Radiation-curable formulations

The relative reactivities of various other resins, monomers and combinations of monomers have been measured in a similar manner. From this information, it was learned that many commercially available monofunctional monomers were not suitable for use in radiation curable formulations. Mobil Chemical Company has now developed several proprietary monofunctional monomers which provide low volatility, high reactivity and safe handling properties to fulfill these needs. In addition, other material suppliers have begun to make suitable monomers available, so the overall availability of materials for formulating has improved greatly within the last few years. 

Choice from a wide range of radiation curable formulations to achieve the desired target properties of the coatings is of foremost importance (Defoort et al. 2001, Kumar et al. 2006, 2008). Radiation curable formulations typically consist of the oligomer (or prepolymer), reactive diluents, additives, and photoinitiators (in case of UV curing). Therefore, the understanding of the structure-property relationship of the different components of the coating formulation recipe is a must (Ruiz et al. 2002). 

Despite a wide range of available radiation curable formulations, the oligomers and reactive diluents alone are not sufficient to meet some of the desired target applications. Therefore, some special... 

Chem. Descrip. Aliphatic amine acrylate Uses Hydrogen donor source for radiation-curable formulations Features Copolymerizable exhibits inc. line speed and non-blooming props. contributes to performance characteristics Properties Low odor... 

CAS 2156-97-0 EINECS/ELINCS 218-463-4 Uses Flexibilizer, adhesion promoter, water resistance aid in coatings, all radiation-curable formulations Features Good weatherability very low VOC Properties Gardner 2 max. clear liq. dens. 7.3 Ib/gal vise. 6-10 cps acid no. 0.5 max. sapon. no. 225-235 flash pt. > 200 F 0.1% max. moisture Storage Store in a cool, shaded, well ventilated area away from direct sources of heat and sunlight Photomer 4814 [Cognis/Coatings Inks]... 

For some time, radiation-curable formulations have been on the market The potential for using them in UV-curing textile finishing applications has been investigated (Castelein et al., 2011, Goelhals et al., 2014). Radiation-cured coatings or finishes are chemically cured, which results in the inability of reuse. Besides the water-based radiation-curable formulations, there is a lot of interest in the 100% systems because they contain no water. 

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. 

Fig. 10. Generalized formulation design outline for radiation-curable coatings and adhesive systems. The cross-linker is a multifimctional unsaturated cross-linking agent or oligomer, rj = viscosity CR = cure rate S = shrinl ge H = hardness F = flexibility A = adhesion 7 = surface energy ...

The objective of the present work was to determine the influence of the light intensity on the polymerization kinetics and on the temperature profile of acrylate and vinyl ether monomers exposed to UV radiation as thin films, as well as the effect of the sample initial temperature on the polymerization rate and final degree of cure. For this purpose, a new method has been developed, based on real-time infrared (RTIR) spectroscopy 14, which permits to monitor in-situ the temperature of thin films undergoing high-speed photopolymerization, without introducing any additive in the UV-curable formulation 15. This technique proved particularly well suited to addressing the issue of thermal runaway which was recently considered to occur in laser-induced polymerization of divinyl ethers 13>16. 

The software sends location information to the laser/mirror system that then directs radiation energy to specific regions of a thin layer of photoreactive chemical (UV-curable formulation) present on a movable platform in the reservoir. Simultaneously, the information package directs the system to lower the platform slowly with the cured slice of the object into the reservoir.27... 

The two most prominent liquid radiation curable adhesives are free radical polymerization epoxy acrylates and cationic polymerization epoxies. Such adhesives are generally used as polymerizable syrups. A wide range of prepolymers can be acrylated including epoxies, urethanes, polyesters, polyethers, and rubbers. Elastomer-tackifying resin blends are often used in these formulations. 

Formulation details are then presented in Chapters 11 through 14 for the various possible forms of epoxy adhesive systems room temperature and elevated-temperature curing liquids, pastes, and solids. The more or less unconventional forms of epoxy adhesives are also identified and discussed, since these are now achieving prominence in industry. These include uv and electron beam radiation curable, waterborne systems, and epoxy adhesives capable of curing via the indirect application of heat or energy. 

The individual RMC for polymer materials is not the only factor in cost analysis of a coating system. In order to make a fair comparison between conventional and radiation curable coatings one must consider the entire coatings formulation. Shown below is a cost range calculated for a conventional solvent-... 

The cost of the radiation curable coatings formulation is 5.13/gal, but it covers 2 to 2.5 times more surface area than the solvent-based coating. The cost for equal coverage of radiation curable coating is 18.50 gal/hr 2 or 2.5 times 5.13/g l = 37.96/hr to 47.45/hr. 

Radiation-curable coatings were developed by W. J. Burlant (of the Ford Motor Company) in 1962. Acceptance of finishes designed for radiation curing (high-solids materials formulated to be cured by UV and EB systems) is growing at roughly 8 percent per year with a market size of approximately 85 million lb. 

However, in many ways, these pressures have strengthened the industry. Efficiency and productivity have been enhanced by the adoption of modern computer techniques for formulation, inventory control, scheduling, production, etc. New technologies have been developed and implemented (e.g., electrodeposition, autodeposition, high solids, powder coatings, radiation curables, metal prefinishing, and robots) that will serve the industry well into the future. 

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