Coatings curing conditions

The maximum recommended film thickness is 25 p.m. At greater thicknesses, volatiles from the curing reaction, mainly water and some formaldehyde and phenol, can cause defects. These coatings have excellent electrical insulation properties, ie, up to 20 V/p.m, because of low moisture absorption and low conductance. The coatings are hard with low flexibiUty, depending on curing conditions and film thickness. 

Typical substrates for siUcone release coatings are supercalendered kraft paper, glassines, and thermally sensitive films such as polyethylene and polypropylene. Ideal curing conditions are 150°C or lower, and line speeds are as fast as 460 m /min. Key properties for release coatings are cure speed, integrity of cure, and stable release values. 

One-step vulcanization, wide range of curing conditions, high loading elasticity, snappiness, no deformation, weatherability. ozone resistance, heat resistance, tear resistance, coating performance, adhesive properties, skid resistance, abrasion resistance... 

Epoxy phenolic coatings These materials are also cured at relatively high temperatures and are made by the reaction of the epoxy resin with the phenolic resin. They are slightly less critical in application requirements, are less sensitive to curing conditions and can be applied in thicker coats. The best use for both these materials is as tank linings used for the storage or food products, drinks, etc. or for process plant, evaporators, etc. that contain boiling water. 

Modification of the FT-IR analysis techniques to analyze coatings under isothermal cure conditions provides the data needed to determine the rate constants for each reaction. An effective method to generate the rate constants from the experimental data has been found and will be described. 

The composition and functionality of the systems greatly vary according to the substrate material to be coated, as they demand different curing conditions, adapted physical properties and characteristics as well as functionality for better wetting and adhesion. Dyes, pigments... 

Figure 5. Percent retention of strength of latex coated 3701 fabric with 3-amlnopropylpolyslloxane coating, after Imnerslon In alkali for 7 days at 80°C., as a function of number of dips In latex, kind of latex, and curing conditions.

Table 7.8 Typical Curing Conditions for UV Powder Coatings on MDF. ..169...

Table 9.2 summarizes some technological characteristics of typical one-pack and two-pack FBZ formulations, as well as the curing conditions. Viscosity is sufficiently tow and suitable for spray or roll applications. In most cases, high-solid coatings can be obtained. The materials described herein include the bicomponent polyurethanes obtained by addition of Z1030 to Z1072 or Z1073... 

R. O. Williams III and J. Liu. Influence of processing and curing conditions on beads coated with an aqueous dispersion of cellulose acetate phthalate. Eur. J. Pharm. Biopharm. 49 243-252, 2000. 

The Importance of Curing Conditions in Overall Energy Requirements for Organic Coatings... 

Optimization of Cure Conditions During Processing of Acrylic Latex Coatings... 

A primer surfacer, composed most often of a polyester to be cross-linked with a blocked isocyanate or melamine cross-linker, is applied next at a dry film thickness of approximately 1.0 mil by conventional spray application. The function of this coating is to provide filling and leveling properties as well as some stone-chip resistance. Cure conditions range from 250 to 325°F for 20 min. 

The clear-coat is referred to as a two-component (2K) clear-coat when isocyanate is used as the cross-linker. The isocyanate must be added to the hydroxy functional acrylic just prior to spray application to prevent premature cross-linking (or gelation). For this reason, the two-part mixing is referred to as 2K. Cure conditions for isocyanate-cured clear-coat range from room temperature (car refinish) to 250°F for 30 min. 

One component, or IK clear-coats are equivalent to 2K clear-coats with the exception that they are cross-linked with melamines. Cure conditions for 1K clear-coats are 250°F for 30 min. Blocked isocyanate versions of IK clear-coats also are available, but cure requirements necessitate 275°F or higher. 

Choice of appropriate coating method along with drying/curing conditions can yield a stable defect-free membrane. 

---