Paint adhesion

Most of the acetic acid is produced in the United States, Germany, Great Britain, Japan, France, Canada, and Mexico. Total annual production in these countries is close to four million tons. Uses include the manufacture of vinyl acetate [108-05-4] and acetic anhydride [108-24-7]. Vinyl acetate is used to make latex emulsion resins for paints, adhesives, paper coatings, and textile finishing agents. Acetic anhydride is used in making cellulose acetate fibers, cigarette filter tow, and ceUulosic plastics. 

Product Utilization. Zinc phosphate coatings form the basis for paint adhesion in a variety of industries. These are used when long-term quahty is of concern in appHcations such as for automotive parts and vehicles, cod-coated products, and appHances. 

Testing of Painted Products. The enhancement of paint adhesion is one of the principal functions of conversion coating (20—22). A group of tests based on product deformation is used to test the painted product. The appHance and cod-coating industries use the mandrel bend, the cross-hatch adhesion test, and the direct and reverse impact tests. Adhesion after a water soak is judged using a cross-hatch test performed on the exposed surface. 

Zinc phosphate, Zn2(P0 2> forms the basis of a group of dental cements. Chromium and zinc phosphates are utilized in some metal-treating appHcations to provide corrosion protection and improved paint adhesion. Cobalt(II) phosphate octahydrate [10294-50-5] Co2(P0 2 8H20, is a lavender-colored substance used as a pigment in certain paints and ceramics. Copper phosphates exhibit bioactivity and are used as insecticides and fungicides. Zinc, lead, and silver phosphates are utilized in the production of specialty glasses. The phosphate salts of heavy metals such as Pb, Cr, and Cu, are extremely water insoluble. 

Orifice. Orifice viscometers, also called efflux or cup viscometers, are commonly used to measure and control flow properties in the manufacture, processing, and appHcation of inks, paints, adhesives, and lubricating oils. Their design answered the need for simple, easy-to-operate viscometers in areas where precision and accuracy are not particularly important. In these situations knowledge of a tme viscosity is uimecessary, and the efflux time of a fixed volume of Hquid is a sufficient indication of the fluidity of the material. Examples of orifice viscometers include the Ford, Zahn, and Shell cups used for paints and inks and the Saybolt Universal and Furol instmments used for oils (Table 5). 

The Hercules viscometer was originally designed for paper and paperboard coatings, but its use has been extended to paints, adhesives, mineral slurries, emulsions, and starch solutions. The iastmment, noted for being robust and rehable, is particularly well suited for quaUty control and product formulation. It is capable of measuting viscosity over a moderate range 1-10 mPa-s) up to high shear rates (115,000 ). A more recent model is the... 

Because of its high cold flow, poly(vinyl acetate) is of little value in the form of mouldings and extrusions. However, because of its good adhesion to a number of substrates, and to some extent because of its cold flow, a large quantity is produced for use in emulsion paints, adhesives and various textile finishing operations. A minor proportion of the material is also converted into poly(vinyl alcohol) and the poly(vinyl acetal)s which, are of some interest to the plastics industry. 

Petrochemicals in general are compounds and polymers derived directly or indirectly from petroleum and used in the chemical market. Among the major petrochemical products are plastics, synthetic fibers, synthetic ruhher, detergents, and nitrogen fertilizers. Many other important chemical industries such as paints, adhesives, aerosols, insecticides, and pharmaceuticals may involve one or more petrochemical products within their manufacturing steps. 

Fig. 9.23 Welded areas of an offshore platform structural tubular displaying premature corrosion due to (a) lack of surface grinding (resulting in poor paint adhesion and performance) and (b) the fact that the weld metal is anodic relative to the parent material of the tubular...

Designs should therefore avoid, as far as possible, all features that allow water (whether seawater, rainwater or moisture from any source) to be applied, entrapped or retained. These conditions are not only corrosive towards bare metals they also adversely affect the life of protective coatings both directly and by the fact that it is often difficult at areas subject to these conditions to give sound and adequate surface preparation for good paint adhesion and subsequent performance. 

