Yuan Lei tells you what you must know about inorganic mineral fillers for plastics.

Release time:

2024-01-29 09:38


Yuan Lei tells you what you must know about inorganic mineral fillers for plastics.


plastic filling modificationRefers to the addition of non-metallic minerals, organic materials, metal powders and other fillers in pure resin to improve the various properties of plastic resins to achieve the required technical indicators or improve cost performance.



1. Definition of filler


ASTM (American Society for Testing and Materials) defines fillers as more inert substances added to plastics to improve strength and various properties, or to reduce costs. Therefore, plastic fillers are often selected.non-metallic mineral.


As the name implies, plastic with non-metallic mineral filler can usually be considered to exist in nature by artificial mining, processing and utilization of non-metallic mineral materials with the above defined properties and added to the plastic, usually made into powder.



2. Basic properties of filler


  • Maintain the stability of chemical properties and physical forms during the processing and use of plastics;

  • Improve some properties of the resin: improve rigidity, improve heat resistance, improve electrical insulation;

  • Improve weather resistance and increase dimensional stability;

  • Tinting strength, thermal conductivity, electrical conductivity, flame retardancy;

  • The price is low.



3. Basic requirements of packing


  • Stable chemical properties, high relative purity, low impurity content;

  • The color is white or light as far as possible, and does not contain impurities such as iron that are easy to heat and turn yellow;

  • No serious damage to the physical and chemical performance indicators of plastic products;

  • Easy to disperse and mix, appropriate particle size;

  • The oil absorption value is relatively low, which has no great influence on the processability;

  • have suitable crystal structure;

  • have a lower Mohs hardness;

  • There is a relatively cheap price compared to resin.



4. Classification of filler


According to its shape is divided into powder, spherical, flake, columnar, needle and fibrous filler.


The fillers used in plastics are classified according to their chemical composition as follows:


Oxides:Silica, diatomaceous earth, alumina, titanium dioxide, iron oxide, zinc oxide, magnesium oxide, antimony trioxide, barium ferrate, strontium ferrate, beryllium oxide, alumina fibers.


Hydroxide:Aluminum hydroxide, magnesium hydroxide, salt-based magnesium carbonate.


Carbonate:Calcium carbonate, magnesium carbonate, dolomite, basic aluminum carbonate.


(Sub) Sulphates:Barium sulfate, calcium sulfate, ammonium sulfate, calcium sulfite.


Silicate:Talc, clay, mica, asbestos, calcium silicate, montmorillonite, bentonite, glass beads, glass fiber.


Carbon:Carbon black, graphite, carbon hollow spheres, carbon fiber.


Other:Zinc borate, calcium borate, sodium borate, barium metaborate, potassium titanate.


5. The functionality of the filler


The functionality of the filler refers to the addition of filler, so that polymer building materials can obtain previous performance or strengthen and change some properties, such as electrical properties, barrier properties, optical properties, combustion properties, etc:


(1) Dewetting functional filler: magnesium oxide, alumina;


(2) flame retardant functional fillers: magnesium hydroxide, aluminum hydroxide, zinc carbonate, antimony trioxide, molybdenum disulfide, etc;


(3) anti ultraviolet linear filler; carbon black, titanium dioxide, zinc oxide, iron oxide, etc;


(4) Electromagnetic wave absorbing filler: charcoal powder, graphite powder, ferrite, etc;


(5) light reflective filler: titanium dioxide, zinc oxide, iron oxide, carbon black, etc;


(6) Lubricity filler: graphite, molybdenum disulfide, flower stone powder, glass beads, boron nitride, PTFE powder, etc;


(7) conductive filler: all kinds of metal powder, carbon black, part of the metal oxide powder


(8) Thermal conductive filler: various metal powders, fibers, alumina, aluminum nitride, boron nitride, beryllium oxide, etc;


(9) magnetic filler: iron oxide powder and other magnetic powder;


(10) sound insulation filler: aluminum powder, iron powder, wood powder, hollow glass beads, barium sulfate, calcium sulfate, etc;


(11) wear resistance filler: carbon fiber, graphite, molybdenum disulfide, chromium oxide, quartz powder;


(12) Impact modified filler: glass fiber and various fibers, ultra-fine powder;


(13) heat-resistant filler: rare earth tailings, mineral wool,


(14) Shear-resistant modified filler: aluminum oxide


(15) acid modified filler: barium sulfate, calcium sulfate



6, the effect of filler on the performance of the product law.


  • The specific gravity increases as the amount of filler added increases.

  • The surface hardness increases with the addition of filler.

  • The rigidity increases with the addition of filler.

  • The bending strength decreases with the increase of the amount of filler.

  • The elongation at break decreases with the addition of filler.

  • The surface gloss decreases as the amount of filler added increases.

  • The impact strength generally decreases with the increase of the amount of filler;

  • If the filler is needle-like and fibrous, it is generally reinforced.

  • The temperature resistance increases with the addition of filler.



7, the actual application requirements of the characteristics of the filler


  • Particle size and particle size distribution.

  • Crystal structure.

  • Oil absorption.

  • Dispersion.

  • Viscosity characteristics.

  • Rigidity and hardness.

  • Electrical performance.


(1) The product has high chemical stability, good heat resistance, does not decompose at the processing temperature, and does not affect the original physical and mechanical properties of the plastic resin. The whitening phenomenon caused by bending and stretching of the product after the addition of the example is small.


