Acrylics cure enhancers

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. 

Cure enhancers for UV/EB and peroxide-cure systems are low-volatility liquid monomer SR-502 ethoxylated trimethylolpropane triacylate, curing rapidly in systems to increase flexibility, weather resistance, chemical resistance, shrinkage, abrasion resistance, and impact strength, for coatings, PVC flooring, and photopolymers and CD-501 propoxylated trimethylolpropane triacrylate, for low shrinkage in acrylics, adhesives, coatings, electronics, and photopolymers. 

Interestingly, later grades of Vamac to become available did not employ the cure site monomer, using instead a peroxide-curing system. Some of these copolymers also contained higher levels of methyl acrylate (up to 69%) to enhance the oil resistance. 

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)... 

An enhancement effect exists between NVP and the acrylate components in the cure of these systems. This behavior is interpreted as synergistic effect resulting from a variety of complex interactions between the components and not simply as a solvent effect. 

Saccharin and its sodium salts are used as components of curing agents for adhesives for acrylates on metal films. Surface-enhanced Raman spectroscopy has been used to show that the saccharin molecules migrate to the metal surface, so that they must be directly involved in the binding process <90L72i>. There are numerous patents on azo dyes based on 3-azo-substituted 2,1-benzisothiazoles. 

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