Carboxy functional acrylic

Chem. Descrip. Modified, hydrory- and carboxy-functional acrylic polymer (50%) in solv. naphtha 150/180 / rylene Uses Ttcrylic for automotive clear coats (OEM)... 

Another route to the production of hydroxy functional acrylic is via a carboxy functional acrylic, which is subsequently post reacted with the glycidyl ether of Versatic acid (Cardura ElO, Shell chemicals), see Figure 4-3. 

In single pack heat cured coating systems, carboxy functional acrylics can be crosslinked at elevated temperatures with amino and epoxy resins, as shown in Figure 4-5. 

Crosslinking Reactions for Carboxy Functional Acrylic Resin... 

However, the major use for heat cured, carboxy functional acrylics is in combination with either Bisphenol A based glycidyl ether epoxy resins, or hexamethoxy methyl melamine resins, for metal decorating applications, where their flexibility and deep draw properties are essential. 

In the early days, although paint manufacturers flirted with acrylamide chemistry for automotive topcoats, their higher curing temperatures of 150 C and above precluded commercialisation in this end use. Carboxy functional acrylics have inferior weathering performance. Consequently, thermosetting acrylic topcoats are almost exclusively based on hydroxyl functional polymers. These are crosslinked with either alkylated melamine formaldehyde resins or as 2 component (2K) systems, with aliphatic isocyanate adducts. The 2 component systems are an extremely important class used mainly in automotive repair applications and warrant a chapter in their own right (see Chapter V on component isocyanate curing systems). 

Isoxazolines can be transformed into a,p-enones by several methods from the initial aldol product. This strategy was applied by Barco et al. (285) toward the synthesis of ( )-pyrenophorin (98), a macrocychc fow(enone-lactone) with antifungal properties. The hydroxy group was introduced from the nitrile oxide component (95), while the carboxy function was derived from the acrylate dipo-larophile. Thus, cycloaddition of the optically active nitropentyl acetate 94 to methyl acrylate 95 afforded isoxazoline 96 as a mixture of optically active diastereomers. Reductive hydrolysis using Raney nickel/acetic acid gave p-hydro-xyketone (97), which was subsequently utilized for the synthesis of (—)-pyreno-phorin (98) (Scheme 6.63) (285). 

Organofunctional silanes with hydroxy-, epoxy-, acryl-, ester- and carboxy-functions are produced industrially. They are in particular utilized as additives for modification of polymers and for functionalizing silicones for different application sectors. Most of these compounds are manufactured by the addition of appropriately functionalized alkenyl-compounds. 

Banthia et al. [44] first performed the polymerization of ethyl hexyl acrylate in DEP conditions (Table 6) but without using any solvent. The calculated carboxy functionalities were around 2 and the molecular weights were about 104. The number-average molar masses (Mn) were unexpectedly high for DEP conditions and were probably due to the bulk conditions. 

Scheme 32 Main structures of carboxy-functional poly( -butyl acrylate) (PBA) synthesized by RAFT polymerization initiated with either a,a -azobis(isobutyronitrile) or 4,4 -azobis(4-cyanovaleric acid)...

A carboxy-functionalization of magnetic nanoparticles for further bioconjugation could also be obtained in magnetic poly(ethylmethacrylate) (PEMA) particles by copolymerizing EMA with acrylic acid [150,151], or by using 4,4 -azo-bis(4-cyanopentanoic acid) (ACPA) as initiator [152]. 

C. Wang, G. Lin, J. H. Pae, F. N. Jones, H. Ye and W. Shen, Novel synthesis of carboxy-functional soybean acrylic-alkyd resins for water-reducible coatings , J Coat Technol, 2000, 72, 55-61. 

Oligomerization methods for preparing carboxy-functionalized liquid oligomers have been described in the patent and technical literature [143-156]. The main chemical agent employed here is maleic anhydride (MA) thus, the products obtained are called maleic oils or maleic resins [157]. Also, beta unsaturated mono-or dicarboxylic acids can be used as well as some of their functional derivatives such as acrylates, itaconic anhydride, citraconic anhydride, and fumaric and meth-arcrylic esters [155,156]. 

It is advisable to include some carboxy functionality also as the cure reaction between acrylic and melamine resins is acid catalysed. In the more sophisticated industrial markets for acrylics, stoving temperatures are well controlled and adequate cure cycles are achievable. However, in the competitive general metal finishing market, low temperatures and short times are common, so whilst it is possible to externally catalyse using PTSA (para toluene sulphonic acid), this polar material remains in the film after curing to act as a pathway for water. Blistering on exposure to humidity is a common problem in acrylic-melamine systems which have been catalysed by sulphonic acids. 

The carboxy/epoxy system displays a very fast lacquer type dry but, in comparison to a 2 pack polyurethane, relatively slow through cure. Tertiary amines can be used to enhance the cure of the coating. However, careful selection of the catalyst is critical since some amines can also make the coating water sensitive. There is also the potential to catalyse the system internally by incorporating an amine functional monomer onto the backbone of the acrylic resin by copolymeiisation of amine functional acrylic or vinyl monomers. 

DWI external coatings are split between acrylic and polyester systems, both of which contain carboxy functionality, neutralised with an amine such as dimethylethanolamine. Current developments in DWI basecoat technology are towards hybrid acrylic polyester water systems. The acrylic portion provides good pigment dispersion properties, whilst the polyester will give improved performance during the spin necking operation. 

Experimental studies of the adsorption of polyelectrolyte have been reported by several authors Pefferkom, Dejardin, and Varoqui (3) measured the hydrodynamic thickness of an alternating copolymer of maleic acid and ethyl vinyl ether adsorbed on the pore walls in cellulose ester filter as a function of the molecular weight and the concentration of NaCl. Robb et al. (4) studied the adsorption of carboxy methyl cellulose and poly (acrylic acid) onto surfaces of insoluble inorganic salts. However, their studies are limited to the measurements of adsorbance and the fraction of adsorbed segments. 

In 1996, Gauglitz and coworkers coated surfaces with various amino-and carboxy-substituted polymers [198], The polymers tested were branched poly-(ethyleneimine), a,co-amino-functionalized PEG, chitosan, poly(acrylamide-co-acrylic acid) and an amino-modified dextran. The amino-substituted polymers were immobilized on glass by first immobilizing an aminosilane, followed by succinic anhydride/A-hydroxysuccinimide linker chemistry. Poly(acrylamide-co-acrylic acid) was directly coupled to an aminosilanized surface. When probed with 1 mg mL 1 ovalbumin solution, nonspecific adsorption was lowest for the dextran derivative. Notably, nonspecific adsorption increased in most cases when a hydrophobic hapten (atrazine) was coupled to the polymer-modified surface. 

For the outer-shell compositions, the choice of a monomer alters the reactive functional group(s) on the surface of the particle (e.g., epoxy, carboxy, mercaptan, etc.). Such groups will enable the toughener particles to compata-bilize with, and possibly chemically bond with, the matrix resin. Thus for the outer shell, methyl methacrylate (M) and ethyl acrylate (E) were copolymer-... 

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