Research work · 2005
Epoxy Resins
Ha Pham, Maurice J. Marks
Ullmann's Encyclopedia of Industrial Chemistry
Abstract
Abstract Epoxy resins are reactive intermediates used to produce a versatile class of thermosetting polymers. They are characterized by the presence of a three‐membered cyclic ether group commonly referred to as an epoxy group, 1,2‐epoxide, or oxirane. The most widely used epoxy resins are diglycidyl ethers of bisphenol A derived from bisphenol A and epichlorohydrin. The outstanding performance characteristics of the thermosets derived from bisphenol A epoxies are largely conveyed by the bisphenol A moiety (toughness, rigidity, and elevated temperature performance), the ether linkages (chemical resistance), and the hydroxyl and epoxy groups (adhesive agents). In addition to bisphenol A, other starting materials such as aliphatic glycols and both phenol ando‐cresol novolacs are used to produce specialty resins. Epoxy resins may also include epoxide‐bearing compounds based on aromatic amine, triazine, and cycloaliphatic backbones. A variety of reagents have been described for converting the liquid and solid epoxy resins to the cured state, which is necessary for the development of the ultimate end‐use properties. The curing agents or hardeners are categorized as either catalytic or coreactive. Catalytic curing agents initiate resin homopolymerization, either cationic or anionic, as a consequence of using a Lewis acid or base in the curing process. Coreactive curing agents are polyfunctional compounds typically possessing active hydrogens that are employed up to stoichiometric quantities with epoxy resins. The important classes of coreactive curing agents include multifunctional amines and their amide derivatives, polyphenols, polymeric thiols, polycarboxylic acids, anhydrides, phenol–formaldehyde novolacs and resoles, and amino–formaldehyde resins. The largest single use of epoxy resins is in the protective coatings market where high corrosion resistance and adhesion to substrates are important. Epoxies have gained wide acceptance in protective coatings and in electrical and structural applications because of their exceptional combination of properties such as toughness, adhesion, chemical and thermal resistance, and good electrical properties. The article contains sections titled: 1. Introduction 2. History 3. Industry Overview 4. Classes of Epoxy Resins and Manufacturing Processes 5. Liquid Epoxy Resins (DGEBA) 5.1. Caustic Coupling Process 5.2. Phase‐Transfer Catalyst Process 6. Solid Epoxy Resins Based on DGEBA 6.1. SER Continuous Advancement Process 6.2. Phenoxy Resins 6.3. Epoxy‐Based Thermoplastics 7. Halogenated Epoxy Resins 7.1. Brominated Bisphenol A Based Epoxy Resins 7.2. Fluorinated Epoxy Resins 8. Multifunctional Epoxy Resins 8.1. Epoxy Novolac Resins 8.1.1. Bisphenol F Epoxy Resin 8.1.2. Cresol Epoxy Novolacs 8.1.3. Glycidyl Ethers of Hydrocarbon Epoxy Novolacs 8.1.4. Bisphenol A Epoxy Novolacs 8.2. Other Polynuclear Phenol Glycidyl Ether Derived Resins 8.2.1. Glycidyl Ether of Tetrakis(4‐hydroxyphenyl)ethane 8.2.2. Trisphenol Epoxy Novolacs 8.3. Aromatic Glycidyl Amine Resins 8.3.1. Triglycidyl Ether ofp‐Aminophenol 8.3.2. Tetraglycidyl Methylenedianiline (MDA) 9. Specialty Epoxy Resins 9.1. Crystalline Epoxy Resins Development 9.2. Weatherable Epoxy Resins 9.2.1. Hydrogenated DGEBA 9.2.2. Heterocyclic Glycidyl Imides and Amides 9.2.3. Hydantoin‐Based Epoxy Resins 9.3. Elastomer‐Modified Epoxies 10. Monofunctional Glycidyl Ethers and Aliphatic Glycidyl Ethers 11. Cycloaliphatic Epoxy Resins and Epoxidized Vegetable Oils 12. Epoxy Esters and Derivatives 12.1. Epoxy Esters 12.2. Glycidyl Esters 12.3. Epoxy Acrylates 12.4. Epoxy Vinyl Esters 12.5. Epoxy Phosphate Esters 13. Characterization of Uncured Epoxies 14. Curing of Epoxy Resins