JPS58118824A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester excellent in color and sanitariness, by using a reaction product of titanium tetrabutoxide with diethylene glycol as an ester interchange/polycondensation catalyst in the production of a polyester. CONSTITUTION:Titanium tetrabutoxide is reacted with ethylene glycol at a temperature of about 200 deg.C for about 2hr under normal pressure. Then, the purpose polyester is obtained by reacting an esterifiable derivative of an aromatic dicarboxylic acid component based on terepthalic acid (e.g., dimethyl terephthalate) with an alkylene glycol (e.g., ethylene glycol, 1,4-butanediol) using the above- produced reaction product as an ester interchange/polycondensation catalyst. Here, the amount of the catalyst used is suitably about 5-15ppm (as titanium metal) of the polymer, which is smaller than that of conventional titanium compound catalysts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aromatic polyester with good color tone and excellent hygiene properties.

Aromatic polyesters containing aromatic dicarboxylic acids and alkylene glycols as main acid components have excellent physical and chemical properties, and are widely used in fibers, films, molded products, and the like. Generally used as such polyester is polyethylene terephthalate, which contains terephthalic acid as the main acid component and uses alkylene glycol and ethylene glycol. These polyesters are manufactured by polycondensing the reaction product obtained by the transesterification reaction between tere-7tal dimethyl and ethylene glycol or the esterification reaction between terephthalic acid and ethylene glycol under reduced pressure. In this case, a catalyst is also used to advance the transesterification reaction or polycondensation reaction, but the quality of the polyester produced depends on the type and amount of this catalyst.

Generally, the production of polyethylene terephthalate uses calcium compounds, zinc compounds, etc. as transesterification catalysts.
Magnesium compounds, manganese compounds, etc. are used, and antimony compounds, germanium compounds, etc. are used as polycondensation catalysts. In total, more than 1,001 pra of the metal used in the pyrimer is used, which is not yet sufficiently sanitary.

In addition, when a titanium compound is used as a catalyst, the amount used may be relatively small, but it has poor solubility in ethylene glycol, so vinegar a! Attempts have been made to increase the solubility by using compounds such as 1-oxalic acid. However, in this case, corrosion due to acid is large and it is not industrially advantageous. In addition, the reaction rate has not been improved, and J
It is necessary to add OPP111 or more, and the polymer color is also strong yellowish, so it is currently difficult to use it industrially.

The present inventors conducted extensive research on a method for producing a polymer that has a high reaction rate, excellent productivity, good color tone, and excellent hygiene properties even when a titanium catalyst is added in a small amount.As a result, titanium tetrabutoxide and diethylene glycol are reacted. By using the reaction product obtained as a catalyst, transesterification and polycondensation reactions can proceed with a very small amount of addition, and a polymer with extremely good whiteness can be obtained. The present invention has been achieved 〇 That is, the present invention is Terephthal II! In producing polyester by reacting an ester-forming derivative of an aromatic dicarboxylic acid mainly consisting of alkylene glycol with alkylene glycol in the presence of a catalyst, a reaction product obtained by reacting titanium tetrabutoxide and diethylene glycol in advance is used. This is a method for producing polyester, which is characterized in that it is used as a transesterification reaction catalyst and a polycondensation reaction catalyst.

A typical example of the ester-forming derivative of an aromatic dicarboxylic acid mainly composed of terephthalic acid used in the present invention is dimethyl terephthalate. In addition, when carrying out the present invention, it is possible to copolymerize other acid components in a range of less than jO mole of the total acid components. ! - It is possible to copolymerize 2 to 70 mol% of sodium sulfoisophthalate brewing component and adipine (1.8 min) in a range of 3 to -0 mol%. This foreign acid component can also be copolymerized. can be done^ Also, examples of the alkylene glycol include ethylene glycol and/or butanediol.

