Urea resins, plasticizers

Polymers. AH nitro alcohols are sources of formaldehyde for cross-linking in polymers of urea, melamine, phenols, resorcinol, etc (see Amino RESINS AND PLASTICS). Nitrodiols and 2-hydroxymethyl-2-nitro-l,3-propanediol can be used as polyols to form polyester or polyurethane products (see Polyesters Urethane polymers). 2-Methyl-2-nitro-l-propanol is used in tires to promote the adhesion of mbber to tire cord (qv). Nitro alcohols are used as hardening agents in photographic processes, and 2-hydroxymethyl-2-nitro-l,3-propanediol is a cross-linking agent for starch adhesives, polyamides, urea resins, or wool, and in tanning operations (17—25). Wrinkle-resistant fabric with reduced free formaldehyde content is obtained by treatment with... 

Urea is used to make urea-formaldehyde plastics and resins and, increasingly, as a nitrogenous fertilizer (46.7% N). World production of urea was 23 million tonnes in 1984. 

Thermosets A number of thermosets have been used as adhesives. Phenolic resins were used as adhesives by Leo Baekeland in the early 1900s. Phenolic resins are still used to bind together thin sheets of wood to make plywood. Urea resins have been used since 1930 as binders for wood chips in the manufacture of particle board. Unsaturated polyester resins are used for body repair and PUs are used to bond polyester cord to rubber in tires, and vinyl film to particle board, and to function as industrial sealants. Epoxy resins are used in the construction of automobiles and aircraft and as a component of plastic cement. 

The United States production of amino plastics was more than 3 billion pounds in 2001. The urea-formadehyde polymers account for slightly more than 85% of the total. The amino plastics are similar in properties to the phenolics but are clearer and colorless. They are also harder but have somewhat lower impact strength and resistance to heat and moisture. The melamine resins are better than the ureas in hardness and resistance to heat and moisture. The melamine and urea resins are rated for continuous use at temperatures of 130-150°C and 100°C, respectively. The general applications of the amino and phenolic plastics are the same but there are uses where the amino plastics are superior. The melamine resins find an important niche due to their combination of clarity and lack of color compared to the phenolics and their superior hardness and heat and moisture resistance compared to... 

Another use of urea is for resins, which are used in numerous applications including plastics, adhesives, moldings, laminates, plywood, particleboard, textiles, and coatings. Resins are organic liquid substances exuded from plants that harden on exposure to air. The term now includes numerous synthetically produced resins. Urea resins are thermosetting, which means they harden when heated, often with the aid of a catalyst. The polymerization of urea and formaldehyde produces urea-formaldehyde resins, which is the second most abundant use of urea. Urea is dehydrated to melamine, which, when combined with formaldehyde, produces melamine-formaldehyde resins (Figure 96.2). Melamine resins tend to be harder and more heat-resistant than urea-formaldehyde resins. Melamine received widespread attention as the primary pet food and animal feed contaminant causing numerous cat and dog deaths in early... 

Urea is also used as a protein food supplement for ruminants, in melamine production, and as an ingredient in the manufacture of pharmaceuticals (e.g., barbiturates), synthetic resins, plastics (urethanes), adhesives, coatings, textile antishrink agents, and ion exchange resins. It is an intermediate in the manufacture of ammonium sulfamate, sulfamic acid, and pthalocyanines. 

Urea has the chemical formula (NH2)2CO and is also known by its older name carbamide. Urea is manufactured industrially from ammonia (NH ) and carbon dioxide (C02) and is used mainly as a fertilizer. It is also added to animal feeds to increase their nitrogen content, and is used to make resins, plastics, and pharmaceuticals. Urea peroxide is simply a combination of urea and hydrogen peroxide and as such is a useable source of this latter chemical in the form of a stable white crystalline solid. 

Plastics (polyvinyl acetate, alcohol, chloride, monovinyl acetate, phenolic, urea, and melamine resins, plastics in rods, sheet, and other forms)... 

Silicone resins Soybean plastics Styrene resins Styrene-acrylonitrile resins Tar acid resins Urea resins Vinyl resins... 

Note As this table shows, the largest outlet for amino resins by far is their use as adhesives or binders for reconstituted wood products made from sawdust and wood chips. Urea-formaldehyde resin is most commonly used. Melamine-formaldehyde resin can provide improved water resistance and may be combined with the urea resin to provide an improved product. Molding compounds are about the next most important outlet for amino resins. It is approximately evenly divided between urea and melamine. The primary use for urea moldings is in the electrical field, while the most important area for molded melamine plastic is dinnerware. 

If the formaldehyde test is positive, heat a sample of the plastic with a 10% glycolic solution of potassium hydroxide (dissolve 10 g KOH in approximately 95 ml ethylene glycol). A smell of ammonia (confirmed by blue color of moist red litmus paper) indicates urea resins. Melamine resins do not... 

Uses Catalyst, hardener for acid-curing one-pack wood coatings, plasticized urea resins, amino-al blends Features Long storage stability... 

We will conform to Carothers classification in the sections devoted to the preparation of synthetic polymers. However, when considering the application of polymers it is more useful to consider the following three categories (1) plastics, which include thermosetting resins, such as urea resins, polyesters, or epoxies, and thermoplastic resins, such as poly-... 

Additives used in final products Plasticizers 2-ethylhexyl diphenyl phosphate, acetyl tributyl citrate, acrylic resin (Aoronal 700 L), aliphatic polyurethane, butyl benzyl phthalate, camphor (plasticizer of celluloid), castor oil, dibutyl phthalate, dimethyl phthalate, dllsooctyl phthalate, epoxidized soybean oil, glyceryl triacetate, glyceryl tribenzoate, glyceryl tribenzoate, N-ethyl (o,p)-toluenesulfonamide, octyl diphenyl phosphate, sucrose acetate isobutyrate, tricresyl phosphate, triethylene glycol, urea resin Antistatics poly(3,4-ethylenedioxythiophene sulfonate), vanadium pentoxide Slip alumina, silica Amines (stabilizers of gunpowder) ... 

Plastics materials and resins), for example, acrylics, acrylonitrile-butadiene-styrene, alkyds carbohydrate, casein, and cellulose acetate plastics cellulose nitrates elastomers epoxy, ethylene-vinyl acetate, ion exchange, methyl cellulose, methyl methacrylate, nitrocellulose, nylon, polyacrylonitrile, polyamide, polycarbonate, polyester, polyethylene, polyethylene terephthalate, polyurethane, polyvinyl alcohol, polyvinyl chloride, silicone, urea, resins thermoplastics, thermosets... 

Pyroelectricity, piezoelectricity, and fieiroelectricity in polyurea and polythiourea have not attracted much interest until recently. Urea resins are highly cross-linked amorphous polymers and have been used as insulating plastics for many years. Polyurea and polythiourea are usually synthesized by condensation or addition polymerization, and the products are mostly in the form of powders. Owing to their insolubility, preparation of films was not possible. 

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