Yuan Lei tells you about the selection of fillers for plastic products.

Release time:

2024-01-29 09:38


Yuan Lei tells you about the selection of fillers for plastic products.


Fillers are also known as fillers, and their main purpose is to reduce the cost of plastic products.Other positive effects include improving the heat resistance, rigidity, hardness, dimensional stability, creep resistance, wear resistance, flame retardancy, smoke suppression and biodegradability of the products, and reducing the molding shrinkage to improve the accuracy of the products;Side effects have led to a decline in some of the properties of the product or even a significant decline, the most obvious decline in performance impact, tensile strength, processing fluidity, transparency and product surface gloss.

Fillers can be divided into two categories: inorganic fillers and organic fillers.

(1) Mineral filler


Calcium carbonate


It has the advantages of low price, wide source, non-toxic and tasteless, white color and easy to color, low hardness, easy to dry, high chemical stability, etc. It has become the largest and most widely used first class of fillers.


Depending on the density or source, calcium carbonate can be divided into two categories: heavy and light. Heavy calcium carbonate with natural calcite grinding and grinding, light calcium carbonate with limestone as raw material by calcination and other chemical processes. Heavy calcium carbonate is mainly used in PP plastic woven bags, woven cloth, packing belt (20-40 parts),PVC floor (150 parts), floor leather (30-40 parts), shutters (100 parts), wall panels (200 parts),LDPE garbage bags (30%), etc. Light calcium carbonate is mainly used in PVC artificial leather (10-20 parts), pipes and profiles (5-10 parts),PE corrugated boxes (100 copies), etc.


Talcum powder


The composition of talcum powder is 3MgO · 4SiO2 · H2O, the structure is similar to mica, and it has a flaky structure. The appearance is white or light yellow fine powder, soft and smooth, which is conducive to the rigidity and heat resistance of composite materials, with low hardness, certain lubricity and light wear on equipment. It is the second largest filler after calcium carbonate. Varieties.

Because of the flake structure, the reinforcing effect of talc powder is greater than that of calcium carbonate, but when the filling amount is large, it affects the welding performance of the product. Talc powder has a blocking effect on infrared rays with a wavelength of 7 ~ 25um, and can be used for night heat preservation in agricultural greenhouses. Talc powder can be used as a nucleating agent for PP, and can also be used as a slip agent for PO films.


Talcum powder is the most widely used in PP modification, and is generally compounded with elastomer materials to increase rigidity while toughening.




There are many types of mica, and its industrial fragments can be used for plastic fillers by dry or wet crushing. The crystal form of mica is flaky, and its thickness-diameter ratio is large. If this thickness-diameter ratio can be maintained in the filling, the reinforcing effect is remarkable, so it is called reinforcing filler.

Another feature of mica is that it has a blocking effect on infrared rays with a wavelength of 7 ~ 25um, and its effect is better than talcum powder and kaolin with similar functions, and its sunlight transmittance is higher than other filling materials, which is most suitable for daytime warming and night moisturizing in agricultural greenhouses. The surface energy of mica particles is high, and it is not easy to realize coating and coupling treatment, so the dosage has been low, and it is only used for reinforcement or film insulation.


Mica is commonly used in PVC, PP, PE, ABS and PA, and the addition amount is 10% ~ 40%.




Kaolin is a kind of clay, also known as clay. The bound water contained in itself can be removed at high temperature, but it is easy to adsorb water in the air, so the kaolin used as a filler should pay special attention to the influence of moisture.


