Gel-coat resins

Gel-coat resins are a particular class of unsaturated polyester resins. Gel coats provide finish appearance to the unsaturated polyester parts and may also provide... 

NPG [Eastman]. TM for the glycol of choice for premium-quality gel coats. It reacts rapidly with isophthalic acid to produce low-color gel-coat resins. 

Uses Colorant for polyester resins, match metal molding compds. (SMC, BMC, TMC, preform, premix), flat panels, gel coats, resin transfer molding... 

The samples used in this study include a modified blocked isocyanate, isophorone diisocyanate (IPDI), (B-1370, Huls AG, Gelsenkichen-Buer, W. Ger.) and both catalyzed and uncatalyzed polyester gel coat resins. Gel coat cure reactions were initiated with the addition of 1.0 wt. percent of methyl ethyl ketone peroxide (MEKP, Lucidol Div., Pennwalt Corp., Buffalo, N.Y.) and catalyzed with the addition of 0.15 wt. percent cobalt octoate solution (12% cobalt in mineral spirits, Mooney Chemicals, Cleveland, OH.). 

The cure reaction in polyester gel coat systems makes them particularly useful model coatings materials since the cure kinetics can be studied by several analytical techniques. The initiation of cure in polyester gel coat resins begins with the decomposition of hydroperoxide (MEKP is predominately hydroperoxide) and the subsequent copolymerization of styrene with the unsaturated groups, either fumarate or maleate, incorporated into the resin backbone. ... 

The Arrhenius plot generated from cure kinetics parameters (Figure 3) for this system essentially is linear through the cure region. The excellent fit obtained with the linear least squares regression over the temperature range of the cure reaction confirms the validity of the nth order kinetic model used to describe the cure of the uncatalyzed gel coat resins. 

Fig. 2. DSC scan of curing uncatalyzed gel coat resin showing the reaction exotherm (72-148°C) and the temperature range (84-133 C) selected for kinetics evaluation.

Table 1. Experimentally Determined Kinetics Parameters For The Cure of Catalyzed and Uncatalyzed Gel Coat Resins...

Surfactants, nucleating agents and catalysts used in foaming processes Thixotropic additives for gel coat resins to control flow on the mould Tribological additives that reduce mechanical wear by friction. 

A clear, light-coloured, UV stabilised chemical resistant NPG-isophthalic gel coat resin as used in the manufacture of all varieties of cultured marble, offering good sprayability and excellent thermal shock resistance on hot-cold water cycling. 

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