Primer surfacer

As discus.sed earlier, puny filling is generally not advisable unless the surface is poor, uneven or has pin holes. If is advisable to use primer surfacer, which provides a thicker coal and helps to fill such surfaces. The epoxy primer is thicker and may do this job in most cases. 

The scale of the microscopic surface roughness is important to assure good mechanical interlocking and good durability. Although all roughness serves to increase the effective surface area of the adherend and therefore to increase the number of primary and secondary bonds with the adhesive/primer, surfaces with features on the order of tens of nanometers exhibit superior performance to those with features on the order of microns [9,14], Several factors contribute to this difference in performance. The larger-scale features are fewer in number... 

Grundierungs-bad, n. Dyeing) impregnation bath, -mittel, n. Paint) groimding, primer, surfacer. 

After the bare metal is primed, the whole area is built up with primer-surfacer. After light sanding where necessary, the repair is completed with topcoat. The materials used in the primer-surfacer are matched to the selection of topcoat. Topcoat is chosen from four main types. 

With these lacquers, nitrocellulose-based primer-surfacers are used. As well as liquid plasticisers, a wide range of materials are used as plasticising resins short oil alkyds, maleinised oils, ester gum, rosin and bodied castor oils. Pigmentation is usually inert. Thermoplastic acrylics are often preferred under acrylic lacquers these are based on acrylic resins and cellulose acetate butyrate. 

Automotive primers and primer surfaces Coatings for domestic electrical appliances... 

Illinois. A 30 percent minimum TE is required for automotive. Automotive VOC limits (lb/gal) are primer/surface, 2.8 topcoat, 2.8 repair, 4.8. The rules allow higher VOC limits for automotive topcoats if the finishing method can be demonstrated to achieve a TE of over 65 percent. In such cases, topcoats may be used with a VOC of up to 3.6. For the wood industry, a minimum TE of 65 percent is required with the... 

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. 

A second generation of phenolic dispersions, patented by J. S. Fry (33). involved the post dispersion of phenolic resins in a mixture of water and water-miscible solvents. To conform with air pollution regulations, the solvent was held to 20 volume %, or less, of the volatiles. A heat-reactive phenolic resin dispersion (34) and a phenolic-epoxy codispersion have become commercially available based on the above technology. Supplied at 40-45% solids, these products, which have a small particle size (0.75-1.0 ym), are better film formers than the earlier dispersions. Used alone or in blends with other waterborne materials, corrosion-resistant baking coatings may be formulated for coil coating primers, dip primers, spray primer-surfacers, and chemically resistant one-coat systems. Products of this type are also tackifiers for acrylic latexes, and such systems have been employed as contact, heat seal, and laminating adhesives for diverse substrates. 

Hercules AS, RS, SS. [Hercules] Nitrocellulose film-formers, bases for air-dry finishes, primers, surfacers, topcoats for transp( tation industry, lacquers, printing inks, adhesives, cements. 

Fillers are applied with electrostatic spraying devices (fast-rotating bells) to give dry film thicknesses of about 40 pm. Waterborne fillers with polyester-melamine binders (primer surfacers) have been developed to reduce the volatile organic content. They yield a film thickness of 30 pm after a prereaction time of 10 min at lOO C and a reaction time of 20 min at 165 °C. The properties of the films are similar to those formed by solventborne paints. More recently, waterborne fillers based on blocked isocyanates have been developed. Field trials have shown that their mechan-ieal resistance is very good. 

RP components continue to find more use in the OEM and replacement field. They include such items as primary structural supports, fenders, hoods, etc. Most of the RP used is SMC (Chapter 4). The continued development of improved primer surfacing for the RPs will undoubtedly increase the use of RPs in bodies and components. 

As indicated in Table 10.18, a zinc-rich primer is often recommended. It can be an organic zinc-epoxy or an inorganic zinc-ethyl-silicate primer. Zinc-rich primers are also used as so-called shop primers, or prefabrication primers, for temporary protection of semi-manufactured steel goods. After fabrication, e.g. of welded steel structures, the shop primer surface must be cleaned (degreased), and possible shop primer defects and weld joints have to be blast cleaned and coated with a primer before the whole structure is painted. Iron oxide is also used as a pigment in some shop primers. These must not be overpainted with a zinc-rich paint. 

Chem. Descrip. Fatty acid-modified polyester PU resin (45%) in water/N-methyl pyrrolidone, neutralized with dimethyl ethanolamine Uses Polyester for highly flexible aq. stoving systems, e.g., stone chip-resist. primer surfacers for on-line automotive finishing Features Rec. in combination with water-thinnable amino resins Properties Ylsh./brnsh. cloudy appearance 45 015 nm mean particle size sol. in water, alcohols, glycols, glycol ethers dens. = 1.1 ml (20 C) vise. 200-2000 mPa-s-(23 C) add no. 13 02 pH 7.25 00.75 (1 3 in DW) equiv. wt. = 1417 anionic 4501%NV Bayhydrol PR 135 [Bayer AG]... 

Uses Urethane for aq. parquet coatings, air- and force-drying primer surfacers for aufomofive refinishing additive resin to improve drying, hardness, and blocking resist, of aq. coatings Features Compat. with acrylic disps., other PU disps., water-thinnable polyesters and amino resins... 

Uses Leveling agenf, gloss aid, anficrafering agenf for aq. sysfems, aq. air-dried and baked indusfrial coatings, automotive fopcoafs, automotive primer surfacers, inks... 

Chem. Descrip. Aliphatic PU disp. (40%) in water with N-methylpyrroli-done (6.5%) and neutralizer N,N-dimethylethanolamine (1.9%), as salt Uses Urethane for highly flexible coafings, primers, decorafive top coats for plasfics, aq. primer surfacers... 

Uses Binder for one-pack stoving PU systems for highly flexible primers, intermediate coats, primer surfacers, and thin coil coating primers Properties Thinnable with esters, ketones, aromatic hydrocarbons dens. = 1.10 g/cm vise. 2000 01200 mPa-s-(23 C) flash pt. = 25 C 69 02% NV... 

Chem. Descrip. Branched sat. polyester resin in xylene Uses Polyester for solv.-based coatings, industrial coatings, bicycle and motor bike coatings, metallic base coats, primer surfacers, automotive accessory coatings... 

Uses Acrylic for fast drying two-pack systems, primer surfacers for car repair and general Industrial applies., automotive refinishinq, hlqh-qrade Industrial paints... 

Chem. Descrip. Highly reactive unsat. polyester resin (69%) in styrene Uses Binder for highly filled primer surfaces, e.g., knifing and spray fillers for automotive refinishing Features Produces hard films... 

---