(2) No chemical reaction occurs after the product is mixed with other processing aids.


(3) The product has good dispersion and mixing in the plastic resin, does not affect the processing performance, and has little wear on the equipment.


(4) product oil absorption and absorption of plastic resin amount is small.


(5) The product does not contain impurities that promote the accelerated decomposition of the resin.


(6) products do not dissolve in water, grease, all solvents, do not absorb moisture, do not contain crystal water (except flame retardant), acid and alkali resistance.


(7) The appearance of the filler powder of the product is uniform in color and uniform in particle size.


(8) The product is cheap and the source is rich and stable, and the quality fluctuation between different batches of fillers is small.



8. Several common nano-mineral fillers


(1) Nano-montmorillonite (MMT)


Montmorillonite is a natural mineral material that can be used for barrier modification of plastics. Montmorillonite has hydrophilic and oleophobic properties, and has poor compatibility with most resins. To form a good composite material with resin, it must be modified by hydrophobic and lipophilic to improve the compatibility with resin.


The good intercalation properties of montmorillonite can be used to intercalate long-chain organic compounds, greatly improve the compatibility with various types of resins, manufacture a variety of nano-plastic filling materials, and improve the tensile strength, bending strength, bending modulus and impact strength of composite materials, which is the current research focus of nano-materials.


At present, composite materials such as PA6/montmorillonite, PET/montmorillonite, PMMA/montmorillonite, PI/montmorillonite, EP/montmorillonite, PS/montmorillonite have been successfully developed.


(2) Nano-attapulgite clay (AT or ATP)


Attapulgite clay is a kind of hydrated magnesium aluminum silicate non-metallic mineral, which has a crystal chain layered structure, but it is obviously different from the layered structure of montmorillonite. Attapulgite is a kind of natural fibrous crystal structure of water-rich magnesium aluminum silicate ore.


Because nano-scale crystal rods are easy to aggregate, the mixing of attapulgite and polymer can only be micron-scale mixing, which plays the role of incremental filling. A large number of silicon hydroxyl groups on the surface of attapulgite have poor compatibility with non-polar polymers, and surface treatment should be carried out before filling. At present, the application of attapulgite in plastics is mainly concentrated in PET and PA nucleating agents and thermal insulation materials.


(3) Nano-Illite


Illite is a potassium containing aluminum silicate mica clay mineral, also known as "water muscovite". The composition of illite is more complex, and its specific composition changes in a certain range, so its application is limited.


As a flaky reinforcing filler, Yili stone powder has both incremental and modified effects. In PVC, for example, when the amount is about 3 parts, the tensile strength and impact strength reach the maximum, while the bending strength, bending modulus and heat distortion temperature increase slowly before 10 parts. While strengthening and toughening, illite can improve the dimensional stability, creep resistance, gas barrier, insulation and warpage prevention of plastics.


(4) Nano-sepiolite


Sepiolite is a hydrous magnesium silicate with a transition structure of chain and layered fibers, belonging to 2:1 layer chain structure clay.


Sepiolite as an acicular reinforcing filler has both incremental and modified effects, which is similar to illite. In PVC filling, for example, the addition of about 3 parts, tensile strength, impact strength reached the maximum, bending strength decreased, while the bending modulus and heat distortion temperature in 10 parts before the slow increase, especially the bending modulus increased faster.


(5) Nano opal


Opal, also known as opal, is an aqueous amorphous or colloidal active silica. The appearance of opal is a dense glass-like block body, the color is white, gray and light blue porous, the relative density is 2.07, belongs to the relatively light inorganic filling material.


Opal filling in polyethylene has obvious rigidity and toughness modification. For example, when 3000 mesh opal treated with titanate coupling agent is added to HDPE by 30%, the tensile strength is basically the same, while the impact strength is increased by 160. Adding ABS can also significantly improve the impact strength.


(6) Nano calcium carbonate


Nano-calcium carbonate is a kind of light calcium carbonate, which is obtained by controlling the carbonization process conditions and adding crystallization-directing agent in the process of carbonization of light calcium carbonate. The use of different shapes of nano calcium carbonate is different. Needle-like and chain-like nano calcium carbonate can achieve the purpose of reinforcement, spherical nano calcium carbonate can achieve the purpose of toughening, hollow spherical nano calcium carbonate can achieve the purpose of lightweight filling, flake nano calcium carbonate can improve the barrier property of composite materials, and can also use its high hiding power to replace part of titanium dioxide.


(7) Nano-silica


Nanometer silica is fumed silica, which is one of the most important high-tech ultra-fine inorganic new materials. Due to its small particle size, it has large specific surface area, strong surface adsorption, large surface energy, high chemical purity, good dispersion performance and excellent performance in thermal resistance and resistance. With its superior stability, reinforcement, thickening and thixotropy, it has unique characteristics in many disciplines and fields, it has an irreplaceable role.


In plastics, silica is a filler with reinforcing effect second only to carbon black. It is often used to form composite plastics with plastics, with an addition of 3% to 5%, and can improve the performance of composite plastics. In particular, silica filled with silica is a typical reinforced composite material. In the PP/silica composite system, the impact strength can reach 3.7kJ/m2. The impact strength of PP/silica composites can reach 45.7kJ/m by micro-foaming2.










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