Di Octyl Terephthalate production process

Google Patent
https://patents.google.com/patent/WO2014185872A1/en?oq=google+patent+cahit+y%C4%B1ld%C4%B1r%C4%B1m

DESCRIPTION

DOTP (DI-OCTLY TEREPHTHALATE)PRODUCTION METHOD

TECHNICAL FIELD

The invention is DOTP (Di octly terephthalate) production method at normal atmospheric pressure without using any inert gas by separating the water formed in the reaction by means of column in PVC plastic production industry.

BACKGROUND OF THE ART

DOTP (Di octly terephthalate) is used in the production of PVC plastic used in many fields such as artificial leather, shoes, slippers, cable, car parts.

DOTP (Di octly terephthalate), can be obtained from the reaction of di methyl terephthalate, and 2-ethyl hexanol with a titanium catalyst. However, the reaction proceeds very slowly and there are foaming problems.

In other known DOTP (Di octly terephthalate) production methods, DOTP (Di octly terephthalate) is produced by reacting terephthalic acid and 2-ethyl hexanol with a titanium catalyst, with or without pressure in the environment open to the atmosphere. However, the reaction time is too long in all these methods and as the reaction could not be fully completed, acid number of the product does not fall below 0.1 mm g OH. Therefore, the product after reaction is washed with 2.5% NaOH and acid number is reduced to below 0.1 mm g KOH. Despite all these procedures, as the colour of DOTP produced is around 40 hazen, generated product is treated with activated carbon and filtered for the second time. All this extra processes lead to environmental pollution and at the same time as it lead to loss of product. Also excess alcohol used in the reaction begins to turn yellow after use a few times.

BRIEF DESCRIPTION OF THE INVENTION

PTA and 2-EH are reacted with a catalyst with or without pressure in the environment open to the atmosphere. Carbon number of the alcohol used is at least 6 up to 10. The reaction temperature is between 170 and 220 °C. There is a tower in the system independent from the reactor. The reactor is connected to towers with a total of 4 pipelines in different diameters. Alcohol and water formed during the reaction vapour go to the tower from both of these lines. From other two lines, completely water-free alcohol in the tower returns back to the reactor. DOTP produced by this method need to be washed with the 2.5% NaOH, and only washing with water is sufficient. After washing with water, Although the product is sent directly to the filter without being processed with active carbon, colour of the product is 10 hazen. Even if the excess alcohol used in the reaction is used for hundreds of times, it definitely does not turn yellow, and does not lose its properties.

DETAILED DESCRIPTION OF THE INVENTION DESCRIPTION OF FIGURES

Figure 1: Figure 2:various views of the tower and reactor from which the present is produced

Reference numbers

10- Reactor

20- Small columns (which alcohol and water vapour into the tower)

30- The main column (alcohol and water vapour carrying the tower) 40- The column bearing water-free alcohol to the tower

50- Spare line (when the column 40 used to bearing water-free alcohol to the tower is not enough)

60- Platform

70- Collecting tank (Water vapour and alcohol escaping from the tower without condensing)

80- Collecting boiler(which pumps the alcohol that cannot be returned to the reactor into the reactor due to pressure differences)

90- The Tower

100- The water line that cools exchangers

110- The water line that cools exchangers

The catalyst used in the production method of DOTP (Di octly terephthalate) is selected from the group consisting of TIPT (Titanium (IV) isopropoxide (97+%) (Tetraisopropyltitanate, tetrapropylorthotitanate), TIBT (Titanium (IV) n-butoxide (98+%) (Tetraisobutyltitanate), TNBT (Titanium (IV) n-butoxide (98+%) (Tetra n-butyl titanate), MSA (Methanesulfonic acid), tin(ll) oxalate ( stannous oxalate ).

To achieve the mentioned objectives, the present invention is the use of Di octyl terephthalate (DOTP) esters obtained according to the above considerations as plasticizers.

Water and alcohol carried formed in the reaction with small columns (20) and the main column (30) which is the connection between the reactor (10) and the tower (90); and carrying alcohol, and water vapour to the tower is sent to the tower. The reason why there are two lines carrying alcohol and water vapour formed between the reactor (10) and the tower (90) is to prevent foaming and pressure generation in the reactor (10).

In the tower (90), there are at least 2 and maximum of 12 heat exchangers and at least 2 but no more than 12 rooms. Water and alcohol condensing in the tower (90) are separated from each other due to the difference intensity. Condensed water is collected at the bottom of the tower (90). The completely water-free alcohol carried in the tower (90) together with water returns to reactor (10) from the column carrying water-free alcohol to the tower (40) and from the spare line (50). Albeit in very small amounts, water or alcohol not condensing in the tower (90) passes through the top of tower, water vapour and alcohol escaping from the tower without condensing is collected in the collection tank (70). Excess alcohol that cannot be returned to the tower due to pressure differences is collected collecting boiler (80) and is pumped to the tower (90).

A reactor (10)used in the production of Di-Octyl terephthalate (DOTP) ester of the present invention is illustrated in Figs. The reactor (10) has a structure having a simple stirrer and a heater which is controlled by a temperature control element. The reactor ( 0) is connected to the tower by two columns, a small column (20) carrying alcohol and water vapour in the tower and a main column (30) carrying alcohol, and water vapour in the tower. The tower (90) is open to atmosphere from the collecting tank (70) where the escaping alcohol and water vapour are deposited, and accordingly, the system works at atmospheric pressure. PTA, the alcohol and a catalytic amount of catalyst are introduced in the reactor (10). The reactor (10) is heated by the heater. When the reactor (10) temperature rises, excess alcohol and the water formed in the reaction begins to mobilize along the tower (90). Alcohol condensed by means of heat exchangers located in the tower (90) is separated from water and returns through the column (40) and spare lines (50) carrying alcohol-free water to the tower and which are the columns for returning to the reactor (10). The condensed water is collected at the bottom of the tower (90) before returning the reactor (10). PTA; alcohol molar ratios is 1 ; 2. However, excess alcohol is used in production. Excess alcohol content is 10% to 80%. Excess alcohol is taken back at the end of the production. The reaction time is between 4 to 6 hours. The amount of the resulting water and acid number of the product is followed, when acid number falls below 0.1 mg / KOH, the production is terminated. Under vacuum, excess alcohol is taken back. The crude product is washed with water, filtered and the production is ended.