Topcoat materials

The material used in this study is a model styrenated -acrylic/melamine topcoat over a black basecoat. The thickness of the topcoat is -40 pm. The topcoat material is known to have long-term reproducible mechanical properties. 

Topcoats can be used to protect the surface of coating from wear, abrasion, chemical attack, and environmental deterioration. For example, gold is used as a topcoat for many metallization systems in order to prevent corrosion and allow easy wire-bonding to the film surface. Polymer topcoat materials of acrylics, polyurethanes, epoxies, silicones, and siloxanes are available and are very similar to the coating materials that are used for conformal coatings and basecoats. These topcoats are used to improve abrasion and corrosion resistance of the film. 

The topcoat needs to completely encapsulate the CFRP system with no fiber strands exposed and needs to be applied within the manufacturer-specified application time window to ensure appropriate adhesion to the reinforcing fabric and to prevent amine blush. If conditions prevent the application of the topcoat within the manufacturer s specified application window, a solvent wipe, as recommended by the manufacturer, is to be apphed to the surface of the structural laminate to remove all amine blush. Localized and small blisters are to be removed and sanded, and the topcoat material reapplied as per the manufacturer s recommendations. The topcoat is to be inspected periodically and maintained as specified by the manufacturer to ensure its effectiveness. 

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. 

Synthetic MIO is used in primers as well as in topcoat paints the natural MIO was too coarse for use in undercoats. Weathering tests with different paint binders indicated that the performance of the synthetic product was as good or better than, that of the natural product (Carter and Laundon, 1990). The aspect ratio of MIO produced by hydro-thermal synthesis can be altered by doping with Al, Mn or Si, thus enabling a more lustrous material with a reddish-brown colour to be produced this material is suitable for decorative as well as for purely protective purposes (Pfaflfand Reynders, 1999). 

For several years the bonding agents have consisted of proprietary polymer/solvent solutions, with a primer coat based on phenolic-style resins and a topcoat formed from solutions of polymers and other ingredients. The formulation of these materials is not disclosed, but much patent literature is available. Bond formation appears to be associated with the development of a very high modulus layer in the rubber immediately adjacent to the surface of the substrate. The thickness of the layer is of the order of 15 pm and... 

Chlorinated polyolefins (CPOs) also are a mainstay of adhesion promotion to TPO. The CPO generally is applied as a dilute solution (5-35 wt. %) in aromatic solvents to the TPO to act as a tie-coat, to which the topcoat is applied. These materials are often humidity sensitive and only adhere to TPOs with EPDM levels of greater than 5 percent. 

Fig. 3 represents an example of the mat-like paving materials. According to the execution method as shown in Fig. 4, the mat-like paving materials are generally bonded to cement concrete or asphalt concrete substrates by using adhesives, and finished with acrylic resin topcoatings. Sometimes, fresh compositions with the same formulations are placed on the primer-treated cement concrete or asphalt concrete substrates, pressed with hot rollers, and finished with the same topcoating in the field. 

Ihe topcoat thickness, , (cf. Figure 1 and Eq. 4) is unspecified. In practice wiTl be dictated by considerations of the UV absorber solubility limit in the topcoat matrix material, by the topcoat thickness required to provide other beneficial effects (e.g., abrasion resistance, erosion resistance), by available topcoat application techniques, and by economics. However, we can construct a hypothetical topcoat of thickness L equal to that of the polymer films. Then... 

This diol was mixed with other diols, then reacted with diisocyanates to form polyurethanes. The electrically conducting polymers, polyaniline and polypyrrole, prevent corrosion of steel.105 One of the best formulations uses polyaniline with zinc nitrate, which is then covered with an epoxy resin topcoat. Polyorganosiloxanes have been grafted to starch using the sol-gel method with alkoxysi-lanes. These materials have been complexed with cerium ions to provide corrosion protection for aircraft that is expected to be 50% cheaper than conventional coatings.106... 

Table VII distributes automotive topcoat usage by type, with predictions for 1987. The progression from low-solids, high-emission coatings to high-solids systems is shown. Research and development of HS-E are active at each of the auto companies and at every major coatings supplier and raw materials producer. Certainly, problems such as specific polymer design and cross-linker choice still exist—as well as application, flow, and aluminum flake orientation. However, current and future research and development should reduce these problems rapidly to manageable levels.

Track-generated defects are classified as originating from the process films (topcoat, resist, and BARC), develop process, or from particles shed from track construction materials. When they are imaged, particles shed from the track will manifest the same types of defects as those from the scanner, as explained... 

Modified phenolic resins are condensation products of the resol type which contain other starting materials besides phenol and formaldehyde (e.g., acrylic monomers). The phenolic component itself is often modified (alkyl- or arylphenols). Modification with rosin is the most important one. The compatibility of phenolic resins with other binders can be substantially improved by modification. Rosin-modified phenolic resins may be combined with linseed oils and alkyd resins. Examples of use include putties, priming coats, rust protection paints, and colored topcoats. 

Geon 121AR Geon 124A Geon 213 raw material, automotive OEM topcoats... 

K Vestoll P1361 K raw material, coil coating topcoats... 

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