Kaolin Magic: Transforming Industries with Precision

The four major areas of application of calcined kaolin are papermaking, paints and coatings, rubber, and plastics. Ultra-fine, high-white, high-quality calcined kaolin accounts for 60% in the paint and coating field, 20% in the paper industry, and 20% in rubber, plastics, medicine, and other fields.

Paper industry

Calcined kaolin ink has good absorbency and a high covering rate. It can partially replace expensive titanium dioxide and is especially suitable for use with high-speed blade coaters. Calcined kaolin as a filler can also improve the writing and printing properties of the paper, increase the evenness, smoothness, and gloss of the paper, improve the opacity, air permeability, flexibility, printability, and writing of the paper, and reduce the cost.

Paint industry

The use of calcined kaolin in the coating industry can reduce the amount of titanium dioxide, give the coating film good properties, and improve the processing, storage, and application performance of the coating. The dosage of calcined kaolin in mid-to-high-end coatings is 10 to 30%, and the calcined kaolin used is mainly -2um with a content of 70 to 90%. This article discusses the application of latex paint and automotive paint with everyone.


The performance of coatings and films obtained by adding this finely calcined kaolin to latex paint will make us feel that kaolin is not just an ordinary filler, it can become a functional filler to improve the quality of the paint. 1. Due to the high refractive index of the hexagonal crystal structure, the contrast ratio (hiding power) of the coating is greatly improved and excellent color ductility is provided. 2. Excellent suspension, moisture absorption, and impact resistance. 3. The flat nature of kaolin provides a good balance between paint flow and leveling properties. Flat particles also tend to be arranged parallel to the surface of the paint film, which can effectively prevent the penetration of water and improve the wash resistance and pollution resistance of the paint film. For sticky paint films, flat particles can improve the pressure resistance and viscosity of the paint. 4. Calcined kaolin is hydrophilic, so it is easy to disperse and has small particle bulk density and good suspension performance. 5. It has a narrow distribution range of colloidal particles, which tends to keep the viscosity of the paint unchanged and can provide the required rheology and thixotropy (high shear and high flow and low shear and low flow), so the coating film is relatively plump. And it can improve the problems of floating color and blooming of pigments. 6. Strong chemical inertness, small optical axis angle of the crystal, and a high degree of crystal arrangement order will significantly increase the coating’s ability to shield against ultraviolet rays.

First, let’s give a brief introduction to the latex paint commonly used in homes. Latex paint has the following advantages:

• Latex paint does not pollute the environment, is safe, non-toxic, and has no fire hazard.

• Latex paint is easy to apply and can be applied by brush, roller, or spray. Latex paint application tools can be washed with water.

• The latex paint film dries quickly. After the latex paint is applied, the water will basically evaporate and the film will form. It can be painted 2 to 3 times a day, shortening the construction period.

• The latex paint coating has good air permeability, so it can avoid bubbling caused by the difference in humidity between the inside and outside of the coating film. It is very suitable for painting new walls that are not yet dry.

Let’s have a brief understanding of the formula of exterior wall latex paint:

The total amount of pigments and fillers in the formula ranges from 20% to 45%. High PVC exterior wall latex paint generally does not use light calcium carbonate and talc powder. 8% uses rutile titanium dioxide, 10% calcined kaolin, 15% wollastonite powder, 12% % heavy calcium powder, low PVC exterior wall 17% rutile titanium dioxide, 5% mica powder, 5% calcined kaolin, 10% wollastonite powder.


The performance of coatings and films obtained by adding this finely calcined kaolin to latex paints for automobiles will make us feel that kaolin is not just an ordinary filler, it can become a functional filler to improve the quality of the paint. Car paint is roughly divided into three categories:

1. Ordinary paint

Ordinary paint is the most common type, and it is the most basic car paint. It is a very single color. White is white, red is red, and the same is true for other single colors. There is no excess or doping with other colors. Ordinary paint looks the same. Compared with metallic paint and pearlescent paint, the cost is lower, but the color will be relatively monotonous. Under the sunlight, it will not emit the luster of metal or chip-like metallic paint or pearlescent paint, but will always remain unchanged, which can be understood as relatively low-key.

