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The very practical challenge of achieving a combination of high gloss and block resistance in a low-odor, zero VOC paint formulation has, up to now, been an impossibility. To achieve these desired properties required solvent-borne systems. All that changed with the advent of multiphase acrylic latex systems.
In conventional latex systems, coalescing solvents are required to achieve low MFFT and high block resistance. Up to now, low Tg and block resistance have been mutually exclusive properties. On the other hand, multiphase technology now makes it possible to have high gloss and excellent block resistance in a low-odor, zero VOC paint. The multiphase technology may also be used in flat and semi-gloss zero VOC paints, offering excellent block resistance and wet adhesion, along with good rheological response.
This article will discuss these characteristics, as well as formulation issues such as pigment and thickener selection and freeze/thaw stability.
High gloss and block resistance without VOCs
A multiphase acrylic latex has complex particles consisting of at least two distinct polymer phases. These polymer phases differ in properties, such as glass transition and chemical composition.
A comparison of a VOC-free multiphase latex gloss enamel to several commercially available conventional VOC latex gloss enamels is shown in Figure 1. The chart compares gloss angles (at 60 deg and 20 deg) and blocking resistance (at room …