Water resistant epoxy resin development

Functionalized, liquid polybutadiene derivatives have also been developed as hybrid flexiblizers for epoxy resins. Carboxyl-terminated butadiene/acrylonitrile polymers, butadiene homopolymers, and maleic anhydride-amino acid grafted butadiene homopolymers have been used as flexibilizers to impart good low-temperature strength and water resistance to DGEBA-based epoxy adhesives. An epoxy system toughened by polybutadiene with maleic anhydride is claimed to provide a hydrophobic backbone, low viscosity, softness, and high tensile strength and adhesion (Table 7.10). 

Later (1935—45), new materials such as silicone were developed as water repellent and heat resistant paint. The development of epoxy resins offered a structural material for boat and car bodies. Poly(tetrafluoroethylene) (PTFE), polycarbonate, poly(ethylene terephthalate) (PET), polypropylene, polyurethane, ABS and acetals are the latest additions to find their way into plastics technology. Studies have also been carried out with the use of fillers and plasticisers as part of the next generation of materials. 

Until the early 1970s, all ED binders used industrially were based on maleinised natural oils, acidic alkyd resins or epoxy resin esters. Later, binders based on maleinised polybutadiene oils (LMPBs= low-molecular-weight polybutadienes) also came into industrial use, particularly in Western Europe. All these systems were of the anionic type, i.e. their water solubility and their deposition at the anode were due to the presence of carboxylate groups in the binder molecules. More recently, cathodic ED, with binders carrying cationic groups (e.g. -N 2h)j has proved to be an interesting alternative. This paper describes development work directed towards improving the corrosion resistance of anionic, and more briefly, cationic ED binders. 

With a view to lowering raw material costs (the DMPA used in binder LR-2052 is rather expensive), we later developed another OH-rich binder, designated LR-2053. This system is based on a linear backbone containing a liquid epoxy resin, EPIKOTE 828, diphenylolpropane, adipic acid and CE 10 (molar ratio 3/2/2/2) and again is rendered water-soluble with a TMA/CE 10 combination (2.5 moles TMA and 2.6 moles CE 10 per mole of backbone). This binder performs as well as LR-2052, with an only marginally lower salt-spray resistance. 

Recent developments in this field seem to suggest that both epoxy or polyester resins are often times used for similar applications with no apparent difference in the performance of the materials. Ohama and co-workers (15) compared the resistance of polymer concretes to boiling water for periods of up to 12 months and found that epoxy resins were more resistant than orthopthalate based... 

The binders for cathodic electrodeposition are epoxy resin combinations dispersed in water (see Section 3.8). Advantages of anticorrosive electrocoatings include excellent corrosion resistance at a dry film thickness of ca. 20-30 pm. Electrocoats are stoved at 165 -185 °C to obtain films with the desired properties. The paint industry is now developing electrocoats that can be cured at lower temperatures (140 150 "C). Electrocoating produces a homogeneous film that covers the entire car body surface, including recesses and cavities. 

P(2) Epoxy resins should be considered where higher shear strength than is available with polyester resins is required and the application requires good mechanical properties at elevated temperatures or durability. Epoxies occur in many varieties, feature high strength properties (as seen in some of the most effective engineering adhesives) and have been developed for water resistant coatings. 

So, the properties of water containing epoxy composites were developed and investigated as well as the possibility of applying a hydrophihc filler as an additive that increase the fire resistance of hardened epoxy compositions based on epoxy resin ED-20 was shown in the chapter. 

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