SESN PRODUCTS FOR PAPER INDUSTRY

Introduction

Like in many others industry fields, foam is a disturbing agent in the paper production.
Entrapped air bubbles in the material used for paper manufacture can cause breaking of the sheet. Air contained in the stock can also affect negatively the quality, for example sheet formation, of end product and cause a higher energy absorption of the pumps.
Foam can occur in many parts of the paper production:  in the stock where it can better be defined air inclusion, in the size press, in the coating and in the waste water treatment; another process with big foam problems is also the cellulose pulp production. According to these uses and also according to the type of paper produced and the row materials used normally are used different categories of defoamer.

Action mechanism
Foam is normally formed by the action of a surfactant (natural or syntethic) that is a chemical product containing in its molecule a hydrophilic and a lipofilic group. In a phase interface the hydrophilic group is directed to the water and the lipofilic to the fat or to the air. This allows the formation of a very stable thin layer of liquid which includes air, that is a foam bubble.
The defoamer must be able to destroy this equilibrium and to permit the air to escape. For this reason the defoamer is always insoluble in water and must come slowly to the surface (of the bubble or of the water). In many cases a certain disperdibility in the water is desired in order to have a better distribution in the medium and to reach the single bubbles.

Choise of the suitable defoamer
As already said, there are several product categories having a defoaming effect and in many cases it is not possible to establish in advance which one will be the most suitable for a specific case. We can tray to make a list pointing out the most important characteristics. In any case we suggest to do the necessary tests with the specific medium. Our technicians are at your disposal to suggest the best way to carry out the tests and eventually to do them together with you.

Fat defoamers: Not very effective, good against foam caused by surfactant occurring in nature, normally biodegradable

Silicone defoamers: Very effective, often undesired because of the substantivity of silicone

Defoamers containing
metal soaps: Very effective, normally good against foam caused by synthetic surfactans.

Wax and fat dispersion
Defoamers: Not very effective, normally used where it is desired a good compatibility with the medium to defoam in order to avoid strong and sudden reactions, for example in paper production

Defoamers contaning
alkylene oxides: Often used in the food industry and biotechnologies. Better effective at higher temperature.
 

Producrs range

Type Chem. base Colour Active cont Main field of application Nexfoam OCT fatty acid alcoxylated yellow 100% tissue Nexfoam ACT alcohol emulsion white 30% ca paper stock Nexfoam MAS fatty alcohol alcoxylated pale yellow 100% ca paper stock Nexfoam PAT metal soap yellow light brown 100% ca coating Nexfoam AS1 fatty acid/ alcohol brown 100% ca waste water