Waterborne polyurethane was first produced in 1943 by t […]
Waterborne polyurethane was first produced in 1943 by the West Germany P.Schlack for the first time in 1967, the polyurethane emulsion for the first time in the industrialization and the advent of the US market in 1972, Bayer first took the polyurethane emulsion as a leather finishing agent, water-based polyurethane began to become important commodity. Although the water-based polyurethane is not long history, but because of its own non-toxic, easy to burn, pollution-free, energy-saving, safe and reliable and difficult to scratch the surface is coated, etc., its development is very rapid.
Waterborne polyurethane adhesives are adhesives that dissolve polyurethane in water or disperse in water, have no solvent, no pollution, good film formation, strong adhesion, and other polymers in particular, Is easy to mix the emulsion polymer is conducive to modification and so on. With the strengthening of people's safety and environmental awareness, water-based polyurethane adhesive research to the rapid development. Successfully applied to leather finishing, paper coating, steel rust, fiber processing, plastic and wood coating, glass coating and other fields.
Waterborne polyurethane adhesives can be classified according to a variety of methods:
1, according to the structure of polyurethane classification
A, according to the raw materials and structure can be divided into polyurethane emulsion, vinyl polyurethane emulsion, polyisocyanate emulsion, closed polyurethane emulsion.
B, according to the molecular structure can be divided into linear polyurethane emulsion (thermoplastic) and cross-linked polyurethane emulsion (thermosetting). Crosslinking type is divided into internal cross-linked and cross-linked type.
2, according to the nature of hydrophilic groups
A, anionic: Most waterborne polyurethane adhesives are based on carboxyl or sulfonate extended chain introduction of carboxyl or sulfonic acid ions.
B, cationic type: generally refers to the main chain or side chain containing ammonium ions (mostly quaternary ammonium ions) or sulfur ions of water-based polyurethane.
C, non-ionic: molecules containing non-ionic hydrophilic segments or hydrophilic groups.
D, mixed type: molecular structure in the presence of ionic and non-ionic hydrophilic segments or groups.
3, according to the preparation method classification: A, self-emulsification and external emulsification; B, prepolymer method, acetone method, melt dispersion method; C, ketimine-ketone with nitrogen method.
4, according to the use of the form of classification: the use of the form can be divided into single-component and two-component water-based polyurethane adhesive.