1. The definition and function of filler
Filler is a kind of fine granular substance with the main function of "filling" in the medium , which is insoluble in the dispersion medium, and is also called extender pigment. The appearance of filler dry powder is mostly white or light gray, and generally in the medium, its hiding power and decolorizing power are very low. By adding fillers to the medium, the non-color physical and chemical properties in the medium can be effectively changed.
Fillers have two main functions in coatings, one is to "fill" and reduce costs; the other is to change . Modern paint technology pays more attention to the second role of fillers. For example, by choosing different types and several star fillers, the storage performance and construction performance of the paint can be effectively improved, and the mechanical strength, abrasion resistance, and water resistance of the paint film can be improved. properties such as resistance, UV resistance, heat insulation and crack resistance. Compared with pigments, most fillers have the advantages of low cost, low oil absorption and easy dispersion.
2. Typical properties of fillers
The properties of materials can be well identified by using the performance characteristics of fillers, and fillers with different properties can be compared and evaluated. Typical properties of fillers
Physical state:
It is generally in the form of solid powder, but it can also be in the form of pre-dispersion.
Chemical composition: Inorganic or organic compound, which may also be a single substance, a natural product, a mixture , or a material of a characteristic composition.
Particle shape: spherical, cubic, irregular, massive, flake, flake, fiber, mixture .
Particle size: can be from a few nanometers to tens of millimeters (can be from nanocomposites to paving or textured coatings).
Aspect ratio: from 1 (spherical or cubic) to 1600 C fibers).
Particle Size Distribution: Can be monodisperse, or a mixture of different sizes, or Gaussian, or irregular.
Particle surface area: from 10m to more than 400m 2 /g. Depending on the specific surface area, the filler particles can have different
The porosity can range from completely non-porous and smooth particles to porous particles with pores of different sizes.
Particle internal structure: from hollow to porous to non-porous solids.
Particle-particle associations: individual, agglomerated, aggregated, flocculated material.
Thermal Properties: The coefficient of thermal expansion and thermal conductivity are very different.
Electric and magnetic properties: from nonconductors to conductors, from magnetic to nonmagnetic, the possibilities are endless.
The general technical requirements for appearance, color, density, pH value, oil-absorbing wipes, and refractive index fillers vary with different materials.
3. Classification of fillers
According to the appearance and color, it can be divided into white filler and colored filler; according to the preparation method, it can be divided into natural filler and synthetic filler; according to its function, it can be divided into heat-resistant filler, conductive filler, anti-sedimentation filler, etc.; According to the composition, it can be divided into compound fillers and mixture fillers, and can be divided into paint fillers, water-based paint fillers, building materials fillers, paper fillers, and plastic fillers according to their uses. Fillers, fillers for cosmetics and pharmaceuticals, fillers and fillers for printing materials, etc.
Fourth, the development trend of packing
Fillers have been widely used in coatings, paints, building materials, paper, plastics, cosmetics, medicine, food and printing materials and other industries. With the low-carbon economy proposed by the country, energy saving (energy and resources) and environmental protection have become the main theme of development. We It can be predicted that the future trend of fillers is functionalization, differentiation, ultra-fine, nano, dust-free, environmental protection and safety, etc.
