Waterborne UV Research Articles

Study on the silica-polymer hybrid coated SrAl2O4:Eu2+, Dy3+ phosphor as a photoluminescence pigment in a waterborne UV acrylic coating

Abstract In this paper, the preparation of SrAl2O4:Eu2+, Dy3+ (SAOED) phosphors coated with SiO2 and poly (methyl methacrylate-co-butyl acrylate) [P(MMA-BA)] was reported, the water resistance and afterglow performance of SAOED phosphors coated with different layers were compared. The photoluminescence behavior and dispersion stability of coated SAOED phosphor as a pigment used in waterborne UV acrylic coating (WUV) were also evaluated. The scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FTIR) analysis results showed continuous and uniform SiO2 and P(MMA-BA) layers on the coated phosphors, respectively. Based on X-Ray Diffraction and Excitation and emission spectra, the coating process did not cause damage to the phosphor crystal. The pH value of water solution versus time showed that the phosphors can obtain excellent water resistance with a 5wt.% SiO2 coating. Fluorescence performance test showed that when the mass fraction of coated phosphor in the WUV was 15%, and the light excitation time was beyond 180s, the afterglow performance of the WUV was the best with the excitation brightness exceeding 120 Lux. The dispersibility test results showed that the SiO2–P(MMA-BA) hybrid coating layer could maintain the uniform dispersion stability of SAOED phosphor in WUV for more than 72 h.

Preparation and antibacterial properties of waterborne UV cured coating modified by quaternary ammonium compounds

AbstractIn this article, the antibacterial properties and mechanism of waterborne UV cured acrylic coatings (WUV) modified by quaternary ammonium compounds (QAC) is discussed, as well as the changes in the antibacterial properties of QAC under the action of different additives. (60 wt% methanol, 60 wt% ethanol, and 75 wt% ethanol). And the chemical cross‐linking method is used to combine WUV with QAC. The scanning electron microscopy (SEM), Fourier transforms infrared spectrometer (FTIR), and X‐ray photoelectron spectroscopy (XPS) was employed to characterize the modified WUV. The antibacterial properties of three antibacterial agents in liquid coatings (WUV‐L) and cured coating films (WUV‐C) are investigated. The SEM images showed many irregular wrinkles appeared on the surface of modified coating films. The FTIR result showed the hydroxyl groups promoted the binding ability of the antibacterial agents and coating, and the XPS result revealed that the increase of −NR4+ concentration enhanced the antibacterial properties of coating films. The antibacterial properties of WUV‐L and WUV‐C improved with the increase of QAC. Theoretical antibacterial agents mass fraction of 5% or higher was found to have the highest antibacterial rate (>90.00%) for WUV modification, among, the WUV modified by QAC‐m60 is the best with the antibacterial rate reaching to 99.73% in WUV‐L and 99.67% in WUV‐C.

Development and finishing technology of waterborne UV lacquer-coated wooden flooring

To develop a waterborne wooden flooring coating, the existing problems of the current waterborne coated wooden floorings were analyzed, and their corresponding solutions were considered. In this paper, based on the final effects of a novel waterborne UV wooden floor coating, the authors used a waterborne UV coating with different solids contents, as well as finishing and drying technology to treat the substrate with different tree species. According to the LY/T standard 1859-2009 (2009) and Q/YFL standard 0035-2018 (2018), the performance of the varnish film of the waterborne UV wooden floor coating was determined. The waterborne coating wooden flooring processes and effects of the varnish film were optimized to provide excellent performance. The performance of the varnish film and the developed waterborne coated wooden flooring met the standard requirements: the surface wear-resistance was less than or equal to 0.15 g/100r, the varnish film hardness was greater than or equal to H, the level of varnish film adhesion was less than or equal to 2, and the total volatile organic compounds was less than or equal to 20 µg/m3. This study provided a demonstration and basis for wooden flooring companies to develop a waterborne wooden floor coating.

