JP2902673B2 - Method for producing modified polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a direct gravity method using
In the production of polyester by the direct weight method, a modified polyester is produced using a modifier whose terminal functional group has a functional group selected from alcoholic hydroxyl group, carboxyl group and glycidyl group. How to do it.

(Problems to be Solved by the Prior Art and the Invention) Since polyester has excellent chemical and physical properties, it is widely produced and widely used for fibers, films, and other industrial materials. Further, in order to cope with various uses, polymer modification using a large number of modifiers to give special functions has been widely performed. Compared to the case where additives are simply mixed, a method of performing a copolymerization reaction using a carboxylic acid component and / or an alcohol component as a modifier, particularly in a method of performing a copolymerization reaction, is described in, for example, No. 1932 can be cited, and since it has a large modifying effect, it is used in many fields.

However, generally, the copolymerization type modifier is generally added to the state of the oligomer before the polyester is polymerized, but in the direct weight method, the acid value at the stage of the oligomer is reduced. Since it is very high, there is generally a great problem that compatibility with the modifier component is poor and uniform copolymerization cannot be obtained.

Under these circumstances, when producing a modified polyester by the direct-gravity method, it is necessary to carry out the modification only with a modifier having relatively good compatibility, or to carry out the step of terephthalic acid and ethylene glycol as raw materials. Or a modifier is added at a stage where the oligomer has been polymerized to some extent and the acid value has decreased.

However, in the case of fibers, even if the compatibility at the polymerization stage is relatively good, there is a tendency that troubles such as an increase in the pressure of the spinning spin pack and yarn breakage occur frequently.

In recent years, the tendency of polyester production is to produce many kinds in small lots and to reduce the manufacturing cost, and from the reduction of the manufacturing cost to the esterification step, usually to produce large lots, branch the oligomers, and carry out multi-type production in the polymerization step. Systems are becoming mainstream. Therefore, there is a drawback in that the addition of the modifier from the raw material stage is not suitable for diversification. Furthermore, in the method in which the oligomer is polymerized to some extent and the modifier is added at the stage where the acid value is lowered, the degree of polymerization is reduced to 20.
In order to increase the melt viscosity,
In order to uniformly mix the modifier, a large-scale kneading apparatus is indispensable, the heat history is increased, and it is difficult to copolymerize a large amount of the modifier.

Therefore, for the reasons described above, currently, in the case of producing a modified polyester, a method of producing the modified polyester using the DMT method is mainly used. In the case of the DMT method, the raw material is dimethyl terephthalate, and the acid value of the oligomer is very low.
Problems such as the direct weight method are avoided. However, DMT
The method is more expensive than the direct-load method, and has many major problems such as an increase in polymer-containing impurities due to the necessity of a transesterification catalyst.

Furthermore, the terminal functional group of the modifier is other than an alcoholic hydroxyl group or a carboxyl group, and a copolymerization-type modifying raw material requiring a transesterification reaction, for example, the terminal functional group uses a lower alkyl ester of a carboxylic acid or the like. JP-B-62-56893 discloses that ethylene glycol is added to an oligomer before polymerization so that the concentration of alcoholic terminal hydroxyl groups is 3000 to 9000 μeq / g, and then the oligomer is modified. There is disclosed a method for producing a modified polyester, which comprises adding a raw material, stirring the mixture at a predetermined temperature and time, and then performing polycondensation under vacuum. However, in this case, since alcohol other than ethylene glycol such as alkyl alcohol is generated as a by-product of the reaction, it is impossible to use a recovery device in a normal line, a transesterification catalyst is required, and before the polymerization reaction, temperature·
There is a problem that control of conditions such as stirring time is required.

The present invention relates to a method for producing a modified polyester by a straight-weight method, in which various modifiers can be uniformly mixed and a uniform copolymer can be obtained, and further, that a reaction by-product is not produced, It does not require an exchange catalyst, after adding a modifier to the oligomer before polymerization, it can be smoothly performed without controlling conditions such as temperature and stirring time until the polymerization reaction is performed, and satisfies the above conditions. It is an object to provide a method for producing a modified polyester.

(Means for Solving the Problems) In order to solve the above problems, the present invention has the following configuration.

That is, in the direct polymerization method using terephthalic acid as a main raw material, copolymerization is carried out using a modifier whose terminal functional group has a functional group selected from an alcoholic hydroxyl group, a carboxyl group, and a glycidyl group. When producing a modified polyester, an alkali metal compound and ethylene glycol are added to an oligomer having an esterification ratio of 90% or more before being polymerized, and the mixture is completely refluxed, so that the terminal carboxyl group concentration is less than 200 μeq / g. And then polymerizing the oligomer by adding the modifier to the oligomer.

 Hereinafter, the constituent features of the present invention will be specifically described.

In the present invention, ethylene glycol is added to the oligomer before being polymerized to reduce the terminal carboxyl group concentration.
Less than 200μeq / g, but terminal carboxyl group concentration is 200μ
At eq / g or more, the acidity of the oligomer is high, so that the compatibility with the modified raw material having a terminal functional group of an alcoholic hydroxyl group and a carboxyl group becomes poor, and a uniform copolymerized polyester cannot be obtained. Also, without adding ethylene glycol, in order to reduce the terminal carboxyl group concentration to less than 200 μeq / g, the degree of polymerization must be increased to 20 or more, and the melt viscosity also increases. Uniform mixing is difficult. For this reason, in the present invention, ethylene glycol is added in a state where the esterification rate has been increased to 90% or more.

