JPH0356528A - Production of modified polyester - Google Patents

Abstract

PURPOSE:To obtain the subject polymer having excellent uniformity in high efficiency while suppressing the formation of by-products by adjusting the terminal carboxyl concentration of an oligomer for direct polymerization process to a specific level, adding a modifier to the oligomer and copolymerizing the components. CONSTITUTION:Terephthalic acid is made to react with ethylene glycol in esterification reactors 1,2 preferably at a molar ratio of 1.12 to obtain an oligomer having an esterification degree of preferably >=90%. The oligomer is continuously transferred through a branched path 2a to a depolymerization reactor 3 and ethylene glycol is added to the oligomer through an intermediate feeding port to obtain an oligomer having a terminal carboxyl concentration of <=200mu eg/g. A modifier [e.g. 5-sodium sulfobis(beta-hydroxyethyl) isophthalate] is added to the oligomer through a feeding port 3b and the oligoner is polymerized in polymerization reactors 4,5 to obtain the objective polymer having an absolute viscosity of preferably >=0.55.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to the production of polyester by the direct loading method (hereinafter referred to as the direct loading method) using terephthalic acid as the main raw material. This invention relates to a method for producing a modified polyester using a modifier having a functional group selected from alcoholic hydroxyl groups, carboxyl groups, and glycidyl groups. (Prior art and problems to be solved by the invention) Polyester has excellent chemical and physical properties, so it is produced in large quantities and widely used for fibers, films, and other industrial materials. Polymer modification using a number of modifiers to impart functionality is also widely carried out.Compared to simply mixing additives, carbon farc minutes and/
Alternatively, as a method of carrying out a copolymerization reaction using an alcohol component, for example, Japanese Patent Publication No. 55-1932 can be mentioned, and because of its great reforming effect, it is used in many fields. However, copolymerization type modifiers are generally added to the oligomer state before polyester is polymerized, but in the direct polymerization method, the acid value at the oligomer stage is Because of its extremely high content, it generally has poor compatibility with the modifier, making it difficult to obtain uniform copolymerization, which is a major problem. Under these circumstances, when producing modified polyester using the direct loading method, it must be carried out only with a modifier that has relatively good compatibility, or when the raw materials terephthalic acid and ethylene glycol are mixed at the stage. The modifier is added from the beginning, or the modifier is added after the oligomer has been polymerized to a certain extent and the acid value has decreased. However, in the case of textile applications, even if the compatibility at the polymerization stage is relatively good, problems such as increases in spin-puncture pressure and yarn breakage tend to occur frequently. In addition, in recent years, the production trend of polyester has been to produce a wide variety of products in small lofts and reduce manufacturing costs.The esterification process is usually produced in large lofts, and oligomers are branched to produce a wide variety of products in the polymerization process. system is becoming mainstream. Therefore, the disadvantage of adding a modifier at the raw material stage as described above is that it is not suitable for diversification.
Furthermore, in the method of adding the modifier after the oligomer has been polymerized to a certain extent and the acid value has decreased, the degree of polymerization must be increased to 20 or more, which also increases the melt viscosity, so the modifier is uniformly added. A large-scale mixing device is essential to mix the modifier, which increases the thermal history, and it is difficult to copolymerize a large amount of the modifier. Therefore, for the above reasons, the DMT method is currently the mainstream method for producing modified polyester. In the case of the DMT method, the raw material is dimethyl terephthalate, and the acid value of the oligomer is also very low, so problems like the direct weight method can be avoided. However, D.
The MT method has higher manufacturing costs than the direct weight method, and
There are many major problems, such as the need for a transesterification catalyst, which increases the amount of polymer-containing impurities. Furthermore, if the terminal functional group of the modifier is other than an alcoholic hydroxyl group or a carboxyl group, and a copolymerization type modification raw material that requires a transesterification reaction, for example, the terminal functional group is a lower alkyl ester of carboxylic acid, etc. Regarding the case where copolymerization is carried out, Japanese Patent Publication No. 62-56893 discloses that ethylene glycol is added to the oligomer before polymerization to increase the concentration of alcoholic terminal hydroxyl groups from 3000 to 9000.
A method for producing a modified polyester is disclosed, which comprises adding a modifying raw material to the oligomer, stirring the oligomer at a predetermined temperature and time, and then polycondensing it under vacuum. However, in this case, alcohols other than ethylene glycol such as alkyl alcohols are generated as reaction by-products, so normal line recovery equipment cannot be used, a transesterification catalyst is required, and a transesterification catalyst is required before the polymerization reaction. There are problems such as the need to control conditions such as temperature and stirring time. The present invention provides that when producing a modified polyester by the direct loading method, various modifiers can be mixed uniformly, a uniform copolymer can be obtained, and further, that reaction by-products are not produced; The above conditions are met: no transesterification catalyst is required, and there is no need to control conditions such as temperature and stirring time between the addition of a modifier to the oligomer before polymerization and the polymerization reaction, which can be carried out smoothly. The purpose of this paper is to provide a method for producing modified polyester. (Means for Solving the Intelligence Problem) In order to solve the above-mentioned problems, the present invention has the following features. That is, in the direct loading method using terephthalic acid as the main raw material, the terminal functional groups are alcoholic hydroxyl groups, carboxyl groups. Copolymerization is carried out using a modifier having a functional group selected from glycidyl groups, and when producing a modified polyester, ethylene glycol is added to the oligomer before polymerization to reduce the terminal carboxyl group concentration. 2
00 μeq/g, and then adding the modifier to the oligomer and polymerizing the modified polyester. The structural requirements of the present invention will be explained in detail below. In the present invention, ethylene glycol is added to the oligomer before polymerization to reduce the terminal carpoquine group concentration to 2.
However, if the terminal carboxyl group concentration is 200 μeq/g or more, the acidity of the oligomer is high, resulting in poor compatibility with modified raw materials whose terminal functional groups are alcoholic hydroxyl groups and carboxyl groups. Uniform copolymerized polyester cannot be obtained. In addition, without adding ethylene glycol, the terminal group concentration was reduced to 20%.
In order to make it less than 0 μs q/g, the degree of polymerization must be increased to 20 or more, and the melt viscosity also increases, making uniform mixing difficult in a normal polymerization reactor. In order to make the terminal carpoxyl group concentration less than 200 μeQ/g by adding ethylene glycol, it is desirable to perform total reflux for 30 minutes with 5 to 15% by weight of ethylene glycol based on the oligomer.

