Acrylated oligomers, classes

Epoxy acrylate oligomers that are used in uv/EB curing are very low-viscosity systems with high vapor pressures. Within this group of oligomers, there are several major subclassifications aromatic difunctional epoxy acrylates, acrylated oil epoxy acrylate, novolac epoxy acrylate, aliphatic epoxy acrylate, and miscellaneous epoxy acrylates. Characteristics of these various classes are summarized in Table 4.8. 

An acrylic oligomer is a higher molecular weight functional acry-lated molecule which may be, for example, polyesters of acrylic acid and methacrylic acid. Other examples of acrylic oligomers are the classes of urethane acrylates and urethane methacrylates. Urethane acrylates are manufactured from aliphatic or aromatic or cycloaliphatic diisocyanates or polyisocyanates and hydroxyl-containing acrylic acid esters. 

Acrylated oligomers can be divided into three main classes polyester acrylates, epoxy acrylates, and urethane acrylates. Urethane acrylates are an especially important commercial class of oligomers. Applications Include binders for magnetic media, vehicles for inks, and coatings for vinyl floor tiles, optical fibers, and paper. Each application has certain performance requirements that must be met by the urethane oligomer. This paper will discuss the effect of urethane acrylate composition on end properties. 

The composition of urethane acrylates can be varied In order to achieve certain end properties required by the Intended application. The structure-property relationships discussed In this paper can provide guidance In the intelligent design of this class of radiation cure oligomer. 

The primary chemical classes from which adhesives are made include epoxies, acrylics, phenolics, urethanes, natural and synthetic elastomers, amino resins, silicones, polyesters, polyamides, aromatic polyheterocyclics, and the various natural products such as carbohydrates and their derivatives as well as plant- and animal-based proteins. Chemical class was once a relatively clean differentiator of adhesives, but so many adhesives now are hybrids, designed to take advantage of specific attributes of more than one chemical class or type of material. Hybridization can be accomplished by incorporating into an adhesive a nonreactive resin of a different chemical class adding another type of reactive monomer, oligomer,... 

The photosensitive resin consists either of a liquid functionalised oligomer, usually with acrylate groups, or a reactive polymer which will be applied as hot melt. There are two main classes of reactive polymers acrylic hot melts which may contain a tackifying monomer, and thermoplastic rubbers which predominantly block copolymers with polybutadiene or polyisoprene chains [3]. A radical-type photoinitiator is always needed to produce, upon UV-exposure, the free radicals that will initiate the polymerisation or cross-linking process. 

Acrylated epoxies comprise one of the largest classes of UV/EB oligomers. These resins were described in patents as early as 1968 (91. Originally developed for thermal cure applications, the diacrylate of the diglycidyl ether of bisphenol A, remains the largest volume oligomer of this class used today. Acrylated epoxies were much faster curing than... 

Polyaniline (PAn)/inorganic composites have been considered as new class of materials due to their improved properties compared with those of pure conducting polymers and inorganic materials [73-77]. For example, the combination of electrical conductivity of PAn and UV sensitivity of anatase Ti02 are expected to find applications in electrochromic devices, nonlinear optical system, and photochemical devises [73], From this point of view, it is in particular interest to prepare fluoroalkyl end-capped oligomers/PAn/titanium oxide nanocomposites. In fact, fluoroalkyl end-capped acrylic acid oligomer [Rp—(ACA) —Rp]/, 2-methacryloyloxyethane sulfonic acid oligomer [Rp—(MES) —Rp]/, 2-acrylamido-2-methylpropanesulfonic acid... 

Another important class of modified epoxy resins, known as epoxy acrylates, are reaction products of a low MW epoxy resin and acrylic acid or methacrylic acid, which are used in radiation curable systems. The acrylate functionality is 2, but higher functionality variants can also be prepared by using epoxy phenol novolac in place of BPA epoxy resin. Radiation curable formulations from these oligomers provide a better balance of properties and cost compared to some of the alternative polymer systems. 

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