Properties of UV-curable polyurethane acrylates using nonyellowing polyisocyanate for floor coating

Abstract

SYNOPSISUV-curable polyurethane acrylates for poly(viny1 chloride) (PVC) floor coating were prepared using nonyellowing polyisocyanates. The effects of the chemical structure of the polyisocyanates and hydroxyacrylates, and the compositions of the prepolymer/diluent on the properties of the UV-curable polyurethane acrylates were investigated. Several different urethane acrylate prepolymers from four different polyisocyanates, isophorone diisocyanate (IPDI) adduct, hexamethylene diisocyanate (HDI) adduct, HDI biuret, and HDI isocyanurate, and two different hydroxyacrylates, hydroxypropyl acrylate (HPA), polycaprolactone modified hydroxyethylhexylacryylate (PCMHEA). UV-curable coating materials were formulated from the prepolymers and 1-hydroxycyclohexylphenyl ketone as a photoinitiator with polyethylene glycol diacrylate (PEGDA) as a diluent. The polyurethane acrylates prepared with HDI isocyanurate and the equimolar mixture of HPA and PCMHEA showed balanced coating properties such as tensile properties, hardness, weatherability, and good adhesion. The dynamic mechanical studies showed the properties of those polyurethane acrylates were well correlated with their glass transition temperature behaviors. It was also found that the adhesion was best as a PVC floor coating with the appropriate viscosity (below 150 P a t 25OC) when 35% PEGDA as a diluent was used.

Preparation and properties of poly(urethane acrylate) films for ultraviolet‐curable coatings

“…Typical FTIR spectra of four different urethane acrylate oligomers and UV‐cured poly(urethane acrylate)s are depicted in Figures 1 and 2, respectively. The spectral analysis was mainly used to check the completion of the polymerization reaction in terms of the disappearance of the NCO band at 2265 cm −1 and the appearance of the NH band at 3000–3400 cm −1 , which could be ascribed to the hydrogen bonding between NH and carbonyl groups 2, 4, 5. The completion of the reaction was confirmed with the following analysis.…”

“…The weatherability of the UV‐cured poly(urethane acrylate) films with different polyol and diisocyanate types was investigated in terms of ΔYI, which has been widely used as a semiquantitative expression of the weatherability; that is, the smaller ΔYI is, the better the weatherability is in coatings 2. Regardless of the functionality in the polyol, ΔYI showed a lower value in a poly(urethane acrylate) coating containing the aliphatic diisocyanate IPDI than the corresponding poly(urethane acrylate) with the aromatic diisocyanate TDI.…”

“…Growing concerns about environmental protection have driven industry toward the use of solvent‐free polymerization systems, and UV curing has become a viable alternative to the conventional thermal curing of solvent‐containing polymer formulations. Added benefits of UV‐curable materials, such as fast curing speeds, energy conservation, high efficiency, and less pollution, have led to their increased use in various applications such as paints, thin‐film coatings, adhesives, packaging overcoat films, and inks 1–4. During use, a low viscosity and a high curing speed are two important properties pursued for UV‐curable oligomers.…”

Fabrication of 3D biocompatible/biodegradable micro-scaffolds using dynamic mask projection microstereolithography

“…Crosslinking density is strongly dependent on the exposure time, the wavelength of the light, the type of photoinitiator, as well as the reactivity of monomers. In general, increasing the crosslinking density of the polymers increases the strength of cured polymers (Ha et al, 1996;Jung et al, 1998). In terms of the crosslinking density, the PPF used in the present research was not purified, and so some unreacting materials could have remained in solution, and these materials did not participate in crosslinking, and thus, reduced the crosslinking density (Varadan et al, 2001).…”

“…That is, on increasing the molecular weight of polymers, the polymers are more difficult to use in manufacturing due to an increased melt viscosity (Menon et al, 2002), despite the strength of the polymer increasing with viscosity. The manufacturability of polymers is further impacted by the molecular weight distribution within the polymer (Ha et al, 1996;Jung et al, 1998). The DEF content used in this work was fixed at 30%, similar to that used in the work of Fisher et al (2002b), because Fisher et al showed that a solution of PPF with 30% (w/w) of DEF had the highest elastic modulus and fracture strength.…”