Coatings from acrylic polyols

Kugel AJ, Jarabek LE, Daniels JW et al. (2009) Combinatorial materials research applied to the development of new surface coatings XII novel, environmentally friendly antimicrobial coatings derived from biocide-functional acrylic polyols and isocyanates. J Coat Technol Res 6 107-121... 

Urethane resins are synthesized from isocyanates and chemical compounds with hydroxyl or urethane groups (—N—C—O—) including water, polyesters, epoxies, and acrylics [8,9]. The chemical structure of urethane coating is shown in Fig. 13.4. Polyester and epoxy have better barrier resistance to moisture and chemical attack than the acrylic polyol. Ahphatic isocyanate-based coatings are resistant to UV hght and have excellent gloss and color retention. 

The weatherability of PU coatings depends on the nature of both main components the isocyanate and the polyol. From the weatherability point of view, the following order was established polyethers[Pg.73]

Aqueous two-component polyurethane systems for automotive topcoats are under development. Currently the automotive topcoats are made from solvent-based two-component or blocked one-component systems based on HDI trimer (Desmodur N) or IPDI trimer (Desmodur Z) or both in conjunction with an acrylic polyol. The polyurethane topcoats provide the vehicles with a tough and durable finish with excellent long-lasting glossy appearance ( wet look ) One-component aqueous dispersions are already used in electrodeposition primers and pigmented base coats. Soft-feel polyurethane coatings are increasingly used for instrument panels and seat covers. 

Various forms of polyurethane coatings are available. For maximum toughness and light stabihty, an acrylic polyol and a light-stable polyisocyanate, e.g. the HDI derivatives, may be applied (Thapliyal and Chandra, 1990). Polyisocyanates and derivatives are freqnently added to alkyd resins to improve their properties of toughness and adhesion. They suffer from many of the instabilities of the parent aUcyds. 

Figure 7 is a plot of the measured total volume of shoulders of a mar, made under a normal force of 190 iN at the surface of an Acrylic Polyol / HDI coating obtained from Bayer Corporation, over a six hour period, and the theoretical predicted value, with the recovery rate k=0.02/min., Vvis=6.86 im, and Vpia=0.21pm. They agreed with each other very well. 

In Tables 6.18 to 6.20 the properties of two hybrid dispersions prepared using the same method la (see Section 3.2) and having the same structure of the acrylic/styrene part of the hybrid but based on different polyols, as well as of films and coatings made from them are presented. Neither dispersion contained coalescent (NMP)... 

One-pack or two-pack polyurethane surface coatings, which may sometimes be combined with acrylic resin systems. The one-pack system, which has a long shelf life, is an adduct of resin with polyisocyanate dissolved in a moisture-free solvent. When applied to a surface the film cures and hardens, as moisture in the air reacts with the isocyanate groups in the resin. The two-pack system consists of a polyisocyanate (frequently derived from an aliphatic isocyanate monomer) and a polyol as separate components. Once the two components are mixed, the shelf life is very limited. 

Recently, a liquid crystal face cleanser that does not use a polymer has been introduced [28]. This material is made of a lyotropic liquid crystal formed by a nonionic surfactant/polyol/water system, which makes use of the phase-transition behavior caused by the amount of oil and water. A scrubbing agent such as polyethylene powder or sodium poly(acrylic acid) can be added to improve cleaning power and leave a fresh feeling. Pack is used for several hours by forming a coating on the face to provide nutrients and water to the skin as well as to remove dirt from the skin. Poly(vinyl alcohol) or carboxymethyl cellulose is used as the film former. A typical recipe is listed in Table 1 [29]. 

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