Research on the Performance of Series Waterborne Polyurethane Acrylate Modified Epoxy Acrylates

In this study, a series of bifunctional-based UV curable waterborne polyurethane acrylate modified epoxy acrylate (UV-WPUA) was prepared by using 2,4-toluene diisocyanate (TDI), Epoxy resin (E51) and polyethylene glycol (PEG) as the main materials. Waterborne resin and UV curing film with content of C-O-C were obtained by using polyethylene glycols with different molecular weights. The infrared spectra (FT-IR) demonstrated the presence of C=C and epoxy bond in the UV curing film chains. In addition, the molecular weight of the oligomer, and glass transition temperature, gelation rate and thermogravimetric analysis of the films were investigated.

Polymerizable Hydrophobically Modified Ethoxylated Urethane Acrylate Polymer: Synthesis and Viscoelastic Behavior in Aqueous Systems

Hydrophobically modified ethoxylated urethanes (HEURs) comprising hydrophilic poly(ethylene glycol) backbone and hydrophobic end groups are widely applied as rheological additives to regulate the viscoelastic behavior of waterborne systems such as coatings and inks. However, the conventional HEURs are usually nonreactive and remain free in final films, which may bring some defects and damages to the final cured films during the service time. An appealing way to improve filming properties may be to design reactive HEURs, which can participate in the post-crosslinking reactions with other components in formula during the film curing. In this work, a polymerizable acrylic-type HEUR (acrylic-HEUR) end-functionalized by the reactive methacrylate group and hydrophobic octadecyl tail is reported. The typical free radical polymerization feature of acrylic-HEUR based on the highly reactive methacrylate group is carefully clarified by dynamic light scattering, in situ nuclear magnetic resonance (1H NMR), and rheological measurements. The excellent thickening performance of acrylic-HEUR in waterborne UV emulsions and its effective copolymerization reactivity with the UV-curable matrix resin are demonstrated by in situ rheological measurements under UV irradiation in detail. Compared to conventional nonreactive HEURs, the copolymerization reactivity of acrylic-HEUR may make it especially suitable for applications in waterborne UV coatings to avoid its migration from final UV-cured films. This work may not only open a new perspective for the fabrication of HEUR polymers with high chemical reactivity but also promise the potential of polymerizable HEURs as superior associative thickeners in industry.

Preparation and Characterization of Waterborne UV Lacquer Product Modified by Zinc Oxide with Flower Shape.

In this paper, the waterborne UV lacquer product (WUV) was used as the main raw material, zinc oxide (ZnO) was used as the additive, and the stearic acid as the surface modifier. According to the method of spraying coating on the surface of poplar wood (Populus tomentosa), a simple and efficient preparation method was carried out to generate a super-hydrophobic surface and enhance the erosion resistance of the coating. By testing, the contact angle (CA) of water on the coating surface can reach 158.4°. The microstructure and chemical composition of the surface of coatings were studied by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The results showed that under acidic conditions, the non-polar long chain alkyl group of stearic acid vapor molecule reacted with the hydroxyl group in acetic acid, the metal ions of the ZnO were displaced to the stearic acid and generated globular zinc stearate (C36H70O4Zn). The hydrophobic groups –CH3 were grafted to the surface of zinc stearate (ZnSt2) particles and the micro/nano level of multistage flower zinc stearate coarse structure was successfully constructed on the surface of poplar wood, which endowed it with superhydrophobic properties. It is shown that the coating has good waterproof and erosion resistance.

Dispersion Characteristics and Curing Behaviour of Waterborne UV Crosslinkable Polyurethanes Based on Renewable Dimer Fatty Acid Polyesters

In the last few years there has been a great deal of interest in modifying the methodologies for obtaining polyurethanes using more sustainable strategies. Following this tendency, in the present work, waterborne UV-curable polyurethanes were synthesized using commercially available dimer fatty acid based polyols obtained from renewable resources (Priplast from Croda). The polyols, characterized by proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC) and size exclusion chromatography (GPC–SEC), were semicrystalline and presented very broad melting related with their complex molecular weight distribution. Different polyurethane dispersions were obtained by changing the percentage of the hard segment. Comparing with waterborne polyurethane dispersions obtained from non-renewable resources, the dispersions showed higher particle size even using similar or higher amounts of internal emulsifier. The curing behaviour was characterized by photo-differential scanning calorimetry (Photo-DSC) and the results showed that the conversion and polymerization rate decreased with the hard segment content and temperature. The obtained products displayed good thermal characteristics with phase-separated structures.

