Heat resistance, colorants

A totally different method is being used if the aluminum pigments are coated with colored metal oxides. By this method very heat resistant, colored metallic pigments can be produced of various shades depending on the applied metal oxide. These shades are less intense and less brilliant [8] if compared to aluminum pigments colored with organic colorants [9]. 

Though polyolefins are suitable polymers to use in outdoor durable applications they must be used in concert with weatherfast, heat resistant colorants to maintain color. Dyes are not recommended for use in polyolefin applications because they will be soluble and migrate out of the matrix. 

A polyester-type fluorescent resin matrix (22) is made by heating trimellitic anhydride, propylene glycol, and phthaUc anhydride with catalytic amounts of sulfuric acid. Addition of Rhodamine BDC gives a bright bluish red fluorescent pigment soluble in DME and methanol. It has a softening point of 118°C. Exceptional heat resistance and color brilliance are claimed for products of this type, which are useful for coloring plastics. 

Vinyl Acetate—Ethylene Copolymers. In these random copolymers, the ratio of ethylene to vinyl acetate (EVA) is varied from 30—60%. As the vinyl acetate content increases, the oil and heat resistance increases. With higher ethylene content the physical strength, tensile, and tear increases. The polymers are cured with peroxide. The main properties of these elastomers include heat resistance, moderate oil and solvent resistance, low compression set, good weather resistance, high damping, exceUent o2one resistance, and they can be easily colored (see Vinyl polymers, poly(VINYL acetate)). 

Titanate Pigments. When a nickel salt and antimony oxide are calcined with mtile titanium dioxide at just below 1000°C, some of the added metals diffuse into the titanium dioxide crystal lattice and a yellow color results. In a similar manner, a buff may be produced with chromium and antimony a green, with cobalt and nickel and a blue, with cobalt and aluminum. These pigments are relatively weak but have extreme heat resistance and outdoor weatherabihty, eg, the yellow is used where a light cadmium could not be considered. They are compatible with most resins. 

Porcelain enamels meet a variety of performance characteristics required for different appHcations. The common characteristics of all enamels include good adherence to the substrate and good thermal expansion fit to the metal. Specific properties depend on usage for example, acid and alkaH resistance, hot water resistance, abrasion resistance, thermal shock resistance, high gloss, high reflectance, specific color, heat resistance, and cleanabihty. 

Polysulfone It is a high performance amorphous plastic that is tough, highly heat resistant, strong and stiff. Products are transparent and slightly clouded amber in color. Material exhibits notch sensitivity and is attacked by ketones, esters, and aromatic hydrocarbons. Other similar types in this group include polyethersulfone, polyphenyl-sulfone, and polyarylsulfone. Use includes medical equipment, solar-heating applications and other performance applications where flame retardance, autoclavability and transparency are needed. 

Alkyd They are easy to mold, have high heat resistance, and excellent electrical performance, and may be light-colored. 

The pigments are also required to have a specific heat resistance. This is tested on five colorations with different pigment concentrations in the range 0.01 to 1% together with 10 times the amount of chalk. The colorations placed side by side are vulcanized hot for 15 minutes at 140°C and evaluated coloristically against the corresponding untreated comparison coloration. 

P.Y.116 is also used in plastics. In plasticized PVC, it shows little tendency to bleed and is thermally stable up to 180°C. The lightfastness of transparent PVC colorations (0.1% pigment) equals step 7-8 in 1/3 SD (with 5% TiOz), it corresponds to step 6 on the Blue Scale. Insufficient heat resistance limits the application of P.Y.116 in polyolefins, polystyrene, and other polymers which are processed at high temperature. 

In polymers, P.R.146 is only used to color rigid PVC. Transparent colorations (0.1 %) afford a lightfastness which matches step 8 on the Blue Scale, while opaque specimens equal between step 6-7 and step 6, depending on the standard depth of shade and on the TiOz content. Insufficient heat resistance in polyolefins (less than 200°C) precludes its use in such media. 

The plastics type is suitable among others for HDPE, PP and for PVC. 1/3 SD colorations of HDPE (1% TiOz) require 0,35% pigment. These colorations are heat resistant up to 300°C and equal step 8 on the Blue Scale for the lightfastness. The shrinkage of the polymer is only slightly affected at temperatures between 220 and 260°C and somewhat affected at temperatures up to 300°C. P.O.71 has a very good bleeding fastness in plasticized PVC. It is also of interest for the use in PP fibres. 

The plastics industry uses these pigments mainly for polyolefins. The tinctorial strength is comparatively moderate. 1/3 SD HDPE colorations (1% TiOz), for instance, require between 0,22 and 0,7% of these pigment grades. Such colorations are heat resistant up to 300°C. Transparent colorations in 1/3 SD are stable up to 250°C. 

Phenolic resins are the cheapest of all molding materials, since they usually contain more than 50% filler—sawdust, glass fibers, oils, etc. Their main properties are heat resistance, excellent dielectrics, and ease of molding. However, they have poor impact resistance (they crack) and they don t hold most dyes very well, except black. Their use is thereby restricted— they re functional but not pretty. When the telephone companies started making phones in colors, they quit using phenolic resins and instead bought more expensive thermosets. 

Titanium (Ti) is used as a major component of Ti alloys, which are used as heat-resistant Ught metals for the construction of aircraft and rockets. Though Ti is also used as an anti-acid metal, it bums in air when heated above 1500 K. TiCl4 is a Uquid used to form colored smoke in air. 

Combines good properties of P/F and U/F resins Water and heat resistant Pastel colors... 

There are important modifications of alkyds that help in specific applications. Phenolics can be added to improve film hardness and water resistance, but these confer increased yellowing tendencies on the final coating. Silicones impart heat resistance and exterior durability. Styrene increases the drying speed. Methyl methacrylate when added gives faster drying properties and improves the color and durability of the coating. 

At temperatures above 160°C, PAN begins forming cyclic imines that dehydrogenate forming dark-colored, heat-resistant, fused ring polymers with conjugated C=C and C=N bonding. This is described in Section 12.17. 

At temperatures above 160 C, PAN forms cyclic imtnes which dehydrogenate in the presence of oxygen to produce dark-colored heat-resistant ladder polymers with conjugated C C and C=N bonds. 

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