Acrylate systems

A second type of uv curing chemistry is used, employing cationic curing as opposed to free-radical polymerization. This technology uses vinyl ethers and epoxy resins for the oligomers, reactive resins, and monomers. The initiators form Lewis acids upon absorption of the uv energy and the acid causes cationic polymerization. Although this chemistry has improved adhesion and flexibility and offers lower viscosity compared to the typical acrylate system, the cationic chemistry is very sensitive to humidity conditions and amine contamination. Both chemistries are used commercially. 

Smith P. and Eisenberg A., lonomeric blends. I. Compatibilization of the polystyrene-poly(ethyl acrylate) system via ionic interactions, J. Polym. Sci., Polym Lett., 21, 223, 1983. 

From the metal loss determinations it was possible to construct the mean corrosion rate - time curves for the acrylic and vinyl-acrylic systems. From Figure 6 it is clear that an initial interface metal loss process in the chlorine-containing vinyl-acrylic system quickly arrests within 12 days exposure, and the overall metal loss at 50 days is only of the order of 0.75 micron. The acrylic system shows no such arrest and indeed the corrosion rate increases with time to destruction of the foil. 

The low metal loss figures for the chlorine containing vinyl acrylic system noted above were supported by analytical measurements of iron pick-up in coatings on grit blasted Q panels. Under constant immersion in 3J NaCl the iron pick-up, equivalent to 0.13 micron metal loss, remained virtually unchanged after 14 days over the 63 days exposure. However, the acrylic system had an equivalent metal loss of 0.55 micron at 14 days which increased steadily to 1.43 microns at 63 days. 

The interactions between the components that make up a photopolymer are extremely important in arriving at a working formulation. Here we show that inclusion of pyrrolidone derivatives like NVP or NMP in acrylate systems enhances the ambient cure of a film. From the reactivity parameters of some simple systems we have derived an empirical scheme for the formulation of fully and/or partially reactive systems based on the molar equivalent ratios of the acrylate to pyrrolidone components. The data support the presence of a synergistic effect between NVP and the acrylate components. 

We focus here on a different type of monomer, N-vinyl pyrrolidone (NVP). This monomer is extensively used in the coating industry to add strength, dye receptivity, hardness, hydrophylicity and improved adhesion to copolymers of acrylate systems. Further note has been made of NVP use because of its low viscosity and its ability to enhance curing. (1-2)... 

Dodd and co-workers (5) reported the first known synthesis of 11//-indolizino[8,7-h]indoles by the cycloaddition reaction of a nonstabilized ylide 21 and diethylacetylene dicarboxylate (DEAD). The azomethine ylide, formed by the alkylation of the 3,4-dihydro-p-carboline (22) with trimethylsilyl methyl triflate to the triflate salt, followed by in situ desilyation with cesium fluoride, underwent cycloaddition with DEAD at low temperature. The expected major cycloadduct 23 was isolated, along with quantities of a minor product 24, presumed to have been formed by initial reaction of the ylide with 1 equiv of DEAD and the intermediate undergoing reaction with a further equivalent of DEAD before cyclization. Dodd offers no explanation for the unexpected position of the double bond in the newly generated five-membered ring, although it is most likely due to post-reaction isomerization to the thermodynamically more stable p-amino acrylate system (Scheme 3.5). 

In that publication a dependence of the shape of the rate-time function on such parameters as initial monomer concentration, emulsifier concentration, and dose rate was shown for the methyl acrylate system. The behavior of this system tentatively was explained by assuming a strong gel effect even at low conversions, of prolonged particle formation, and some kind of interparticle radical termination—all factors which are included neither in the Harkins view nor in the classical Smith-Ewart theory. 

Aberration, spherical, 7 Acetaldehyde, in Novolak resins, 346 p-Acetamidostyrene, preparation, 286 Acetophenone derivatives, 457 p-Acetoxystyrene, preparation, 271 Acrylate systems, UV-laser initiation, 222 Acrylic backbones, pendant groups, 277-80... 

The two most commonly used latex systems arc acrylic systems (40% of usage), which perform very well, but are relatively expensive, and die vinyl-acrylic copolymer systems (57% of usage and growing), which do not perform as well, but are less expensive. 

Sumitomo, H., and Y. Hachihama Radiation-induced graft copolymerization in acrylic systems. K6gy6 Kagaku Zasshi 60, 840 (1957) Chem. Afcstr. 53, 10834 (1959). 

The W(CO)4(4-Me-phen) complex also displays a number of spectroscopic features that lend themselves to utility as a probe [106], Figure 20 depicts electronic absorption spectra recorded from a 0.25-mm thickness film of a photosensitive acrylate system comprising a 1 1 (by weight) ratio of TMPTA and medium weight PMMA. Incorporated are the photoinitiators benzophenone (4% by weight) and 4,4/-bis(dimethylamino)benzophenone (0.5% by weight), and the probe complex W(CO)4(4-Me-phen) (0.3% by weight). The major absorption feature in this acrylate film is observed at 353 nm and is due to the photoini-... 

Four polymerization examples are presented here to illustrate both available sensitivity, experimental difficulties, and hopefully some interesting aspects of the polymerization processes. The first two examples are the semi-continuous emulsion polymerization of methyl methacrylate (MMA) and styrene, respectively. The third example is a batch charged copolymerization of butyl acrylate (BA) with MMA. The fourth example is a semi-continuous solution polymerization of an acrylic system. In this last example aliquots were taken manually and analyzed at 29.7°C under static conditions. No further polymerization occurred after the samples were cooled to this temperature. 

A method for calculating apparent reactivity ratios based on run number theory has been applied to "starved-feed" styrene/ ethyl acrylate systems. The reactivity ratios found are in agreement with those determined from solution polymerization data. The further confirmation of the observed agreement between reactivity ratios determined at low conversions and those determined by run number theory in "starved-feed" high conversion copolymerization requires the analysis of other comonomer pairs. 

It has been demonstrated that the incorporation of this type of reactive fluorosurfactant into a radiation curable acrylic system provides for a high gloss coating due to wetting, flow and leveling attributes, but results also in increased stain resistance of the coating. 

McGinniss, V. C., "Photoinitiator of Acrylate Systems for UV Curing," 3rd International Radiation Curing Conference, Proc. of SME Radiation Curing Conference, FC76-486 (1976). 

Cloud-Point Curves in Ethylene-Acrylate-Poly(ethylene-co-acrylate) Systems... 

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