Coating Process Optimization and Self-Healing Performance Evaluation of Shellac Microcapsules Coated with Melamine/Rice Husk Powder

Xiaoxing Yan,Yan Han,Taiyu Yin

doi:10.3390/app11188373

Abstract

To explore the implication of the coating process on the comprehensive properties of water-based coating containing shellac microcapsules coated with melamine/rice husk powder on the Tilia cordata surface, the optical properties, mechanical properties, liquid resistance, aging resistance, chemical composition, and microstructure of the coating were analyzed comprehensively. After the best coating process was determined, compared with the coating without microcapsules, the self-repairing performance of the water-based coating containing shellac microcapsules coated with melamine/rice husk powder was explored via aging resistance test and scratch test. The results showed that the best comprehensive performance of the coating was obtained by three times primer, two times finish, and 6.0% shellac microcapsules coated with melamine/rice husk powder added in the primer. The coating with shellac microcapsules had significant stability, aging resistance, and self-healing performance, which can repair cracks in a certain period of time and inhibit the formation of cracks. At the core wall ratio of 0.75, the shellac which plays a role of the repair agent as the core material can effectively fill the microcracks in the coating to repair by flowing from the broken microcapsule because it can be physically cured at room temperature. The modification of waterborne coatings with shellac microcapsules coated with melamine/rice husk powder contributes the improved self-repairing properties of surface coatings containing heterogeneous natural polymer composites.

Highlights

Compared with the microcapsules without rice husk powder, the infra longs to -NH- stretching vibration peak, which is the characteristic peak of melamine of the microcapsules with rice husk powder in the wall material split at 1157 resin
It can be inferred that this peak is affected by the C-H vibration of husk powder, and it can be judged that the wall material of microcapsule c aromatic core and the C-O-C antisymmetric “bridge” stretching vibration peak in rice lose
The the best coating process of “three times of primer, Thewaterborne waterbornecoating coatingprepared preparedbyby the best coating process of “three times of pritwo times of finish, and microcapsule which contained rice husk powder in wall mer, two times of finish, and microcapsule which contained 5.5% rice husk powder in material addedadded into the had the comprehensive properties

Summary

Introduction

Zhang et al [11] fabricated the poly urea-formaldehyde coated epoxy microcapsules via in-situ polymerization, and the coating with microcapsules had good self-healing performance and good corrosion resistance. Cotting et al [12] prepared poly(urea-formaldehydemelamine) microcapsules containing epoxy resin via in-situ polymerization. By in-situ polymerization, Lang et al [13] successfully prepared a kind of self-healing coating which contained microcapsules embedded with linseed oil in the shell structure composed of poly ureaformaldehyde. Compared with the artificial epoxy resin coating, this coating showed excellent self-healing performance on artificial cracks. The microcapsules exhibited excellent self-healing properties after being added into waterborne coatings. The types and properties of adhesives in microcapsules are very important for the self-repairing effect of microcracks [15,16,17]

Methods

Results

Conclusion