Notes on the application of titanate coupling agent
Titanate coupling agent is a bridge agent for connecting organic and inorganic materials. If it is not used properly, it will not have a good effect. The following are the problems that need to be noted in its use:
The usual addition amount of titanate coupling agent. In the treatment of powder, it depends on the total amount of filler, pigment and other inorganic auxiliary materials, as well as on the particle size and fineness of powder, specific surface area, soft products and hard products 0.5% ~ 3% Finally, the best dosage is determined by efficiency.
Equipment selection of titanate coupling agent modified powder
Equipment requirements: slg3 / 300 powder surface modifier, high-speed mixer, etc. If the high-speed mixer is selected, the rotating speed is more than 1000r / min, and the volume is 200-500l. Under the condition of high-speed rotation, the powder is required to rotate in the mixing chamber. The high-speed rotating material flow hits the baffle plate, changing the flow direction, thus strengthening the mixing and dispersion effect of the material, making the powder fully dispersed in the aggregation state, and the coupling agent is wrapped on each powder particle interface Coating a layer of molecular film, high-speed mixer is a very important factor for coupling agent modified powder. The general process of powder filler modification can put the powder filler into the high-speed mixer by 50% - 75% of the volume of the high-speed mixer. When the temperature (friction heat generation) reaches 90-100 ℃ under high-speed mixing, the water gas will be discharged, and then the coupling agent dilution solution prepared by measurement will be added. When the temperature reaches 105 ℃, the material will be shut down and ready for use (sealed packaging to prevent moisture absorption). The whole process time depends on the high-speed mixer performance Can decide
Reaction of water content of two inorganic powder materials with coupling agent
If the fatty acid monoalkoxytitanate (VK such as CS-101 105130) is selected, the water content of the filler shall be lower than 0.5% Otherwise, monoalkoxy titanate coupling agent is easy to hydrolyze and lose efficacy. For fillers with high moisture content, such as clay, mica, talc, etc., pyrophosphate titanate coupling agent can be selected. In addition to reacting with the surface hydroxyl of fillers to form coupling, pyrophosphate ester group (such as cs-201) can also decompose to form phosphate ester combined with part of water. For the aqueous polymer system of high humidity filler, such as wet SiO2, ceramsite, talcum powder, aluminum silicate, water treatment glass fiber, carbon black, phthalocyanine and iron red in aqueous solution, the chelating titanate coupling agent cs-311 or cs-311w with excellent hydrolysis stability can be selected.
3： Some problems in adding coupling agent and other auxiliaries
Titanate coupling agent will react with ester plasticizers and other ester compounds in different degrees. In this case, coordination type titanate coupling agent can be selected. Generally, surfactants will affect or resist the coupling effect of titanate coupling agent and inorganic fillers, such as zinc oxide, stearic acid, etc. these materials must be added after the fillers, coupling agents and polymers are fully mixed to avoid affecting the coupling effect. The main thing is to pay attention to some surface active agents.
4： Treatment method
Generally, the pretreatment method (inorganic powder direct treatment method) is used, the effect is better than the direct addition method, and the dosage is relatively less, but the process is more. Inorganic fillers and pigments are modified by coupling agent first, and then mixed with polymers and other additives. Its advantages are that it can be applied to the blending modification of engineering plastics with complex polymer components or plastic alloy system, as well as some engineering plastics with high processing temperature, which can prevent unnecessary side reactions. Specific pretreatment methods: there are two mixed methods: wet and dry. It can be diluted with gasoline, benzene, ethanol and other solvents, mixed with the filler evenly, and then removed by heating or decompression. This method is completely coupled, but it costs too much and is not economical. The pyrophosphate coupling agent can be added together with the white oil diluting lubricant in the formula; the aohe coupling agent has good water resistance and can be diluted with water. If it does not dissolve in water, it can be dissolved in water with the aid of amine auxiliaries, and then it can be mixed with plastics and pigments to remove water. In dry mixing, titanate coupling agent is mainly used in plastics. In order to make a small amount of titanate coupling agent uniformly cover the surface of filler and pigment, a small amount of diluent (the dosage of anhydrous solvent and coupling agent is 1:1) is generally added.