Addition of Organosilicon Modified Waterborne Polyurethane
Aug 11, 2023
Due to the structure and properties similar to dendritic polymers, hyperbranched polymers have a large number of cavities, branching points, and a nearly spherical structure, and their preparation steps are simple without the need for purification. However, hyperbranched polymers and dendritic polymers cannot be directly used as materials due to the lack of molecular chain entanglement. Grafting linear polyurethane onto hyperbranched polymers not only endows them with certain mechanical properties, but also improves the performance of polyurethane by utilizing the branched structure and narrow hydrogen bonds of hyperbranched polymers.
Firstly, hyperbranched polyurethane pulse (HPU) with tibial end groups was prepared using toluene 2,4-diisocyanate (TOI) and diethanolamine (DEOA) as raw materials and DMAC as solvent. Then, polycarbonate glycol CPCDL and TOI were used as raw materials to obtain a linear oligomer (A2) with an isocyanate terminal. A hyperbranched polyurethane terminated with isocyanate was prepared by reacting the two as raw materials, and a hybrid polyurethane was prepared by reacting with isocyanate using an appropriate silane coupling agent (KH550).
Finally, the unreacted isocyanate was wet cured into a film in atmospheric environment to obtain a hybrid polyurethane. The obtained product is represented by HPU-KH550-n. Among them, HPU is a hyperbranched polyurethane vein, KH550 is a silane coupling agent, and n is the molar ratio of KH550 to isobaric acid.
The results of functional group analysis, hydrogen bond analysis, thermogravimetric analysis, and mechanical properties of polymers through infrared analysis indicate that due to the presence of a large number of functional groups such as light groups, amino ester groups, and pulse groups within the hyperbranched polyurethane J step molecule, a large number of hydrogen bonds can be formed within the molecule. The content of silane coupling agents has a significant impact on the thermal and mechanical properties of polymers. The heat resistance of polymer components increases with the increase of KH550 content, reaching a temperature of 200 ° C at the beginning of splitting and a corresponding temperature of 362 at the maximum weight loss rate 9 ° C. But the tensile strength of the polymer gradually decreases with the increase of KH550 content. N CKH550): n (NCO)=0 At 30 o'clock, the tensile strength of the polymer decreased to 4 4MPa.
Organosilicon modified waterborne polyurethane: Firstly, a polysiloxane polyurethane block copolymer is synthesized, and then the copolymer is dispersed in water. By utilizing the hydrolysis condensation crosslinking of siloxane, the performance of waterborne polyurethane is improved, and a crosslinked waterborne polyurethane dispersion is obtained. According to the different feeding methods and the order of adding siloxane monomers or polysiloxane oligomers, it can be divided into one-step feeding method and step-by-step feeding method.
The one-step feeding method refers to the reaction in which the main raw materials and organosilicon monomers or polysiloxane oligomers are added to the reactor at once during the prepolymer synthesis process. The prepolymerization reaction lasts for 5-6 hours, and appropriate acetone is added to reduce viscosity. When the - NCO group content in the system approaches the theoretical value. Lower the temperature, add solvent to reduce the viscosity, add neutralization salifying agent after full mixing, and then add distilled water to disperse, EDA (ethylene diamine) chain extension to obtain amino siloxane modified waterborne polyurethane composite lotion. The stable lotion can not be obtained in this feeding sequence. The appearance of lotion is lime water with large particle size and poor film forming performance.
Our main products are Acrylic Modified Silicone Resin Emulsion，Epoxy Modified Silicone Resin Emulsion，Smokeless Silicone Resin，Self-drying Silicone Resin，Highly Active Silicone Resin，Methyl Silicone Resin Intermediate.
