# Research on Preventing High-Density Materials from Settling in Liquid Resin

## TL;DR

This paper presents a method to prevent high-density magnetic particles from settling in liquid resin by creating low-density composite materials.

## Contribution

A novel approach using anion–cation composite technology and surface modification to reduce magnetic particle density in resin.

## Key findings

- Coating magnetic particles on hollow silica reduces their density.
- Amino and carboxyl interfacial layers were successfully formed for better compatibility.
- The composite material showed improved suspension in resin solutions.

## Abstract

The applications of magnetic particles in anti-counterfeiting and anti-absorbing coatings and other functional materials are becoming increasingly widespread. However, due to their high density, the magnetic particles rapidly settle in organic resin media, significantly affecting the quality of the related products. Thereby, reducing the density of the particles is essential. To achieve this goal, high-density magnetic particles were coated onto the surface of hollow silica using anion–cation composite technology. Further, the silane coupling agent N-[3-(trimethoxysilyl)propyl]ethylenediamine was bonded to the surface of magnetic particles to form an amino-covered interfacial layer with a pH value of 9.28, while acrylic acid was polymerized and coated onto the surface of hollow silica to form a carboxyl-covered interfacial layer with a pH value of 4.65. Subsequently, the two materials were compounded to obtain a low-density composite magnetic material. The morphologies and structural compositions of the magnetic composite materials were studied by FTIR, SEM, SEM-EDS, XRD, and other methods. The packing densities of the magnetic composite materials were compared using the particle packing method, thereby solving the problem of magnetic particles settling in the resin solution.