Resin alkyd

Alkyd resins are a special family of three-dimensional polyesters used by the coatings industry.These materials are condensation products from dibasic acids or their anhydrides and trifunctional or tetrafunctional alcohols. Phthalic anhydride and glycerol are the most common raw materials. Fatty 

Maleic anhydride can function both as a dibasic acid in the polyesterification reaction and a dienophile for Diels-Alder reaction with the fatty acid. The total functionality of the alkyd resin is significantly enhanced by MA. Thus, the replacement of phthalic anhydride by MA produces a more complex molecular structure with high viscosity and possible gelation. In normal alkyd production, MA or fumaric acid is usually restricted to about 1-10% of the phthalic anhydride content. Maleic anhydride incorporation improves color, processing time, and water resistance of the alkyd coating. Alkyd molding compositions are also being used to some extent in automotive and electrical applications. 

The term alkyd resins represents a broad class of compounds commonly used in coatings and is a particular type of polyester formed by the reaction of polyhydric alcohols and polybasic acids. 

The most common method of preparation of alkyd resins is the fatty acid method in which a glyceride oil is catalytically treated with glycerol at 225 to 25CPC. The glyceride oil is simultaneously esterified and deesterified to a monoglyceride. 

The esterification of a polybasic acid with a polyhydric alcohol yields a thermosetting hydroxycarboxylic resin, commonly referred to as an alkyd 

Alkyd resins are also polyesters containing unsaturation that can be cross-linked in the presence of an initiator known traditionally as a drier. A common example is the alkyd formed from phthalic anhydride and a glyceride of linolenic acid obtained from various plants. Cross-linking of the multiple bonds in the long unsaturated chain produces the thermoset polymer. 

The processing equipment (reaction kettle and blending tank) used for unsaturated polyesters can also be used for manufacturing alkyd resins. 

According to DIN 53183, Alkyd resins are synthetic polyester resins produced by esterifying polyhydrlc alcohols with polybasic carboxylic acids where at least one of the alcohols must be tri-hydric or higher. Alkyd resins are always modified with natural fatty acids or oils and/or synthetic fatty acids and may be additionally modified with compounds such as resin acids, benzoic acid, styrene, vinyltoluene, isocyanates, acrylic, epoxy, or silicone compounds.  

Despite the development of a vast variety of other synthetic resins, alkyd resins have remained a large fraction of the resins for the paint industry because of a number of reasons. They are a single-pack system with excellent storage stability they are relatively inexpensive as well as soluble in inexpensive solvents they are versatile and can be engineered for a wide variety of properties ranging from hard, fast-drying compositions to softer, more fie- 

Another early material, still in wide use, that formed polymer networks, was the alkyd resins. The alkyds are a group of resins which can be called oil-modified polyesters. These polymers are formed through the condensation and exchange reactions among polybasic acids, polyhydric alcohols, and fatty monobasic acids. Typical polybasic acids are phthalic acid anhydride, maleic anhydride, etc. The polyhydric alcohol may be glycerin, pentaerythritol, etc., while the fatty acids may originate in soy bean or linseed oil. A typical alkyd has the following structure  

Materials Methods of blending with alkyd resins 

More recently, a number of interstitially crosslinked coating materials have been prepared.These are blends in which a water-soluble or water-dispersible resin, capable of crosslinking, is blended with an ordinary thermoplastic emulsion. The main resins include aminoplast, phenol-formaldehyde, polyurethane, epoxy, and drying oils. Applications include sealants, adhesives, and architectural coatings. 

Solomon recently reviewed the subject of vinyl and acrylic modified oils and alkyds. While his emphasis is on the grafting reactions, of course all of these materials are semi-IPNs, since the oil or alkyd crosslinks during polymerization. 

The performance of glyptal polyester coatings was upgraded by Kienle [1], who in 1927 incorporated unsaturable vegetable oils in these polyesters and coined the acronym alcid from the first and last syllables in the reactants, viz. alcohol and acid, and then changed this name to the more euphonious alkyd. 

The term modified alkyd, which formerly was used to describe these products, now is associated with chemical modifications that are carried out during alkyd preparation, and that incorporate chemical agents of types other than those included in the definition. For example, the term rosin-based alkyd resins or rosin-modified alkyd refers to alkyd resins in which all or a portion of the monobasic fatty acid is replaced by rosin. Unmodified alkyd resins are polyester products composed of polyhydric alcohol, polybasic acid, and monobasic fatty acid. When no fatty acids are used, or when they are completely replaced by other types of acid, the products can be considered as oil-free alkyds. 

The chemical reactions that occur during preparation of alkyd resins are polycondensation, polyaddition, and side reactions such as decarboxylation. 

