JPS6118567B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a high degree of polymerization polyester. More specifically, the present invention relates to a method for rapidly producing aromatic polyester with good thermal stability and high degree of polymerization, which is useful for industrial fibers, films, and plastics, by solid phase polymerization. It has been well known that aromatic polyesters, particularly polyethylene terephthalate, are useful as materials for fibers, films, plastics, and the like. In addition, when fibers, films, etc. are used for industrial purposes using these aromatic polyesters,
It is also known that the higher the degree of polymerization of the aromatic polyester and the lower the amount of terminal carboxyl groups, the better the aromatic polyester. As a method for producing polyester with a high degree of polymerization and a small amount of terminal carboxyl groups, a prepolymer with a relatively low degree of polymerization obtained by melt polymerization is solid-phase polymerized at a temperature below the melting point of the polymer. A so-called solid phase polymerization method has been proposed. However, solid phase polymerization has a low polymerization rate and is difficult to complete within an economical time.
In particular, when attempting to produce a polyester having a high degree of polymerization and a particularly low amount of terminal carboxyl groups, it has the disadvantage that the polymerization time is extremely long. Although the polymerization rate can be increased by using a polyester with a high amount of terminal carboxyl groups as a prepolymer, the so-called purpose is not achieved because the amount of terminal carboxyl groups in the resulting polyester is not sufficiently reduced. As a method for improving the deficiencies of such inherent polymerization methods, methods have already been proposed in which 1) diaryl carbonate and/or diaryldicarboxylate is used, or 2) a specific oxalic acid ester is used in the step of producing a prepolymer. . However, even with these methods, when trying to obtain a polyester with a sufficiently high degree of polymerization and a small amount of terminal carboxyl groups, the specific polymerization time becomes long and the quality of the obtained polyester with a high degree of polymerization varies greatly. However, it has the disadvantage that it is difficult to obtain polyester of constant quality with good reproducibility. This tendency is remarkable when trying to obtain a polyester with a high degree of polymerization having an intrinsic viscosity of 1.0 or more, particularly 1.1 or more. The present inventors have conducted extensive research on a method for rapidly producing a polyester having a high degree of polymerization and a small amount of terminal carboxyl groups by inherent polymerization without such drawbacks, and as a result, they have arrived at the method of the present invention. That is, the present invention uses a molten aromatic polyester and a small proportion of 1,2- It is characterized by using an aromatic polyester having an intrinsic viscosity of 0.6 to 0.8 and a terminal carboxyl group weight of 2.5 equivalents/10 ⁶ g or less obtained by reacting glycol with a cyclic carbonate and/or a monoepoxy compound. This is a method for producing high polymerization degree polyester. The aromatic polyester used in the method of the present invention is an aromatic polyester containing an aromatic dicarboxylic acid as a main acid component and a fatty acid diol as a main glycol component. These aromatic polyesters can be produced by: 1) directly reacting an aromatic dicarboxylic acid with an aliphatic diol, or 2) transesterifying an ester of an aromatic dicarboxylic acid and a lower aliphatic alcohol with an aliphatic diol; 3. Melt polymerizing a low polymer obtained by reacting an aromatic dicarboxylic acid with ethylene oxide and/or ethylene carbonate to obtain a relatively low polymer polyester (hereinafter referred to as prepolymer); It is manufactured through a process of pulverizing the obtained prepolymer and performing solid phase polymerization. Examples of the aromatic dicarboxylic acids include terephthalic acid, naphthalene-2,5-dicarboxylic acid,
Naphthalene-2,7-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, diphenyl-4,4'-
Examples include dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, and examples of aliphatic diols include ethylene glycol, trimethylene glycol, tetramethylene glycol, Polymethylene glycols such as pentamethylene glycol, hexamethylene glycol and the like can be mentioned. The aromatic polyester used in the method of the present invention may be an aromatic homopolyester as described above, but it is a copolymer in which a third component is copolymerized with the aromatic homopolyester in an amount of 40 mol% or less, preferably 20 mol% or less. It may also be polyester. The third component is an acid component and/or a glycol component other than the aromatic homopolyester component, and the acid component and glycol component used as the third component include the aromatic dicarboxylic acid, fatty acid, In addition to group diols, isophthalic acid, phthalic acid, adipic acid, sebacic acid, decamethylene dicarboxylic acid, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hydroquinone, bis Phenol A, bis-1,4-β-hydroxyethoxybenzene,
Examples include bis-4,4'-β-hydroxyethoxydiphenyl sulfone. For the production of the prepolymer, conventionally known catalysts (for example, Li, Na, K, Mg, Ca, Ba, Sr, Zn,
Metals such as Ti, Ge, Sn, Sb, Bi, Mn, and Co or compounds containing these metals), stabilizers (for example, trivalent or pentavalent phosphorus compounds, etc.) can be used.