A major feature of the present invention is that a reaction product obtained by reacting titanium tetrabutoxide and diethylene glycol in advance is used as a catalyst during the transesterification reaction and the polycondensation reaction. This makes it possible to significantly reduce the amount of titanium compounds used compared to conventionally used titanium compounds. Moreover, the white color of the obtained compound is extremely good, and it has excellent characteristics.The reaction product of titanium tetrabutoxide and diethylene glycol is not particularly limited, but is heated at 2000℃ for 1 hour under normal pressure. Just heat it up. In this case, the concentration of titanium tetrabutoxide in diethylene glycol is preferably 10% by weight of NSO. If the concentration of titanium tetrabutoxide in diethylene glycol is too low, less titanium tetrabutoxide will be incorporated into the polymer during the polyester reaction, but more dense diethylene glycol components will be incorporated into the polyester, resulting in a lower softening point of the resulting polymer. Therefore, it is preferable that the concentration of titanium tetrabutoxide be higher.

In the present invention, by using the above-mentioned reaction product of titanium tetrabutoxide and diethylene glycol, only a small amount of titanium metal is needed.
In this case, by using a titanium compound as a titanium metal relative to the polymer so that the ratio is 3~/jPl>1!1, the reaction rate is high and a polymer with a good desired color tone can be obtained. In the present invention, it is stable. The present invention will be specifically explained with reference to Examples below, in which agents, additives, etc. may be added within a sanitary range. In the examples, the polymer color tone and polymer viscosity (ηr・1) were determined by the following method. Polymer one color tone; Hunter value (
〇Polymer viscosity (ηr@ln) shown in Le&eb): A sample of 00 was dissolved in m-cresol solvent of 0 and measured using an Ubbelohde viscometer.

Example 1 (1) Reaction product of titanium tetrabutoxide and diethylene glycol #1ll1 Refining column 73!
Titanium tetrabutoxide (1009) and ethylene glycol ioog (1009) were added to 7 rasps of t00ω, heated to -000, and reacted for 1 hour to obtain a colorless and transparent reaction solution.

-) Polyethylene terephthalate m-made terephthal-plated dimethyl sookg, ethylene glycol coco Oki,
As a catalyst, SO9 (as titanium metal!/g) of the reaction product of (1) above was charged into a transesterification tank equipped with a rectification column of 1/m" and heated from 13Q to 0C for a lifetime. The methanol produced was taken out of the prefecture.

It took 720 minutes for 97-methanol to distill off.
Next, the obtained transesterification reaction product was poured into a polycondensation vessel of /m'', and the pressure was reduced from normal pressure to Q/torr while raising the temperature to 4IO to 1OC, and then the one-hour type reaction mixture was added. The obtained polymer was made into chips by passing it through cooling water.The quality of the polymer was as follows: It was a polymer with little taste.

Comparative Example: Titanium tetrabutoxide was used as a catalyst! Example 1 The procedure was repeated in the same manner as in Example 1, except that the sample was added as it was. It took 9% aqt to distill off the metal. In addition, the crystallinity of the obtained polymer is 4' r・1 is 16 U o 1, diethylene glycol is 101 superposition - 1 L value is 410% a
The -djXb value was 0, resulting in a strongly yellow colored polymer. 0'9, dimethyl isophthalate JOkg, and ethylene glycol Coco θ~Further implementation fl/(1) Nite flIAI 1 ml! A transesterification reaction was carried out in the same manner as in Example 1 by adding Shita reaction solution 409. 9' It takes 125 molecules to distill 1 kg of methanol: II! The resulting reaction was transferred to a polycondensation vessel and the reaction was carried out in the same manner as in Example 1.The resulting polymer product IIM was η
r・1 is l'1lls diethylene glycol is t, q4
*Equipment, L value 1) E100% a value is -l, b value is
0, which was a polymer with little yellowness.

Claims (1)

[Claims] In producing polyester by reacting an ester-forming derivative of an aromatic dicarboxylic acid mainly consisting of terephthal mt with an alkylene glycol in the presence of a catalyst,
A l1lfi method for esters, characterized in that a reaction product obtained by reacting titanium tetrabutoxide and diethylene glycol in advance is used as a transesterification reaction catalyst and a polycondensation reaction catalyst.