JPS6310731B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester, and its purpose is to produce a polyester having a low content of terminal carboxyl groups and having excellent hydrolytic stability, which is particularly useful as a polymer for manufacturing industrial fibers, films, and plastics. An object of the present invention is to provide a method for producing polyester. Traditionally, polyethylene terephthalate has been produced by transesterifying ethylene glycol and dimethyl terephthalate, or by directly condensing ethylene glycol and terephthalic acid.
Alternatively, a method is known in which ethylene oxide and terephthalic acid are reacted to substantially form bis-(β-hydroxyethyl) terephthalate, and this is subjected to a polycondensation reaction at 250° C. or higher under reduced pressure. However, in this polycondensation reaction, the organic compound is heated at 250°C or higher, particularly near 300°C, for a long period of time, so thermal decomposition reactions cannot be avoided. Therefore, the obtained polyethylene terephthalate has a large amount of terminal carboxyl groups and has poor hydrolytic stability. Conventionally, in order to improve such drawbacks, it is well known to react with an end-blocking agent such as an epoxy compound. However, well-known monoepoxy compounds such as phenyl glycidyl ether and 1-octene oxide are not practically satisfactory in terms of high volatility, poor compatibility with polyester, and low reactivity with terminal carboxyl groups. It's not worth it. To improve this drawback, N-glycidyl phthalimide and other N-
-Glycidylimide compounds are known, but they are still not sufficient. The present inventor has conducted extensive research on a new method for producing polyester that does not have these drawbacks, and as a result, has arrived at the method of the present invention. That is, the present invention provides (A) an aromatic dicarboxylic acid component and
(B) is composed of an organic dihydroxy compound component, or (C) is composed of a hydroxy aromatic monocarboxylic acid component, or is composed of the above-mentioned (A), (B), and (C) components, and has an intrinsic viscosity of 0.3 or more. of polyester,
In its molten state, the following formula [However, in the formula, R ₁ and R ₂ are each a saturated aliphatic group, alicyclic group, or aromatic group that does not have an ester-forming functional group, and R ₁ and R ₂ may be the same or different from each other. good. Further, R ₃ is a hydrogen atom or a saturated aliphatic group. ] This is a method for producing a polyester having a small amount of terminal carboxyl groups, which is characterized by reacting with an epoxy compound represented by the following. In the present invention, the epoxy compound reacted with the polyester is a compound represented by the above formula, where R ₁ and R ₂ are saturated aliphatic groups,
Alicyclic groups or aromatic groups, specifically aliphatic groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl, lauryl, alicyclic groups such as cyclohexyl, cyclopentyl, and phenyl. , tolyl, 2,4-dimethylphenyl, chlorophenyl, α-naphthyl, β-naphthyl, and P-phenylphenyl. Further, R ₁ and R ₂ may be the same or different from each other. Further, R ₃ is a hydrogen atom or a saturated aliphatic group, and specific examples of the aliphatic group include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl, lauryl, and the like. Specific examples of the epoxy compound represented by the above formula include N-glycidyl N-methylmethanesulfonamide, N-glycidylmethanesulfonylanilide, N-glycidyl N-methylbenzenesulfonamide, N-glycidyl N-ethylbenzenesulfonamide, N-glycidyl N-ethylbenzenesulfonamide, -Glycidylbenzenesulfonanilide, N-glycidyl p-toluenesulfonanilide, N-glycidyl-1-naphthalenesulfonanilide, N-glycidyl-N-methyl p-
Toluenesulfonamide, N-glycidyl-N-
Examples include ethyl p-toluenesulfonamide. These can be used alone or in combination of two or more. Such an epoxy compound can be easily synthesized by reacting an N-substituted sulfonamide and epichlorohydrin in the presence of a dehydrochlorination agent. In the present invention, the epoxy compound can be reacted with the molten polyester at any time during or after the polymerization of the polyester until melt molding is completed. However, the intrinsic viscosity of the polyester reacted with the epoxy compound needs to be 0.3 or more. Even if a polyester whose intrinsic viscosity does not reach 0.3 is reacted with the above epoxy compound and then the polyester is further polymerized, it is difficult to obtain a polyester with a sufficiently low amount of terminal carboxyl groups and a high degree of polymerization, which is not preferable. . The preferred time to react the polyester with the epoxy compound is during the polymerization stage of the polyester, especially when the intrinsic viscosity of the polyester is 0.3, preferably 0.4.
From the polymerization stage after reaching , more preferably from the time when the polymerization of the polyester is substantially completed until the completion of molding. The amount of the epoxy compound to be used is about 0.05 to 5 mol%, preferably about 0.1 to 3 mol%, particularly preferably about 0.2 to 1 mol%, based on the total acid components constituting the polyester.