2. Pearlescent paint

Pearlescent paint also called mica paint, is also a popular car topcoat. In its paint base, mica pigments coated with titanium dioxide and iron oxide are added. After the light hits the mica particles, it first brings titanium dioxide and oxidized iron. The color of the iron then undergoes complex refraction and interference in the mica particles.

At the same time, mica itself also has a special, transparent color, so that the reflected light has a pearl-like sparkle. At the same time, titanium dioxide itself has a yellow color, which changes to light blue when you squint. Viewed from different angles, it has different colors. Therefore, pearlescent paint gives people a novel, colorful, and dazzling feeling.

3. Metallic paint

“Metallic paint” is a direct translation of the original text “Metallic Paint” because this kind of paint is mixed with metal powder. At different angles, due to the refraction of light, the color and even the outline of the car will change. In addition to its high hardness, metallic paint can also express the beauty of the car body. Another reason why “metallic paint” is becoming more and more common is that it is mixed with metal powder. With the metal component, the hardness of the paint increases and the paint surface becomes hard, making it less likely to be scratched.


Plastic industry

In engineering plastics and general plastics, the filling amount of calcined kaolin is 20 to 40%, used as a filler and reinforcing agent. Calcined kaolin is used in polyvinyl chloride cables to improve the electrical properties of plastics.

As a plastic filler, kaolin can make plastic products smooth in appearance, precise in size, resistant to chemical corrosion, reduce thermal shrinkage and thermal fission, and facilitate the polishing and grinding process.

There are a large number of hydroxyl groups in kaolin, which is very polar. When kaolin is calcined, the dehydration of the hydroxyl groups reduces the polarity of the surface. It is used in plastics and rubber and has good compatibility with plastics and rubber. The main raw material for papermaking is cellulose, which also contains a large number of hydroxyl groups. Using water-washed kaolin clay, the hydroxyl groups of kaolin clay and the hydroxyl groups of cellulose can form a large number of hydrogen bonds, making kaolin and cellulose more capable of binding, thus improving the performance of paper. In addition, calcination requires a large amount of energy, and even if it can be used, it is not cost-effective.

Engineering plastic classification

1. Liquid crystal polyester (LCP)Products: quick connectors, coils, switches, sockets, pump parts, valve parts, automotive fuel peripheral parts, and containers for electronic stoves.

2. Modified polyoxyethylene resin (MPPO)Products: connectors, switches, timer housings, spool breakers, cameras, rectifier housings, instrument panels, sight glass housings, rear windshields, machine housings, motor covers, water meters, etc.

3. Polyamide (PA, nylon)Products include electronic and electrical connectors, reels, timers, cover circuit breakers, switch housings, automotive cooling fans, door handles, fuel tank caps, air intake grilles, water tank covers, lamp holders, industrial parts chair seats, Skate bases, textile shuttle, pedals, skates.

4. Polyamide-imide (PAI)Products include sockets, connectors, switch parts, IC circuit boards, electric heater parts, automobile exhaust and turbine parts.

5. Saturated polyester butyl terephthalate (PBT)Products include fusible breakers, electromagnetic switches, flyback transformers, home appliance handles, connectors, casings, car door handles, bumpers, distributor covers, fenders, wire shields, rim covers, and industrial parts OA fans, keyboards, fishing reels, parts, lampshades.

6. Polycarbonate (PC)Products include electronic and electrical CDs, switches, home appliance casings, signal tubes, telephones, car bumpers, distribution boards, safety glass, camera bodies, machine shells, safety helmets, diving goggles, and safety lenses.

7. Polyethylene terephthalate (PCT)Products include electronic connectors, switches, coil frames, automotive relays, and connectors.

8. Polyether copper (PEEK)Products include wire coverings, clutch parts, copier parts, high-temperature connectors, and flexible printed circuit boards.

