UV-cured Polyurethane-acrylate Coatings Research Articles

Castor oil based high transparent UV cured silicone modified polyurethane acrylate coatings with outstanding tensile strength and good chemical resistance

Castor oil based high transparent silicone modified UV cured polyurethane acrylate coatings with outstanding tensile strength and good chemical resistance were developed with castor oil based polyurethane acrylates and thiol silicone resin. The UV cured coatings are with transparency in range of 90–98%, tensile strength as high as 10.2 MPa and elongation at break in the range of 88.4–162.5%. It is worth noting that the tensile strength of the coatings immersed in 3.5 wt% hydrochloric aqueous solution 144 h increased from 6.2 MPa to 15.5 MPa while the elongation at break is almost not changed, which reveals that the UV cured coatings also exhibit good chemical anti–corrosion performance. The UV cured coatings also show quite good UV resistance and adhesive properties.

Preparation and properties of UV-curable polyurethane-acrylate coatings of pre-coated metal (PCM): effect of polyol type/contents on adhesive property

Since UV curing coatings form a coating film with low adhesive property, it is difficult to use it as a coating for pre-coated metal (PCM) of post-processing method which has been actively studied recently. In this study, to apply UV-curing type coatings to pre-coated metal (PCM), which is applied as a method to improve productivity and to shorten the coating process, urethane acrylate oligomers were synthesized by using the content of polycaprolactone diol and hydrogenated polybutadiene glycol as a soft segment. UV-curable polyurethane acrylate coatings were prepared by varying the kind and content of the reactive diluent (IBOA, TMPEOTA). The urethane-acrylate oligomer and the coatings were well-prepared and confirmed using FT-IR. The storage modulus at RT, tensile strength and modulus were the highest values and the elongation at break was low. Also, as TMPEOTA content increased, the Tg of hard segment and storage modulus at RT, tensile strength and modulus increased, but elongation at break decreased. The surface free energy of all coating films was lower than that of metal plate. And the adhesive property of coatings using HPBD polyol of 30 and 50 mole% was the best and pencil hardness was also high in these coatings. MEK rubbing was increased with the increase of HPBD polyol and TMPEOTA content.

Enhancement of UV-aging resistance of UV-curable polyurethane acrylate coatings via incorporation of hindered amine light stabilizers-functionalized TiO2-SiO2 nanoparticles

In this study, polymeric hindered amine light stabilizers (HALS)-functionalized silica coated rutile titanium dioxide (TiO2-SiO2) nanoparticles were prepared by encapsulating commercially available TiO2-SiO2 nanoparticles with methyl methacrylate (MMA) and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPM) copolymers via miniemulsion polymerization. The obtained functional (TiO2-SiO2/P(MMA-co-PMPM)) fillers have been added to polyurethane acrylate (PUA) oligomers to get UV-curable nanocomposite coatings. The functionalization of the TiO2-SiO2 nanoparticles with polymeric HALS has been confirmed by infrared spectra (IR), thermogravimetric (TG), and X-ray photoelectron spectroscopy (XPS) analyses. The scanning electron microscope (SEM) micrographs indicated that homogeneous dispersion of TiO2-SiO2/P(MMA-co-PMPM) composite nanoparticles resulted in improved transparency and mechanical properties of the UV-curable PUA coatings. Rhodamine B (Rh.B) photodegradation measurement confirmed the excellent UV-shielding performance of PUA nanocomposite coatings containing TiO2-SiO2/P(MMA-co-PMPM). The addition of TiO2-SiO2/P(MMA-co-PMPM) composite nanoparticles reduced the UV-curable PUA coatings degradation rate dramatically. The UV-aging resistance of PUA coatings was improved significantly. Over all, the combination of TiO2-SiO2 nanoparticles and polymeric HALS offers an attractive way to fabricate the multi-functional fillers, which can be used to improve the mechanical properties and UV-aging resistance of PUA coatings simultaneously.

Synthesis and Curing Kinetics of UV-Curable Waterborne Bisphenol-S Epoxy Acrylate/Polyurethane-Acrylate Coating

In ouder to prepare the waterborne UV-curable polyurethane acrylate coatings, the anionic polyurethane acrylate emulsifier and bisphenol-S eopxy acrylate were synthesized. The curing process, kinetics and properties of waterborone UV-curable epoxy acrylate/polyurethanes acrylate coating were investigated by FTIR, DSC and DMA. The results show that the static initial curing temperature Ti is 52.36 oC, peak temperature Tp is 71.58 oC, the finished temperature Tf is 89.15 oC. The curing reaction can be described by two-parameter autocatalytic Šesták-Berggren (S-B) model.This coating has a better UV-curing property. The dynamic mechanical analysis showed that the glass transition temperature Tg of coating film is 52.70 oC.

