company news about Application of polyaspartic resin in the preparation of high solid acrylic polyurethane coatings

The proposal of "double carbon" target fully reflects the responsibility and commitment of China as an international power, and is also forcing China's industries to upgrade and transform, and carbon emission management has become a major focus. For coatings companies, the focus of coating formulation design efforts has become on improving coating performance while reducing the amount of volatile organic compounds (VOCs) in coatings.

Acrylic polyurethane coatings, as the mainstream material for outdoor anti-corrosion topcoats, some of the resins widely used at present have relatively low solid content, which leads to unsatisfactory coating film fullness and a large number of organic volatiles causing serious pollution to the environment.

With the continuous updating of technology, 80% solid content of hydroxypropyl resin appeared on the market, but due to its viscosity and low reactivity, the preparation of coatings need to add a large number of solvents, up to 70% solids content in actual construction, there are still a large number of volatile organic compounds.

The solvent-free, low-viscosity polyaspartic resin developed by Feiyang can effectively reduce the VOC content and improve the drying speed for acrylic polyurethane coatings, while also improving the mechanical properties of the coating film.

Polyaspartic acid ester resin (referred to as "polyaspartic resin") is a solvent-free, low-viscosity resin, at the same time, has excellent weather resistance, corrosion resistance and abrasion resistance and other comprehensive properties, in recent years, it has been widely used in waterproofing, anticorrosion, flooring and other fields.

Chemically speaking, polyaspartic resin is an aliphatic secondary amine, which is a general term for a class of materials that are polymerized by Michael addition of maleic acid ester and primary diamine, and the principle of synthesis is shown in the figure below:

Reaction principle of polyaspartic resin synthesis

Due to the abundance and variety of diamine main chain structures (X), common polyaspartic resin main chain (X) structures are as follows:

Polyaspartic resin main chain (X) structure

The performance of the polyaspartic resin synthesized with it varies greatly, so we can prepare acrylic polyurethane coatings that meet various performance requirements and characteristics by selecting polyaspartic resins with different performance characteristics.

In general, polyaspartic resin used in acrylic polyurethane system has the following characteristics:

First, reduce viscosity and VOC content.

Polyaspartic resin solid content is generally about 96%, and with hydroxypropyl resin has good compatibility, in the hydroxypropyl coating formula design mixing and assembling asparagus resin can improve the solid content of the system, the construction of the solid content of up to 85%. At the same time, polyaspartic resin belongs to small molecules of low-viscosity aminocompounds, the viscosity ranging from 60cps to 1000cps for the propylene polymerization system has a good dilution, thereby reducing the number of VOCs and improving film fullness. Volatile organic compounds and improve the fullness of the coating film.

Second, improve the drying speed of the system.

Acrylic polyurethane coatings generally dry in 24 hours or so, and at low temperatures, low hydroxyl activity, coating drying requires high temperature baking.

Polyaspartic resin with HDI trimer gel time is generally ranging from 2 ~ 130min, the molecular structure of the amino group belongs to the site-resistant secondary amino group, the group on the reactivity of the reactive hydrogen relative to the hydroxyl group on the reaction activity is higher, and hydroxypropyl mixing and splicing to improve the drying speed of the system, the hardness of the coating in a few hours to achieve the effect of polishing and sanding to achieve a higher construction efficiency, and at low temperatures (-15 degrees Celsius) do not need to bake. At low temperature (-15 degrees Celsius), it can be self-drying without baking, thus avoiding baking and achieving the purpose of energy saving and emission reduction.

We have verified the above characteristics by adopting Zhanxin's high solid content hydroxyacrylic resin 1753 and our in-house polyaspartic resin F420 in a certain ratio of mixing with HDI trimer to prepare a coating film.

From the above test results, it can be seen that polyaspartic resin can significantly improve the solid content of acrylic polyurethane coatings, drying speed and the mechanical properties of the coating film, according to the performance requirements, we can choose a different structure of polyaspartic resin compounded with hydroxypropyl resin to prepare coatings with different properties.

At present, this kind of program has been widely used in automobile repair, aviation, large-scale machinery, outdoor steel structure and other industries, and has made a greater contribution to the promotion of the "double carbon" goal.