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Associative non-ionic polyurethane thickeners (Pseudo-plastic and Newtonian Grades)

The thickeners can be applied to control the rheological profile of a number of products containing aqueous polymer dispersions as binders, such as paints, coatings (for both indoor and outdoor use) and adhesives. They are applied especially in products cured by UV irradiation or by oxygen from air (with a siccative).

The thickeners are 40 % solutions of active agents in a mixture of water and organic solvents of low viscosity (facilitating their dosing) and have density of about 1.03 g/cm3. They are well soluble in water, forming viscous, opaque and opalescent liquids. The pseudo-plastic grade thickeners may be applied e.g. to increase viscosity in the range of low shear rates, enabling this way to reduce an unfavorable phenomenon of binder and filler particles sedimentation, and their amount in the product depends on required rheological effect. Usually 0.1–2 wt. % of the thickener is used relative to the final product mass. The Newtonian grade does not cause such big increase in viscosity in the range of low shear rates as the pseudo-plastic version does. The thickeners can be added at any manufacturing stage of the coating production.


A brief description of the technology

The process comprises a two-stage reaction of addition of poly(oxyethylene glycol), alcohol and isocyanate, and then dissolving the obtained thickener in a mixture of solvents.


Advantages of the technology offered

The thickener synthesis process is performed in the bulk, without any organic solvents, what is favorable from both the ecological and economical point of view. It allows to avoid a costly process of solvents recovery or utilization. Advantageous is also big simplicity of apparatus washing at each production stage.


Equipment

  • two reactors with an anchor stirrer and a heating / cooling jacket, capable to keep inert gas atmosphere and conduct the process under reduced pressure,
  • high-speed mixer,
  • tanks to store reactants.

Laboratory equipment:

  • equipment to determine the hydroxyl value and NCO groups contents,
  • viscometer or rheometer.


Patents

Patent application No P-390 104 (2009) „Method to produce modifiers of rheological properties of aqueous polymeric dispersions”.


Market competitiveness

At present, there are numerous market-available technologies to obtain associative non-ionic polyurethane thickeners, to be applied in paints and coatings based on aqueous polymeric dispersions. They have, however, no ability to permanently build themselves into the product structure. On the contrary to thickeners presently available on the market, the thickeners developed are able to build themselves into the structure of the coating and participate in formation of the coating under UV irradiation or with a siccative, together with the binder contained in the coating material. It allows to improve water-resistance of the coating in comparison to coatings obtained with using traditional thickeners.


Information

Dr. Janusz Kozakiewicz, D.Sc., Chem. Eng., prof. of ICRI

phone: + 48 22 568 23 78


Jarosław Przybylski, M.Sc., Chem. Eng.

phone: + 48 22 568 26 46, + 48 22 568 26 47