Want to sell a good price? Learn about talc modification
Talc is a layered hydrous magnesium silicate with a hydrophilic group on its surface and a high surface energy. It has a large chemical structure and physical form between the inorganic filler and the organic polymer molecular material. The difference, lack of affinity, makes the talc powder and polymer mixed unevenly, weak adhesion, resulting in reduced mechanical properties of the product. To this end, the talc must be surface modified.
The mechanism of surface modification of talc powder is to modify the surface of one or both of the composite materials by using some small molecules or polymer compounds with amphoteric groups to change the surface from hydrophobic to hydrophilic. The purpose is to make the two substances better combined.
1. Surface Covering Modification Surface coating modification method is to cover the surface of the particles with a surfactant or a coupling agent, so that the surfactant or coupling agent is combined with the surface of the particles by adsorption or chemical bonding, so that the surface of the particles is pro- The water becomes hydrophobic, giving the particles new properties and improving the compatibility of the particles with the polymer. This method is currently the most commonly used method. It can be roughly understood as: for the disadvantage that the talc powder has low affinity with the polymer, the surfactant with the amphiphilic group covers the particles, the hydrophilic group faces the particle surface, and the lipophilic group faces outward, so that the polymer When combined, it has good compatibility, achieves the purpose of modification, and expands the application range of talc. For example, the addition of silane coupling agent-modified talc powder can significantly improve the mechanical properties of the matrix. As the amount of talc powder and polypropylene increase, the bending properties of the material increase. When the polypropylene content in the matrix is ​​50%, the resistance is The tensile strength is essentially unaffected by the filler content.
2. Mechanochemical method Mechanochemical method is to make larger particles smaller by pulverization, friction, etc., so that the surface activity of the particles becomes larger, that is, the surface adsorption capacity is enhanced, the process is simplified, and the cost can be reduced. It is easier to control the quality of the product. Ultra-fine pulverization is an important means of deep processing of materials, and its main purpose is to provide high-performance powder products for modern industry. This process is not a simple material particle size reduction, it contains many complex powder material properties and structural changes, mechanochemical changes. Studies have shown that: after superfine pulverization of talc powder by stirring mill, the surface activity is enhanced, the thermal effect is improved, the whiteness is improved, and the change of powder properties is closely related to the thermodynamic properties of the ultrafine pulverization process.
3. Outer film layer modification The outer film layer modification is to uniformly coat a layer of polymer on the surface of the particles, thereby imparting new properties to the surface of the particles. Zuo Jianhua et al. used TDI (toluene diisocyanate) and HPA to surface-treat the inorganic talc powder. Compared with the conventional talc powder filler, the maximum tensile strength of the coated talc powder after filling the polymer material The impact strength is obviously improved, and the improvement rate is 136% and 162%, respectively, which can be used as a new strong filling modifier for PVC cable materials.
4. Locally active modified local active modification The chemical reaction is used to graft some polymer-compatible groups or functional groups on the surface of the particles to make the inorganic particles have better compatibility with the polymer, thereby achieving inorganic particles. The purpose of compounding with a polymer. For example, the ACP-active calcium carbonate of the Japanese tri-powder fine powder is obtained by surface grafting of calcium carbonate adsorbed with an acrylic monomer under the action of a force chemistry.
5. High-energy surface modification High-energy surface modification utilizes the huge energy generated by high-energy discharge, plasma ray, ultraviolet light, etc. to modify the surface of the particles, making the surface active and improving the compatibility of the particles with the polymer. 6. Precipitation reaction modification The precipitation reaction modification is modified by precipitation reaction. This method uses the precipitation effect to coat the surface of the particles to achieve the modification effect.
As people's understanding of the characteristics of talc powder gradually deepens, the application of talc in the coatings, plastics and other industries will continue to expand. Since the production capacity of modified high-grade talcum powder is far less than the demand of domestic and foreign markets, the rational modification of talc powder has been paid more and more attention. Therefore, while we are familiar with the various physical and chemical properties of talcum powder and its application characteristics in various industries, we must continue to summarize in the experimental and production applications, continue to explore and innovate, and use the current high-tech means to expand the deep processing of low- and medium-end products, and develop high. Added value talc products.