Ordinary kaolin. One is to use calcined kaolin to improve the insulation of plastics. Adding 10% calcined kaolin to PVC can improve the electrical insulation by 5 to 10 times. The second is to use it to have the same as talcum powder and mica to have a blocking effect on infrared rays with a wavelength of 7 ~ 25um, which is used for agricultural greenhouse film thermos bottle agent. In addition, kaolin can also be used as a nucleating agent for PP.


barium sulfate


The surface gloss of barium sulfate filled composite materials is higher than other filling materials, and the application range is not wide, and it is mainly used in several special fields. One is to use its high density, manufacturing high-density plastic products such as speakers and fishing net pendants, etc.; the second is to use it to absorb X-rays and Y-rays, making radiation-proof plastic products; the third is used for sound-absorbing and heat-conducting filling materials.


glass microbeads


There are two types of glass beads, one is extracted from fly ash, the natural color is slightly gray, the sink bead is solid core, and the floating bead is hollow core; The second is extracted from fly ash, the natural color is slightly gray, the sink bead is solid core, and the floating bead is hollow core. The second is artificial synthesis, all hollow core, itself white. Glass beads can be a typical lightweight filler with a smooth surface, spherical, hollow structure. Glass beads can be added to PP, PS, ABS, PE and PA for light filling, heat insulation, sound insulation, shockproof and other modified products, but also for optical products.




Clay is a general term for a class of materials, in addition to the aforementioned kaolin, there are montmorillonite (MMT), attapulgite clay (TA), illite, sepiolite, hydroxyapatite (HA) and so on. These materials are natural nanomaterials and have good use value.


Porous powder quartz


New material: porous powder quartz, can be used as a high-performance filler for all kinds of plastic products.

Porous powder quartz belongs to a volcanic ash sedimentary rock. The natural particle size of the product is fine (about 0.5μm), the particle distribution is uniform, the specific surface area is large (8.3 m2/g), and the shape structure is similar to spherical without angular shape. From the electron microscope image, the surface is full of nano-scale mesopores, and the average pore diameter is about 8.8nm (nanometer).

Porous powder quartz features: porous structure, natural fine particle size, light weight and surface approximate spherical. This makes the polymer composite material has better fluidity, dispersibility and is not easy to precipitate. It has a very wide range of uses in the plastics industry.

Porous powder quartz is a kind of silica system, the safety of use is recognized, has been widely used in the plastic products industry, cheap porous powder quartz can also reduce costs.



(2) Industrial waste residue


fly ash


Fly ash is the waste residue discharged from thermal power plants, which is composed of more than ten components. Among them, silica accounts for about 61%, aluminum oxide accounts for about 21%, and other components include Fe2O3, CaO, MgO, NaO and K2O. The appearance of fly ash is gray, the average particle size is 80um, the relative density is 2.0~2.4. Because the fly ash contains round and smooth glass beads, it is easy to disperse evenly in the resin, and the filling amount can reach about 40%. Mainly used in PVC and PP products such as floor tiles, etc., the surface can be treated with silane coupling agent.


red mud


Red mud, also known as red mud, code RM, is the waste residue discharged from the production of alumina by bauxite alkali method. China's aluminum plants are rich in red mud resources, is a cheap and easy to get filler. The relative density of red mud is 2.7~2.9, the particle size is 20um, which is close to the size of colloid, and its PH = 10~12, which is alkaline.

The composition of red mud is very complex, roughly composed of SiO2, CaO, Fe2O3, Al2O3 and TiO2, etc. The composition of different production methods is also different, of which Bayer red mud is best used as plastic filler. Bayer red mud is fine and soft, which is beneficial to improve the performance of plastic products, followed by sintering red mud, and finally combined red mud. Red mud is easy to absorb water and should be dried before use. The drying conditions are 105 ℃, 3h, and then sintered at a temperature above 1000 ℃ for 1h.


salt mud

The code name of salt mud is SM, which is the waste residue discharged from alkali plant. Its main components are SiO2, CaO, Fe2O3, Al2O3, CaCO3, CaSO4, Mg(OH)2, MgO and NaCl, etc. The appearance of salt mud is gray wet mud, feel smooth, PH value is about 10.

The surface of salt mud needs to be coupled before filling, and the coupling agent is the best choice of titanate NDZ-101. When 40 parts are added to PVC, the tensile strength only decreases by 10%, while the impact strength increases slightly. In addition, salt mud can also improve the oil resistance of PVC, and can reduce the outlet expansion of extrusion molding.

