Process description – SSP for recycled PET pellets

SSP for the PET recycling process meets the same basic requirements as virgin polymers: increase of molecular weight (IV) and removal of organic byproducts. However with recycled material the increase of IV is less (due to IV degradation in previous PET heating processes), and organic byproducts are not caused by side reactions during PET synthesis, but are mostly migrated substances from consumer usage.

SSP for recycled PET is optimized for the specific recycling requirements: it is more flexible and has only two steps, starting with crystallized material. Inside the solid-state reactor, the product reaches its final temperature and is upgraded to the desired IV. Homogeneous product quality is guaranteed through even heating and the narrow residence time distribution. Maximum IV flexibility is obtained through a reactor design that allows a wide range of process temperatures. During processing, all degradation products, which partially present as volatile contaminants and are partially bound to the polymer molecular structure, are removed or re-polymerized accordingly.

For quick cool-down, a fluid bed cooler is used. The cooling process also provides a final dedusting of the material. Cooling is performed under air; polycondensation under nitrogen prevents any undesirable oxygen degradation of PET. The nitrogen is constantly cleaned in a gas purification loop where all reaction products and any residual contaminants are removed.

Due to reversing degradation from previous processing, the acetaldehyde content is reduced to values below even virgin PET.


a former Bühler Group Company
Sandackerstr. 24
9245 Oberbüren
Telefon: +41 71 552 10 00

Please visit our new homepage,
online on April 2, 2015

Further contacts

Mr. Mike Hendley
Minneapolis, MIN 55441-4509
Mobile +1 6128 50 8269

Mr. Mingkai Tang
Buhler (Beijing) Polymer Technology Co. Ltd.
718 Room, Jingtai Tower
C No.24 Jianguomenwai Street
Chaoyang District, Beijing, 100022
Republic of China
Mobile +86 138-0109-0532
Phone +86 10 65157138

Mr. Yong-Gyu Lee
South Korea
Phone + 82 70 8638 4235
Mobile + 82 10 6205 4235

Mr. Hara Hideki
Buhler K.K.
3-22-11, Shinyokohama, Kohoku-ku
222-0033 Yokohama
Phone +81 45 477 3048

Mr. Vincent Halgand
Buhler SARL
22 avenue des Nations
BP 59442 Villepinte
95944 Roissy CDG Cedex
Phone +33 1 49 89 6129
Mobile +33 6 08 91 65 52

Mr. Claudemiro Ferreira
Mr. Mauricio Rodrigues

Rua Prefeito Chagas, 305 / 307
37701-010 Poços de Caldas – MG
Claudemiro Ferreira:
Phone +55 35 3697 1567
Mobile +55 35 9135 0161 
Mauricio Rodrigues:
Phone +55 35 3697 1568 
Mobile +55 35 9843 8378