Polyurethane products can be roughly divided into foams, elastomers, and polyurethane resins. Below, WHAMINE will analyze the selection of polyurethane catalysts for these three types of products.
You can find more information on our web, so please take a look.
Foamed polyurethane catalyst products are mainly synthesized from polyethers, isocyanates, foaming agents, catalysts, etc. The main process of foam formation is generally considered as follows:
(1) Foam is generated in the polyurethane reaction system by physical and chemical methods, and the foam is uniformly dispersed in the reaction system. The main foaming method is to use water and isocyanate to produce carbon dioxide for foaming.
(2) The foam generation process requires the viscosity of the reaction system to increase accordingly so as to stabilize the foam from escaping.
(3) When the foam formation reaches the required number and size, the viscosity of the reaction system needs to continue to increase or even form a cross-linking system to stabilize the foam and shape it into a product.
In this case, we need at least two catalysts to adjust the progress of the reaction. One catalyst is to promote the reaction between isocyanate and water, that is, to promote the foaming reaction. Usually, an amine catalyst is selected; To promote the reaction of isocyanate and polyether or alcohol, that is, the reaction of polyurethane molecular chain growth and cross-linking, metal catalysts are generally used.
Yourun Synthetic Material supply professional and honest service.
Therefore, in the synthesis process of polyurethane catalyst, we generally use amine catalysts and organometallic catalysts to produce synergistic effects to achieve the best results. The specific types and ratios of amine catalysts and organometallic catalysts need to be adjusted and selected according to different products through experiments or experience.
The reaction of elastomer polyurethane catalysts to isocyanate (NCO) and water should be strictly avoided, so metal catalysts are generally used at this time, such as organic tin, organic bismuth, and even eliminated organic mercury.
In the synthesis process of resin polyurethane catalyst, the reaction of NCO and water should be avoided as much as possible, so organic bismuth and organic tin are generally used.
Polyurethane is an essential polymer, renowned for its versatility and adaptability across a multitude of industrial applications. Its popularity is primarily attributed to its unique chemistry, enabling the fabrication of materials with a vast spectrum of different potential mechanical and physical properties. Thus polyurethanes are used in a wide range of applications including, coatings, adhesives and sealants, plastics and foams.
The adaptability of polyurethane also lies in its unique chemistry, which allows for the creation of products with a wide range of hardnesses, flexibility, and densities[1]. Polyurethanes are primarily produced through the reaction of a polyol (an alcohol with multiple reactive hydroxyl groups) and an isocyanate, often catalyzed by various additives including tertiary amines and metals such such as inorganic tin, organotins, bismuth, zinc, zirconium and and iron.
The production of polyurethanes is a complex process requiring precise control over the specific reactions that occur during polyurethane synthesis. This is where catalysts play a critical role. They help to advance the polyurethane-forming reactions and control the polymer structure, thereby significantly influencing the properties of the resultant polyurethane.[3]
Metal-based catalysts used in polyurethane synthesis are used to selectively accelerate both the polymerization and crosslinking reactions. Tin and bismuth catalysts are ideal for catalyzing the hydroxyl/isocyanate reaction whereas zinc catalysts are primarily active for the crosslinking reactions. The functionality of these metal catalysts can be enhanced via ligand selection. For example, sulfur-based ligands enhance the selectivity of the hydroxyl/isocyanate reaction (versus the water reaction) and build in front-end reaction delay.
Reaxis offers a wide range of tin, bismuth and zinc catalysts for polyurethane formulation development. Common inorganic tin catalysts supplied include REAXIS® C125 (Stannous Neodecanoate) and REAXIS® C129 (Stannous Octoate). Common organotin catalysts supplied include a wide range of octyl-, butyl-, and methyl-based products including REAXIS® C218 (Dibutyltin Dilaurate) REAXIS® C233 (Dibutyltin Diacetate) REAXIS® C216 (Dioctyltin Dilaurate) REAXIS® C325 (Dimethyltin Dineodecanoate), REAXIS® C248 (Dibutyltin Oxide) and REAXIS® C228 (Dioctyltin Diacetate). For sulfur-based tin catalysts, we supply REAXIS® C319 (Dibutyltin Dimercaptide) REAXIS® C214 (Dioctyltin bis-(Isooctyl Mercaptoacetate)) and REAXIS® C322 (Dibutyl bis-(Ethylhexyl Mercaptoacetate)). Bismuth catalysts supplied include REAXIS® C716 (Bismuth Neodecanoate) REAXIS® C (Bismuth Octoate) and REAXIS® C739W50 (water soluble sulfur-based bismuth). Zinc catalysts offered include REAXIS® C616 (Zinc Neodecanoate) REAXIS® C620 (Zinc Octoate) and REAXIS® C708 (Bismuth/Zinc Neodecanoate).
At Reaxis, we are dedicated to providing a wide range of metal-based catalysts for polyurethanes and the expertise to help you implement them effectively. Our comprehensive range of inorganic tin, organotin, bismuth and zinc catalysts can meet the various formulation objectives pertaining to reactivity and environmental/toxicity concerns. With a long history of manufacturing a wide range of metal-based additives and catalysts on commercial scales, combined with new product development and an understanding of polyurethane chemistry, Reaxis is an ideal partner in new formulation development and problem-solving. Our commitment to quality, reliability, and technical support makes us a trusted choice for formulators aiming to enhance their product performance and achieve optimal process efficiency.