Pliogrip resins & Chemicals Pvt ltd, W-78, Phase 2, MIDC, Dombivili (E)-421203, Thane, Maharashtra, India
Phone : 91-251-2871078, 91-022-27780742 / 29202870 / 29252090 Fax : 91-251-2873498
3.0 PLiOGRIP VINYL ESTER RESINS FOR FIBRE REINFORCED PLASTICS
It was more than 40 years ago that FRP was being acknowledged as a cost eff-ective solution to corrosion problems in chemical processing. The methodology of fabrication was also much the same; layering resins w~tted glass fibre or carbon fibre. However, there was limitation on selection of resins. The polyester based resins that were available were not good enough for the demanded higher performance of possessing equipment in hostile chemical environment at elevated temperatures, at higher stresses and under cyclic loading.
Intensive research in USA led to the production of Vinyl ester resins which were much superior in performance compared to the then available polyester resins.
Vinyl ester resins are produced by reacting methacrylic acid with epoxide and dissolving the resultant product in styrene monomer. They exhibit superior thermal, mechanical and chemical resistance properties imparted by epoxides with processing ease of unsaturated polyester resin; especially excellent ambient temperature cure.
Pliogrip produce a series of vinyl ester resins catering to the requirements of chemicals process equipment manufacturers all over the country. Pliogrip general purpose vinyl ester resin P-111, based on Bisphenol-A epoxy backbone, is now the workhorse of Indian process equipment industry. Pliogrip P-222 and P-223 are Superior vinyl ester resins based on epoxy novolac backbone. They are used where resistance to severe corrosive conditions at elevated temperatures is required. Pliogrip P-121, Brominated vinyl ester resin based on brominalod epoxy backbone finds applications where the process requires fire retardancy in addition to mechanical strength and chemical resistance. Further to it, optimum ignition resistance is achieved by adding antimony compounds to the Brominated vinyl ester resins. Pliogrip P-122 is based on brominated vinyl ester and antimony compound; specially formulated for military marine applications.
Pliogrip vinyl ester resins have now found applications in mining, pulp & paper, chemical processing, water treatment, power generation, air pollution control, petrochemical, transportation,
entertainment, steel and many other industries. compression moulding, resin transfer / infusion moulding and pultrusion
3.1 Formulation, Processing and Cure:
Pliogrip vinyl ester resins are formulated and processed the same way as unsaturated polyester resins. Free radical reaction initiated by peroxide causes crosslinking and cure. Cobalt promoters and amine accelerators are used to enhance the cure rate. Retarders are used to extend the gel time. Fillers, thixotropic agents, wetting agents and internal mould release are the other additives used in formulations. These formulated resins and fibre are processed to fabricate composite using several techniques such as, hand lay-up, spray up, filament winding, compression moulding, resin transfer / infusion moulding and pultrusion.
Structure Property Relationship
3.4 Pliogrip Superior Vinyl Ester Resin:
Pliogrip P-111 is the most commonly used epoxy vinyl ester resin in the FRP for its resistancE to broad range of acids, alkali, bleaches and solvents upto 105°C. The superior toughness provide~ the equipment made from this resin a higher level of safety factors against impact durin~ transportation and installations.
Figure 1 & 2 represent the structure of Bisphenol-A fumeric acid and Isophthalic polyester resins The pliogrip vinyl ester resins with bisphenol-A based epoxy backbone is shown in figure 3 The analysis of structure of these resins would serve as a basic guildline to their properties 3.3 Pliogrip General Purpose Vinyl Ester Resin:
Pliogrip superior vinyl ester resin grades P-222 and P-223 are based on epoxy novolac, which haVE much higher functionality compared to those having backbone of bisphenol-A epoxy resin The higher crosslink density of the cured P-222 and P-223 provides them the exceptional resistancE to solvents and chemicals in addition to the property of retention of strength and toughness a elevated temperatures. These resins are generally used in fabrication of equipment which would bE subjected to high concentration of severely corrosive materials; e.g. Chlorination and sulfonation a higher temperature, solvent extraction and hydrochloric acid transportation.
3.5 Pliogrip Fire Retardant Vinyl Ester Resin:
Pliogrip P-121 and P-122 are based on tetrabromo bisphenol- A epoxy resin. In addition to the hig~ degree of mechanical and chemical resistance, the bromine contents impart these resins a propert) offire retardancy. They are used mainly in the areas where equipment are specified to handle ho air / gas mixtures or flammable liquids or vapours; such as ducts, scurbbing units, stack liners building panels etc.
Pliogrip P-122 is further optimized in terms of fire retardancy using an antimony compound However, the mechanical properties and chemical resistance are still retained.