Tijs Nabuurs

Novel, water-based fluorinated polymers with excellent antigraffiti properties

In this article we describe novel, water-based, crosslinkable fluorinated polymers that form coatings with excellent antigraffiti properties. The synthesis of the binders and the surface and bulk properties of their coatings are discussed. The surface properties of these coatings are characterized in terms of their surface-free energy, as calculated from static contact angle measurements. The distribution of the fluorine atoms throughout the coating is measured by X-ray photoelectron spectroscopy (XPS). The bulk properties are studied by determining the crosslink density through dynamic mechanical thermal analysis (DMTA), and the effect of the crosslinking conditions on the crosslink density and the antigraffiti properties is discussed. The results indicate that a combined action of surface and bulk properties gives these coatings their excellent antigraffiti properties. The applicability of these polymers as protective coatings for metal and concrete surfaces are demonstrated.

Defect free coatings from two-pack isocyanate curable acrylic dispersions

Abstract The combination of isocyanate crosslinking groups and water as continuous phase in coatings provides a real challenge to the coatings industry. Especially the ability of the crosslinker to react with water and liberate carbon dioxide is a problem. CO 2 will be entrapped in the film, resulting in poor aesthetic properties and porous films with reduced resistance properties. In this paper it will be shown that the choice of acid monomer and the acid value have a significant effect on the physical drying rate of the films’ on the level of water remaining in the film after cure, and on the rate of decrease of the NCO concentration and CO 2 blister formation. Increasing the acid value will result in faster NCO loss and more CO 2 . The same effects are reached when acrylic acid is chosen over methacrylic acid, which in turn yields a faster NCO concentration decrease and more CO 2 blisters than βCEA. A faster decrease of the NCO group concentration does not necessarily lead to a faster tack free time. By careful selection of the type of acid defect free films without CO 2 blisters can be formed with a thickness of at least 300 μm (dry). CO 2 blister formation is caused by the presence of water soluble poly-acid which remains in the film enabling the reaction of the isocyanate group with water.

Detection of coalescing agents in water-borne latex emulsions using an environment sensitive fluorescent probe

In this paper we report the determination of partitioning of coalescing agents (organic co-solvents) in water-borne latex emulsions by means of a fluorescence method. An environment-sensitive fluorescent probe was copolymerized via emulsion polymerization. The presence of organic co-solvents inside the polymer particles is revealed by the photophysical properties of the probe. In particular, the position of the fluorescence emission maximum of co-polymerized can be used to measure the amount of coalescing agent present in the polymer particles. The spectral shifts are shown to be due to the softening of the matrix, rather than to solvation of the probe by the added co-solvent.

Probing of cosolvents in polymer latex materials by using solvatochromic fluorescence

The process of film formation is of great importance for the application of organic coatings. In waterborne coatings, organic cosolvents are still indispensable, but regulations force the industry to reduce their amounts. Here we describe a method that uses the solvatochromic fluorescence of a probe molecule copolymerized in an emulsion polymerization process with different monomers to shed light on the partitioning of cosolvents in polymer latex materials. The formulation of the latex with organic cosolvents that are not very water soluble leads to a quantifiable redshift of the emission of the probe. The transfer of the cosolvent upon mixing of cosolvent‐containing and cosolvent‐free compartments can also be monitored.