How do you make polyurethane dispersion?
Two basic steps are needed in order to make a waterborne urethane dispersion: a prepolymer step and a chain extension step. Internal surfactants, i.e., surfactants that are incorporated into the backbone of the polymer, are commonly used in PUD’s.
What is crosslinked polyurethane?
Crosslinked polyurethanes (CPUs) were synthesized by reaction of (ethylene oxide-propyleneoxide- ethyleneoxide) (EO-PO-EO) triblock copolymer with diisocyanate and a low molecular weight triol as a crosslinking. agent. The short diol was used as a chain extender.
What is self crosslinking?
They are also less toxic and safer to use.” Self-crosslinking explained. Crosslinking involves chemically joining two or more polymer chains by covalent bonds. In a process distinct from similar 2K systems, self-crosslinking systems involve attaching the crosslinking agent to the polymer backbone in the resin.
Is polyurethane a cross linked polymer?
The polymer usually has a highly crosslinked molecular structure, resulting in a thermosetting material which does not melt on heating; although some thermoplastic polyurethanes are also produced.
What is waterborne polyurethane dispersion?
Waterborne polyurethane dispersions (PUDs) are polyurethane polymer resins dispersed in water. They are widely used for environmentally friendly, low volatile organic compound (VOC) water-based paints, adhesives, ink binders, and coatings.
What is dispersion resin?
A resin dispersion contains a low-molecular-weight tackifier resin dispersed in water with the aid of a surfactant. These tackifier resins include hydrocarbon resins or rosin ester resins.
What is the process of cross-linking?
Crosslinking is the process of chemically joining two or more molecules by a covalent bond. Crosslinking reagents (or crosslinkers) are molecules that contain two or more reactive ends capable of chemically attaching to specific functional groups (primary amines, sulfhydryls, etc.) on proteins or other molecules.