Study on the Synthesis of Waterborne UV Curable Polyurethane Acrylate

Water-brone UV-curable polyurethane acrylate was synthesized based on the toluene diisocynate, polypropylene glycol, dihydroxy methyl acrylic acid and hydroxyethyl acrylate. The structure and the influencing factors on the water solubility and photosensitivity of the waterbrone UV-curable polyurethane acrylate were analyzed. Results show that the water solubility of the resin is enhanced with the increasing of the content of hydrophilic group in the resin. The UV-curing rate of the waterborne coating is good by adding the 819-DW photoinitiator. Triethylamine is a good neutralizer in the waterbrone UV-curable system for having 90% neutralization degree.

Study of the crosslinking process of waterborne UV curable polyurethane acrylates

Abstract UV curable acrylic end capped polyurethane dispersions were obtained by the acetone process, using different molecular weight polyols. Photo Differential Scanning Calorimetry (Photo-DSC) was employed to study the effect of the photoinitiator concentration as well as the curing temperature in the curing reaction rate. The penetration capacity of UV radiation was determined by “in situ” Attenuated Total Reflectance Infrared Spectroscopy (ATR-FTIR). In addition, Temperature Modulated Differential Scanning Calorimetry (TM-DSC) was used to calculate the crosslinking degree through the measurement of the Heat Capacity (Cp). According to Photo-DSC data, the conversion of the curing reaction increased with temperature and no dependence with the photoinitiator concentration was found. Cp values of the cured samples enabled us to compare the crosslinking degree as a function of photoinitiator concentration, polyol molecular weight and curing temperature.

High bio-based content waterborne UV-curable coatings with excellent adhesion and flexibility

A series of bio-based unsaturated polyesters was synthesized by melt polycondensation of itaconic acid with 1,4-butanediol and glycerol. Their chemical structures were confirmed by FT-IR, 1H NMR, acid and hydroxyl values. Waterborne UV curable dispersion coatings based on these polyesters and acrylated epoxidized soybean oil (AESO) were formulated. The average particle size and their stability before curing as well as the coating properties after curing, including adhesion, flexibility, pencil hardness and solvent resistance, were investigated. Results demonstrated that the glycerol segment in the polyesters together with AESO led to the excellent coating properties in terms of highest grade of adhesion (5B), 0T flexibility, pencil hardness of 5H and excellent solvent resistance (no appearance change after 250 double rubs with ethanol and acetone). This work provided us the coating systems combining the merits of being bio-based, UV-curable and water dispersible.

Synthesis of bio-based unsaturated polyester resins and their application in waterborne UV-curable coatings

In this paper, three bio-based unsaturated polyesters were synthesized from itaconic acid and different diols which could be derived from renewable resources. Their chemical structures were confirmed by FT-IR, 1H NMR and acid value as well as hydroxyl value. Waterborne UV curable networks based on these polyesters were manufactured and their mechanical properties, thermal stability and coating properties including pencil hardness, flexibility, adhesion, water resistance and solvent resistance were investigated. Results showed that the UV-cured polyester coatings exhibited high hardness, good water resistance and solvent resistance. The coatings reported in this paper combined the merits of bio-based materials, UV-curing process and water distribution.

Preparation of UV Curable Waterborne Polyurethane and its Application in Coatings

Waterborne UV curable polyurethane emulision containing C=C bond was prepared with self-emulsification. 3% water soluble photoinitiator was added to the polyurethane emulision, and polyurethane films was prepared by ultraviolet irradiation. The structure of the polyurethane emulision and films were confirmed by means of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis. FTIR test result shows that cross linking and solidification reaction of C=C double bond happened after UV irradiation. When C=C content increases, the particle size of polyurethane emulision increases, crosslinking degree of films increases, water resistance and heat resistance have both been improved. When C=C content is 8.51%, gel content is more than 90% and the lowest water absorption can be 12.5%.

