Applications of Poly vinyl ethers (Lutonal)

Introduction

Lutonal series is saponification-resistant soft resins for increasing the adhesion and flexibility of printing inks and of cellulose nitrate and resin coatings.

Applications

Lutonal A 25 and A 50 differ only in their degree of polymerisation, and thus in their viscosity. Their main use is as plasticizing soft resins for cellulose nitrate coatings. Their soft resin character also improves the adhesion of such coatings.

In the manufacture of paints that contain less Lutonal A than cellulose nitrate, it is necessary to add a genuine gelling agent for cellulose nitrate, e. g. a phthalate.

Formulations that contain more Lutonal A than cellulose nitrate, on the other hand, do not require any additional plasticizer. The solvent mixture used in the paint should contain 25 – 40% ethanol, while the proportion of low-volatility solvents should be kept as small as possible, otherwise the layers of paint dry too slowly and remain tacky. 

Lutonal A is also used to manufacture so-called resin paints based on natural and synthetic resins (gum dammar, ester resins, lime resin, maleate resin, ketone resin or phenol-containing rosin).

The Lutonal A grades can be added to printing inks for packaging to improve their adhesion to aluminium foil and cellophane in flexographic and intaglio printing.

The viscosity of solutions of the Lutonal A grades depends on their solids content and on the solvent. For the same concentration, the viscosity obtained with different types of solvent increases in the following order: esters, aromatic solvents, alcohols, chlorinated hydrocarbons. Lutonal A 25, which contains no solvent, can only be dissolved in a reasonable time in a pug mill.