Polymer resin urea-formaldehyde

Syntactic Cellular Polymers. Syntactic cellular polymer is produced by dispersing rigid, foamed, microscopic particles in a fluid polymer and then stabilizing the system. The particles are generally spheres or microhalloons of phenoHc resin, urea—formaldehyde resin, glass, or siUca, ranging 30—120 lm dia. Commercial microhalloons have densities of approximately 144 kg/m (9 lbs/fT). The fluid polymers used are the usual coating resins, eg, epoxy resin, polyesters, and urea—formaldehyde resin. 

Amino resins. Llrea, the first recorded, synthetically produced, organic compound, can be reacted with formaldehyde to form polymers called urea-formaldehyde resins or amino resins. Its chemistry is similar to the phenolic resins. 

Urea resins (urea formaldehyde polymers) are formed by the reaction of urea with formaldehyde (Fig. 1). Monomethylolurea (HOH2CNHCONH2) and dimethylolurea ((HOH2CNHCONHCH2OH) are formed first under alkaline conditions. Continued reaction under acidic conditions gives a fairly linear, low-molecular-weight intermediate polymer. 

CNC REZ TLG is a high polymer modified urea-formaldehyde syrup resin. 

Urea, (p-ethoxyphenyl)-. See Dulcin Urea, 1,3-ethylene. See 2-lmidazolidinone Urea/formaldehyde adduct Urea/formaldehyde condensate Urea/formaldehyde copolymer Urea/formaldehyde oligomer Urea/formaldehyde polymer Urea/formaldehyde precondensate Urea/formaldehyde prepolymer. See Urea-formaldehyde resin Urea-formaldehyde resin CAS 9011-05-6... 

Aminopropyltrimethoxysilane 2-(3,4-Epoxycyclohexyl) ethyltrimethoxysilane Formaldehyde/toluenesulfonamide polymer Glycidyl ether 100 Isocyanatopropyltriethoxysilane Mercaptopropyltrimethoxysilane Terpene resin Urea-formaldehyde resin adhesion promoter, concrete Diacetone acrylamide adhesion promoter, concrete-curing compounds Terpene resin... 

Styrene/butadiene polymer Styrene/methyl methacrylate copolymer Styrene/a-methyl styrene resin Tall oil rosin Tallow amide Terpene resin Tetrasodium pyrophosphate Trimethylolpropane Urea-formaldehyde resin Urea-formaldehyde resin, butylated Vinyl chloride/vinyl acetate copolymer Vinyl chloride/vinylidene chloride copolymer coatings, food-contact acrylate ester copolymer Sodium borate... 

Formaldehyde f6r- mal-d9- hld, fer- [ISV form- + aldehyde] (1872) (formic aldehyde, methanal, oxymethylene) n. HCHO. A colorless gas with a pungent, suffocating odor, obtained most commonly by the oxidation of methanol or low-boiling petroleum gases such as methane, ethane, etc. The gas is difficult to handle, so it is sold commercially in the form of aqueous solutions (formalin), solvent solutions, as its oligomer, paraformaldehyde, and as the cyclic trimer, 1,3,5-trioxane (a-trioxym-ethyl-ene). High-molecular-weight, commercial polymers of formaldehyde are called poly-oxymethylene or acetal resin. Formaldehyde is also used in the production of other resins such as phenolic resin (phenol-formaldehyde) and amino resin (urea formaldehyde). Syn methylene oxide, methanal. See formalin. 

Melamine was first isolated by Liebig in 1834 from the mixture obtained by heating ammonium thiocyanate. A technically feasible route to melamine was developed in 1935 by Ciba AG (Switzerland) and at the same time Henkel patented the production of resins from melamine and formaldehyde. In general, melamine-formaldehyde polymers resemble urea-formaldehyde pol)miers but they have improved resistance to heat and water. The two materials have therefore found application in similar areas, melamine-formaldehyde resins now being widely used in the production of moulding powders, laminates, adhesives, surface coatings and textile finishes. 

The reaction conditions can be varied so that only one of those monomers is formed. 1-Hydroxy-methylurea and l,3-bis(hydroxymethyl)urea condense in the presence of an acid catalyst to produce urea formaldehyde resins. A wide variety of resins can be obtained by careful selection of the pH, reaction temperature, reactant ratio, amino monomer, and degree of polymerization. If the reaction is carried far enough, an infusible polymer network is produced. 

Some commercially important cross-linked polymers go virtually without names. These are heavily and randomly cross-linked polymers which are insoluble and infusible and therefore widely used in the manufacture of such molded items as automobile and household appliance parts. These materials are called resins and, at best, are named by specifying the monomers which go into their production. Often even this information is sketchy. Examples of this situation are provided by phenol-formaldehyde and urea-formaldehyde resins, for which typical structures are given by structures [IV] and [V], respectively ... 

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... 