Study on UV Curable Waterborne Polyurethane Modified by Epoxy Resin

In this paper, UV curable waterborne polyurethane emulsions were prepared by fractional step method using toluene diisocyanate (TDI), polyethylene glycol (PEG, MW=1000), α,α-dimethylol propionic acid (DMPA), 2-hydroxyethyl methacrylate (HEMA) as raw material, and UV-WPUs were modified with epoxy resin. The effect of different content of epoxy resin on the viscosity, the water resistance, and other properties was investigated. The synthesized polyurethane structure was confirmed by the Fourier transform infrared spectroscopy (FTIR). The FTIR analysis identified that the target product was expected epoxy modified waterborne UV polyurethane. And with –COOH content increasing, the emulsion viscosity of the WPU increased and the water absorption of the films increased; with epoxy content increasing, the viscosity of the WPU emulsion increased and the water resistance of the films was improved.

Synthesis and Properties of Waterborne UV Polyurethane

Toluene diisocyanate(TDI), polyethylene glycol(PEG), double-propionic acid(DMPA), hydroxyethyl methacrylate(HEMA) and other raw materials were used to synthesis UV-curable waterborne polyurethane, and the effect of the synthesis condition on the particle size of the emulsion was investigated in this paper. The structure of the polyurethane was identified by infrared spectroscopy (IR), thermal decomposition properties was measured through the thermogravimetric(TG). The results showed that, the target product is expected waterborne UV polyurethane by IR. With DMPA content increasing, the particle size decrease, stability and appearance of the emulsion turn better. With the mole ration of PEG/DMPA decreasing, adhesion and water absorption of the film increase. TG analysis indicates that the thermal decomposition performance of the Waterborne UV Polyurethane （WPUA） is excellent.

Highly branched polyurethane acrylates and their waterborne UV curing coating

A series of UV curable highly branched waterborne polyurethane acrylates (BWPUAs) were synthesized using an “oligomeric A 2 + B 3” approach. The thiol-endcapped difunctional oligomeric A 2 was synthesized first by the addition reaction of isophorone diisocyanate, α,α-dimethylol propionic acid and 2-hydroxyethyl acrylate, then further underwent thiol-Michael reaction with 1,6-hexamethylene bis(thioglycolic acetate). Trimethylolpropane triacrylate was used as a B 3 monomer. The molecular structures were characterized with FT-IR and 1H NMR spectroscopy. 1,6-Hexanediol diacrylate (HDDA) was incorporated into the polymeric chain for preparing the HDDA-modified BWPUAs (BWPUA-Hs). For the comparison, the linear waterborne polyurethane acrylate (LWPUA) was synthesized. The UV curing kinetics study results by using the photo-DSC approach showed that the BWPUAs possessed higher photopolymerization rate and final unsaturation conversion in the UV cured films compared with the LWPUA, which increased with the increase of unsaturation concentration in BWPUA. Moreover, the photopolymerization performance, and water and solvent resistance properties were greatly enhanced by the incorporation of HDDA segment into the BWPUA chain. The dynamic mechanical thermal analysis results showed that the elastic modulus in the rubbery plateau, and the glass transition temperature of UV cured film increased with increasing unsaturation concentration in BWPUA, whereas decreased with the introduction of HDDA flexible segment. The thermogravimetric analysis confirmed the high thermal stability of UV cured BWPUA films. All UV cured BWPUA and BWPUA-H films showed better flexibility and middle refractive indices due to the thioether linkage in the polymer network.

Study on Photopolymerization Performance of Waterborne UV Cured Ink

The anion UV-curing water soluble prepolymer was synthesized with toluene diisocyanate, dihydroxy compound, dihydroxyalkyl carboxylic acid and polyurethane acrylate. The structure of the prepolymer was characterized by infrared spectroscopy. The effect of different photoinitiators, pigment content, drying technology on the curing speed of ink was also researched. The results shown that the photoinitiator system 819DW and MBF was best matched with the yellow pigment, cyan pigment and black pigment, the optimum content of the pigment was about 10 percent, 10 percent and 11 percent. The photoinitiator system 819DW and 500 was best matched with the magenta pigment, the optimum content of the pigment was about 10 percent．Under the conditions of this experiment, the best pigment content of the yellow, magenta, cyan, black was about 6 percent, 7 percent, 6 percent and 7 percent. The curing rate without pre-drying increased.

