Alkyd blends

Urea formaldehyde /alkyd blends Sloving Condensation polymerisation Aromatic hydrocarbons and alcohols Fairly good Fairly good Very good Good Fair Water white Gives white finishes of excellent colour... 

Wiersma et al. at DSM Research, Geleen, The Netherlands [284] described an interesting way of coating textile fibers with CP/polyurethane and CP/alkyd blends from aqueous colloidal dispersions made in a commercially available aqueous resin dispersions. The dispersions included a polyurethane-in-water dispersion (DSM Resins URAFLEX XP 401 UZ, 40% solids content). A variant of the template-type in-situ polymerization was used. After polymerization, the dispersed CP sol could be applied as a coating onto the textile fibers. CPs used included P(Py) and P(ANi). 

Types of internal enamel for food containers include oleoresins, vinyl, acryflc, phenoHc, and epoxy—phenoHc. Historically can lacquers were based on oleoresinous products. PhenoHc resins have limited flexibiHty and high bake requirements, but are used on three-piece cans where flexibiHty is not required. Vinyl coatings are based on copolymers of vinyl chloride and vinyl acetate dissolved in ketonic solvents. These can be blended with alkyd, epoxy, and phenoHc resins to enhance performance. FlexibiHty allows them to be used for caps and closures as weU as drawn cans. Their principal disadvantage is high sensitivity to heat and retorting processes this restricts their appHcation to cans which are hot filled, and to beer and beverage products. 

Modification of Alkyd Resins by Blending with Other Polymers... 

One of the important attributes of alkyds is their good compatibiUty with a wide variety of other coating polymers. This good compatibiUty comes from the relatively low molecular weight of the alkyds, and the fact that the resin stmcture contains, on the one hand, a relatively polar and aromatic backbone, and, on the other hand, many aUphatic side chains with low polarity. An alkyd resin in a blend with another coating polymer may serve as a modifier for the other film-former, or it may be the principal film-former and the other polymer may serve as the modifier for the alkyd to enhance certain properties. Examples of compatible blends foUow. 

Vinyl resins ie, copolymers of vinyl chloride and vinyl acetate which contain hydroxyl groups from the partial hydrolysis of vinyl acetate and/or carboxyl groups, eg, from copolymerized maleic anhydride, may be formulated with alkyd resins to improve their appHcation properties and adhesion. The blends are primarily used in making marine top-coat paints. 

Silicone resins with high phenyl contents may be used with medium or short oil alkyds as blends in air-dried or baked coatings to improve heat or weather resistance the alkyd component contributes to adhesion and flexibiUty. AppHcations include insulation varnishes, heat-resistant paints, and marine coatings. 

Although blending with other coating resins provides a variety of ways to improve the performance of alkyds, or of the other resins, chemically combining the desired modifier into the alkyd stmcture eliminates compatibiUty problems and gives a more uniform product. Several such chemical modifications of the alkyd resins have gained commercial importance. 

The polyester alkyd moulding compositions are also based on a resin similar to those used for laminating. They are prepared by blending the resin with cellulose pulp, mineral filler, lubricants, pigments and peroxide curing agents on... 

This monomer has been used as the basis of a laminating resin and as a reactive diluent in polyester laminating resins, but at the present time its principal value is in moulding compositions. It is possible to heat the monomer under carefully controlled conditions to give a soluble and stable partial polymer in the form of a white powder. The powder may then be blended with fillers, peroxide catalysts and other ingredients in the same manner as the polyester alkyds to form a moulding powder. Similar materials may be obtained from diallyl isophthalate. 

Blends with alkyd or other organic resins have, however, been preptu ed and these show heat resistance intermediate between those of the organic resins and the silicones. Of ptu ticular interest is the use of silicone-organic resin blends filled with aluminium powder for the coating of metal chimneys and furnace doors. At the operating temperatures the resins are destroyed, leaving a layer of aluminium film. 

For high-quality stoving finishes the alkyd is frequently blended with a lesser quantity of an amino resin. This reduces the stoving schedule and enhances most of the physical properties of the finish. 

Several other resins can be blended with alkyd resins to introduce desired improvement in properties, e. g. cellulose nitrate, chlorinated rubber, phenolics, amino resins or silicons oils. Vinyl monomers like styrene can be added to alkyd resins along with initiator to get a tougher resin with shorter drying times and lighter colour. 

Amino resms are probably the mos important modifiers for alkyd resins. Many industrial baking enamels, such as those for appliances, coil coatings, and automotive finishes (especially refinishing enamels), are based on alkyd-amino resin blends. Some of the so-called catalyzed lacquers for finishing wood substrate require very low bake or no bake at all. 

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

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