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Application of modified talcum powder in plastics, coatings and paper making

time:2021/5/19 9:40:05    Views:

Talcum powder is an important inorganic filler material, but the properties of talcum powder are very different from the polymer material, and the lack of affinity makes its use in the polymer material is limited. In order to further improve its function and expand its application field, it is necessary to modify the surface of the powder.


1. Appearance modification method and product characteristics of talc powder.


The commonly used surface modifiers of talc powder mainly include titanate ester, silane and aluminate coupling agent, phosphate ester, surfactant, wax and organic polymer, etc.


(1) titanate coupling agent


Modification method: the dry process is that the talc powder is mixed and dried in a high-speed mixer preheated to 100℃-110℃, and then the modified talc powder can be obtained by evenly mixing with the metered titanate coupling agent (diluted with an appropriate amount of 15# white oil) for several minutes. In the wet process, the titanate coupling agent was diluted with a certain amount of solvent, and then mixed with a certain amount of talc powder at 95℃ for 30min. The modified talc powder was obtained by filtration and drying.


Characteristics: the talc powder filler modified by titanate coupling agent can improve the compatibility with PP, reduce the viscosity of the system, add system fluidity, improve the processing function of the system, reduce deformation, improve the stability of the scale, and expand the scale of PP.


(2) aluminate ester coupling agent


Modification method: an appropriate amount of aluminate ester (such as L2) is dissolved in solvent (such as liquid white wax), 1250 intent fine talcum powder to participate in the drying is ground for 30min modification, and at 100℃ constant temperature for a period of time, the modified product is obtained after cooling.


Usage characteristics: compared with common talc powder, the viscosity of talc powder modified by aluminate ester in liquid white wax is obviously reduced, the water penetration time is increased, and the organic hydrophobic modification effect is obvious. The rubber was filled with talc powder modified by aluminate ester instead of semi-reinforced carbon black, and its mechanical properties such as tensile strength and elongation were improved. Together, there's a lot of substitution. It can achieve the effect of reducing cost and reducing environmental pollution.


(3) Silane coupling agent


Modification method: the silane coupling agent (such as KH-570) was mixed into a solution and mixed evenly. Drop the solution into the dried talcum powder, mix it for 40-60min, make the treating agent fully cover the filler 4, and then heat and dry to prepare the modified talcum powder.


Application characteristics: talcum powder modified by silane coupling agent can be used as the filler of polymer material, which can make the strength and modulus of the filling system have obvious progress, and the modification effect is outstanding, and it has good practical use value.


(4) Phosphate ester


Modification method: first, the talcum powder was mixed at 80℃ and pre-coated in the aqueous solution of phosphate ester for 1h, and then dried at about 95℃. Finally, the temperature was increased to 125℃ and the heat treatment was carried out for 1h. The amount of phosphate ester is 0.5%-8% of talcum powder.


Use characteristics: phosphate ester and talcum powder surface chemical absorption agrees with the physical adsorption reaction to form the surface coating, adding the amount of external coating can improve the talcum powder slacking situation, can significantly change the shape of the filling system and mechanical function.


2. Application field of modified talc powder


(1) Plastics


Talc powder can be widely used in PP, PE, PS, PA, ABS, PC, PVC and other products. Talc powder filled plastic, can improve the rigidity of the product, scale stability, lubricity, can prevent high temperature creep, reduce the wear of molding machinery, can make the polymer after filling progress hardness and creep resistance together with the impact strength is basically unchanged. If properly handled, it can make the polymer heat-resistant impact strength progress, can improve the plastic forming shrinkage, flexural elastic modulus of products and tensile yield strength. The low price of talc powder makes it suitable for use as an additive (the price of the compound is low and the physical function of the resin is minimized), together, the flake structure or high aspect ratio of talc powder makes it suitable for use as an enhancer (to improve the mechanical function of the compound).


For example, talcum powder filled PP, widely used in car bumper, engine parts, air conditioning parts, instrument panel, lights, chassis, pedals and other parts; The winding modulus of ABS and nylon can be improved by filling ABS and nylon with talcum powder. PVC floor tiles with good functions can be produced by filling PVC with talcum powder with higher fiber content.


(2) coating


Talc powder has excellent suspension and easy to scatter, and low abrasion, as a coating filler, chip particle structure of talc powder can make the film has a high water resistance and enamel impermeability, mainly used in primer and intermediate coating; The talcum powder with fibrous particle structure, because of its high oil absorption capacity and outstanding rheological properties, makes the storage stability of the coating improved. And can make the coating rheological and leveling property is very good improvement, together can improve the coating weather resistance.


When the film is completely dried, talcum powder has higher impact strength and fracture toughness due to its higher aspect ratio. The effect of talcum powder in the dry film is similar to that in the polymer composite.


(3) papermaking


Talcum powder has unique properties such as layered structure, softness and hydrophobicity. It has obvious advantages when used in the paper making industry:


It is helpful to improve the retention rate of the filler and improve the opacity, smoothness and printability of the paper, giving the paper a higher ink absorption;


The chemical properties are stable, not only suitable for making paper under acidic conditions, but also can be used with calcium carbonate in neutral conditions.


The appearance is hydrophobic, organic matter is simply adsorbed on the layered appearance of talc, which reduces the cost of dye and effectively saves the cost. In addition, the lipophilicity makes it can be used as resin, adhesive inhibitor and waste paper deinking agent.


Can be combined with the sizing agent outstanding and improve the sizing agent retained, and can reduce the absorbability of the page, prevent printing ink penetration of the page;


Talc powder has a low conflict factor, can make the coating surface smooth and smooth, can reduce the fracture of the coating, reduce the printing pressure, etc.;


As a coating pigment with high shape ratio, talcum powder has excellent fiber covering ability and good printing effect, and can also improve the quality of gravure printing.


Talc powder has special lubricity, made of its coated paper in the calender can obtain high finishing degree, and can reduce the use of lubricant coating.


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