Colorants plastic resins colored with

Unsaturated polyester and methacrylate resins are frequently colored with pigment-plasticizer (DIDP) pastes. They have no measurable adverse effect on the important mechanical properties of the finished article. To a small extent pigments are also dispersed directly in one part of the monomer. 

One of the primary fields of application for P.R.151 is in polystyrene, although there is a slight color change at temperatures above 260°C, at which the pigment partially dissolves. It is also used to a considerable extent in ABS. Cast resins based on methylmethacrylate and unsaturated polyesters are also frequently colored with P.R.151, which is resistant to the peroxide catalysts that are used to harden the plastic. The lightfastness in these media is good it equals step 6-7 on the Blue Scale. 

In addition to jetness, plastics pigmented with carbon blacks typically exhibit color undertones. Undertone in black plastics appears as a distinct blue or brown-to-orange undertone, depending on the particle size of the carbon black used. In general, in full-shade, black molded applications, fine-particle-size carbon blacks impart a bluer tone. This behavior reverses itself in tints. Large-particle-size carbon blacks impart bluer undertone. Note that the effects of fillers, polymers, and dispersion can alter the typical behavior described above. Tint strength is the relative ability of the carbon black to darken a resin colored with chromatic pigments. 

Very frequently, the polymer material from the materials manufacturer does not go directly to the processor. There is often an intermediate step that involves the addition of other materials (chemicals, additives, modifiers) that serve to impart special properties or enhance the qualities of the polymers or resin. For example, polymers can be integrally colored (with polymers or dyes), made more flexible (with plasticizers), more heat and light resistant (with stabilizers), or stronger and more impact resistant (with fiber reinforcements). These modifiers may be supplied by the companies that manufacture the plastics themselves or by companies that specialize in the production of one or more modifiers. 

The number and amount of additives incorporated in a resin vary with resin type and application. A polyethylene resin, for instance, may have only an antioxidant incorporated, or a colorant may also be added. A PVC resin may require several plasticizers, a filler, a heat stabilizer, and a colorant. There are many variations, and in most cases, the final resin formulation is considered by the manufacturer to be proprietary information. A confidentiality agreement may be necessary to make certain that the material meets regulatory compliance, unless the supplier can give the end-user sufficient information to make the determination. 

The exact color a plastic resin or part must match to be acceptable. Resin suppliers often submit color chip samples of the matched resin color to be compared to the molded part. The color chip, or standard, is usually 51 X 76 mm with one polished surface and various textured surfaces on the opposite side. Suppliers use similar standards to verily the color of each lot of resin shipped to their customer. 

Extrusion coloring n. the method of adding colorants to a plastic compound by dryblending the colorant with the solid granular resin, extruding the mixture into strands, and cutting these strands into pellets for use in subsequent processing operations. 

Polypropylenes (PPs) are in the polyolefin family of plastics. They are semitranslucent and milky white in color, with excellent colorability. They are produced by a stereoselective catalyst that puts order in their molecular configuration so that the basic resin has a predominantly regular, uniform structure. This means that the molecules crystallize into compact bundles, which makes them stronger than other members of the polyolefin family. PPs are an extremely versatile plastic available in many grades as well as copolymers like ethylene propylene. Neat PP has a low density of 0.90, which, combined with its good balance of moderate cost, strength, and stiffness as well as excellent fatigue, chemical resistance, and thermal and electrical properties, makes PP extremely attractive for many indoor and outdoor applications. 

In many commercial applications, where rapid degradation is not required, it is convenient to prepare a concentrate containing 2 to 5% of the ketone monomer. This concentrate, which may also be colored with selected pigments, can then be blended with natural resin in ratios of 1 9 to 1 20 and extruded or molded to provide products with the desired rate of degradation. Control of the rate is provided by changes in concentrate and/or pigment concentration. In some cases, the ketone groups can be introduced by a chemical post-treatment. Because of the minor amount of modification required, the physical properties of the photosensitive resin are almost identical with those of the untreated plastic. 

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