Other industrial waste residues include: iron mud, waste residue from pyrite to sulfuric acid, whose main component is Fe2O3, etc. White mud, waste residue from paper mills; Alkali mud, waste residue from causticization, whose main component is CaCO3, etc. Filter mud, waste residue discharged from sugar mills; In addition, there are peat, etc.


2. Organic filler


Natural fibers


Natural fiber refers to the product of crushing wood, straw, fruit shell and other raw materials, such as all kinds of wood powder, paper powder, corn stalk, wheat straw, rice straw, rice husk, hemp, cotton seed, walnut shell, cotton shell, peanut shell, coconut shell and bagasse. Natural fiber fillers are composed of organic substances such as cellulose, hemicellulose and lignin, and cellulose is the main component. The biggest advantage of natural fiber filler is the reinforcement effect, although not as strong as inorganic fiber and organic synthetic fiber, but far more than ordinary filler. Natural fiber filler contains lignin and has good processing performance. Because it contains cutin, it can improve the gloss of filling products. In the natural fiber filler, wood powder and paper powder are the most commonly used.

Compared with synthetic fibers and glass fibers, the advantages of natural organic fibers:

1, easy to degrade at high temperature, processing temperature should not be higher than 230 ℃, only suitable for low melting point resin;


2. The compatibility with the matrix resin is poor, which affects the processing fluidity.




Starch is a kind of polysaccharide compounds, which widely exists in plants, such as corn, potato, sweet potato, cassava, sugar beet and so on. Starch has the ability of complete biodegradation in various environments, the degradation product is carbon dioxide gas, which does not harm the soil and air, is cheap and renewable, and is rich in resources. Therefore, the degradable plastics with starch as the main raw material are highly valued by people and are currently the research hotspot of natural degradable materials. However, starch itself does not have thermoplastic energy, can not be directly used for degradation materials, and need to be blended with other materials or modified treatment, can be used as degradable plastics.

Starch is a natural polymer material with abundant sources and low price. Native starch consists of two parts, amylose and amylopectin, and the ratio of the two parts varies with plant species. Amylose is soluble in water, while amylopectin is insoluble in water, so the two can be water separated. Amylose is a thermoplastic polymer material, also known as thermoplastic starch, heating can be melted, can be processed by thermoplastic methods; amylopectin is insoluble in water, is a thermosetting polymer material, can not be processed by thermoplastic methods.

Starch has excellent biodegradability and is the preferred degradable filler, especially in recent years, the variety, yield and application of degradable plastics are increasing, and the importance of starch is increasing. Adding starch to biodegradable plastics can not only greatly reduce its cost, but also improve some properties.



Cellulose is one of the natural polymer materials produced in the life activities of plants on the earth. It is the main component of the outer cell wall of plant cells, and it is the largest natural high molecular material on the earth. According to rough statistics, 1000 billion tons of new plants are added every year in the world, of which 80% are cellulose, 15% are lignin and 5% are hemicellulose. Cellulose is the most abundant carbohydrate on the earth, containing 10% to 25% in herbs, 40% to 45% in wood, 60% to 85% in flax and other bast fibers, and 90% in cotton flowers. In short, the straw, leaves, roots and husks of any plant contain a lot of cellulose, and it regenerates year after year, and it will rot naturally if it is not used.

There are usually two ways to obtain cellulose: one is to select plants with extremely high natural cellulose content, such as wood pulp and cotton lint; the other is to extract from wood and other woody plants. To obtain high-purity cellulose, it must be completely delignified Lignin and hemicellulose, but there is no satisfactory method for separating pure cellulose.

The crushing of cellulose can not be used in general crushing equipment, but must be crushed like popcorn by flash explosion, and the particle size can reach about 800 mesh.

The plastic products with good mechanical properties, low price and fast degradation rate are made by blending cellulose derivatives with degradable synthetic resins. The degradation products of cellulose degradable plastics are xylose, xylobiose, right helix glucose, cellobiose, acetaldehyde, acetic acid, carbon dioxide and water vapor, which have no pollution to the environment and belong to the category of green degradable plastics.







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