The most common alkyd raw materials are polybasic acids (phthalic anhydride, isophthalic acid, maleic anhydride, fumaric, azelaic, succinic, adipic, and sebacic acids), oils (linseed, soya, dehydrated castor, tung, fish, safflower, oiticica, cotton seed, and coconut), polyhydric alcohols (glycerol, pentaerythritol, dipen-taerythritol, trimethylolethane, sorbitol, trimethylolpropane, ethyleneglycol, propylene glycol, neopentyleneglycol, and dipropylene glycol), and monobasic acids (tail-oil fatty acids and synthetic saturated fatty acids). 

Maleic acid, or more commonly the anhydride, and fumaric acid possess the basic requirement (difunctionality) for polyester formation. They also possess an additional functionality from their double bond, which enables them to form Diels-Alder and other adducts with unsaturated acids in drying oils [12]. 

Detailed discussions of those subjects can be found elsewhere in this Encyclopedia (see Eibers, polyester Polyesters, thermoplastic Polyesters, unsaturated). 

The first appearance of the term alkyd resin in the subject index of Chemicaly bstracts 2iS. in 1929, under Resins. It was not until 1936 that Alkyd Resins was Hsted in its alphabetical place, but stiU appeared as See Resinous Products. The proliferation of Hterature on alkyd resins peaked from the 1940s through the 1960s. Research activities on alkyds in the United States, as indicated by the number of pubHcations, has apparentiy tapered off since the 1970s. Readers interested in alkyd history can find more detailed historical reviews elsewhere (1 4). 

As Eigure 1 implies, there is usually some residual acidity as well as free hydroxyl groups left in the resin molecules. Stmcture-property relationships and the principles commonly followed to design the resin stmcture are discussed later. 

Alkyd resins are usually referred to by a brief description based on certain classification schemes. Erom the classification the general properties of the resin become immediately apparent. Classification is based on the nature of the fatty acid and oil length. 

Alkyd resins are classified into four classes by oil length  

Major polymer applications coatings, paints, varnishes, electrical applications, pavement marking, artist s paints, putties, printing inks 

Important processing methods compounding/mixing, molding 

Typical fillers calcium carbonate, titanium dioxide, glass fiber, silica, iron oxides, clay, mica, zinc oxide, lithopone 

Auxiliary agents flow control additives, wetting and dispersing additives, antifloating additives 

Special methods of incorporation grinding, sand milling 

The first appearance of the term alkyd resin in the subject index of Chemical Abstracts in 1929, under Resins. It was not until 1936 that Alkyd 

Fatty acid Linseed oil Soy oil Safflower oil Sunflower oil Tung oil Castor oil 

If a higher Tg of the resin is desired, for example to obtain harder coatings, the chemistry of the alkyd resin can be modified after the polycondensation process by incorporation of phenolic (see Section 16.2) and/or colophonium resins. 

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Much of the benzoic acid produced is converted to sodium benzoate, which is used as a food preservative (as is the acid) and a corrosion inhibi tor. Other important uses of the acid are in the manufacture of alkyd resins, plasticizers, caprolactam, dyestuffs and pharmaceuticals. 

Methyl-2-pentanoi b.p. 132 C, a solvent for nitrocellulose, urea-formaldehyde and alkyd resins. It is also used in ore flotation. 

The polycondensation of di-isocyanates with polyhydric alcohols gives a wide range of polyurethanes which are used as artificial rubbers and light-weight foams, and have other important properties. Isocyanates are also used as modifiers in alkyd resins. ... 

Most naphthalene produced is utilized in the manufacture of phthalic anhydride, for plasticizers, alkyd resins and polyesters. It is also used in the manufacture of 2-naphlhol and insecticides. Naphthalene derivatives are of importance, particularly as dyestufT intermediates. 

Used as fibres, particularly in textiles and film. Many other polyester polymers are of importance, e.g. unsaturated polyester resins from phthalic anhydride, propylene glycol and maleic anhydride used with reinforcement in boats, cars, etc. (alkyd resins). U.S. production 1983 1-7 megatonnes. 

HOaQCHjlfiCOiH, CSH14O4. Important dicarboxylic acid obtained by oxidizing ricino-leic acid (from castor oil) also obtained by oxidation of cyclo-octene or cyclo-octadiene formerly obtained from cork. Used in the formation of alkyd resins and polyamides. Esters are used as plasticizers and heavy duty lubricants and oils. 

Polyesters from polybasic acids and polyhydric alcohols. Alkyd resins. The condensation of polyhydric alcohols and polybasic acids or anhydrides leads to polj esters known as alkyd resins. The most common member of the group is a glycerol - phthahc acid polymer, and this has led to the term glyptal resins being frequently apphed to the whole group. 

The properties of the polymers may be modified by mixing abphatic acids or anhydrides with the phthalic anhydride. Many alkyd resins find application in the paint industry. 

Alkoxysilanes Alkyd coatings Alkyd paints Alkyd resins... 

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