic polyester oligomer and the reaction solvent used in synthesizing the cyclic polyester oligomer, the polyester and the cyclic polyester oligomer are supplied to an extruder having vent holes, Under a temperature condition equal to or lower than the crystallization temperature of the polyester, the degree of pressure reduction of the vent hole is 6650 Pa
In the following, a method of making the pressure preferably 1330 Pa or less is exemplified. The removal of water present in the polyester and the cyclic polyester oligomer and the reaction solvent used for synthesizing the cyclic polyester oligomer is preferable because hydrolysis of the produced polyester and deterioration of the color tone of the polymer can be suppressed.

In the present invention, if the reaction time is short, a large amount of unreacted material remains. On the other hand, if the reaction time is long, the polyester is thermally decomposed to deteriorate the color tone or the degree of polymerization, and also from the viewpoint of productivity. Since it is not preferable, the heating time of the cyclic polyester oligomer and the polyester is preferably 1 to 120 minutes. In the present invention, the purity of the cyclic polyester oligomer is preferably 60% or more, but is preferably 70% or more, more preferably 80% or more. Use the above. Further, when the amount of the linear polyester oligomer contained in the produced cyclic polyester oligomer is 10% or less, the amount of the oligomer in the produced polyester can be reduced, which is preferable in that a polyester having a higher polymerization degree can be obtained. It is more preferably at most 5%, further preferably at most 2%.

In the present invention, a conventionally known phosphorus compound or cobalt compound may be added to the finally obtained polyester at any time for the purpose of improving heat resistance and color tone. In the present invention, known compounds, for example, inorganic particles for matting, antioxidants, heat insulating materials, antistatic agents, ultraviolet absorbers, and the like may be added and contained as necessary.

As described above, in the present invention, the cyclic polyester oligomer is added to the polyester in a weight ratio of 0.01 to 0.01%.
By blending at a ratio of 0.9 to 0.9 and heating in the range of 200 to 320 ° C, it becomes possible to obtain a high polymerization degree polyester more economically than conventionally known solid-state polymerization processes and ring-opening polymerization processes. .

[0029]

The present invention will be described in more detail with reference to the following examples. The physical properties in the examples were measured by the methods described below. (1) Intrinsic viscosity [η] of polymer Measured at 25 ° C. using orthochlorophenol as a solvent. (2) Purity of Cyclic Polyester Oligomer It was calculated from the ratio of the oligomer peak area (UV absorption standard:%) of each degree of polymerization identified in advance by liquid chromatography. (3) Color tone of polyester Hunter values (L, a, b values) were measured using a color difference meter (SM color computer model SM-3) manufactured by Suga Test Instruments Co., Ltd.

Example 1 7 kg of polyethylene terephthalate chips (PET) having an intrinsic viscosity of 0.80, 3 kg of cyclic polyethylene terephthalate powder (99% purity) and 0.3 kg of 534 mg of tetraisopropyl titanate (Ti = 30 ppm) as a polymerization catalyst. / Min to the feed port of a twin screw extruder having a vent hole. The screw rotates at 70 rpm,
Heat with an electric heater while reducing the pressure to
C. After returning to normal pressure with nitrogen, the mixture was heated to 280 ° C. and the screw rotation speed was adjusted so that the average residence time was 10 minutes. Next, after the molten polymer was discharged in a gut shape, it was pelletized with a cutter through a cooling bath to obtain polyethylene terephthalate.

The obtained polyethylene terephthalate had an intrinsic viscosity of 1.52 and a color tone b value of 5.0, and a polyester having a high degree of polymerization was obtained.

Example 2 50 kg of molten polybutylene terephthalate (PBT) having an intrinsic viscosity of 0.66 and 17.5 kg of a powder of cyclic polybutylene terephthalate (purity: 74%), 3.14 g of tin tetraisopropyl as a catalyst (Sn = 60 ppm).
It was fed at a feed rate of 5 kg / min to the feed port of the twin screw extruder. The average residence time in the extruder is 5 minutes, the reaction temperature 250
C. Under nitrogen, the resulting reaction product had an intrinsic viscosity of 1.20,
The color tone b value was 3.9.

Examples 3, 6, 7, 10, 11 According to the procedure of Example 1, a ring-opening polymerization was carried out using a vented twin-screw extruder under the conditions shown in Table 1. The results are shown in Table 1. In each case, the desired high-polymerization degree polyester could be obtained.

Example 4 80 kg of molten polypropylene terephthalate (PPT) having an intrinsic viscosity of 0.83, 55 kg of a cyclic polyethylene terephthalate powder (85% purity), and 59.9 g of samarium isopropoxide (Sm = 500 ppm) as a catalyst. 40.4 g of zirconium propoxide (Zr = 250 ppm) was fed to the feed port of the single screw extruder at a feed rate of 0.5 kg / min. The average residence time in the extruder is 2 minutes, the reaction temperature 290
The reaction was carried out at a temperature of 0 ° C. under nitrogen, and the obtained polyester had an intrinsic viscosity of 1.43 and a color tone b value of 4.1.