The concentration of the terminal carboxyl group of the oligomer decreased rapidly during the first 30 minutes due to total reflux of ethylene glycol.
Even if it is carried out for a longer period of time, the effect will be small and the number of ether bonds in the oligomer will increase, which is not preferable. When the amount of ethylene glycol is 5% by weight, the targeted reduction in the terminal carboxylic group concentration cannot be achieved by total reflux for 30 minutes. In addition, if the amount is 15% or more, the temperature of the oligomer will drop significantly and the oligomer will solidify partially or completely, which is undesirable and causes problems such as a large loss of heat due to total reflux. Furthermore, if an alkali metal compound is also added during total reflux with ethylene glycol, the increase in ether bonds in the oligomer is effectively suppressed, and the reduction of antimony dioxide, which is a polymerization catalyst, is also suppressed. Here, the alkali metal compound is at least one kind of alkali metal compound selected from Li, Na and K compounds.
These include alkali metal hydroxides, alkoxides, aliphatic carboxylates, etc., including alkali metals themselves, and acetates are particularly preferred. The amount of the alkali metal compound added is 50 to 5000 (ppm), preferably 10 to 5000 (ppm) based on the polymer.
The range of 0 to 1000 (ppm) is good, and the addition time can be any time before the end of total reflux with ethylene glycol, preferably at the same time as the addition of ethylene glycol. (Example) Hereinafter, an example will be given, and one example of a modified polyester manufacturing apparatus will be described.
A detailed explanation will be given based on a drawing (Figure 1) showing an example. Example 1 Production of cationically dyeable polyester Terephthalic acid and ethylene glycol were mixed at a molar ratio of 1.12 in esterification tanks (1) and (2). The reaction was carried out to an esterification rate of 90% or more, and the reacted oligomer was continuously extracted through the branch path 2a.
is continuously transferred to the depolymerization tank (3), and the branch path 2a
Through the supply port in the middle of the tank, 10% by weight of ethylene glycol and 20ppm of lithium acetate were continuously supplied to the polymer, and total reflux was carried out for 30 minutes, and the mixture was transferred to the depolymerization tank (3). At this time, the concentration of terminal carboxylic groups was continuously decreased.

Furthermore, through the supply port 3b, 5-sodium sulfobis(β-hydroxyethyl) isophthalate was continuously added as an ethylene glycol solution at 2 mo 1% relative to the terephthal M fraction, and lithium acetate was added at 400 ppm relative to the polymer. It was supplied to the public. The oligomer mixed with the modifier was polymerized in two polymerization tanks (4) and (5), and the absolute viscosity was increased to 0.55.

The obtained polyester has a diethylene glycol content of 3. It was a good product containing no coarse particles of Ti○ at Omol%, and showed uniform dyeability even with cationic dyes. Comparative Examples 1 to 3 Polyesters were produced in the same manner as in Example 1, except that the amount of ethylene glycol added to the oligomer before polymerization was changed. The results are shown in Table 1. Comparative Examples 4 to 5 Immediately after adding the modifier, polymerization was carried out in the same manner as in Example 1, except that 5-sodium sulfodimethyl isophthalate, which requires transesterification, was used as the cationically dyeable modifying raw material. A reaction was conducted to produce polyester (Comparative Example 4). Furthermore, in the same manner, the modified raw material 5
- Sodium sulfodimethyl isophthalate was added to the oligomer before polymerization, and the polymerization reaction was not performed immediately, but after stirring at a temperature of 250°C for 100 minutes under normal pressure, the polymerization reaction was performed under vacuum to produce polyester. (Effects of the Invention) According to the present invention, various modifiers can be mixed uniformly and a uniform copolymer can be obtained in the production of modified polyester by the direct loading method. Furthermore, since a modifier that requires transesterification is not used, the formation of reaction by-products can be suppressed, and there is no need to control conditions from the addition of the modifier to the polymerization reaction. This has the advantage of increasing sexual efficiency. INDUSTRIAL APPLICATION This invention can provide the manufacturing method of modified polyester in which various modifiers are mixed uniformly, and is extremely useful industrially.

[Brief explanation of drawings]

Figure 1 shows an example of an apparatus for producing modified polyester according to the present invention.

Claims (1)

[Claims] (1) In the direct polymerization method using terephthalic acid as the main raw material, copolymerization is performed using a modifier whose terminal functional group has a functional group selected from alcoholic hydroxyl groups, carboxyl groups, and glycidyl groups. When producing modified polyester, ethylene glycol is added to the oligomer before polymerization to reduce the terminal carboxyl group concentration to 200%.
A method for producing a modified polyester, which comprises adding the modifier to the oligomer and polymerizing the oligomer after the polyester is reduced to less than μeq/g.