Urea formaldehyde

urea formaldehyde slide share

1. Urea Formaldehyde Presented By Himmat Purohit

2. Index Introduction Chemical structure Manufacturing Process Properties Advantages & disadvantages Application

3. Introduction UF resin was first produced in 1884 by Holzer, who was working with Bernhard Tollens. Urea-formaldehyde, also known as urea- methanal , so named for its common synthesis pathway and overall structure, is a non-transparent thermosetting resin or plastic. It is produced from urea and formaldehyde. These resins are used in adhesives, finishes, particle board, and moulded objects. UF glue resins were the most important type of adhesives in the wood industry last 60 years, especially for the production of wood based panels.

4. In industrial production, urea resins are made by the condensation of formaldehyde and urea in an aqueous solution, using ammonia as an alkaline  catalyst . The condensation reaction  gives a colourless, solution that can be spray-dried to a powder for later use in coatings or adhesives. it can also be mixed with cellulose filler to produce powders for moulding into solid objects. Under the influence of heat and pressure, the resin, at this point made up largely of low-molecular-weight intermediate polymers or prepolymers, is cured to its final state, which consists of a three-dimensional network of interlinked polymer.

5. Chemical Structure

6. UF Condensation Reaction

7. Manufacturing Process Urea and formaldehyde reacted at reflux under acid conditions to a required viscosity. Resin is neutralized and cooled. A further amount of urea is added to react with remaining free formaldehyde. Resin is evaporated to obtain the correct viscosity and solids

8. Diagram

9. Process control Formaldehyde and urea are weighed into a reactor from a weigh vessel. Precision on formalin weighing is 0.02%. Precision on urea weighing is 0.5%. Viscometers and pH meters are calibrated daily. Thermocouples are calibrated bi-annually

10. Properties It has a very high tensile strength. Has the property of flexural modulus. Has the property of heat distortion temperature. Has the capacity of low water absorption . It has the property of mould shrinkage. Has a property of high surface hardness.

11. Advantages Higher maximum operating temperature. Better dielectric constant. Tracking resistance. Dimensional stability compared with cellulose filled urea formaldehyde Lower cost Good electrical insulator

12. Disadvantages Lower High Density Temperature(HDT). Higher water absorption and mould shrinkage. Lower surface hardness. can have toxic effects breathing difficulties,

13. Application Electrical Casings Tableware Decorative worktop laminates Plug & switches Buttons Paints Surface coating

14. Urea formaldehyde powder glue is used in many wood practices and its shell life is only 1 month but it can be longer in liquid glues.

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