Examples 5, 9, and 12 In accordance with the procedure of Example 2, ring-opening polymerization was carried out under the conditions shown in the table. In Examples 5 and 12, a polymer in a molten state was used, but in Example 9, polybutylene terephthalate (PBT) was used in the form of chips. The results are shown in the following table. In each case, the desired high-polymerization degree polyester could be obtained.

Examples 8 and 13 In accordance with the procedure of Example 4, ring-opening polymerization was carried out under the conditions shown in the table. In Example 8, a polymer in a molten state was used, but in Example 13, chip-like polyethylene terephthalate (PET) was used. The results are shown in the following table. In each case, the desired high-polymerization degree polyester could be obtained.

Comparative Example 1 Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.66
11 kg and cyclic polyethylene terephthalate (purity 98
%), A reaction temperature of 300 ° C., a reaction time of 240 minutes, and titanium isopropoxide 0.78 as a catalyst.
The reaction was carried out in the same manner as in Example 1 except that kg (Ti = 12000 ppm) was added. However, the intrinsic viscosity of the obtained polymer was 0.57, and the color tone b value was 17.0.

Comparative Example 2 Polyethylene terephthalate (PET) having an intrinsic viscosity of 1.65
300 g and cyclic polybutylene terephthalate (purity 65
%) Was stirred in a test tube in which 150 g was replaced with nitrogen, and 896 mg of tin isopropoxide was used as a catalyst (Sn = 2000 ppm).
Was added. The mixture was heated to 280 ° C. while stirring at 30 rpm using a stirring blade, and the reaction was completed in 25 minutes. Thereafter, the mixture was discharged into cold water in the form of a strand and immediately cut to obtain polyester pellets. As a result, the intrinsic viscosity of the obtained polymer was 0.49, and the color tone b value was 9.8.

Comparative Example 3 Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.45
10 kg and cyclic polypropylene terephthalate (purity 8
5%) 3.5 kg, a reaction temperature of 290 ° C. and a reaction time of 15 minutes, and 4.1 g of antimony trioxide (S
b = 500pm) and 33.7 g of yttrium triflate (Y = 200
The reaction was carried out in substantially the same manner as in Example 1, except that the amount was 0 ppm). However, the intrinsic viscosity of the obtained polymer is 0.5
5. The color tone b value was 11.0.

Comparative Example 4 Polybutylene terephthalate (PBT) having an intrinsic viscosity of 0.66
10 kg and cyclic polybutylene terephthalate (purity 80
%), A reaction temperature of 190 ° C. and a reaction time of 120 minutes, and 7.5 g of aluminum ethoxide as a catalyst.
(Al = 250 ppm) The reaction was carried out in substantially the same manner as in Example 1. However, the intrinsic viscosity of the obtained polymer was 0.53, and the color tone b value was 18.1.

Comparative Example 5 Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.70
In a test tube in which 1000 g and 490 g of cyclic polypropylene terephthalate (purity: 85%) were replaced with nitrogen, 293 mg of tin isopropoxide was added as a catalyst so that the tin atom content became 200 ppm. The mixture was heated to 330 ° C. while stirring at 30 rpm using a stirring blade, and the reaction was completed in 20 minutes. Thereafter, the mixture was discharged into cold water in the form of a strand and immediately cut to obtain polyester pellets. As a result, the intrinsic viscosity of the obtained polymer was 0.60, and the color tone b value was 16.5.

[0042]

[Table 1]

[0043]

According to the method for producing a high polymerization degree polyester of the present invention, it is possible to obtain a high polymerization degree polyester in a shorter time as compared with a conventionally known production method.

Continuation of the front page F term (reference) 4J029 AA03 AA05 AB04 AC02 AC04 AC05 AD01 BA03 BA04 BA05 BA08 BD06A CB06A CC06A CG09X JA061 JB131 JB171 JC021 JC121 JC751 JF221 JF261 JF271 JF321 JF331 JF03 JF03 JK05 KBK

Claims (5)

[Claims] (1) mixing and heating a cyclic polyester oligomer and a polyester having an intrinsic viscosity of 0.5 to 1.5,
When obtaining a polyester having an intrinsic viscosity of 0.65 or more, the cyclic polyester oligomer is blended with the polyester in a weight ratio of 0.01 to 0.9, and the temperature at the time of heating is 200 to 320 ° C. A method for producing a high-polymerization degree polyester, which is a feature. 2. When mixing and heating, Ti, Sb, Bi, Sn, Al, Ge,
The high polymerization degree according to claim 1, wherein a compound having at least one selected from the group consisting of Zr, Hf, Y, Sc, and a lanthanoid compound (La, Ce, Sm, Eu, Yb) is used as a catalyst. Polyester manufacturing method. 3. The method for producing a polyester having a high degree of polymerization according to claim 1, wherein an extruder is used for mixing the cyclic polyester oligomer, the polyester and the catalyst. 4. The method according to claim 3, wherein the extruder is a twin-screw extruder. 5. The method according to claim 3, wherein the extruder is a single-screw or twin-screw extruder.