UV curable polyurethane acrylate coatings for metal surfaces

Purpose – The purpose of this paper is to synthesise environment friendly UV curable polyurethane acrylate resins for various industrial applications and study the performance properties of the cured coating films applied over metal surfaces.Design/methodology/approach – The polyurethane acrylate resin was synthesised using polyester polyol (synthesised using ethylene glycol, adipic acid and 1,6 hexane diol), isophorone diisocynate (IPDI) and 2‐hydroxy ethyl methacrylate (HEMA). The different formulations were developed using various reactive diluents viz. monofunctional, difunctional, trifunctional and tetrafunctional (ethoxylated phenol monoacrylate, 1, 6 hexane diol di acrylate, dipropylene glycol di acrylate, trimethylol propane triacrylate, propoxylated trimethylol propane triacrylate, pentaerythrol triacrylate – PETA). These samples were cured under UV radiation. For effective curing, various compositions of oligomers, photoinitiator and reactive diluents were used. The mechanical, optical, rheologi...

How to speed up the UV curing of water-based acrylic coatings

Water-based polyurethane-acrylate (PUA) coatings have been cured, after drying, by a short exposure to UV radiation in the presence of a radical-type photoinitiator. The light induced polymerization has been followed quantitatively by means of real-time infrared spectroscopy, by monitoring continuously the disappearance of the acrylate double bonds. The UV curing of the dry film was markedly accelerated by adding to the PUA formulation a reactive plasticizer (diacrylate monomer), by operating in a humid atmosphere or by raising the temperature. The neutralizer of the carboxylic groups, needed to get a stable dispersion, plays a key role in both the polymerization kinetics and in the hydrophilic character of the UV-cured polymer, the best performance being achieved by using a volatile tertiary amine. Water-based UV-cured PUA coatings combine hardness and flexibility and are, therefore, quite resistant to abrasion and scratching.

Weathering resistance of waterbased UV-cured polyurethane-acrylate coatings

The light stability of waterbased UV-cured polyurethane-acrylate (PUA) coatings has been tested in an accelerated QUV-A weatherometer. Infrared spectroscopy was used to monitor both the ultrafast polymerization of the acrylate double bond upon intense illumination, and the chemical changes occurring upon photoageing of 30 μm thick clearcoats. The UV-curing reaction was hardly affected by the addition of the HALS radical scavengers and UV absorbers needed to improve the light stability of waterbased UV-cured PUA coatings. The α-hydroxyphenyl ketone used as photoinitiator was shown to disappear rapidly upon UV-curing and early QUV exposure, thus having no detrimental effect on the weathering resistance. The urethane linkage (C-NH) is the most sensitive to photodegradation. Such waterbased PUA coatings were found to be as resistant to weathering as typical UV-cured PUA coatings. In the presence of light stabilizers, they undergo only minor chemical changes after as much as 4800 h QUV-A ageing, the surface erosion being restricted to a few micron thick layer. The observed permanency of the UV-absorber after such heavy exposure ensures a longlasting UV-screen effect of the protective coating. Waterbased UV-cured PUA coatings proved to be more resistant to hydrolysis than melamine-acrylate thermosets.

Weathering performance of thermoset and photoset acrylate coatings

Thermosetting and photosetting acrylate polymers have been tested for their resistance to accelerated weathering. The chemical changes occurring both upon curing and upon photoaging have been followed by infrared spectroscopy. In the photodegraded polymers some functional groups are lost (ether, amide, CH groups) and oxidation products are formed (carbonyl and hydroxyl groups). The UV-cured polyurethane-acrylate coatings were found to be more resistant to accelerated weathering than the melamine/acrylate thermosets currently used as automotive finishes. The light stability of both thermoset and photoset acrylate clearcoats was substantially increased by the addition of a hydroxy-phenyltriazine UV-absorber and a HALS radical scavenger. The weathering resistance of painted metallic panels has been markedly enhanced by means of properly stabilized UV-cured acrylic coatings.