Waterborne Acrylic Coatings Research Articles

Enabling zero added-coalescent waterborne acrylic coatings with cellulose nanocrystals

Waterborne acrylic coatings contain volatile and non-volatile coalescents. Volatile organic compound (VOC) coalescents enable film formation of hard acrylic polymers at ambient temperature, but their evaporation results in air pollution and health concerns. Non-volatile alternatives are available, but they remain in the coating long-term and as a result films are often tacky and lack adequate hardness. Reinforcing mineral fillers are available, but are associated with sustainability challenges inherent to mineral mining. An alternative approach demonstrated here utilizes a renewably-sourced, plant-based hardening filler dispersed in the water phase, with soft polymer latexes that don’t require VOCs for film formation. We reinforced coalescent-free and ambient film-forming butyl acrylate/methyl methacrylate/methacrylic acid latexes with cellulose nanocrystals (CNCs) by a post-synthesis blending approach. CNCs possess high elastic modulus and tensile strength, making them promising candidates to improve the mechanical performance of soft ambient film-forming acrylic latexes. CNCs form aggregates within the interstices between latex particles as water dries, however film coalescence is not compromised. Films with 15 wt% CNC showed almost 230 % improvement in Koenig hardness and 10x improvement in the nanoindentation hardness compared to neat films, achieving properties similar to hard VOC-containing acrylic binders in a zero-added VOC formulation.

Effect of Urea-Formaldehyde (UF) with Waterborne Emulsion Microcapsules on Properties of Waterborne Acrylic Coatings Based on Coating Process for American Lime

The purpose of this paper is to explore the effect of urea-formaldehyde (UF) with waterborne emulsion microcapsules on the optical, mechanical and aging resistance properties of waterborne coatings from the perspective of coating process. In this paper, the microcapsules were prepared with UF resin as the wall materials and waterborne emulsion as the core materials. Based on the coating process, the optical, mechanical and aging resistance properties of the waterborne acrylic coatings with microcapsules for American lime were tested. The good coating process is three layers of primer, two layers of topcoat, and adding microcapsules into primer. The results showed that the coating process had little effect on the color difference of the paint film with microcapsules, the gloss of the paint film prepared by the good coating process was basically not changed, and the mechanical properties of the paint film were good. At this time, the hardness grade of the paint film was 3H, the adhesion was grade 0, the impact resistance was 110.0 N·cm−2, and the elongation at break was 29.7%. The microcapsules added to the primer had better liquid resistance than those added to the topcoat. The paint film had good stability and aging resistance, and could inhibit the generation of microcracks to a certain extent. The paint film prepared by the good coating process had better comprehensive performance. This work provides a technical reference for self-healing of the waterborne coatings on American lime.

Evolution of the film properties of 3‐methacryloxypropyl trimethoxysilane containing waterborne acrylic coatings during storage

AbstractThe use of alkoxysilane monomers is one of the most attractive methods to obtain one‐pot self‐crosslinkable latexes for coating applications. The copolymerization kinetics shows that the alkoxysilane monomer is effectively incorporated into the copolymer. However, the hydrolysis and condensation reactions that give the latex the self‐crosslinking ability can also prematurely happen. As a result, the microstructure of the latex, and consequently of the dried polymer film, will change during the storage. Herein, the evolution of key film properties, such as, water uptake and tensile strength as a function of the storage time of latexes with different alkoxysilane monomer loadings is presented. As storage time increases, there is an improvement on the mechanical properties, obtaining a harder polymer as the result of the development of the hydrolysis and condensation reactions during the first 4 weeks. However, for more extended storage periods (17 weeks) there is a significant decrease in the mechanical performance, because the crosslinking in the latex has developed enough to hinder the film formation.

