Resins metallic pigment processing

Sanding is carried out at this stage and, after clean-up, the final colour or top-coat is applied. There is some variation in the resin chemistry used. Alkyds crosslinked with melamine-formaldehyde are widely used for non-metallic pigmentation. Metallics are usually based on acrylics for better durability. The acrylic may be thermoset with melamine-formaldehyde or a thermoplastic lacquer (plasticised copolymer of methyl methacrylate). A thickness of about 50ftm is applied and stoved for 20 min at 130°C (lacquers receive a bake-sand-bake process for a smoother appearance). 

The SCORIM Process. It is possible to attach the SCORIM unit to the injection molder to manipulate the filling process of the mold so that in the area of the weld lines the resin is mixed [16]. This will improve the structural strength substantially and at the same time the unwanted orientation of metallic pigments is prevented. This process typically requires a 10-15°C higher temperature of the resin and the mold. The process is based on a prolonged flow ability of the polymer. 

Aluminum pigments are not overly resistant to acids, alkali, chlorine, etc. For most plastic applications, this is of minor importance because these types of chemicals are not present during processing. Once the metallic pigments are imbedded into the plastic, the resins protect their surface and these chemicals have little effect. 

Uses Biocide, preservative for aq. systems, paints/coatings, latexes, resin emulsions, pigment slurries, dispersed colors, Joint cements, adhesives, metal working fluids, textile processing sol ns. 

Pigmented resins are applied as dry powders and then fused by heating to 220°C or higher. The process is effective with lightweight metal components and pipework. It is likely to remain uneconomic for use on heavy sections, e.g. hot-rolled steel universal beams and columns. 

A number of resinated grades are produced in order to provide higher transparency and to optimize other aspects of pigment properties in application. For reasons connected with process engineering, the resin is typically incorporated as a metal (calcium) resinate. In the past, types of P.R.57 1 additionally contained certain amounts of barium sulfate. 

It is also discussed in the literature that, under moist conditions, basic complexes can be formed by reaction of zinc phosphate with inorganic ions or with carboxylic groups of the resin used, which lead, by reaction with metal ions, to so-called adhesion, cross-linking and inhibitor complexes [5.67-5.69]. Under the assumption, that the hydrolyzation process is the prerequisite for the effectiveness of zinc phosphates, this means that such pigments need a certain time before becoming active [5.69]. 

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