Method for manufacturing a recycled material composition

1 . A process for preparing a recycled raw material composition, which comprises:

(1) pretreating a waste polyester with an apparent density of 0.1 kg/L or less to have an apparent density of 0.5 kg/L or more;

(2) depolymerizing the pretreated waste polyester; and

(3) purifying a reactant obtained through the depolymerization,

wherein step (2) comprises:

(2-1) subjecting the waste polyester whose apparent density has been adjusted to depolymerization through a first glycolysis reaction at a temperature of 180 to 200° C. to obtain a first reactant; and

(2-2) subjecting the first reactant to depolymerization at a temperature of 150 to 170° C. through a second glycolysis reaction to obtain a second reactant.

2 . The process for preparing the recycled raw material composition of claim 1 , wherein the pretreatment in step (1) is carried out through melt extrusion.

3 . The process for preparing the recycled raw material composition of claim 2 , wherein the melt extrusion is carried out at a temperature of 250 to 300° C. and an extrusion speed of 100 to 350 rpm for 2 to 15 minutes.

4 . The process for preparing the recycled raw material composition of claim 2 , wherein the melt extrusion is carried out without the addition of an additive.

5 . The process for preparing the recycled raw material composition of claim 1 , wherein the waste polyester whose apparent density has been adjusted to 0.5 kg/L or more in step (1) has a size of 5 mm or less and a cylindrical shape.

6 . The process for preparing the recycled raw material composition of claim 1 , wherein the waste polyester to be pretreated in step (1) comprises a waste polyester fabric, a waste polyester film, a waste polyester flake, a waste polyester powder, or a combination thereof.

7 . The process for preparing the recycled raw material composition of claim 1 , wherein step (3) comprises cooling the reactant to a temperature of 100 to 150° C. and pressurized-filtering the reactant at a pressure of 0.01 to 0.5 MPa, and the pressurized filtration rate of the cooled reactant is 1.5 L/minute or more.

8 . The process for preparing the recycled raw material composition of claim 1 , wherein step (3) comprises cooling and crystallizing the reactant.

9 . The process for preparing the recycled raw material composition of claim 1 , wherein step (3) comprises distilling the reactant.

10 . The process for preparing the recycled raw material composition of claim 1 , wherein, when the recycled raw material composition obtained through steps (1) to (3) is analyzed by high-performance liquid chromatography (HPLC), a total sum of a peak area fraction of diethylene glycol ester compounds and a peak area fraction of monohydroxyethyl terephthalate is less than 4.0%.

11 . The process for preparing the recycled raw material composition of claim 1 , wherein, when the recycled raw material composition obtained through steps (1) to (3) is analyzed by high-performance liquid chromatography (HPLC), a peak area fraction of an acetate-based ester compound is less than 0.4%.

12 . The process for preparing the recycled raw material composition of claim 1 , wherein, when the recycled raw material composition obtained through steps (1) to (3) is analyzed by high-performance liquid chromatography (HPLC), a peak area fraction of bis(2-hydroxyethyl) terephthalate is 95% or more.

13 . The process for preparing the recycled raw material composition of claim 1 , wherein a process yield (Y) according to the following Equation 1 is 80% or more:

Y

⁢

(

%

)

=

(

W

1

/

W

2

)

×

100

[

Equation

⁢

l

]

in Equation 1, W 1 is the weight of the recycled raw material composition obtained through steps (1) to (3), and W 2 is the theoretical weight of the recycled raw material composition prepared from the waste polyester used in step (1).

14 . A recycled raw material composition, which is prepared by the preparation process of claim 1 .