Coupling agent, also known as adhesion promoter or surface treatment agent, is a substance with amphoteric structure. It is centered around titanium, and one end of the molecule can react with chemical groups on the surface of inorganic substances to form strong chemical bonds; The other end group has the property of being organic, which can react or physically entangle with organic molecules, thereby firmly combining two materials with vastly different properties.
Inorganic substances treated with titanium acid ester coupling agents are hydrophobic and hydrophobic. When added to the polymer system, it can promote adhesion and has a catalytic effect; Improve dispersion and rheological properties; Improve impact strength without producing brittleness; Improve mechanical performance, increase filling volume, and reduce costs; Prevent phase separation, have anti-corrosion, antioxidant, flame retardant and other functions.
In short, it is a multifunctional and highly flexible additive that serves as both a coupling agent and a dispersant, wetting agent, adhesive, crosslinking agent, and catalyst. Therefore, it has a wide range of applications.
There are four main types of titanium ester coupling agents:1. Monoalkoxy type; 2. Pyrophosphate type; 3. Boiling type; 4. Coordination type.
Operating instructions:
Coupling agents can be diluted with anhydrous solvents or subjected to surface pretreatment by high-speed stirring and heating, which can save solvent consumption and achieve good treatment effects. The steps are as follows: add the filler into the mixer, start stirring, and raise the temperature to around 70 ℃ -80 ℃ (the higher the speed, the more favorable it is for the dispersion of the coupling agent on the surface of the filler), then evenly add the titanium ester coupling agent or coupling agent solution, which can be added by drip or spray method. After adding, continue stirring for 15 minutes (the stirring time depends on the speed).
Using coupling agents for surface treatment of inorganic fillers, and then mixing them with resins and other additives for granulation, can achieve good coupling effects. The surface of the filler treated with coupling agent changes from hydrophilic to hydrophobic, does not absorb moisture, and has stable performance.
matters needing attention:
1. Surfactants such as zinc oxide and stearic acid should be added after the filler interacts with the coupling agent, otherwise it will interfere with or reduce the reaction of the coupling agent at the interface.
2. Most titanium ester coupling agents undergo ester exchange reactions with polyester plasticizers, so polyester plasticizers should be added after the coupling agent has acted; Petroleum derived plasticizers are not a problem, so they can be used to dilute coupling agents, allowing for better dispersion and better interaction with fillers.