Large CeO2 nanoflakes modified by graphene as barriers in waterborne acrylic coatings and the improved anticorrosion performance

Large CeO2 nanoflakes in diameter of 3∼5 μm were used as barriers in waterborne acrylic coating to improve the anticorrosion. Meanwhile, graphene (Gr) was adopted to modify the CeO2 nanoflakes which were linked by bifunctional ligand p-aminobenzoic acid (PABA), forming a more efficient barrier Gr-P-CeO2. The electrochemical test indicated that the acrylic coating using Gr-P-CeO2 as barrier improved the anticorrosion performance obviously when compared with the coatings using pure Gr, pure CeO2 nanoflake, and the Gr-CeO2 without PABA linking. The composite coating with Gr(3%)-P-CeO2 had a corrosion current (icorr) of 2.29 × 10−7 A/cm2, and coating resistance(Rc) was 3.53 × 103 Ωcm2. The best icorr was almost 53 times lower of CeO2 coating, and 48 times lower of Gr-CeO2 coating.

Comparison of Some Physical and Mechanical Properties of Waterborne Acrylic Coating Systems Containing Commercial UV Absorbers and Tree Bark Extracts

Aim of study: The aim of this study was to compare solid content, dry film thickness, and adhesion strength of different tree bark extract based and a commercial UV absorber.
 Materials and methods: Waterborne acrylic-based coating systems containing 5 different tree bark extracts (maritime pine, Calabrian pine, black pine, alder, fir) and a commercial UV absorber (Tinuvin 400 DW) were applied to 2 different wood species; Scots pine (Pinus sylvestris L.) and beech (Fagus orientalis L.). The dry-film thicknesses of the coatings were measured with light microscopy. The adhesion strength of the coatings was determined to investigate the bonding ability of the coatings with wood surfaces. The solid contents of the coatings were also determined.
 Main results: Permeability is an important parameter for dry-film thickness and adhesion strength. Wood species also influenced the dry-film thickness as well as adhesion strength. The dry-film thicknesses of the coatings containing bark extracts were higher than those with commercial UV absorbers. Similarly, the solid content of the coating containing maritime pine bark extract was found to be the highest.
 Highlights: The dry-film thickness and adhesion strength of waterborne acrylic coatings on wood substrate seem to be affected by addition of tree bark extracts.

Isolation of the interaction between CaCO3 filler and acrylic binder. Part II: Effect of the amount and type of functional monomer

The aim of this work is to better understand the effect that different functional monomers and amounts have on the dispersion of calcium carbonate (CaCO3) fillers in waterborne acrylic coatings. This will allow to improve the final performance of coatings at a certain pigment volume concentration (PVC) or to increase the PVC without significant losses in the properties. In this paper we report the preparation of CaCO3/poly(methyl methacrylate-co-butyl acrylate) P(MMA/BA) latex blends without the use of any additive and with applicable rheology. This has been possible thanks to the direct addition of CaCO3 powder to diluted latex. Paint-like blends have been prepared with latexes synthesized with acrylic acid (AA) and methacrylic acid (MAA) functional monomers at 1, 3, and 5 wt based on monomer percent (wbm%) and with itaconic acid (IA) at 1 wbm%, at different PVC values of 30, 40 and 50. Moreover, the effect of water soluble species on the final paint properties has been checked by dialyzing latexes synthesized with the minimum and the maximum amount of MAA, before the blending with CaCO3. The effect of all these variables has been investigated by analysing the final paint-like film properties (rheology, gloss, mechanical properties and scrub resistance). The interaction between the different latexes and CaCO3 filler was also studied by investigating the adsorption capacity of polymer particles on the surface of CaCO3 particles with NMR measurements. Higher gloss value, more elastic mechanical properties and higher scrub resistance have been observed for films prepared with the latex containing 1 wbm% of MAA functional monomer.

