Styrene maleic anhydride copolymers are widely used in adhesive applications due to their inherent hydrophobicity and adjustability of the copolymer. The copolymer backbone modification of the styrene/maleic anhydride ratio and Mw has a large effect on Tg, hydrophobicity/hydrophilicity, and solubility and explains their success in many applications.
Styrene maleic anhydride copolymers contribute to adhesion improvement as they can:
• Improve bond strength
• Improve hydrophobicity and chemical and corrosion resistance
• Improve compatibility
• Offer high heat resistance
• Increase cross-linking density
• Increase alkaline solubility and removability
More specifically styrene maleic anhydride works synergistically with starch in water based adhesives to significantly improve water resistance which is necessary for most bottle labeling applications requiring ice water resistance and alkaline removability. This property makes XIRAN® suitable for debonding on demand applications. It has also been used in reactive hot melt adhesives to improve green strength and expand temperature range as well as open time. In standard hot melts styrene maleic anhydride copolymers are used to allow removability under alkaline conditions and are also considered reactive polymeric dispersing agents and have been used to produce emulsion polymerization polymers due to the ability to improve hydrophobicity, temperature resistance and shear protection. As a matter of fact, XIRAN® improves the heat resistance of emulsion polymerization latex such as styrene acrylic allowing them to be used in heat seal coatings for flexible packaging.
The polymeric structure of styrene maleic anhydride results in higher steric hindrance which is extremely beneficial for dispersing agents and also ensures less migration compared to traditionally used monomeric surfactants.
Other applications include FDA approved tackifier dispersions, reactive compatibilizer for amine terminated silane functional polymers and alcohol scavengers for thermosetting adhesives.