In order to provide good adhesion for natural nail coatings and to avoid loss of adhesion between the substrate and the coating, the mechanical properties of the coating should be close to those of the substrate. Three different mono-functional monomers (HPMA, THFA, THFMA) and one bi-functional monomer (EGDMA) have been added to decrease the viscosity of un-polymerized composition. Optimal monomer concentration was found evaluating monomer concentration effect on viscosity. Polymerized coatings were tested with monomer concentrations of 30% and 40%. The tensile strength properties of the polymerized coatings were determined 24 hours after polymerization. Polymerization T and conversion rate of unsaturated links were also studied to find the best monomer for natural nail coatings.

An increased demand for new and improved coating systems, for environmental & health & safety and performance reasons, have appeared during the recent decades. Currently, there is new interest in preparation of thin UV curable urethane acrylate (UA) composite coatings with short-term properties. Cellulose based additives: nitrocellulose, cellulose acetate butyrate, sucrose benzoate and silica were evaluated to determine their influence on unreacted composite characteristics (viscosity, pigment suspension stability) and characteristics of cured film (ultimate tensile strength, elongation at break, surface gloss, surface scratch resistance and film adhesion loss time). The most suitable additive content was found to provide required viscosity. All additives increase surface scratch resistance, but cellulose based additives increase surface gloss values and decrease the time of adhesion loss. Silica has great effect on the interaction between linear and hyperbranched urethane acrylates, which has crucial influence on the stability of uncured pigmented mixture samples.

Thin UV curable coating systems is an important research field from the industrial perspective due to the improved environmental profile and wide varieties of characteristics. When used for short-term applications as coatings on natural nail for esthetical and medical reasons, the system may be manipulated to attain various properties, either desired or required by the manufacturer e.g. ensuring both excellent long-term properties (deformability, toughness, and good adhesion) and short-term properties (ability to be destroyed quickly after use). Performance of thin UV curable urethane acrylate composite coatings was investigated depending on the content of the additive. Nitrocellulose (NC), cellulose acetate butyrate (CAB), sucrose benzoate (SB), and silica were evaluated to determine their influence on unreacted composite characteristics (viscosity, suspension pigment stability) and reacted film characteristics (ultimate strength, elongation at break, surface gloss, surface micro hardness, and film adhesion loss). According to the tests performed all additives increase the modulus of elasticity. CAB and NC increase the elongation at break values, and strongly increase the uncured gel viscosity, what makes it inconvenient for application.

The testing of thin colored coatings based on urethane acrylate composition is a technologically advanced, highly specialized and complex process. For decorative pigmented coatings color stability is crucial quality parameter. The photo chemically curable polymer films were prepared by addition of 3 different radical initiators (KTO, TPO, TPO-L) to aliphatic urethane acrylate composition with various pigments (solid and fluorescent). Coating color change were evaluated in UV chamber (with luminous intensity 130 mw spectrum λmax = 405 nm) after 1 h, 48 h and 72 h. Color measurements were performed according to the CIEL*a*b* color standard to evaluate their stability over time. It was found that pigmented coatings have higher risk of yellowness than clear coatings. Also fluorescent pigments containing red has tendency to yellow after UV light exposure. The influence of the photoinitiator on the color stability were inconsiderable.

Thin film coatings on fingernails and toenails are used for aesthetic reasons or to strengthen fragile nails. Coating disintegration is one of the most important characteristics of short-term coatings. The aim of this research was to investigate adhesion test methods for UV-cured urethane acrylate coatings. Coatings was compared evaluating gel fraction and degree of conversion of C=C bonds. Adhesion was measured using pull-off adhesion test and coating removability was evaluated after coating soak-off in solvent media with cross-cut tester. Systems with four different monomers in two concentrations was evaluated. All systems show a strong correlation of adhesion with the time of disintegration.