Acrylate reactive diluents

It was found, when an attempt was made to conduct ship trials that the paint applier would be required to wear long sleeves, gloves, safety glasses, and a protective face shield. It is also a requirement that an eyewash fountain be nearby. These requirements were imposed because acrylates are skin, eye and respiratory tract irritants, but the problem lies mostly with the acrylated reactive diluent rather than with the acrylated resin (2,3). To avoid these problems, tests have been performed with use of trimethylolpropane trimethacrylate (TMPTMA) as a replacement for TMPTA. TMPTMA has been shown to be much less of an irritant than TMPTA, and is used in dental restorations. 

Figure 2.35 Some commonly used monomeric acrylates (reactive diluents)...

A great variety of resia formulations is possible because other thermosets, such as epoxies or acrylates, and reactive diluents, such as o-diaUyl phthalate [131-17-9] triaUyl cyanurate [101-37-17, or triaUyl isocyanurate [1023-13-6J, can be used to further modify the BT resias. The concept is very flexible because bismaleimide and biscyanate can be blended and copolymerized ia almost every ratio. If bismaleimide is used as a major constituent, then homopolymerization of the excess bismaleimide takes place ia addition to the copolymerization. Catalysts such as ziac octoate or tertiary amines are recommended for cure. BT resias are mainly used ia ptinted circuit and multilayer boards (58). 

Since the commercially available epoxy acrylate is extremely viscous, it is necessary to thin the formulation with a reactive diluent. A mixture with satisfactory viscosity for brush-on application contains about 45% diluent. Of the diluents tested, TMPTA (trimethylolpropane triacrylate) proved most successful. 

The formulation which performed best contained 1% BAPO/HMPP photoinitiator, 50% acrylate ester of bisphenol A epoxy (Ebecryl 3700), 45% reactive diluent, 5% pigment, and a few drops of the fluorocarbon surfactant FC-171. 

Two of the main considerations in the development of totally reactive liquid photopolymer systems are the resin(s) and the reactive diluents (monomers). The resins play a major role in determining the end properties and therefore the applications of the cured polymer. The reactive diluents are used to provide a fully reactive system with the appropriate reactivity, viscosity, coatability before cure and the desired crosslink density, chemical resistance and dielectric character once it is cured. The pho-toreactive monomers most commonly used are acrylate based derivatives because of the properties they impart, and their high reactivity and wide solubility range. 

A typical UV-cured coating has three or sometimes four main ingredients (1) a multifunctional acrylate monomer, (2) a reactive oligomer, (3) possibly a monoacrylate as reactive diluent, and (4) a photoinitiator (Table 2.20). 

The acrylate or methacrylate functional PIBs have also been used in UV-curable solventless coatings formulation in the presence of reactive diluents (multifunctional acrylate or methacrylate esters) and a UV-sensitizer [104]. The products were transparent, flexible films, with very little extractables, in which hard polyacrylate or polymethacrylate domains were dispersed in the soft PIB matrix. Tensile strength and ultimate elongation have also been obtained. 

A typical EB curable formulation will generally consist of a relatively high molecular weight solid or semi-solid difunctional acrylic resin reduced to application viscosity with combinations of liquid mono- and multifunctional acrylic monomers. These acrylic monomers, along with a few other selected polymerizable monomers, serve as reactive diluents and allow formulation of solvent-free compositions. Usually, small amounts of additives are also used in order to provide special properties, such as slip. 

Measurement of conversions of various formulations at various EB doses can be used to rank the reactivity of the formulation. A particularly useful procedure has been to prepare a standard mixture of an acrylate resin with various reactive diluent monomers in order to compare the volatility and reactivity of new monomers. For these studies, a mixture of 40 weight % of a Bis-phenol A epoxy dlacrylate resin with 60% of the test liquid monomer has proved convenient. A viscosity measurement of the mixture also provides information on the relative viscosity reducing ability of the test monomer. Illustrative examples of these measurements are shown in Table I and Figure 1. Mote from these examples that a monofunctional monomer, Monomer B, can be used to provide the low volatility and high reactivity typical of the multifunctional monomers, while also serving to reduce the crosslinking. Many other available monofunctional monomers are found to be either more volatile or less reactive than Monomer B. 

Data on Uvimer 740 Is presented in Table VII, while Uvimers 765 and 775 are compared in Table VIII, Uvlmer 740 is somewhat stiffer and harder than either 765 or 775, primarily due to the difference in the structures of oligomers D and E. It should also be noted that Uvimers 765 and 775 have better color and do not exhibit yellowing on aging. Since the latter two resins employ the same basic oligomer, it is evident that on the basis of viscosity reduction 2-ethoxyethyl acrylate is a more effective diluent than the 2-ethylhexyl acrylate/hydroxyethyl acrylate combination. Thus, it is possible in Uvimer 775, to employ a lower level of reactive diluent and thereby obtain a harder, stiffer, faster-curing formulation. 

Use Modifier for alkyd resins and thermosetting acrylic systems, reactive diluent for epoxy resins. 

As mentioned earlier, UV-curable resin formulations are very attractive for fiber coating because of the rapid cross-linking rates that are achievable. Most commonly, epoxy- or urethane-acrylate resins are employed (18-22), and viscosity and cross-link density are controlled through the addition of reactive diluents. With these systems work has focused on producing low modulus, low T properties (20-22) through the incorporation of appropriate chemical constituents to enhance higher chain flexibility, for example, ether linkages. 

Acrylic acid, isodecyl ester Ageflex FA-10 EINECS 215-542-5 HSDB 615 Isodecyl acrylate Isodecyl alcohol, acrylate isodecyl propenoate 2-Propenoic acid, isodecyl ester Sipomer IDA. Used in adhesives, coatings, UV-curable reactive diluent In Inks and coatings, viscosity index improver. Liquid mp a -100 bp = 304 , bp3" 161-163 = 0,864, Rhone Poulenc Surfactants Rit-Chem. 

Acrylic acid, dodecyl ester A13-03198 Oodecyl acrylate n-Dodecyl acrylate EINECS 218-463-4 Lauryl acrylate n-Lauryl acrylate NSC 24177 2-Propenolc acid, dodecyl ester. UV-curable reactive diluent in inks and coatings, adhesives, viscosity index improver, finishing aid for leather. Solid d = 0.884. Rit-Chem Sartomer. 

The photoinitiated cationic polymerization of liquid epoxidized polyisoprene is an efficient method to generate rapidly crosslinked elastomers. In the presence of a triarylsulfonium salt, the reaction develops readily upon UV exposure, with formation of both inter and intramolecular ether linkages. The formulation reactivity can be substantially enhanced by the addition of a difunctional vinyl ether or acrylate monomer, which acts as a reactive diluent and leads to the formation of an... 

Figure 1. Cure curves for a typical epoxy acrylate varying the amount of reactive diluent.

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