In order to make the terminal carboxyl group concentration less than 200 μeq / g by adding ethylene glycol, total reflux is carried out for 30 minutes with 5 to 15% by weight of ethylene glycol based on the oligomer.

The terminal carboxyl group concentration of the oligomer sharply decreased in the first 30 minutes due to the total reflux of ethylene glycol,
It is not preferable to perform the treatment longer than this, because the effect is small and the number of ether bonds in the oligomer increases.

When the amount of ethylene glycol is 5% by weight, the target decrease in the terminal carboxyl group concentration cannot be obtained by total reflux for 30 minutes. On the other hand, when the content is 15% by weight or more, the temperature of the oligomer is remarkably lowered, and the oligomer is partially or wholly solidified, which is not preferable, and problems such as a large loss of heat due to total reflux occur.

Furthermore, if an alkali metal compound is added together during the total reflux with ethylene glycol, the increase in the number of ether bonds in the oligomer is effectively suppressed, and the reduction of antimony trioxide as a polymerization catalyst is also suppressed. High quality modified polyester can be obtained.

Here, the alkali metal compound is at least one alkali metal compound selected from the group consisting of Li, Na, and K compounds, including alkali metal hydroxides, alkoxides, and aliphatic carboxylate salts, including the alkali metal itself. And acetate is particularly preferred.

The addition amount of the alkali metal compound is 50 to
The range is preferably 5000 (ppm), preferably 100 to 1000 (ppm). The timing of addition may be any time before the end of the total reflux with ethylene glycol, and is preferably simultaneous with the addition of ethylene glycol.

(Example) Hereinafter, an example will be specifically described based on a drawing (FIG. 1) showing one example of a modified polyester production apparatus.

Example 1 Preparation of Cationic Dyeable Polyester Terephthalic acid and ethylene glycol were reacted at a molar ratio of 1.12 in esterification tanks (1) and (2) to an esterification ratio of 90% or more, and the reacted oligomer was continuously branched. 2a
Pulled out through.

This direct-weight method oligomer is continuously transferred to the depolymerization tank (3) via the branch 2a, and ethylene glycol is added to the oligomer by a supply port in the middle of the branch 2a.
By weight, lithium acetate was continuously supplied at 200 ppm to the polymer, and total reflux was carried out for 30 minutes to continuously lower the terminal carboxyl group concentration in the depolymerization tank (3).
Further, via a supply port 3b, 5-sodium sulfo-bis (β-hydroxyethyl) isophthalate is continuously added as a 2 mol% to the terephthalic acid component and lithium acetate to the polymer at 400 ppm, each as an ethylene glycol solution. Supplied. The oligomer mixed with the modifier is polymerized by two polymerization tanks (4) and (5), and has an absolute viscosity of 0.5.
Increased to 55.

The obtained polyester had a content of diethylene glycol of 3.0 mol% and was free from coarse particles of TiO ₂ at all, and showed uniform dyeability even with cationic dyes.

Comparative Examples 1-3 Polyester was 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 The polymerization was carried out immediately after the addition of the modifier in the same manner as in Example 1 except that 5-sodium sulfodimethylisophthalate requiring transesterification was used as the cationic dyeing-improving raw material. The reaction was carried out to produce a polyester (Comparative Example 4). Further, similarly, the modified raw material 5-sodium sulfodimethyl isophthalate is added to the oligomer before polymerization, and the polymerization reaction is not immediately performed, but the mixture is stirred at normal temperature and 250 ° C. for 100 minutes, and then polymerized under vacuum. The reaction was carried out to produce a polyester (Comparative Example 5).

(Effects of the Invention) According to the present invention, in the production of a modified polyester by the direct weight method, various modifiers can be uniformly mixed, and a uniform copolymer can be obtained. Furthermore, since a modifier that requires a transesterification reaction is not used, the generation of reaction by-products can be suppressed, and from the addition of the modifier to the polymerization reaction,
There is an advantage that work efficiency is improved without the need for condition control. The present invention, various modifiers are uniformly mixed,
A method for producing a modified polyester can be provided, which is extremely useful in industry.

[Brief description of the drawings]

FIG. 1 shows an example of an apparatus for producing a modified polyester according to the present invention. (1), (2) ... esterification tank, (3) ... depolymerization tank, (4), (5) ... polymerization tank, 2a ... branch road, 3a, 3b,
3c …… Supply port.

Claims (1)

(57) [Claims] In a direct polymerization method using terephthalic acid as a main raw material, a terminal functional group is copolymerized using a modifier having a functional group selected from an alcoholic hydroxyl group, a carboxyl group and a glycidyl group. In producing a modified polyester, an alkali metal compound and ethylene glycol are added to an oligomer having an esterification rate of 90% or more before being polymerized, and the mixture is completely refluxed, so that the terminal carboxyl group concentration is 200 μeq / A method for producing a modified polyester, which comprises adding the modifier to the oligomer and polymerizing the oligomer after the amount becomes less than g.