Paint the old driver to take you to understand the mystery of paint filler! Get in the car! (II)

Xiaobian explained some fillers for building coatings such as calcium carbonate and talcum powder in the previous article, which was recognized and responded by everyone. At the request of everyone, Xiaobian continued to show you what other fillers are used for building coatings. (want to know more about building coatings with filler friends can look at the small part of the previous article oh!) The filler in

paint is usually white or slightly colored, and the refractive index is less than 1.7. It has the basic physical and chemical properties of pigments for coatings, but because the refractive index is similar to that of film-forming substances, it is transparent in coatings, and does not have the tinting power and hiding ability of coloring pigments. It is an indispensable pigment in coatings.

Silica

Silica has natural and artificial two categories. Due to the different sources of natural products and synthetic products, a series of products have been formed, which have great differences in appearance and performance. In the chemical properties have the characteristics of SiO, the appearance of white powder neutral substance, chemical stability is relatively high, acid and alkali resistance, insoluble in water, high temperature resistance, but there is a great difference in the physical state, generally speaking, natural products coarse particles, low oil absorption, color is not pure enough, white or nearly gray, particles are relatively dense, hard texture, strong wear resistance. Synthetic product particles are generally fine, high oil absorption, color white or slightly blue phase, the particle state can be made quite bulky.

(1) Natural crystalline silica. Natural crystalline silica is natural quartz sand, which is obtained by crushing and winnowing. The appearance is white powder, white color, heat resistance, good chemical stability, good brushing performance and good weather resistance. Powdered quartz sand is also used in large quantities in true stone paint.

Natural Crystalline Type

(2) Natural Diatomaceous Earth. Diatomaceous earth is an amorphous silica containing water. It is the remains of marine life, very rich in resources, due to different sources and manufacturing methods, the quality fluctuates greatly, the appearance is from off-white powder to white powder, its density is very small (2 g/cm), light, coarse and fluffy particles, porous, high oil absorption.

natural diatomite

diatomite as a coating filler, with large porosity, strong absorption, stable chemical properties, wear resistance, heat resistance and other characteristics, in addition to non-combustible, sound insulation, waterproof, light weight and heat insulation and other characteristics, but also to adjust the indoor humidity.

When the humidity in the room rises, the ultrafine pores on the diatomite wall material can automatically absorb the moisture in the air and store it. If the moisture in the indoor air decreases and the humidity drops, the diatomite wall material can release the moisture stored in the ultra-fine pores. Secondly, diatomaceous earth also has the function of eliminating odor because of the multi-void structure, which can keep the room clean.

In addition, if you add anatase nano-titanium dioxide to diatomite to make a composite material, it can eliminate odor and absorb and decompose harmful chemicals for a long time, and can keep the indoor wall clean for a long time.

In addition, it is said that the absorption and release of water by diatomite wall materials can produce ionic effects and decompose water molecules into positive and negative ions. Because of the strong oxidation of positive and negative ions, the coating film also has certain bactericidal ability.

(3) Precipitated Silica. The appearance of precipitated silica is white amorphous (non-crystalline) powder. It is a hydrated silica with hygroscopicity. The product still has a certain amount of free water. It is used as a filler in the coating industry and has good stability. But it is difficult to disperse.

(4) Synthetic fumed silica. Synthetic fumed silica is an extremely pure amorphous silica with a purity of more than 98.8 percent without adsorbing water. The appearance is a white loose powder with blue phase, the particles are extremely fine, the chemical stability is strong, and it is insoluble in all solvents except hydrofluoric acid and strong alkali.

fumed silica, also known as white carbon black, has better performance than general silica, has weak acidity, has a thickening effect, and forms a certain structure under static conditions, thus increasing the viscosity of the system. When subjected to external mechanical forces, the formation of the structure is destroyed, the viscosity of the system is reduced, the use of this performance can make the coating present a moderate thixotropic structure, so that the thicker coating film does not appear sagging phenomenon. In general, 1% ~ 4% fumed silica *** can be added to the coating to obtain suitable thixotropy. The main chemical composition of

wollastonite

wollastonite is calcium metasilicate. Wollastonite is used as a filler in the coating industry, and can increase the bright tone of white paint. It can replace part of titanium dioxide without reducing the whiteness and hiding power of the paint, and can maintain this tone for a long time. Wollastonite has low oil absorption and high filling volume, which can reduce coating cost. Wollastonite can also improve the leveling of coatings, but also as a good suspension agent for coatings.

mica powder

mica is a complex silicate, belongs to the flaky filler, glass luster. The composition of mica is very complex, because it contains various metal salts, so it has different luster.

mica powder is natural mica after dry or wet grinding, remove impurities, by grading filtration, drying. The horizontal arrangement of

mica powder in the coating can prevent ultraviolet radiation and protect the coating film, improve the light stability of the whole system, and prevent moisture penetration. Mica powder has excellent heat resistance, acid resistance, alkali resistance and electrical insulation, improve the mechanical strength of the coating, powder resistance, durability.