Impact of silicone additives on slip/mar performance and surface characteristics of waterborne acrylic coatings

Silicone additives are often added to coating formulations for improved slip and mar performance. However, the relationship between the chemical structure of silicone slip/mar additives and their performances has not been well understood. In the current study, six different silicone slip/mar additives made of silicone gum dispersions or silicone polyethers were investigated. Micron-sized silicone gum dispersions (G1 and G2) result in the lowest coefficient of friction and the highest mar resistance in a waterborne acrylic coating; however, they also lead to the highest surface roughness and the lowest gloss. The submicron-sized silicone gum dispersion (G3) results in a smaller improvement in the slip/mar performance and a much smaller detrimental impact on the surface roughness and gloss. All of the silicone polyethers (P1, P2, and P3) contribute to smaller improvement in slip/mar performance compared to silicone gum dispersions, but they have minimum impact on the gloss and roughness of coatings. Studies by AFM and XPS demonstrate coatings with micron-sized silicone gum dispersions have the highest surface segregation of silicone whereas coatings with silicone polyethers have the lowest surface segregation of silicone. A strong correlation between the surface segregation of silicone and the slip/mar performances of coatings is observed.

Effect of membrane structure of waterborne coatings on the transport process of corrosive medium

In this study, gravimetric method and electrochemical impedance spectroscopy combined with atomic force microscopy (AFM) and contact angle measurement were used to study the transport of corrosive medium in waterborne thermosetting and thermoplastic coatings with different structures. Three typical kinds of resin membrane of waterborne coatings (waterborne acrylic, waterborne fluorocarbon, and waterborne epoxy coatings) were analyzed. Results show that the transport of corrosive medium in waterborne thermoplastic coatings and waterborne thermosetting coatings is consistent. The transport in these two kinds of coatings can be divided into three stages. In the first stage, transport is primarily affected by the water concentration in the coating and the medium content is linear with t1/2, which satisfies the Fick diffusion law. Then, medium transport deviates from Fick diffusion and the medium content reaches saturation over time. During condensation of polymer particles in thermoplastic waterborne acrylic coating and waterborne fluorocarbon coating, the intermolecular diffusion of molecular segments on the particle interface is limited. The presence of microstructural defects leads to limited densification of coating and easier formation of medium channels. The waterborne fluorocarbon coating contains symmetric fluorocarbon bonds, resulting in low surface energy, and the hydrophobic properties result in a slower medium transport rate. During coagulation of the latex particles in the waterborne epoxy coating, the crosslinking and curing reaction of the particle interface greatly reduces the microstructural defects, thereby increasing the compactness and resulting in the slowest medium transmission process.

Effect of Zinc Phosphate on the Corrosion Behavior of Waterborne Acrylic Coating/Metal Interface.

Waterborne coating has recently been paid much attention. However, it cannot be used widely due to its performance limitations. Under the specified conditions of the selected resin, selecting the function pigment is key to improving the anticorrosive properties of the coating. Zinc phosphate is an environmentally protective and efficient anticorrosion pigment. In this work, zinc phosphate was used in modifying waterborne acrylic coatings. Moreover, the disbonding resistance of the coating was studied. Results showed that adding zinc phosphate can effectively inhibit the anode process of metal corrosion and enhance the wet adhesion of the coating, and consequently prevent the horizontal diffusion of the corrosive medium into the coating/metal interface and slow down the disbonding of the coating.

Effect of carbon nanotubes on the corrosion resistance of water-borne acrylic coatings

Abstract The effects of multiwalled carbon nanotubes (MWCNTs) on the adhesion strength and corrosion resistance of the acrylic nanocomposite coatings were evaluated on Q235 substrates via pull-off tests and electrochemistry measurements (EIS, LEIS). Addition of MWCNTs to the acrylic resulted in an up to ∼50% increase in the adhesion strength. After 36 h of immersion in 3.5 wt% NaCl, the coating resistance of the native acrylic coating was 235.8 Ω cm 2 , whereas those of the nanocomposite coatings containing 0.5 and 1 wt% MWCNTs were 1.36 × 10 5 and 9.27 × 10 7 Ω cm 2 , respectively. LEIS analysis indicated that the addition of MWCNTs increased the adhesion strength and retarded the delamination. The results demonstrated the positive effects of the incorporation of MWCNTs on the anticorrosive ability of the coatings.