It is desirable that it is mol%. If the amount is too large, not only the degree of polymerization of the polyester will be greatly reduced after reacting with the epoxy compound, but also the amount of discoloration will increase accordingly, which is not preferable. In the present invention, the reaction between the polyester and the epoxy compound is carried out in the molten state of the polyester. This is because reaction time can be significantly shortened by carrying out the reaction in a molten state. Here, this reaction temperature is around the melting temperature of polyester, usually 200 to 350°C. For example, when the polyester is polyethylene terephthalate,
It is preferable to select any temperature between 265 and 310°C, or in the case of polybutylene terephthalate, between 230 and 250°C, and the reaction time also depends on the amount and type of epoxy compound and the polyester. Although it varies depending on the degree of polymerization, etc., any time can be selected from usually about 1 minute up to about 120 minutes if necessary. There is no particular restriction on the reaction pressure, but when this reaction is carried out during the polymerization of polyester, it is possible to select not only a reduced pressure state but also a pressure near normal pressure, and when the reaction is carried out during the molding process, a pressure near normal pressure can be selected. Molding conditions (usually pressurized conditions) can be selected. The reaction product of polyester and epoxy compound can be used as it is as molded products such as fibers, films, and plastics, but if the intrinsic viscosity of the reaction product is 0.5 or less, it may be further subjected to melt polymerization or solid phase polymerization. It is desirable to increase the degree of polymerization of polyester. Also, its limiting viscosity is 0.5
Even in the above cases, the above-mentioned melt polymerization or solid phase polymerization can be performed as necessary. In the present invention, the polyester reacted with the epoxy compound is a polyester composed of (A) an aromatic dicarboxylic acid component and (B) an organic dihydroxy compound component (hereinafter referred to as polyester ()),
(C) Polyester composed of hydroxy aromatic monocarboxylic acid component (hereinafter referred to as polyester ()), (A) aromatic dicarboxylic acid component, (B) organic dihydroxy compound component, and (C) hydroxy aromatic monocarboxylic acid component (hereinafter referred to as polyester). Specific examples of the polyester () and the aromatic dicarboxylic acid of the component (A) constituting the polyester () include terephthalic acid, isophthalic acid,
Diphenyl-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenooxyethane-4,4'-dicarboxylic acid, naphthalene-
It is an aromatic dicarboxylic acid in which a carboxyl group is directly connected to an aromatic nucleus, such as 2,6-dicarboxylic acid and naphthalene-2,7-dicarboxylic acid. Specific examples of the polyester () and the hydroxy aromatic monocarboxylic acids that constitute the polyester () include p-hydroxybenzoic acid, 4-hydroxydiphenyl-4'-carboxylic acid, and 4-hydroxydiphenyl ether. -4'-carboxylic acid, p-β-hydroxyethoxybenzoic acid, p-α-hydroxypropoxybenzoic acid, etc. are hydroxy aromatic monocarboxylic acids in which a carboxyl group is directly bonded to an aromatic nucleus. Furthermore, the organic dihydroxy compound of component (B) constituting polyester () and polyester () includes, as specific examples, ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol ( 1,
4), 1,4-bis β-hydroxyethoxybenzene, 4,4'-bis β-hydroxyethoxydiphenyl sulfone, hydroquinone, bisphenol A, 4,4'-dioxydiphenyl, 4,
These include aliphatic glycols, alicyclic glycols, aliphatic glycols containing aromatic nuclei, and aromatic dioxy compounds, such as 4'-dioxydiphenyl ether and 4,4'-dioxydiphenyl sulfone. Specific examples of preferable polyesters include homopolyesters of terephthalic acid and ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, or cyclohexanedimethanol (1,4): p-β -Homopolyester of hydroxyethoxybenzoic acid component or p-a-hydroxypropoxybenzoic acid component: terephthalic acid component, ethylene glycol component and 1,
Copolyester of 4-bis-β-hydroxyethoxybenzene component: p-oxybenzoic acid component,
Copolyesters of isophthalic acid components and hydroquinone components; homopolyesters of terephthalic acid components and resorcinol components; copolyesters of terephthalic acid components, isophthalic acid components, and bisphenol A components. Among these, polyesters particularly suitable for achieving the object of the present invention are homopolyesters of the above-mentioned terephthalic acid component and ethylene glycol component or tetramethylene glycol component. Such polyester can be produced by a conventionally known melt polymerization method or a method combining melt polymerization and solid phase polymerization. As a method for polymerizing polyester, for example, 1 (A) an aromatic dicarboxylic acid and (B) an organic dihydroxy compound (component (B) is at least 1.2 times the mole of component (A), more preferably 1.2 to 2 times the mole) 2 (A) an ester-forming derivative of an aromatic dicarboxylic acid (for example, a lower alkyl or aryl ester such as dimethyl ester or diphenyl ester) and (B ) Organic dihydroxy compound (component (B) is (A)
(preferably used in an amount of 1 to 2 times the mole, more preferably 1 to 2 times the mole of the component) is subjected to a transesterification reaction. Here, if necessary, the excess organic dihydroxy compound is distilled out of the reaction system during the transesterification reaction or after the transesterification reaction and before the completion of the polycondensation reaction: 3 (C) Ester of hydroxy aromatic monocarboxylic acid Methods such as transesterification of a formable derivative (for example, lower alkyl or aryl ester such as methyl ester or phenyl ester) can be mentioned: 4. Reactions 2 and 3 above are carried out simultaneously. During this polymerization process, the intrinsic viscosity of polyester