Chromating Chromating is considered in Section IS.3. The chromate film on zinc is adherent and can be drab, yellow-green or colourless in appearance the colour varies considerably with the method of application. It retards white rust , the white deposit which sometimes forms on fresh zinc surfaces which are kept under humid conditions (see Section 4.7). A chromate film is damaged by heat and if used as a basis for paint adhesion, should preferably not be heated above 10°C, nor for longer than 1 h. 

Since the previous edition was written, the main development has been the introduction of a range of zinc alloy coatings designed to give increased corrosion resistance and sometimes with additional advantages such as increased formability and retention of paint adhesion with a wider range of paints. 

Adhesion the degree of attachment between a paint or varnish film and the underlying material with which it is in contact. The latter may be another film of paint (adhesion between one coat and another) or any other material such as wood, metal, plaster, etc. (adhesion between a coat of paint and its substrate). Adhesion should not be confused with cohesion (. v.). 

Organic materials Corrosive vapours are sometimes emitted by organic materials used either in packaging or in the manufactured article, and may be troublesome in confined spaces. Some woods, particularly unseasoned oak and sweet chestnut, produce acetic acid (see Section 18.10), and certain polymers used in paints, adhesives and plastics may liberate such corrosive vapours as formic acid and hydrogen sulphide . It may be necessary to carry out exposure trials, particularly where materials capable of liberating formaldehyde or formic acid are involved. Most corrosion problems of this kind can be prevented by using desiccants, and in many cases they are confined to imperfectly cured materials. For an excellent review see Reference 9. 

There are, however, certain materials used as ingredients in the manufacture of plastics, which almost invariably give a corrosive product. Included in this category are wood, which is frequently used as a filler or as part of a composite drying oils, used in paints, adhesives, jointing compounds and linoleum and esters of volatile acids frequently retained in certain cold setting formulations, especially some paints. ... 

Vinyl acetate h2c chococh3 Polyfvinyl acetate) Paint, adhesives, foams... 

The need to paint the blends has also resulted in new painting systems. Recently, a nonpolar color coat based on a hydrogenated polybutadiene diol and melamine resin for TPO bumper fascia was invented. The breakthrough technology allows the elimination of the TPO pretreatment step such as adhesion promoter, flame, or plasma during manufacturing. The paintability of two different types of E-plastomers was evaluated. The olefinic white paint was found to provide excellent paint adhesion for both types of metallocene plastomers. Paint peeling was not observed in any of the test... 

Gooch [4] has reported general deformulation schemes for solid paints and coatings, liquid paints, solid plastics, liquid plastic specimens, solid and liquid adhesives, in which preliminary examination (by OM, SEM, EDXRA) is followed by separation of the individual components and their subsequent identification (Scheme 2.9). Gooch employs different deformulation schemes for solid and liquid specimens, but essentially identical approaches for plastics, paints, adhesives and inks (Scheme 2.10). 

Vinyl polymers [polystyrene, PVC, polyethylene, polypropylene, poly(vinyl acetate), poly(vinyl alcohol), polyacrylonitrile] -1920 Packaging, tubing, household goods, records, carpets, toys, water based paint, adhesives, varnishes Phthalate esters, poly(vinyl alcohol) ... 

This combination gives a very useful blend of mechanical properties. The PBT phase provides melt flow, solvent resistance and the ultimate heat performance of the blend (Tm). The PC phase provides reduced shrink, better dimensional stability, higher heat capability under low load (66 psi HDT) and improved impact strength. Interestingly, the PC also provides improved paint adhesion by being present as a very thin outer layer in molded parts. PBT, by virtue of its solvent... 

Overall, the PC blends improve the HDT and impact, especially in the absence of fillers such as glass fiber. The PC reduces shrink and, in glass-filled blends, reduces warp (the amorphous PC resin shrinking less than the PBT). The PC also improves PBT paint adhesion and other secondary operations such as gluing. 

Back, E.L. and Danielsson, S. (1987). Oxidative activation of wood and paper surfaces for bonding and for paint adhesion. Nordic Pulp and Paper Research Journal, 2(special issue), 53-62. 

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