Alkyd paint binders

Mineral spirits, a type of petroleum distillate popular for use in solvent-based house paints, consist mainly of aUphatic hydrocarbons with a trace of aromatics. This type of solvent finds use in oil- and alkyd-based house paints because of its good solvency with typical house paint binders and its relatively slow evaporation rate which imparts good bmshabiUty, open-time, and leveling. Other properties include lower odor, relatively lower cost, as well as safety and health hazard characteristics comparable to most other organic solvents. 

Saponification Paints are most commonly used to protect steel from corrosion by seawater in marine applications and soil in the case of buried structures. Additional protection is often supplied by the application of cathodic protection to the steel. Any paint coating used in conjunction with cathodic protection must be resistant to the alkali which is produced on the steel at defect sites in the coating. The amount of alkali generated depends on the potential to which the steel is polarized. Some paint binders such as alkyds and vinyl ester are very susceptible to saponification, and should not be used on cathodically protected structures. Cathodic disbondment testing should be undertaken if the relevant information is not available. 

Figure 11 shows the ATR-FTIR spectrum acquired from the surface of the white-colored paint sample after the paint had been dried. Figure 12 shows the closest spectral library database matches obtained Figure 13 compares the spectrum of the surface of the white-colored paint sample with that of a reference library spectrum of a vinyl toluene-modified alkyd. The binder from the dried... 

In addition to natural materials, synthetic polymers might also be present in works of art. Since the end of the nineteenth century, synthetic polymers have been produced and used in the field of cultural heritage, to restore works of art [3], but also as paint binders, such as alkyd resins and acrylic water dispersions. Most synthetic polymers can be detected by GC/MS only through thermal degradation followed by GC/MS [4,5] (Chapter 12 deals with the characterisation of synthetic resins in detail). 

The principal field of application for synthetic polymers as art materials is that of paint binders, which developed in the second half of the twentieth century when manufacturers of artists paints and varnishes realized the potential of synthetic resins used in the decorative household and industrial paint market [81]. The most important families of synthetic artists paints are the acrylics, the vinyl acetate resins, and the alkyds, and Py-GC/MS has been used to identify all these types of modem paints. 

The cementitious substrates include concrete, masonry, sand-cement, and gypsum plasters. All these substrates retain moisture and are alkaline in nature. The surface alkalinity can result in a chemical attack or saponification of certain types of binders used in paints, notably oils and alkyds, resulting in a marked diminution in the paints resistance to washing, abrasion, and weathering. Alkyd paints are, therefore, not used on fresh concrete, masonry, and plaster surfaces. 

The binders used in the production of alkyd paints, namely alkyd resins, are oil-modified or fatty-acid-modified condensation polymers of polybasic acids and polyhydric alcohols. Alkyd resins account for ca. 45 % of the total world production of paint raw materials, excluding plastics latexes and polyvinyl dispersions. 

Traditionally, in alkyd paint preparation, vegetable oils are transesterified to polyols (e.g., pentaerythritol or trimethylolpropane) at high temperature (270°C) to become part of the binder system. Upon (oxidative) drying, the double bonds in the alkyd chains are cross-linked to form the final coating network. Therefore, agricul-... 

Chem. Descrip. Vinyl chloride/acrylates copolymer Uses Binder, film-former for surf, coatings, two-pack paints, primers, undercoats, alkyd paints, stoving finishes, adhesives Features Contains hydroxyl groups char, by exc. toughness, permanent flexibility, abrasion resist., low swelling in presence of water, low gas permeability produces highly water-resist, films with exc. resist, to oils, greases, dil. aq. acids, alkalis, etc. 

Uses Inlermediale in organic synthesis monomer in mfg. of homopolymers and copolymers for solvent coatings, adhesives, paints, binders, emulsifiers, varnishes, inks, glues, adhesives, cleaning and waxing prods., nonwoven fabrics, textiles, paper, leather acrylic toughener acrylic resin comonomer modifier for oils/alkyds in food-contact coatings... 

In this study the use of drying oils (poppy, linseed, walnut) as comonomers was investigated. These natural compounds have been largely employed as paint binders or as components in alkyd resins. 

S. Majumdar, D. Kumar and Y. P. S. Nirvan, Acrylate grafted dehydrated castor oil alkyd A binder for exterior paints, J Coat Technol, 1998,70,27-33. 

One result of the change from the simple oil to the alkyd resin as the main paint binder is that there is more flexibility in the choice of oils. The requirement that the oil should dry within a certain time is not so essential and semi-drying oils, such as soybean oil, are often preferred because they possess other properties. 