9. Polyetherimide (PEI)Products include automobile chassis, electrical parts, heat exchange parts, various fuses, connectors, flex tubes, seat trays, seat belt buckles, engine parts, medical instruments, and printed circuit boards.

10. Polyether styrene (PES)Products include potentiometers, sockets for integrated circuits, X-ray mirrors in the medical and food fields, and dental machine parts.

11. Saturated polyester ethyl terephthalate (PET)Products include breakers, rectifiers, spools, hair dryer air vents, spool lampshades, automotive electrical components, fenders, brake handles, and industrial cooling fan handles.

12. Polyurethane (PFS)Connectors, switches, automotive aviation fuses, special battery boxes, precision machine watch cases, clock internal parts, medical inhalers, sprayers, and contact lens sterilization boxes.

13. Polyimide (PI)Applications: Multi-layer circuit substrates, flexible circuit boards, engine-insulated wire materials, copy machine separation claws, heat-insulating gears, missile radar radomes, and heated roller bearings.

14. Polyacetal (POM)Products include washing machines, juice machine parts, timer components, car handlebar parts, electric window parts, industrial machinery parts, gears, handles, toys, and screws.

15. Polyxylene sulfide (PPS)Products: connectors, coil bobbins, industrial product cases, washing tools, computer and OA parts, various automotive sensors, carburetors, and electronic control parts.

General plastic classification

1. Polyethylene (PE)Usually used to make food bags and various containers

2. Polypropylene (PP)Mostly used for tableware

3. Polyvinyl chloride (PVC)Water pipes, hoses, casings, plates

4. Polystyrene (PS)Used to make lampshades, toothbrush handles, toys, and electrical components

5. ABSCan be used to make piano keys, buttons, knife holders, TV casings, and umbrella handles

Rubber Industry

The rubber industry uses a large amount of kaolin, and the filling ratio in rubber ranges from 15 to 20%. Calcined kaolin (including surface modification) can replace carbon black and white carbon black to produce light-colored rubber products, tires, etc.

Filling the colloidal mixture with calcined kaolin can enhance the wear resistance, chemical stability, and mechanical strength of the rubber, prolong its hardening time, adjust the mixing properties, rheology, and vulcanization properties of the rubber, and improve the viscosity of unvulcanized products. degree to prevent them from collapsing, denting, sagging, flattening, deformation, etc. The permeability, waterproofness, chemical activity, fire resistance, and other properties of rubber products have also been greatly improved accordingly. At the same time, kaolin as a filler can also reduce the amount of other raw materials used in rubber, greatly reducing the production cost of rubber without significantly affecting the performance of the rubber.


Rubber products

1. Latex products – sponges, injection molded products;

2. Daily document supplies: rubber shoes, rubber balls, erasing erasers, and rubber cords;

3. Medical and health products – various catheters, protective equipment, medical packaging accessories, human medical rubber products;

4. Tires – non-motor vehicle tires, motor vehicle tires, special tires (such as car tires, engineering tires, aircraft tires, etc.);

5. Extruded products-hose, door, and window seals, and various rubber profiles;

6. Hard rubber products – electrical insulation products, chemical anti-corrosion linings, microporous hard rubber;

7. Rubber insulation products and cables;

8. Tape products – daily protective tape products, industrial tape products, oil tanks, life-saving products;

9. Tape-conveyor belt, conveyor belt;

10. Model products-rubber seals and shock-absorbing parts;

11. Cots – printing and dyeing cots, printing cots, papermaking cots.

It can be seen from this that the dazzling array of products in society is inseparable from the filling of non-mineral powders. Mastering the basic properties and application fields of non-mineral powders will help practitioners in the non-mineral field consolidate their skills, open up the sales market, and thereby contribute to society. Pengfeng provides you with Calcined Kaolin, a raw material used in copper paper, coatings, latex paints, automotive paints, inks, engineering plastics, general plastics, and rubber industries.

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