Effect of coating thickness and nano additive on permeability of some modified waterborne acrylic coatings

Effect of coating thickness and nano additive on permeability of some modified waterborne acrylic coatings

A new understanding of the failure of waterborne acrylic coatings

Two waterborne coatings, a styrene–acrylic coating and a terpolymer coating based on acrylic acid, vinyl chloride and 1,1-dichloroethylene segments, had their barrier properties and wet adhesion compared after immersion in 3.5 wt% NaCl solution.

Homogeneous Dispersion of Cellulose Nanofibers in Waterborne Acrylic Coatings with Improved Properties and Unreduced Transparency

Cellulose nanocrystal has been widely used as a reinforcement filler in waterborne coatings, but the application of cellulose nanofiber (CNF) as a filler is difficult because of inhomogeneous dispersion. Herein, a facile and effective strategy to improve the dispersion of CNFs in the polymer matrix by mixing with γ-aminopropyltriethoxysilane (APS) is presented. The APS dosages 0.08–0.48 wt % to 0.3 wt % CNFs were investigated, and the dosage 0.16% was found to achieve a superior stability of CNFs in the aqueous solution. The APS(0.16%)-modified CNFs were then incorporated and demonstrated distributing uniformly in the waterborne acrylic coating. The as-prepared coatings retain high light transmittance around 90%, and display improved mechanical properties. The composite coatings show a maximum 500% improvement in Young’s modulus, two-level improvement in hardness, and 35% reduction in abrasion loss as compared with those of neat coating. These results reveal that APS modification induces the homogeneous d...

Waterborne acrylic paint system based on nanoceria for corrosion protection of steel

The corrosion protection efficiency of steel painted with waterborne acrylic coatings loaded with diverse concentration of cerium oxide nanoparticles are presented in this paper. The investigation was carried out by means of Electrochemical Impedance Spectroscopy (EIS) and the salt spray test. EIS has been conducted at two experimental conditions: the intact coating condition as well as in presence of a purposely created macroscopic defect. EIS observations from the intact coatings evidenced the higher protection for the paint systems containing the ceria nanoparticles compared to that without the nanoceria, e.g. higher magnitudes for the charge transfer resistance after certain period of exposure to sodium chloride solution. In addition to that, from the evolution of the double layer capacitance on the defected coatings condition, reduced delamination rates were perceived for those containing 0.5 and 1.0 wt.% of nanoceria. Similarly, after exposure to the salt spray test a reduced delaminated area was suggested for 0.5, 1.0 and 2.0 wt.% compared to that without nanoceria. Generally, a beneficial contribution of nanoceria into an acrylic waterborne paint system on the corrosive protection of steel was found and the optimal concentration of nanoceria associated to higher corrosion protection was verified for the paint system containing 1.0 wt.%.

Electrochemical Impedance Spectroscopy Investigation of the Corrosion Resistance of a Waterborne Acrylic Coating Containing Active Electrochemical Pigments for the Protection of Carbon Steel

Electrochemical Impedance Spectroscopy Investigation of the Corrosion Resistance of a Waterborne Acrylic Coating Containing Active Electrochemical Pigments for the Protection of Carbon Steel

Low VOC self-crosslinking waterborne acrylic coatings incorporating fatty acid derivatives

Acrylic waterborne coatings free of volatile coalescing agents were produced and characterized. The film-formers used in the coatings were resins incorporating an allylic fatty acid derivative (AFAD) and an acrylic fatty acid derivative (AcFAD), either as reactive (non-volatile) coalescing agents or as co-monomers. The minimum film-forming temperatures of the new coatings were lower than the reference, confirming that AFAD and AcFAD act as coalescing agents. On the other hand, the observed reductions in through drying-time and increase in scrub resistance, more evident for AcFAD, indicating that reaction between the conjugated double bonds in the fatty acid derivatives and atmospheric oxygen–oxidative cure–took place and provided an effective self-crosslinking drying mechanism.

