One aspect is a method for producing a first intermediate product. A feedstock is provided that comprises a first polyester. The feedstock is contacted with a first amount of a first organic compound in a volume section V.sub.1 to obtain a first initial mixture. The first amount is in the form of a liquid. The first polyester is transported, and at least a fraction of the first amount of the first organic compound, from the volume section V.sub.1 to a volume section V.sub.2. The volume section V.sub.2 is at least partially filled with the first organic compound. A level of the first organic compound in the volume section V.sub.1 is at a height H.sub.1 from a floor, and a level of the first organic compound in the volume section V.sub.2 is at a height H.sub.2 from the floor. The first polyester is contacted with a further organic compound in a volume section V.sub.3, to obtain a further initial mixture. A weight average molar mass of the first polyester is reduced in the volume section V.sub.3, to obtain a first intermediate mixture. The first intermediate mixture comprises a first intermediate product, the further organic compound. $H_1<H_2.$

One aspect is a method for producing a first intermediate product. A feedstock is provided that comprises a first polyester. The feedstock is contacted with a first amount of a first organic compound in a volume section V.sub.1 to obtain a first initial mixture. The first amount is in the form of a liquid. The first polyester is transported, and at least a fraction of the first amount of the first organic compound, from the volume section V.sub.1 to a volume section V.sub.2. The volume section V.sub.2 is at least partially filled with the first organic compound. A level of the first organic compound in the volume section V.sub.1 is at a height H.sub.1 from a floor, and a level of the first organic compound in the volume section V.sub.2 is at a height H.sub.2 from the floor. The first polyester is contacted with a further organic compound in a volume section V.sub.3, to obtain a further initial mixture. A weight average molar mass of the first polyester is reduced in the volume section V.sub.3, to obtain a first intermediate mixture. The first intermediate mixture comprises a first intermediate product, the further organic compound. $H_1<H_2.$

The present invention relates to recycled polyester yarn using waste fabric. The recycled polyester yarn produced by the method, which includes steps of: adding a predetermined chain extender to a polyester resin in which waste fabric woven with polyester yarn is melted to prevent the viscosity of the melted recycled polyester resin from dropping, and by adding a low melting point alloy agent having low melting point and low crystallinity, thereby improving extrusion (workability) in a process of melting and spinning the recycled polyester yarn and having physical properties equivalent to virgin polyester yarn.

The present invention relates to recycled polyester yarn using waste fabric. The recycled polyester yarn produced by the method, which includes steps of: adding a predetermined chain extender to a polyester resin in which waste fabric woven with polyester yarn is melted to prevent the viscosity of the melted recycled polyester resin from dropping, and by adding a low melting point alloy agent having low melting point and low crystallinity, thereby improving extrusion (workability) in a process of melting and spinning the recycled polyester yarn and having physical properties equivalent to virgin polyester yarn.

The present invention relates to a method for manufacturing a recycled polyester yarn using waste fabric. The method includes steps of: adding a predetermined chain extender to a polyester resin in which waste fabric woven with polyester yarn is melted to prevent the viscosity of the melted recycled polyester resin from dropping, and by adding a low melting point alloy agent having low melting point and low crystallinity, thereby improving extrusion (workability) in a process of melting and spinning the recycled polyester yarn and having physical properties equivalent to virgin polyester yarn.

The present invention relates to a method for manufacturing a recycled polyester yarn using waste fabric. The method includes steps of: adding a predetermined chain extender to a polyester resin in which waste fabric woven with polyester yarn is melted to prevent the viscosity of the melted recycled polyester resin from dropping, and by adding a low melting point alloy agent having low melting point and low crystallinity, thereby improving extrusion (workability) in a process of melting and spinning the recycled polyester yarn and having physical properties equivalent to virgin polyester yarn.

One aspect is a method for producing a first intermediate product. A feedstock is provided that comprises a first polyester. The feedstock is contacted with a first amount of a first organic compound in a volume section V1 to obtain a first initial mixture. The first amount is in the form of a liquid. The first polyester is contacted with a further organic compound to obtain a further initial mixture. A weight average molar mass of the first polyester is reduced to obtain a first intermediate mixture. The first intermediate mixture has a first intermediate product, the further organic compound. A mass ratio of the feedstock to the first organic compound in the volume section V1 is in the range of 0.02 to 3.

One aspect is a method for producing a first intermediate product. A feedstock is provided that comprises a first polyester. The feedstock is contacted with a first amount of a first organic compound in a volume section V1 to obtain a first initial mixture. The first amount is in the form of a liquid. The first polyester is contacted with a further organic compound to obtain a further initial mixture. A weight average molar mass of the first polyester is reduced to obtain a first intermediate mixture. The first intermediate mixture has a first intermediate product, the further organic compound. A mass ratio of the feedstock to the first organic compound in the volume section V1 is in the range of 0.02 to 3.