In addition, the polymerization reaction for producing a prepolymer is usually carried out by keeping the reaction system in a molten state, for example, at a high temperature of 200 to 300°C, under a stream of inert gas such as nitrogen, or, for example,
This is carried out under reduced pressure of 10 mmHg or less while distilling the glycol component produced as a result of the polymerization reaction out of the reaction system. When the aromatic polyester produced by such a melt polymerization method has an intrinsic viscosity of 0.2 or more, preferably 0.3 to 0.9, particularly preferably 0.4 to 0.8, it contains a small proportion of 1,2-glycol cyclic carbonate in the molten state. and/or reacted with a monoepoxy compound to produce a prepolymer having an intrinsic viscosity of 0.4 or more and a terminal carboxyl group weight of 2.5 equivalents/10 ⁶ g or less. The above reaction is carried out for at least 1 minute, preferably for 5 to 30 minutes. At this time, the reaction pressure is not particularly limited, but it is preferable to carry out the reaction under pressure equal to or higher than atmospheric pressure, and the reaction temperature in this case is usually 200 to 300°C. When the intrinsic viscosity of the molten aromatic polyester obtained by the above reaction is less than 0.6, it is necessary to further perform a polycondensation reaction after the above reaction to increase the intrinsic viscosity to 0.6 or more. The resulting prepolymer is cooled and solidified, crushed, cut, or otherwise reduced to fine particles and subjected to autopolymerization. The small proportion is 0.05 to 10 mol %, preferably 0.1 to 2 mol %, particularly preferably 0.1 to 1 mol %, based on the acid component constituting the aromatic polyester.
It is mole%. Even if it is attempted to react by adding too much to the aromatic polyester, the desired effect will not be sufficiently achieved, which is not preferable. An excellent product that can be industrially advantageously subjected to solid phase polymerization by using only a limited amount of additives and reacting with polyester in a molten state having a specific intrinsic viscosity or higher for a limited time. A prepolymer can be obtained. That is, if the amount of the additive is too large or the reaction time between the additive and the molten aromatic polyester is too long, the degree of polymerization of the aromatic polyester will decrease significantly during the reaction between the aromatic polyester and the additive. Not only this, but also the thermal stability of the highly polymerized polyester obtained by solid phase polymerization of the prepolymer thus produced becomes poor during melt molding, which is not preferable. Further, the intrinsic viscosity of the aromatic polyester in the molten state reacted with the additive is 0.3 or more, preferably 0.3 to 0.9, particularly preferably 0.4 to 0.9, as described above.
It is 0.8. If the intrinsic viscosity is too low, when attempting to obtain a polyester with a high degree of polymerization, the polymerization time of the polyester after reaction with additives will be long, making it difficult to obtain a polyester with a sufficiently small amount of terminal carboxyl groups. Furthermore, if an additive is attempted to react with a molten aromatic polyester having a too high intrinsic viscosity, the degree of polymerization of the polyester will decrease significantly during the reaction with the additive, and furthermore, even if this material is subjected to solid phase polymerization, it will not be sufficient. Therefore, it becomes difficult to obtain a polyester with a high degree of polymerization and a small amount of terminal carboxyl groups. 1,2-glycol cyclic carbonate and/or
Alternatively, the aromatic polyester to be reacted with the monoepoxy compound needs to be in a molten state as described above. Aromatic polyester in solid phase state 1,2
- Glycols can be reacted with cyclic carbonates and/or monoepoxy compounds, but
In this case, the above reaction requires a longer time, especially when using highly crystalline aromatic polyester (for example, polyethylene terephthalate), and in order to react uniformly with the aromatic polyester, a longer reaction time is required. Needless to say, there is a drawback in that the solid phase polymerization rate and the quality of the obtained polyester vary greatly. As the 1,2-glycol cyclic carbonate to be reacted with the aromatic polyester in a molten state, for example, the following formula [However, in the formula, R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen atoms,
A hydrocarbon residue having 10 or less carbon atoms, where the hydrocarbon residue may contain an ether bond, and R ₁ and R ₃ may be bonded to each other to form a ring. ] Examples of monoepoxy compounds include compounds represented by the following formula: [However, in the formula, R ₁ , R ₂ , R ₃ , and R ₄ are the same as defined above.] Compounds represented by the following are exemplified. Examples of the hydrocarbon residue include methyl, ethyl, propyl, butyl, phenyl, cyclohexyl, methoxy, ethoxy, and phenoxy. Preferred examples of the cyclic carbonate of 1,2-glycol include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 3-methoxy-1,2-propylene carbonate, and 3-methoxy-1,2-propylene carbonate. Examples include ethoxy-1,2-propylene carbonate, 3-phenooxy-1,2-propylene carbonate, and 1,2-cyclohexylene carbonate. Preferred monoepoxy compounds include, for example, ethylene oxide, propylene oxide,
