Poly varnish

Macromolecular Materials and Engineering 286, No.9, 28th Sept.2001, p.513-5 SYNTHESIS OE URETHANE OIL VARNISHES EROM WASTE POLY(ETHYLENE TEREPHTHALATE)... 

Methyl and ethyl methacrylate polymers, although extensively used in Industry, do not possess the solubility characteristics (low polarity) that would make them appropriate for use over traditional oil paintings and other organic-based museum objects that might be sensitive to polar solvents such as alcohols, ketones and esters. Poly(n-butyl methacrylate), offered as an artists varnish in the late 1930 s, did not become widely accepted in the war-disrupted decade that followed. Accordingly, early in 1951, our laboratory began a detailed study of the higher alkyl methacrylate polymers for potential use as picture varnishes (1). 

Vinyl polymers [polystyrene, PVC, polyethylene, polypropylene, poly(vinyl acetate), poly(vinyl alcohol), polyacrylonitrile] -1920 Packaging, tubing, household goods, records, carpets, toys, water based paint, adhesives, varnishes Phthalate esters, poly(vinyl alcohol) ... 

The first synthetic polymers to be used as paint varnishes were acrylic and vinylic resins. Poly(vinyl acetate) (PVAc), commercialized under the name Mowilith by Hoechst and Vinylite by Union Carbide, has been used in conservation as an adhesive since 1932 and in 1937 it was proposed as a picture varnish by Stout and Cross [63]. PVAc was soon rejected as a varnish because, despite its light stability and good solubility in organic solvents, it demonstrated poor optical properties in terms of colour saturation and the tendency to pick up dirt due to its low glass transition temperature. 

Poly(butyl methacrylate) (PBMA) began to be used as a picture varnish in the early 1930s. It encountered a considerable success because of its resistance to yellowing, adequate flexibility, no dirt pick-up and good solubility in nonpolar hydrocarbon solvents. Products based on PBMA, such as Elvacite 2044 and Elvacite 2045 by Du Pont, were abandoned when it was discovered that under light exposure they cross-link to an unexpected extent becoming insoluble [64]. From this point of view acrylic copolymers based on methyl and ethyl acrylates/methacrylates show a much better long-term stability. 

The glyptals made from phthalic anhydride and glycerol were developed as compositions for use in paints and varnishes. If the reaction was carried out too long the product became intractible. But under milder conditions, other products could be obtained which could be used in making soluble products and then they could be set further after forming. It was learned that by modifying the reaction mixture with some monobasic acid to balance the hydroxyls and carboxyls in the reaction mixture, more soluble products could be obtained. Kienle of General Electric, was one of the early developers of these products. Later many other alkyd resins from other polyhydroxyl compounds and poly acids were produced for technical use. 

Bis(acetylacetonato)manganese shows smoke-retarding properties in poly(vinyl chloride) but Mn203 and MnC03 seem to be superior in this respect.5 The so-called manganese soaps having as anions octanoate, stearate, linoleate, naphthenate and others are used as driers (see Section 66.6.1) for printing inks, varnishes and paints.45... 

The most important properties of some polyphenylsiloxanes and poly-phenylsiloxane varnishes are given in Table 25. 

To obtain resin, the hot product of condensation is poured through the lower drain of condenser 18 to obtain varnish, the resin in condenser 18 is dissolved with ethyl alcohol, which self-flows into the apparatus from batch box 21. While the resin is dissolved, cooler 19 operates in the inverse mode. The obtained varnish is loaded by vacuum into settling box 22, where it is settled at ambient temperature for a long time (24-48 hours) to separate mechanical impurities. There is also a possibility for additional centrifuging in ultracentrifuge 23 for complete elimination of mechanical impurities, as well as clarification" of the varnish. The finished poly-methyl(phenyl)silsesquioxane varnish is sent from the centrifuge into container 24 and packaged. 

Polymers are used frequently in paints and varnishes. These materials are usually filled with opaque materials and are difficult to separate or analyze by other procedures. Pyrolysis can be used to identify the nature of the paint, to measure quantitatively residual monomers, for quality control, and to examine additives [5, 13, 14]. Paints may contain a variety of polymers and copolymers such as vinyl derivatives, polyurethanes, phthalate polyesters, etc. Varnishes may contain various copolymers, siloxanes, etc. and can have a complex composition. This composition can be successfully analyzed using analytical pyrolysis. For example, the composition of a coating material consisting of the terpolymer poly(2-hydroxyethyl methacrylate-co-butyl acrylate-co-ethyl methacrylate) crosslinked with butoxy melamine resin has been analyzed with excellent results based on various monomer ratios resulting from pyrolysis at 590° C [15]. 

