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The classification of the waterborne polyurethane adhesive

by:Sinograce Chemical     2020-06-30
So far, the research of waterborne polyurethane has amounted to more than 40 years of time, due to its formulation and the diversity of raw material, the varieties of waterborne polyurethane are very various, many classification methods. ( 1) To use the form of division of waterborne polyurethane can be divided into two kinds according to its use monocomponent and bicomponent two kinds. One-component refers to the synthesis of waterborne polyurethane can be directly put into production use, do not need to add additional crosslinking agent. Two-component refers to the direct synthesis of waterborne polyurethane cannot be directly put into use, or directly use cannot achieve the required performance requirements, need to add to mixed crosslinking agent, or put one component waterborne polyurethane crosslinking agent is added to improve product performance, the system called two-component waterborne polyurethane systems. ( 2) By fragmented state of aqueous polyurethane dispersion in water can be divided into three categories, the specific classification as shown in the figure below. ( 3) As the main raw material division of main raw materials including waterborne polyurethane oligomer multivariate alcohol and diisocyanate. Oligomer polyols can be divided into polyester and polyether type and polyolefin three categories, respectively is refers to the polyester polyol, polyether polyol, and polybutadiene glycol. In addition to polyester - Polyether and polyester - Polybutadiene and polyether Polybutadiene hybrid. Diisocyanate class can be divided into aliphatic isocyanate, alicyclic isocyanate, aromatic isocyanate, etc. Such as isophorone diisocyanate ( IPDI) , dicyclohexyl methane diisocyanate ( HMDI) , diphenyl methane diisocyanate ( MDI) And six methylene diisocyanate ( HDI) , toluene diisocyanate ( TDI) And so on. ( 4) Structure as a whole division according to structure of raw materials we can be divided into pu, isocyanate polyurethane, vinyl polyurethane, enclosed polyurethane. Refers to polyurethane oligomer multivariate alcohol and diisocyanate as the main raw material, the preparation of synthetic polyurethane with deionized water emulsion dispersed into water medium. Isocyanate polyurethane is the mass of isocyanate hydrophilic radical emulsion in water to form a waterborne polyurethane emulsion. Vinyl polyurethane refers to join in vinyl polyurethane emulsion isocyanate and form a two-component system of emulsion. Enclosed isocyanate is refers to the molecule contains normally closed isocyanate group a with low temperature stability of one-component polyurethane system. According to the molecular structure of polyurethane can be divided into linear ( Thermoplastic) Polyurethane and crosslinking type ( Thermosetting) Polyurethane (pu). According to the crosslinking type and can be further subdivided into the diplomatic and stated coupon type two kinds. Foreign league is added in the polyurethane emulsion can react with groups in the molecular chain of the crosslinking agent, it is a common two-component system. Documentsmust al type polyurethane refers to the system in the process of synthesis of branched molecular structure of crosslinking, it is a stable system of single component. ( 5) With hydrophilic group divided according to whether containing ionic groups on waterborne polyurethane molecular chain, the waterborne polyurethane can be classified into cationic, anionic, nonionic. 1. Cationic waterborne polyurethane, namely the molecular chain or matte containing quaternary ammonium ions of waterborne polyurethane. One of the most often used containing tertiary amine base or secondary amino chain extension agent, through acidification or the role of the alkylation, form the ammonium ion is hydrophilic. In addition can also be after amination of waterborne polyurethane and epoxy chloropropane and acid reaction generated hydrophilic ammonium ions. The commonly used amine such as triethanolamine, n methyl diethanolamine. 2. Anionic waterborne polyurethane and generally can be divided into carboxylic acid and sulfonic acid type two kinds. Usually adopt carboxylic and sulfonic group is added in the system of molecular chain extender to introduce sulfonic acid ions and the carboxyl ion. If using carboxyl as chain extender, will need to add a tertiary amine and ionization, which has a hydrophilic polyurethane system, further emulsifying dispersion synthesis of waterborne polyurethane. 3. Nonionic waterborne polyurethane generally refers to the system does not contain ion in the molecular structure groups. It mainly through the system main chain or side chain import hydrophilic polyether, waterborne polyurethane has good water dispersibility. Common nonionic chain extension agent, such as poly (ethylene oxide, polyethylene ether, hydroxyl ethyl methacrylate, hydroxyl-terminated poly (ethylene oxide, etc.
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