Thermal, rheological, and barrier properties of waterborne acrylic nanocomposite coatings based on boehmite or organo-modified montmorillonite

An organo-modified montmorillonite (Cloisite®30B) or an unmodified boehmite (Disperal®40) have been added to two acrylic latex dispersions (one of them UV-curable) for obtaining nanocomposite coatings. X-ray diffraction and transmission electron microscopy show a high degree of exfoliation in the nanocoatings based on montmorillonite, together with the deagglomeration of the micrometer-sized boehmite powder and the presence of single boehmite crystallites within the polymer matrix. Such morphologies are found to enhance the thermal and thermo-oxidative stability of the latexes and to significantly decrease their oxygen permeability, as well.

Effects of Peripheral Planing on Surface Characteristics and Adhesion of a Waterborne Acrylic Coating to Black Spruce Wood

Abstract Peripheral planing of black spruce (Picea mariana) wood was optimized for rake angle and feed speed. Both cutting parameters affected surface characteristics at the microscopic and macroscopic level. In turn, the interaction between rake angle and feed speed had a significant impact on surface roughness, disperse component of surface energy, and total surface energy, as well as on initial pull-off adhesion strength of a waterborne coating. Loss in adhesion during the accelerated aging treatment was significantly lower for samples machined with a rake angle of 10°. This rake angle combined with a wavelength (feed per knife) of 1.3 mm yielded coated surfaces with high initial pull-off strength. Therefore, this wavelength could be used to increase production rates without significantly affecting surface quality. In addition, no torn grain was observed for surfaces prepared with a rake angle of 10° regardless of feed speed.

Protection of metal with a novel waterborne acrylic/urethane hybrid technology

Coatings are often required to provide multiple properties that seem to be opposed to one another, or at least difficult to obtain at the same time. One key example for waterborne acrylic coatings is the desire for lower volatile organic compounds (VOC) without the loss of hardness properties. Coupling these seemingly conflicting properties with other high performance needs, such as excellent corrosion resistance and weatherability, can present a serious challenge for raw material suppliers and coatings manufacturers alike. A new waterborne technology that satisfies these many requirements will be introduced. This paper describes a unique acrylic/urethane hybrid technology which couples a hard acrylic dominant phase with a soft polyurethane minor phase, and the development of a new self-crosslinking hybrid polymer which combines the low VOC/fast hardness development balance with excellent corrosion resistance and weatherability in a single-component waterborne system. In the hybrid, the soft polyurethane phase acts as a conduit for the rapid diffusion and release of coalescent from the film, leading to improved hardness development relative to a hard acrylic alone. The soft polyurethane phase also contributes to good film formation at reduced VOC levels. The mechanism of the faster coalescent release will be discussed, along with application data showing improvements in block, print and dirt pickup resistance. The excellent corrosion resistance and durability are a consequence of the formation of polymer–pigment composite particles and a film formation process that offers improved pigment distribution in the dry film. Details of the mechanism will be discussed, along with performance properties of the new acrylic/urethane hybrid polymer in corrosion-resistant coatings for the protection of metal.

Performance of waterborne acrylic surface coatings on wood impregnated with Cu-ethanolamine preservatives

Two waterborne acrylic coatings were applied on spruce wood, impregnated with two copper-ethanolamine containing preservatives (CuE and CuEQ), one of them (CuEQ) containing a boron compound, octanoic acid and a quaternary ammonium compound as additives. Lower contact angles and deeper penetration of both coating types were observed on CuEQ treated, compared to untreated or CuE-treated wood. Improved adhesion of coatings on CuEQ impregnated wood was exhibited as well. In general, characteristics of surface finishes on copper-ethanolamine treated wood were comparable to untreated wood. It was also shown that copper leaching from the preserved wood was significantly reduced by application of the surface finishes.