Poly-Solv [Olin], TM for a series of glycol ether solvents for paints, varnishes, dry-cleaning soaps, cutting oils, insecticides. 

After the successful synthesis of a poly(ester-imide) and its use as wire enamel [1], a development of this class of polymers started which is not yet finished today. The progress in chemistry has been reviewed in several papers [2, 3] where general principles were described. The economical importance of poly ester-imide)s made companies uncommunicative and publication work was directed to patent applications. A large number of patents are known on poly(es-ter-imide)s. They cover various areas ranging from raw materials, resin compositions, synthesis and varnish formulations, to uses and processing. 

Additives used in formulations have the purpose of improving the flow of the enamel, to improve the thermo-mechanical properties like heat shock, or to give better adhesion of the cured film to the copper surface. Some of the additives have multiple effects. Because these effects are very specific to a given poly(ester-imide) resin and varnish formulation, the product classes are here only enumerated. Phenolics [112,113], epoxies [114,115], and silicones [116] are well known and some of them were claimed. Better understood is the effect of the phenol... 

A comparison of potential cresol replacements is given in Table 2 [143]. None of the solvents shown there is a full equivalent to cresol. Because of the reduced solvency power for poly(ester-imide)s the varnishes contain less hydrocarbons blended in and the heat of combustion is lower than that of a cresylic varnish, undesired for the existing installed enameling machines. 

The property levels of cresol free solvent based poly(ester-imide) enamels are inferior to the cresylic products. In Table 3 the cresylic poly(ester-imide) varnish, solved in a mixture of cresol and Solvesso and the cresol free varnish 1, solved in a mixture of diethyleneglycol monomethyl and monoethyl ether plus some small amounts of Solvesso have the same resin composition. The cresylic product is superior. The reason is that the preparation of the cresol free resin was made using diethyleneglycol monomethyl ether as solvent in the synthesis, causing a lower average molecular weight of the polymer. The cresol free po-... 

The water based poly(ester-imide) wire enamel from Table 3 has the same resin composition as the cresol free solvent based resin 2. It can be seen that the mechanical and thermal properties of the water based varnish are inferior to the noncresylic product. It was also found that minor amounts of drawing agent residues from copper wire manufacturing were highly detrimental to the surface quality of the enameled wires. 

The good properties of poly(ester-imide) based varnishes led to patents where this type of product is claimed for use as industrial coatings. Formulated with fluorinated resins, films with good adhesion and low friction coefficients were obtained [227-229]. Good adhesion [230] and good corrosion resistance combined with excellent long term temperature resistance were also claimed [231],... 

Besides other linear polycondensates, poly(ester-imide)s with benzophenone structures were claimed [273] as useful for producing photographic images by exposure through a photographic mask. The varnishes were dried at 80 °C, giving on a copper substrata a 1.2 my layer. Exposure is made with a 1000 W UV lamp. The exposed areas, crosslinked by benzophenone hydrogen abstraction, are insoluble and the unexposed areas of the film are removed with N-methyl-pyrrolidone. 

Hydrolytic Stability. The polymers exhibited not only thermal oxidative stability, but also good hydrolytic stability. The hydrolytic stabilities of these polymers in the form of films and varnished wire were evaluated in water and aqueous base. The electrical resistance of th<=ge films ( 0 1.5 mm, 0.035-0.040 mm thick) in boiling water was 10 ohms. After treating in water at 200 C for 30 hours, the electrical resistances and weights of PPT (I)-PPT (V) remained essentially unchanged whereas the film of poly-imide suffered a 9.43% weight loss and failed to be an insulating material under the same condition. In order to make further observation on hydrolytic stability, a varnished wire was made by... 

Bastmat . [BASF AG] Isocyanates hardoim component to polyeds, pr. of prqxdymets, polyurethane adhesives and binders, paints and varnishes. 

Poly-Pale . [Hocules] Rosin derivs. pale thermoplastic resin fw lacquers, varnishes, adhesives, driers, syndietic resins, ink vehicles, flotH tile, rubber comp., solder fluxes, and wax modification taddfier. 

Most soluble resins that are being used as consolidants in conservation today are also used in picture varnish. Thus these resins have a history of satisfactory use that, in the case of poly(vinyl acetate), extends over almost 60 years (6). Consolidants can cause some darkening of wood surfaces much in the way wetting them with water deepens their color, but with proper technique they will not leave a shiny surface film (7). Because excessive... 

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