Dioctyl terephthalate (DOTP) is the ester of terephthalic acid and 2-ethylhexanol. It is a clear, colourless liquid with a slight odour, which is insoluble in water. Dioctyl terephthalate is a very important phthalate-free plasticizer for PVC, preferred over low-chain and ortho-phthalate plasticizers as it is considered a safer alternative due to its low toxicity.
The production method comprises the steps of feeding fine terephthalic acid and 2-ethyl hexyl alcohol into an esterfying reaction kettle by the weight ratio of 1 to 1-1.8, heating while stirring, adding catalyst when the temperature is increased to 170-210 DEG C, controlling the esterfying temperature within the range of 190-200 DEG C, reacting for 7-13h, and stopping esterfying when the acid value is less than 0.3mg KOH/g and transferring the mixture into a neutralizing refining kettle after the temperature of the mixture is reduced below 100 DEG C, neutralizing and rinsing by water at 80-100 DEG C, removing superfluous reaction alcohol, separating water phase, adding a porous absorbing material, stirring, separating solid from liquid, so as to obtain a high-quality pure DOPT (dioctyl terephthalate).
DOTP is a general purpose plasticizer that is considered safer than ortho-phthalate plasticizers due to its reduced toxicity profile. The terephthalates exhibit none of the peroxisome proliferation of liver enzymes that some ortho-phthalates have shown in several studies. It has uses in applications like extrusion, calendering, injection molding, rotational molding, dip molding, slush molding and coating.