SIC 2821 Plastic Materials and Resins
SIC 2821
The plastic materials and resins industry is comprised of companies primarily engaged in manufacturing various resins and plastics for sale to other industries that create plastic sheets, rods, films, and other products. Information on related products can be found under SIC 2822: Synthetic Rubber, SIC 2823: Cellulose Manmade Fibers, and SIC 2824: Organic Fibers—Noncellulosic.
325211
Plastic Material and Resin Manufacturing
Synthetic plastic was invented late in the eighteenth century and did not reach widespread use in the United States until the 1900s. Swift advances in chemical and manufacturing technologies during the twentieth century, however, made plastic one of America's most important manufacturing materials. In 2006 the United States produced 113.2 billion pounds of resins. The most important uses of plastics include packaging, building and construction, transportation, and consumer and institutional uses.
According to the Society of the Plastics Industry Inc. (SPI), plastics products is the fourth-largest manufacturing segment in the United States, behind petroleum and coal, motor vehicles, and motor vehicles parts. The specific category of resins, synthetic material, and rubber production ranked fifteenth among U.S. manufacturing industries.
Approximately 18,250 companies manufacture plastic products or plastics raw materials in the United States. Production facilities are predominately in California, Texas, and the Midwest (Ohio, Michigan, Illinois, and Indiana), with the top 10 states accounting for 60 percent of all plastics employment.
Plastics provide an important alternative to natural materials for a plethora of applications. One of the most important distinguishing factors between plastic and other materials is plastic's ability to "creep" under load, or gradually stretch or flow when subjected to stress. While metals and ceramics exhibit this property as well, they do so only at much higher temperatures. Plastics also resist erosion and do not require a coating to protect them against inorganic acids, bases, and water or salt solutions. Perhaps the greatest advantage that plastics offer, however, is their ability to be molded into any shape and to be processed to exhibit any of a massive number of physical characteristics.
The synthetic materials industry is considered a segment of the overall chemical industry; synthetic materials manufacturers represent about 20 percent. The plastics industry comprises about 70 percent of the entire synthetic materials industry, which also encompasses rubber and manmade fibers. Manufacturers produce about 500 different types of resins and compounds. Each of these products is available from various suppliers in multiple grades, with each grade offering varying physical properties and prices.
Plastics are giant polymers, or long-chain molecules that contain thousands of repeating molecular units. When combined with other ingredients called additives, the polymers can be shaped and molded under heat and pressure into a resin. Resins are produced through chemical processes that combine carbon with other elements such as oxygen, nitrogen, and hydrogen. Resin usually takes the form of pellets, flakes, granules, powder, or a syrupy liquid. Most resins are not used in their natural state, but are instead combined with other materials by mixing or melt-state blending. The end result is a plastic compound, still in the form of pellets, granules, or powder, that is ready to be delivered to a processor. There are two basic kinds of plastics: thermoplastics, which can be re-softened to their original condition by the application of heat; and thermosets, which cannot be re-softened. The production of thermoplastic resins surpasses the production of thermosetting resins by a ratio of about 8 or 9 to 1. Thermosetting resins include epoxy and polyester; thermoplastic resins include polyethylene and polyvinyl chloride, more commonly known as PVC.
The physical properties of the final plastic product can be altered at various stages of the polymerization and production process. The most versatile method of varying properties is by compounding. With this method, additives—such as colorants, flame retardants, heat or light stabilizers, or lubricants—may be added to the resin to achieve a desired result. Fillers or reinforcement—such as glass fibers, particulate materials, or hollow glass spheres—may instead be added to the resin, as may other polymers, which form a polymer blend or alloy.
Plasticizers are the most common additives used to alter plastic resins. Plasticizers increase a resin's flexibility and are often used to make polyvinyl chloride resins used in construction products. Impact modifiers are an additive used to boost a plastic's resistance to stress. Similarly, antidixodiants retard the oxidation and breakdown of plastics, and heat stabilizing additives help resins to maintain their physical structure during processing. Light stabilizers filter out radiation that can cause a plastic to deteriorate as a result of exposure to sunlight, and flame retardants enable resins to resist combustion. Colorants are another major additive used in the compounding process.
Four major commercial...
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