The diacetone acrylamide (DAAM) and adipic acid dihydrazide (ADH) crosslinking system provides several benefits for acrylic and vinyl acrylic paint & coatings and adhesives formulators. From reducing safety concerns to improving performance properties, the benefits of this system are numerous for these industries.
- DAAM and ADH are easy and safe to use, and formaldehyde-free.
- Diacetone acrylamide uniformly copolymerizes with acrylic copolymers, creating well-dispersed pendant ketone crosslinking sites.
- Acrylic emulsions based on DAAM with ADH in the aqueous phase are initially non-reactive and exhibit good long-term stability (e.g. “in-can” stability).
- After film coalescence, crosslinking becomes rapid at ambient temperatures, due to loss of water and a simultaneous reduction in pH arising from the loss of NH3.
- Because crosslinking occurs post-coalescence, the resulting crosslinked polymer network exhibits enhanced mechanical strength and maximum film properties.
- DAAM:ADH crosslinking enhances abrasion, scrub, stain, and blocking resistance; moisture and solvent resistance; gloss retention; and substrate adhesion.
What is the chemical basis of the keto-hydrazide self-crosslinking monomers?
The circled moieties in the chemical structures below highlight the business end of these two molecules.
The DAAM monomer readily copolymerizes with other acrylic monomers to create a pendant keto moiety on the acrylic backbone chain. The keto group can be post-reacted with the difunctional ADH to self-crosslink the system. By adding ADH to an ammonia-neutralized acrylic emulsion containing DAAM, the emulsion remains stable when stored prior to its application and film drying.
How is the self-crosslinking process accomplished?
Self-crosslinking chemistry between DAAM and ADH begins with copolymerizing DAAM into an acrylic copolymer, using DAAM concentration at ~1-5 wt. percent of the monomer mixture. This makes the emulsion copolymer crosslinkable with ADH.
The following steps will complete the process:
- The emulsion is neutralized with ammonia, and ADH is then added to the emulsion as an aqueous solution. The ratio of DAAM to ADH is ~ 2.1 to 1.0.
- On drying off the water and evaporation of the ammonia, coalescence of the film occurs, and the pH decreases, becoming acidic. As the pH decreases, the crosslinking reaction rate begins to increase.
- The crosslinking process then takes place with the formation of a chemical bond between the DAAM and the ADH, called a “ketimine” moiety. The reaction by-product is water.
What monomers copolymerize well with DAAM?
When it comes to monomers for an emulsion copolymerization, diacetone acrylamide boasts a wide range of options. Its co-monomer feeds can include the following:
What are some of the commercial applications for DAAM & ADH crosslinking?
Self-crosslinking DAAM & ADH crosslinking chemistry is being used in multiple industry applications. The most prominent applications for DAAM & ADH crosslinking are for durable interior and exterior paints, as well as coatings for architecture, wood, and concrete surfaces. Other applications to consider for this dynamic duo are adhesives, sealants, inks, textile & paper treatments, and polishes.
What differentiates Gantrade’s DAAM & ADH product offerings?
Gantrade’s DAAM is a white or slightly yellow crystalline solid with a purity level greater than 99 percent. Our ADH is a white crystalline solid, also with a purity above 99 percent. Our DAAM and ADH offerings are the preferred choice for paint and coating applications, due to their low color and high purity levels.
To explore how our DAAM and ADH crosslinking monomers can address your company’s unique product needs, partner with Gantrade. Our team, armed with a wealth of technical knowledge and expertise, can guide you to the best solutions for your applications. Contact Gantrade today to get started. We offer a wide portfolio of monomers for the paint & coatings, adhesives & sealants, inks, textiles & paper treatment arenas, and we have spent decades building a global supply chain that ensures steady sourcing of the building blocks for thousands of products.