1,2-butylene oxide, ethyl glycidyl ether, phenyl glycidyl ether, 1,2
- Examples include cyclohexene oxide. These can be used alone or in combination of two or more. Polyepoxy compounds such as diepoxy compounds are not preferred because they impair the moldability (for example, spinnability) of the high polymerization degree polyester and also increase the variation in quality (for example, intrinsic viscosity). In the method of the present invention, the aromatic polyester having a relatively low degree of polymerization in a molten state may be immediately pulverized to form a prepolymer for solid-state polymerization after reacting with the above-mentioned additives, but the aromatic polyester may be in a molten state again. More preferably, a prepolymer is produced by continuing melt polymerization of a certain polyester under the above-mentioned melt polymerization conditions to a predetermined intrinsic viscosity, and then finely granulating the polyester. The melt polymerization time after the reaction of the molten polyester and the additive is 20 minutes or more, more preferably 40 minutes to 150 minutes. By doing so, the high polymerization degree polyester obtained by the solid phase polymerization of the present invention has excellent stability during melt molding, and a homogeneous polyester molded product can be obtained. The aromatic polyester used as a prepolymer in the method of the present invention has an intrinsic viscosity of 0.6 to 0.8;
Preferably it is 0.7 to 0.8, and the amount of terminal carboxyl group is 25 equivalents/10 ⁶ g or less, preferably 20 equivalents/10 ⁶ g.
5 equivalents/10 ⁶ g or more, particularly preferably 15 equivalents/
10 ⁶ g or less 5 equivalents/10 ⁶ or more. By using such a prepolymer, a polyester having a high degree of polymerization and a small amount of terminal carboxyl groups can be advantageously produced industrially by solid phase polymerization. If the intrinsic viscosity of the prepolymer is too low, the solid state polymerization time will be long even if the amount of terminal carboxyl groups in the prepolymer is large, and as is the purpose of the present invention, it is necessary to obtain a polyester with a high degree of polymerization and a small amount of terminal carboxyl groups. In some cases it is preferable to use prepolymers of higher intrinsic viscosity. Furthermore, if the intrinsic viscosity of the prepolymer is too high, the solid phase polymerization time will be shortened accordingly, but it will be difficult to obtain a highly polymerized polyester with a sufficiently small amount of carboxyl groups. On the other hand, the smaller the amount of terminal carboxyl groups in the prepolymer, the less the amount of terminal carboxyl groups in the highly polymerized polyester obtained, which is preferable, but if the amount of terminal carboxyl groups is too small, the solid phase polymerization time becomes longer, which is not preferable. . The size of the prepolymer to be subjected to solid phase polymerization in the method of the present invention is not particularly limited, but is preferably 3 to 20 meshes, more preferably 4 to 12 meshes. If the particle size of the prepolymer is too large, the solid phase polymerization time tends to be long, which is undesirable.
Further, if the particle size is too small, it is not preferable because it not only requires extra effort to make the particles fine but also the stability during melt molding becomes poor. Conventionally known methods can be used as the solid phase polymerization conditions for the method of the present invention, and the temperature is preferably in the range of 50° C. lower than the melting point of the aromatic polyester to 5° C. lower than the melting point. Further, the reaction pressure may be at least atmospheric pressure under an inert gas flow, for example, a nitrogen flow, or may be at a reduced pressure of 10 mmHg or less. According to the method of the present invention, the polymerization degree is high (for example, the intrinsic viscosity is 1.0 or more) and the amount of terminal carboxyl groups is 10.
Aromatic polyesters having an equivalent weight of /10 ⁶ or less can be easily obtained with less variation in quality. The method of the present invention exhibits particularly excellent effects when applied to polyethylene terephthalate among aromatic polyesters. Next, the method of the present invention will be explained with reference to Examples. In the method of the present invention, the limiting viscosity of the aromatic polyester is a value determined by dissolving the polymer in a 4:6 mixed solvent of tetrachloroethane and phenol at 140°C for 30 minutes and measuring at 35°C. , and the amount of terminal carboxyl groups is A. conycus (A.
Conix) method (Makromol.chem.26 226
(1958)). Example 1 97 parts of dimethyl terephthalate, 69 parts of ethylene glycol and 0.049 parts of manganese acetate were charged.
