Chemtura announced that it has acquired Croda International Plc’s shares in Baxenden Chemicals Ltd. for £13 million in cash ($26 million), increasing its stake from 53.5% to 100%.
Robert Wedinger, manager of Chemtura’s Specialty Chemicals Division, is quoted as saying, “Chemtura sees great potential for Baxenden in the areas of polyurethane dispersions, specialty polyurethane prepolymers and closed isocyanates, and now with the acquisition of Baxenden, such a tremendous business opportunity belongs to Chemtura.” The acquisition of Baxenden will not only bring Chemtura complementary technology and manufacturing experience, particularly in high-performance polyurethanes but will also optimize its product and service mix.
Baxenden has been a world leader in polyurethane technology for the past several decades, and its Specialty Chemicals division has become a widely recognized brand in the high-performance polyurethane and closed-cell isocyanate crosslinker markets. 2007 sales reached $70 million, with two manufacturing sites in Accrington and Droitwich, UK, employing 212 people (of which Baxenden is committed to researching and developing new products to provide a comprehensive range of polyurethanes for coatings, and offers a wide range of polyurethane products, including applications in construction (e.g. flooring coatings and heavy-duty anti-corrosion coatings) and supplies high-performance closed-cell isocyanate crosslinkers for automotive and coil steel coatings.
Polyurethane is a polymer formed by the reaction of a polyisocyanate and polyether or polyester polyol under certain conditions. The prepolymer of polyurethane is simply a reactive semi-finished product obtained by the reaction of polyisocyanate and polyol in a controlled ratio. Due to the wide variety of polyisocyanates and polyols, the reaction ratios vary.
Synthesis method of prepolymer The most commonly used polyurethane prepolymer is the terminal NCO polyurethane prepolymer. The general method for the preparation of end-NCO-based prepolymer is to first remove a small amount of water contained in the oligomer polyol (polyether polyol or polyester polyol, etc.), and then add the oligomer polyol dropwise to the excess polyisocyanate while stirring under the atmosphere of nitrogen, and remove the heat generated by the reaction in time to keep the reaction temperature within a certain limit. Sometimes, according to the need of the reaction, an appropriate solvent can be added to adjust the viscosity of the system, and a catalyst can be added to control the speed of the pre-polymerization reaction.
The synthesis method of terminal OH-based polyurethane prepolymer is similar to that of terminal NCO group prepolymer, which is generally controlled by a slight excess of raw materials containing hydroxyl groups. Prepolymer for adhesives and other main agents is generally based on the end NCO prepolymer with a slight excess of diol to further expand the chain and get. The factors affecting the pre-polymerization reaction are various, except for the properties of isocyanate and oligomeric polyol (such as hydroxyl value, acid value, moisture, and metal ion content, etc.), the operation process is also the main influencing factor. The stability of end-NCO-based polyurethane prepolymer is also influenced by the tightness of the storage container, the nature of the container wall, and the gas inside the container. Sometimes the presence of a small amount of air in the container will affect the stability of the prepolymer, especially MDI-type prepolymer. Sometimes, in order to improve the storage stability and reduce the chance of viscosity building and gelation, it is necessary to add a trace of stabilizers such as benzene sulfonyl chloride.
Closed polyisocyanate: polyisocyanate is capped with phenol, ε-caprolactam, etc., forming closed isocyanate, which can be combined with various oligomeric polyols, stable at room temperature, and can be formulated into one-component baking type coatings for various metal and plastic coatings, such as wire enamel paint, coil coatings.
High-performance polyurethane products as polymer composite materials, its application is very wide. We commonly see exterior wall insulation panels, fillers for the insulation layer of refrigerators, soles of sports shoes, etc. But in fact, the development and application of high-performance polyurethane products are very limited in China, and we have a big gap with Germany, Japan and the United States. Foreign countries have a wide range of applications in high-end manufacturing industries such as aviation, aerospace, shipbuilding, petroleum and automobile manufacturing. The domestic use of high-end polyurethane is very limited. The market prospect of polyurethane is very good because of its superior performance in wear resistance, high-temperature resistance, corrosion resistance, sealing, vibration damping, etc.