The binder is the most important component of any paint it guarantees the cohesiveness of the film and its adhesion on the substrate. A wide variety of synthetic polymers as well as derivatives of fatty acids are employed for this purpose, such as PVC (vinyl paints), PMMA (acrylic paints), epoxies, polyurethanes and mixtures of polyesters with fatty acids (alkyd paints). 

PyGC is also an effective method for identifying and differentiating the organic binder of paint. In some cases, paint additives may readily be detected and identified. Automotive paint binder types can be identified on mg-sized samples of topcoat. Challinor [567] has evidenced various phthalates (DBP, BBP, BCP) in a methyl methacrylate (MMA)-butyl methacrylate (BMA) copolymer, BBP in a MMA-BMA-MA (methacrylic acid) terpolymer, DBP and BCP in MMA-MA copolymer and BBP in MMA-EA (ethylacrylate) copolymer. Paint additives may also be identified in architectural paints. Dimethyl orthophthalate (DMOP) was detected in an architectural alkyd enamel which had been subjected to simultaneous pyrolysis methylation (SPM) [635]. Industrial finishes on a beverage can also contain a variety of plasticisers (DMA, DMOP, DMIP), as also determined by SMP-GC [567]. 

A quick drying of alkyd paints is of enormous commercial importance. Common solvent borne alkyd paints contain small amounts of cobalt based driers (e.g. cobalt ethylhexanoate) besides the main constituents of alkyd resins (binders), pigments and solvents. The cobalt salts increase the oxidative cross-linking rate of the unsaturated fatty acids which are present as constituents of alkyd resins. 

Research projects carried out at A F clearly indicate that effective plasticisers for PVC and other resins and binders and additives for alkyd based decorative paints can be based on those raw materials which are the least undisputed from an environmental point of view i.e. renewable resources. These products are not only renewable based but also durable. Provided a positive life cycle analysis, after further R D work plasticisers and high-solid or water borne alkyd paints based on renewables therefore can make an important contribution to a sustainable chemical industry. 

Whilst there are some thermoset acrylic emulsions cormnerdally available, the bulk of the thermoset resins, used as the main binder system, are produced in solution. Some may then be made waterborne by neutralisation and inversion (dispersion) into a water phase. Lower molecular weights favour this qrproach. The rate of conversion from solvent based to waterborne industrial thermoset coating systems has been, and is, much slower than the conversion from architectural alkyd paints to emulsion altonatives. There are two principle reasons for this. Firstly there are problems of application and substrate wetting of many waterborne systems. Secondly, the modifications frequently required to induce water dispersibility reduce one or more of the essential performance properties required from the cured film, compared to a solvent based system. Water resistance, with many films having an increased tendency for blushing is one example. However, for some applications, such as electrodeposition, only waterborne systems will work. 

Samples of actual lead-based paint on substrates were obtained from the Macon Housing Authority in Macon, Georgia (Gooch, 1991). Old paint usually consists of pigmented oil-based alkyd paint that is usually brittle, multilayered, and often cracking and chipping. Old base layers of alkyd paint have often been painted over with other types of paint, such as water-based acrylic latex. Painted wood samples consisted of shelves, windowsills, soffits, and doors metal samples consisted of vertical and horizontal metal supports and hand rails. The majority of the coatings were alkyd- and acrylic-type binders. 

A time to reach blister temperature for paint removal was used to determine the relative speed of paint removal. In each case, the paint consisted of an alkyd resin binder on painted metal and wood surfaces. A calibrated thermocouple attached to a unit with a digital temperature scale was placed directly on the surface, and the temperature was recorded when the paint blistered Table 11.12 lists the results. This test showed that a metal substrate requires more cleaning time (+5-72 sec) and a higher temperature (+77-82 °F (+22-28 °C)) than less thermally conductive substrate, such as wood. 

Majumdar, S., Kumar, D., Nirvan, Y.P.S., 1998. Acrylate grafted dehydrated castor oil alkyd - a binder for extmo- paints. J. Coat. Technol. 70,27—33. 

Two important product properties of pigmented acrylic and alkyd paints that will be described in detail here are dirt pickup resistance and hiding power. Both of these two product properties can be improved by adding glycerolpropylsilyl-modified silica dispersions to the binder formulation. 

Paints are complex formulations of polymeric binders with additives including anti-corrosion pigments, colors, plasticizers, ultraviolet absorbers, flame-retardant chemicals, etc. Almost all binders are organic materials such as resins based on epoxy, polyurethanes, alkyds, esters, chlorinated rubber and acrylics. The common inorganic binder is the silicate used in inorganic zinc silicate primer for steel. Specific formulations are available for application to aluminum and for galvanized steel substrates. 

---