The methanol produced as a result of the transesterification reaction was distilled off by heating to ~230°C. Next, phosphorous acid
After adding 0.016 part of antimony trioxide and further adding 0.044 part of antimony trioxide, the bath temperature was raised to 275°C and polymerization was carried out at normal pressure for 30 minutes, and then the system was gradually reduced to 0.3 mmHg.
Melt polymerization was carried out for 120 minutes. The intrinsic viscosity of the obtained polyester was 0.62, and the amount of terminal carboxyl groups was 12.5.
Equivalent weight/10 ⁶ g. Here, the reaction system was pressurized to 3 Kg/cm ² with nitrogen gas, 0.75 part of phenyl glycidyl ether (1.0 mol % based on the total acid components constituting the polyester) and 0.03 part of triphenylphosphine were added, and then under pressure After reacting for 15 minutes with stirring, the reaction system was gradually reduced in pressure again after 10 minutes, and polymerization was carried out under reduced pressure of 0.3 mmHg for 90 minutes. The intrinsic viscosity of the obtained polyester was 0.76, and the amount of terminal carboxyl groups was 8.2 equivalents/10 ⁶ g. Here, the polyester was discharged from the polymerization pot, cooled with water, and then finely granulated to a size of 4 mm x 4 mm x 2 mm (5 meshes). The prepolymer obtained here was heated to 4
After drying for an hour, solid phase polymerization was performed at 230°C in a nitrogen stream for 12 hours. The intrinsic viscosity of the obtained polyester is
1.15, and the amount of terminal carboxyl group was 3.5 equivalents/10 ⁶ g. Example 2 Except for using 0.44 parts of ethylene carbonate (1.0 mol % based on the total acid components constituting the polyester) in place of phenyl glycidyl ether,
Melt polymerization of polyester was carried out in exactly the same manner as in Example 1, followed by inherent polymerization. The results are shown in Table 1.

[Table] Example 3 The procedure was carried out in exactly the same manner as in Example 1, except that 0.64 parts of octene-1,2-oxide (1.0 mol % based on the total acid components constituting the polyester) was used instead of phenyl glycidyl ether. Melt polymerization of polyester was carried out, followed by solid phase polymerization. The results are shown in Table 2.

[Table] Comparative Example 1 Transesterification was carried out in exactly the same manner as in Example 1, and then transesterification was carried out at 275°C and 200°C under a reduced pressure of 0.3 mmHg.
A polyester having an intrinsic viscosity of 0.61 and a terminal carboxyl group weight of 130 equivalents/10 ⁶ g was obtained by melt polymerization for a minute. Here, the reaction system was returned to normal pressure with nitrogen gas, 1.59 parts of diphenyl terephthalate (10 mol% based on the total acid components constituting the polyester) was added, and then
The pressure of the reaction system was gradually reduced to 0.3 mmHg over a period of 1 minute.
Polymerization was carried out for 20 minutes under reduced pressure. The intrinsic viscosity of the obtained polyester was 0.76, and the amount of terminal carboxyl groups was
It was 15.5 equivalents/10 ⁶ g. The polyester obtained here was made into fine particles and subjected to solid phase polymerization in the same manner as in Example 1. The intrinsic viscosity of the obtained polyester was 1.07, and the amount of terminal carboxyl groups was
It was 7.2 equivalents/10 ⁶ g. Example 4 In the same manner as Example 1, the intrinsic viscosity ([μ]) was approximately 0.75.
Three batches of the prepolymer were produced by the melt polymerization method, pulverized in the same manner as in Example 1, dried, and then subjected to solid phase polymerization at 230°C for 8 hours. The intrinsic viscosity and terminal carboxyl group content of the obtained highly polymerized polyester were examined. The results are shown in Table 3.

[Table] Comparative Example 2 Same as Comparative Example 1, limiting viscosity ([μ]) approximately 0.75
Three batches of prepolymer were produced by the melt polymerization method, finely granulated in the same manner as in Example 1, and dried at 230°C for 60 minutes.
Time solid phase polymerization was performed. The intrinsic viscosity and terminal carboxyl group content of the obtained highly polymerized polyester were examined. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. When producing a highly polymerized aromatic polyester with an intrinsic viscosity of 1.0 or more using a solid phase polymerization method, a molten aromatic polyester and a small proportion of 1,2-glycol cyclic carbonate are used as a prepolymer to be subjected to solid phase polymerization. and/or a highly polymerized polyester characterized by using an aromatic polyester having an intrinsic viscosity of 0.6 to 0.8 and a terminal carboxyl group weight of 25 equivalents/10 ⁶ g or less obtained by reacting with a monoepoxy compound. Production method.