The inorganic powder industry is undergoing a strategic transformation, shifting from scale expansion to innovation-driven development. In this process, surface modification technology serves as a critical link between powder production and end-use applications. By precisely controlling key indicators such as interface compatibility and dispersion stability, it is reshaping the value chain of inorganic powders. This transforms them from basic raw materials into customized solutions.
1. Five Reasons for Powder Surface Modification
1.1 Improving Compatibility Between Powders and Substrates
In polymer-based composite materials such as plastics, rubbers, and adhesives, inorganic mineral fillers are indispensable. It is due to their cost-effectiveness and functional versatility. However, the inherent high surface energy of inorganic powders and the low polarity of organic polymers create significant interface mismatches. This incompatibility hinders uniform dispersion and effective bonding within the matrix, leading to structural issues such as mechanical weakening and stress concentration in composite materials.
Surface modification technology addresses this challenge through interface engineering. By employing techniques such as grafting coupling and organic coating, the wettability of the powder surface can be adjusted. It reduces the polarity gradient with the polymer matrix. This facilitates chemical bonding or physical anchoring, thereby improving interfacial compatibility with the organic matrix.
1.2 Preventing Particle Agglomeration and Enhancing Powder Dispersibility
Inorganic powders produced through grinding often expose numerous highly active hydroxyl groups and ionic bond breakage sites due to lattice fractures. These surface defects significantly increase particle surface energy, leading to agglomeration driven by van der Waals forces and electrostatic attraction. When unmodified powders are introduced into a polymer matrix, their agglomerates can act as stress concentration points. It induces microcrack formation and disrupting composite interface continuity, ultimately reducing the mechanical properties of the material.
This engineering challenge can be effectively addressed through surface grafting modification. Hydrolyzed groups of modifiers, such as silane coupling agents, undergo dehydration condensation with the hydroxyl groups on the powder surface, neutralizing surface charges and reducing surface energy to below 50 mJ/m².
Additionally, long-chain organic ends, such as C18 alkyl groups, form a spatial barrier layer that helps the powder overcome polymer chain entanglement during melt blending. This results in an ideally dispersed filler structure. It enhanceskpj’ the composite material’s tensile strength by 2-3 times while maintaining a processing viscosity fluctuation rate of less than 15%.
1.3 Reduce the Oil Absorption Value of Powders
The oil absorption value is a key indicator used to measure the adsorption capacity of powders. It significantly affects the dispersion of powders in composite materials, processing performance, and the physical and chemical properties of the final product. Taking the application of plasticizers in plastic products as an example, fillers with high oil absorption values can excessively absorb plasticizers during processing, leading to an increase in system viscosity. This, in turn, weakens the resin’s processing performance and increases production costs.
However, through surface modification, the surface polarity of inorganic powders can be reduced, decreasing friction between particles and enhancing lubricity. As a result, the powders become more densely packed, increasing packing density and correspondingly reducing the oil absorption value. Such optimization not only improves material processing efficiency but also helps lower production costs and enhance the final product’s performance.
1.4 Impart Functional Properties to Materials
Unmodified powders are typically used as fillers to reduce production costs in downstream applications, but their functional properties are limited. When the amount of powder added exceeds a certain critical value, it may even cause a significant decline in material performance. In contrast, surface-modified powders can significantly improve or impart new functional properties to materials by regulating surface chemical composition, modifying physical structure, or introducing functional groups. This not only allows for a higher powder content in the material but also expands its applications across various fields.
1.5 Enhance Energy Efficiency, Safety, and Environmental Protection in Materials
Surface modification technology can greatly enhance material performance in terms of environmental protection, energy efficiency, safety, and health by optimizing the interface characteristics of powders. This promotes the development of materials toward greener, more functional, and intelligent solutions.
For example, calcium carbonate coated with calcium stearate effectively reduces frictional heat during plastic extrusion, lowering energy consumption by up to 30%. Lubricated and modified heavy calcium-filled PP material shortens the injection molding cycle by 20% and reduces unit energy consumption by 18%. Additionally, modified aluminum hydroxide used in electric vehicle battery pack casings increases the limiting oxygen index (LOI) from 21% to 32% while reducing smoke density by 60%, significantly improving safety performance.
2. How to Conduct Powder Surface Modification
2.1 Leverage the Powder’s Intrinsic Properties to Maximize Its Advantages
The surface modification of powders should be based on their intrinsic properties. A thorough understanding of their elemental composition, crystal structure, and physical and chemical characteristics is essential to fully maximize their advantages. Different inorganic powder materials exhibit distinct performance characteristics due to their unique compositions and structures. In the pursuit of high-value-added development, it is necessary to align with downstream application needs, optimize powder performance through surface modification technology, and enhance functionality to meet diverse application scenarios.
2.2 Address Industry Challenges Based on Market Demand
With the advancement of downstream industries and the emergence of new fields, the demand for inorganic powders is shifting toward high performance, sustainability, functionality, and customization. When implementing surface modification, in-depth market research should be conducted to accurately identify the pain points and needs of downstream customers. By providing tailored solutions, companies can help customers enhance product performance and reduce production costs.
2.3 Develop New Functions and Expand Application Fields
In the era of rapid technological progress, particularly in high-tech and intelligent industries, basic materials must meet increasingly stringent requirements. Many inorganic powder materials still possess untapped functional potential, which is key to expanding applications and driving industry development. Through surface modification technology, these latent properties can be unlocked, promoting innovative applications in high-end fields.
2.4 Establish a Scientific Powder Product Evaluation System
As the inorganic powder industry advances toward high-quality development, traditional testing indicators (such as activation, oil absorption value, and particle size) are no longer sufficient to fully assess powder performance. A more comprehensive evaluation system should be established, incorporating factors such as the coating rate and type of modified additives on the powder, surface electrical properties, and micromorphology. Additionally, integrating real-world performance data from downstream applications can provide an indirect assessment of modification effectiveness. A deeper understanding of the powder’s characteristics is essential for guiding modification efforts in the right direction.
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