The mechanism of surface modification of talc powder is to modify the surface of one or both of the composite materials by using some small molecules or polymer compounds with amphoteric groups to change the surface from hydrophobic to hydrophilic. The purpose is to make the two substances better combined.
1. Surface Covering Modification Surface coating modification method is to cover the surface of the particles with a surfactant or a coupling agent, so that the surfactant or coupling agent is combined with the surface of the particles by adsorption or chemical bonding, so that the surface of the particles is pro- The water becomes hydrophobic, giving the particles new properties and improving the compatibility of the particles with the polymer. This method is currently the most commonly used method. It can be roughly understood as: for the disadvantage that the talc powder has low affinity with the polymer, the surfactant with the amphiphilic group covers the particles, the hydrophilic group faces the particle surface, and the lipophilic group faces outward, so that the polymer When combined, it has good compatibility, achieves the purpose of modification, and expands the application range of talc. For example, the addition of silane coupling agent-modified talc powder can significantly improve the mechanical properties of the matrix. As the amount of talc powder and polypropylene increase, the bending properties of the material increase. When the polypropylene content in the matrix is ​​50%, the resistance is The tensile strength is essentially unaffected by the filler content.
2. Mechanochemical method Mechanochemical method is to make larger particles smaller by pulverization, friction, etc., so that the surface activity of the particles becomes larger, that is, the surface adsorption capacity is enhanced, the process is simplified, and the cost can be reduced. It is easier to control the quality of the product. Ultra-fine pulverization is an important means of deep processing of materials, and its main purpose is to provide high-performance powder products for modern industry. This process is not a simple material particle size reduction, it contains many complex powder material properties and structural changes, mechanochemical changes. Studies have shown that: after superfine pulverization of talc powder by stirring mill, the surface activity is enhanced, the thermal effect is improved, the whiteness is improved, and the change of powder properties is closely related to the thermodynamic properties of the ultrafine pulverization process.
3. Outer film layer modification The outer film layer modification is to uniformly coat a layer of polymer on the surface of the particles, thereby imparting new properties to the surface of the particles. Zuo Jianhua et al. used TDI (toluene diisocyanate) and HPA to surface-treat the inorganic talc powder. Compared with the conventional talc powder filler, the maximum tensile strength of the coated talc powder after filling the polymer material The impact strength is obviously improved, and the improvement rate is 136% and 162%, respectively, which can be used as a new strong filling modifier for PVC cable materials.
4. Locally active modified local active modification The chemical reaction is used to graft some polymer-compatible groups or functional groups on the surface of the particles to make the inorganic particles have better compatibility with the polymer, thereby achieving inorganic particles. The purpose of compounding with a polymer. For example, the ACP-active calcium carbonate of the Japanese tri-powder fine powder is obtained by surface grafting of calcium carbonate adsorbed with an acrylic monomer under the action of a force chemistry.
5. High-energy surface modification High-energy surface modification utilizes the huge energy generated by high-energy discharge, plasma ray, ultraviolet light, etc. to modify the surface of the particles, making the surface active and improving the compatibility of the particles with the polymer. 6. Precipitation reaction modification The precipitation reaction modification is modified by precipitation reaction. This method uses the precipitation effect to coat the surface of the particles to achieve the modification effect.
As people's understanding of the characteristics of talc powder gradually deepens, the application of talc in the coatings, plastics and other industries will continue to expand. Since the production capacity of modified high-grade talcum powder is far less than the demand of domestic and foreign markets, the rational modification of talc powder has been paid more and more attention. Therefore, while we are familiar with the various physical and chemical properties of talcum powder and its application characteristics in various industries, we must continue to summarize in the experimental and production applications, continue to explore and innovate, and use the current high-tech means to expand the deep processing of low- and medium-end products, and develop high. Added value talc products.
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