Pelletization plastics coloration

Drum tumbler n. A device used to mix plastic pellets with color concentrates and/or regrind. The materials are charged into cylindrical drums that are tumbled end-over-end or rotated about an inclined axis for a time sufficient to thoroughly blend the ingredients. 

The economics of recycling PET are more favorable than recycling HDPE. To iacrease the recycling of HDPE, the separation of bottles made of these two plastics could be omitted and a mixture processed. Coarse, light-colored powders of the two polymers have been prepared by an experimental soHd state shear extmsion pulverization process (55). The powder has been successfully injection molded without pelletization. 

Capsules— These are primarily intended for oral administration and are solid preparations with hard or soft shells comprised of gelatin or hydrox-ypropyl methyl cellulose and small amounts of other ingredients such as plasticizers, fillers, and coloring agents. Their contents may be powders, granules, pellets, liquids, or pastes. 

Plastic pellets, threat from, 20 231 Plastic pumps, for corrosive liquids, 21 76 Plastic refractories, 21 482 Plastics. See also Styrene plastics adhesion of coatings to, 7 91-92 advanced materials, 1 693 cellulose ester applications, 5 404 chemical exposure tests on, 19 583 citric acid application, 6 648 colloidal suspensions, 7 273t colorants for, 7 358-380 development of, 10 168... 

Polymerization takes place in reactors such as those described previously. The polymer is then usually cooled to solidify it and then it is formed into pellets or beads of a convenient size for shipping and forming. In this process, the solid is usually melted, and mixed with other chemicals (plasticizers, antioxidants, colorants, solvent) or other polymers to form blends. 

In dust-free and dispersed form, they are supplied as concentrated plastic granules (masterbatch pellets), as concentrated pastes, and as liquid colors. These products are added at different stages in the processing of plastics. 

By varying the design of the process section, additional simultaneous processing tasks, such as stabilizing, coloring, mixing-in of plasticizers, filtration, and pelletizing are possible. 

With the exception of solubility in organic solvents, the properties of dyestuffs are the same as other coloring materials. Water solubility is important when extrusion pelletizing of plastics is employed, so no migration will occur to contaminate metal surfaces or reduce the effectiveness of the coloring material. 

All ingredients of a formulation, such as polymers, additives, extender and reinforcing material, and colorants as well as black and white pigments, should be plasticized and dispersed before the addition of aluminum pigments. The aluminum pigment in the form of predispersed pellets or pastes is incorporated into the batch to obtain a uniform blend with no additional dispersion. 

Figure 20.4. Common methods of coloring plastics (a) 100 pellets of natural regin (b) liquid color on pellets (c) 4% pellet concentrate (d) excess of dry color.

Companies will custom formulate colorant and additive products designed to be used by plastic molders, who will, in turn, produce the final consumer products. The raw materials for colorant and additive products may be in powder, liquid, or solid form. The products formulated from them may also be in powder, liquid, or solid form. Dry color formulations (powder form) currently comprise less than 5% of the total colorant and additive products being produced today. Liquid formulations account for another 5% however, this form of product is increasing in popularity and is expected to capture a larger share of the colorant and additives market in the near future. The solid form, known as concentrates or masterbatch products, are concentrated ingredients encapsulated in a carrier resin that is usually in pellet form. This type of product comprises the overwhelming majority of the formulated products used by molders and compounders today. A discussion of the basic production processes associated with the production of the various colorant and additive product types is presented below. 

The desired bottles then proceed to the grinder and the washing machine. The ground plastic is washed to remove product and labels. The paper labels sink and the HD PE is floated off the top and conveyed to a drier. Contaminants such as glass and metals also sink and are discarded with the paper labels. After the material is dry, it can be boxed or extruded and pelletized. Color or additives can be added to the resin prior to extrusion if necessary. 

Carbon black [1333-86-4] is virtually pure elemental carbon (diamond and graphite are other forms of nearly pure carbon) in the form of near-spherical colloidal particles that are produced by incomplete combustion or thermal decomposition of gaseous or Uquid hydrocarbons. Its physical appearance is that of a black, finely divided pellet or powder, the latter sometimes small enough to be invisible to the naked eye. Its use in tires, mbber and plastic products, printing inks and coatings is related to the properties of specific surface area, particle size and structure, conductivity and color. 

The analogy is a three-dimensional pile of coal, catalyst, plastic pellets, soil particles, or other solid material. It could be in the field, plant, or lab. From each of these perspectives, consider how you would physically obtain several randomly chosen individual blocks from this group of 27. How would you access material in the middle, realizing that the material readily accessible on the top or outside may not be representative How would you define a correct sample and extract it Next, reduce the sampling dimension to 2 or 1. Define and extract correct samples. How well would this work in situations you encounter Review your methods and logic after segregating the blocks by color from top to bottom or using some other pattern. 

The pellets of plastic are first transferred from storage to the hopper on the extruder, which serves as a reservoir to feed the solid particles into the barrel. The hopper can be a simple one like the one shown in Fig. 7.1. Most extrusion operations are automated at least to the point of having a vacuum hopper loader to bring material to the hopper. Specialized equipment is available to mix in color and other... 

The process can combine conventional glass fiber roving, aramid, or carbon fiber tows with TPs, most commonly polyethylene terephthalate (PET) and nylon (polyamide/PA). Other plastics used include polyphenylene sulphide (PPS), styrene-maleic anhydride (SMA), high-density polyethylene (HDPE), and polypropylene (PP). The TPs can take the form of pellets, chips, chunks, or shreds, and as the process uses hot-melt injection, no solvents or two-part systems are involved. Additives such as colorants and fillers can be used as required. 

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