Amino resins are thermosetting polymers made by combining an aldehyde with a compound containing an amino (—NH2) group. Urea—formaldehyde (U/F) accounts for over 80% of amino resins melamine—formaldehyde accounts for most of the rest. Other aldehydes and other amino compounds are used to a very minor extent. The first commercially important amino resin appeared about 1930, or some 20 years after the introduction of phenol—formaldehyde resins and plastics (see Phenolic resins). 

Formaldehyde may react with the active hydrogens on both the urea and amine groups and therefore the polymer is probably highly branched. The amount of formaldehyde (2—4 mol per 1 mol urea), the amount and kind of polyamine (10—15%), and resin concentration are variable and hundreds of patents have been issued throughout the world. Generally, the urea, formaldehyde, polyamine, and water react at 80—100°C. The reaction may be carried out in two steps with an initial methylolation at alkaline pH, followed by condensation to the desired degree at acidic pH, or the entire reaction may be carried out under acidic conditions (63). The product is generally a symp with 25—35% soHds and is stable for up to three months. 

Poly(vinyl alcohol) is employed as a modifier of thermosetting resins used as adhesives in plywood and particle board manufacture (314,315). The polymer is added to urea-formaldehyde or urea—melamine—formaldehyde resins to improve initial grab, to increase viscosity, and, in general, to improve the characteristics of the board. 

The thermoplastic or thermoset nature of the resin in the colorant—resin matrix is also important. For thermoplastics, the polymerisation reaction is completed, the materials are processed at or close to their melting points, and scrap may be reground and remolded, eg, polyethylene, propjiene, poly(vinyl chloride), acetal resins (qv), acryhcs, ABS, nylons, ceUulosics, and polystyrene (see Olefin polymers Vinyl polymers Acrylic ester polymers Polyamides Cellulose ESTERS Styrene polymers). In the case of thermoset resins, the chemical reaction is only partially complete when the colorants are added and is concluded when the resin is molded. The result is a nonmeltable cross-linked resin that caimot be reworked, eg, epoxy resins (qv), urea—formaldehyde, melamine—formaldehyde, phenoHcs, and thermoset polyesters (qv) (see Amino resins and plastics Phenolic resins). 

Commonly accepted practice restricts the term to plastics that serve engineering purposes and can be processed and reprocessed by injection and extmsion methods. This excludes the so-called specialty plastics, eg, fluorocarbon polymers and infusible film products such as Kapton and Updex polyimide film, and thermosets including phenoHcs, epoxies, urea—formaldehydes, and sdicones, some of which have been termed engineering plastics by other authors (4) (see Elastol rs, synthetic-fluorocarbon elastol rs Eluorine compounds, organic-tdtrafluoroethylenecopolyt rs with ethylene Phenolic resins Epoxy resins Amino resins and plastics). 

The term aminoplastics has been coined to cover a range of resinous polymers produced by interaction of amines or amides with aldehydes. Of the various polymers of this type that have been produced there are two of current commercial importance in the field of plastics, the urea-formaldehyde and the melamine-formaldehyde resins. There has in the past also been some commercial interest in aniline-formaldehyde resins and in systems containing thiourea but today these are of little or no importance. Melamine-phenol-formaldehyde resins have also been introduced for use in moulding powders, and benzoguanamine-based resins are used for surface coating applications. 

Urea is sufficiently important as an additive to PF resins for OSB to warrant some discussion. It has had a large favorable economie impact on the OSB industry. When used, it is generally added after the polymerization is complete. Thus, it is not part of the polymer and does not have any direet effect on polymer resistance to hydrolysis, as might be expected if it was part of the polymer backbone. Under alkaline pH conditions, urea-formaldehyde adducts do not polymerize at a rate that is significant compared to the PF polymerization therefore, the urea does not participate signifieantly in the euring proeess of the PF, despite the faet that it is present during the cure. Since urea is not present in the cured PF polymer per se, it does not detract from the durability of the polymer. Despite this, it is possible to see redueed OSB durability as a result of formulated urea if its use has led to actual PF polymer application rates that are too low. 

In these reactions, the monomers have two functional groups (whether one or two monomers are used), and a linear polymer results. With more than two functional groups present, crosslinking occurs and a thermosetting polymer results. Example of this type are polyurethanes and urea formaldehyde resins (Chapter 12). 

When crosslinked, amino resins are very resistant to most organic solvents, though they tend to be attacked by both acids and alkalis. Urea-formaldehyde polymers are more susceptible to attack than those prepared from melamine and formaldehyde. 

V. A. Blazhevich, D. A. Khisaeva, V. G. Umetbaev, and I. V. Legostaeva. Polymer plugging solution for oil and gas wells—contains urea-formaldehyde resin, and aluminium chloride containing waste of isopropylbenzene production as acid hardener. Patent SU 1763638-A, 1992. 

Other spherical fillers include carbon black. This has several roles particularly in combination with elastomers, e.g., black pigment, anti-oxidant and UV stabiliser, reinforcing filler, and an electrical conductor when used at 60% concentration. Wood flour is particularly effective in phenol/formaldehyde and melamine or urea/formaldehyde thermoset resins because the phenolic lignin component in the wood reacts with the methylol groups (-CH2OH) in the growing polymer. 

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