After reaching 0.3 or more, it is preferable to add the epoxy compound represented by the above formula and react with the polyester. At this time, if the degree of polymerization of the polyester has not reached the desired value, a polycondensation reaction may be further carried out after the above reaction to obtain a polyester having the desired degree of polymerization. Alternatively, a polyester chip having an intrinsic viscosity of 0.3 or more is made in advance, an epoxy compound represented by the above formula is added to the chip, mixed, and the resulting mixture is heated to a temperature higher than the melting temperature of the polyester to cause the two to react. It's okay. The present invention is effective for producing polyester whose intrinsic viscosity is 0.6 or more. It is particularly effective in producing polyester having an intrinsic viscosity of 0.80 or more. If it is a polyester with a relatively low degree of polymerization, a polymer with few terminal carboxyl groups can be obtained by the conventional method without using the method of the present invention, but when producing a polyester with a high degree of polymerization and an intrinsic viscosity of 0.8 or more. In conventional methods, the resulting polyester contains a large amount of terminal carboxyl groups due to side reactions such as thermal decomposition during the polycondensation reaction, resulting in poor hydrolytic stability. However, since the polyester produced by the method of the present invention has an extremely small amount of terminal carboxyl groups, it has excellent moist heat resistance. The present invention will be described in detail below with reference to Examples. In addition,
In this specification, the intrinsic viscosity of the polymer is determined from the value measured at 35°C using an Ostwald viscometer after dissolving the polymer in orthochlorophenol.
A.Conix's method [Macromol・Chem 26 , 226
(1958)]. Moreover, parts in the examples represent parts by weight. Examples 1 to 4 and Comparative Example 1 97 parts of dimethyl terephthalate, 69 parts of ethylene glycol, 0.058 parts of calcium acetate monohydrate, and 0.044 parts of antimony trioxide were placed in an autoclave, and heated at 180 to 230°C while slowly passing nitrogen through. The transesterification reaction was carried out while removing the generated methanol. After the transesterification reaction was completed, 0.05 part of a 50% aqueous solution of phosphorous acid was added, followed by 0.02 part of potassium iodide, and the temperature of the reaction mixture was raised to 280 °C.
℃, the internal pressure was gradually reduced to a reduced pressure, and polymerization was carried out under high vacuum with a reaction system pressure of 0.2 mmHg or less. When the reaction under high vacuum reached 120 minutes, the reaction system was returned to normal pressure with nitrogen to stop the polymerization reaction, and then the polyester was chipped according to a conventional method. The intrinsic viscosity of the polyester obtained here was 0.70, and the amount of terminal carboxyl groups was 28.5 equivalent/10 ⁶ g
It was hot. The polyester chips were then dried with hot air at 160°C and subjected to solid phase polymerization at 230°C and 0.2 mmHg for 10 hours. The intrinsic viscosity of the obtained polyester is
0.90, and the amount of terminal carboxyl group was 13.8 equivalent/10 ⁶ g. To the high degree of polymerization polyester obtained here, the monoepoxy compounds shown in Table 1 were added at a ratio of 0.6 mol% to the total acid components constituting the polyester.
The mixture was melt-mixed and reacted at ℃ for 5 minutes. Table 1 shows the intrinsic viscosity and terminal carboxyl group content of the obtained polyester. Furthermore, Table 1 shows the ultimate results after 1 part of the obtained polyester chips with a small amount of terminal carboxyl groups were placed in a sealed tube purged with nitrogen gas together with 10 parts of ion-exchanged water and hydrolyzed by keeping it at 130°C for 15 hours. Indicates viscosity. For comparison, the case in which no monoepoxy compound is added is also listed in Table 1, which shows that the monoepoxy compound of the present invention reacts with the polyester in the melt, significantly reducing the amount of terminal carboxyl groups, and as a result, the amount of terminal carboxyl groups in the polyester increases. It can be seen that the hydrolysis resistance is improved. 【table】

Claims (1)

[Scope of Claims] 1 Consists of (A) an aromatic dicarboxylic acid component and (B) an organic dihydroxy compound component, or (C) a hydroxy aromatic monocarboxylic acid component, or (A), (B) ) and (C) components and having an intrinsic viscosity of 0.3 or more, in its molten state, the following formula: [However, in the formula, R ₁ and R ₂ are each a saturated aliphatic group, alicyclic group, or aromatic group that does not have an ester-forming functional group, and R ₁ and R ₂ may be the same or different from each other. good. Further, R ₃ is a hydrogen atom or a saturated aliphatic group. ] A method for producing a polyester having a small amount of terminal carboxyl groups, which comprises reacting with an epoxy compound represented by the following. 2. The method according to claim 1, wherein the amount of the epoxy compound is 0.05 to 5 mol% based on the total acid components constituting the polyester.