Corrosion protection properties of new UV curable waterborne urethane acrylic coatings

Looking to the development of sustainable and low impact chemical technologies, water based paints offer significant advantage especially for in field applications, where the problem of solvent emission is really stringent. Some water based coatings are represented by alkyd and epoxy paints, capable of cross-linking either by auto-oxidation or with polyamines. Polyurethane aqueous dispersions are finding wide acceptance due to their better durability, adhesion and mechanical properties. The research presented here describes the design, application and characterisation of well defined model structures of waterborne UV curing coatings. The waterborne resins used in this work are segmented anionomeric polyurethanes functionalised with acrylic end groups: they were prepared from polytetramethylene glycol, isophorone diisocyanate, dimethylol propionic acid, and hydroxyethylacrylate. The preliminary results concerning the corrosion protection properties of the new UV curable waterborne coatings applied onto metallic substrates are very promising and were obtained by using electrochemical techniques. Water uptake is the critical process determining the corrosion performance. In particular the necessity to formulate the coating starting from higher molecular weight polytetramethylene glycol for good barrier properties is evident from the electrochemical impedance spectroscopy data.

Effect of UV Curable Pretreatments on the Color Quality of Inkjet Printed Polyester Fabrics

Woven and knitted polyester fabrics were pretreated with formulations containing waterborne UV curable resins and silica particles to improve inkjet print quality. The selected formulations were applied with low add-on to reduce the adverse effect on fabric hand without sacrificing the print quality. A print pattern with block areas and lines in cyan, magenta, yellow, and black colors was designed and inkjet printed on the pretreated fabrics with a wide-format inkjet printer (Encad Novajet 750) to investigate the effects of the UV curable pretreatment on the inkjet print color qualities including color depth, color gamut and color lightness. Experimental results show that both the color depth and gamut of prints on the pretreated taffeta and knitted polyester fabrics were enhanced compared to those on untreated polyester fabrics. However, both the color depth and gamut of the prints on the pretreated satin polyester fabrics were reduced. The lightness change of the inkjet printed colors on pretreated knitted fabrics is similar to that of untreated fabrics whereas the lightness change of prints on pretreated satin and taffeta fabrics shows some differences. All colors have increased lightness on pretreated satin fabrics. However, magenta and black have decreased lightness on the pretreated taffeta fabrics.

UV Curable Pretreatment of Polyester Fabrics for Inkjet Printing

Various woven and knitted polyester fabrics were pretreated with formulations containing waterborne UV curable resins and silica particles to improve inkjet print quality. The UV curable resins and silica were chosen to impart the affinity of acid dyebased and direct dye-based inks onto the polyester fabrics. The low add-on of the selected formulation was applied to reduce the adverse effect on fabric hand without sacrificing the print quality. A print pattern with various areas and lines in cyan, yellow, magenta and black colors was designed and the pattern was inkjet printed on the various pretreated fabrics with a wide-format inkjet printer (Encad Novajet 750) to investigate the effects of the UV curable pretreatment on the print quality. Experimental results show that improved line quality in terms of the line width gain and the edge raggedness was observed for the lines printed on the pretreated fabrics. In particular, the 2 pt-line width of magenta color on the pretreated taffeta fabric was reduced by 13.8% and the 2 pt-line raggedness of yellow color on the pretreated taffeta fabrics was reduced by 80% compared to that on the untreated fabrics. Generally, increase in silica content inhibits inter-color bleeding onto the adjacent colored areas. For example, a 6% pretreatment formula of 10 parts UV curable resin and 6 parts of the silica particles can yield sharply defined images, while the printed fabrics still maintain a very good hand.

Carbohydrate modified photoinitiators

As a result of the new trend concerning the development of water-borne UV curable coatings, attention has moved to the synthesis and investigation of water-soluble photoinitiators (Pls). New Pls were synthesized by covalent bonding of carbohydrates such as D-glucose, cellobiose and 1-amino-D-sorbitol to Type I and Type II Pls based on α-hydroxyolkylphenones, thioxonthones and benzophenones.