Phase behaviors and film properties of dispersions and coatings containing associative and conventional thickeners

Phase-separation behaviors of latex dispersions, using commercial latices of three different median sizes, and pigmented coatings are examined. Both the dispersions and pigmented coatings at a 0.32 volume fraction of total dispersed phase were thickened with water-soluble polymers, with and without surfactant hydrophobes. Latex dispersions thickened with water-soluble polymers without hydrophobe modification follow the phase-separation behavior described by the volume restriction flocculation (VRF) concept (i.e., molecular weight of the thickener or particle size of the latex). This is surprising since commercial latices contain a variety of surface-stabilizing moieties, in addition to surfactant. Latex dispersions thickened with commercial and model hydrophobically modified ethoxylated urethane (HEUR) polymers do not follow the phase-separation behavior predicted by the VRF concept. The lack of correlation of phase behavior with latex median size in HEUR-thickened formulations led to an examination of four secondary thickeners, noted for providing high viscosities at low shear rates. With an all-acrylic, large median-size latex, the combinations of commercial HEURs with secondary thickeners are effective in eliminating phase separation; only partial reduction in phase separation is observed with a vinyl acetateacrylic large-particle latex. The influence of HEUR/secondary thickener blends on the film properties also is discussed. © 1993 John Wiley & Sons, Inc.     

Spray applications: Part IV. Compositional influences of HEUR thickeners on the spray and velocity profiles of waterborne latex coatings

In this study, the focus is on the spray behavior of latex coatings thickened with structurally different surfactant-modified, water-soluble polymers (associative thickeners of the hydrophobically modified, ethoxylated urethane [HEUR] type). Particle image velocimetry (PIV) profiles are considered in the perspective of the dynamic uniaxial extensional viscosity (DUEV) of the coatings and an effort to understand the results in terms of the structural aspects of the thickener molecules is undertaken. A high-M _v hydroxyethyl cellulose (HEC) thickened formulation, with a significant DUEV, does not atomize well. Among the HEUR thickeners, the addition of larger hydrophobes in the terminal positions requires less thickener to achieve a 90 KU viscosity and produces lower DUEVs and lower viscosities at high-shear rates. This is necessary to produce formulations with acceptable spray characteristics (i.e., good atomization). The sprayability of these systems is reflected in their velocity profiles and particle size/particle size distributions. Poorer spray characteristics are reflected in ligaments and broad particles size distributions. This study highlights the ability to control the particle size/size distribution and velocity profiles of coatings formulations through the use of structurally different HEUR associative thickeners. Variations in sprayability among different nozzle geometries are also studied. Presented at the 2006 FutureCoat! conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1–3, 2006.     

Waterborne latex coatings of color: II. Surfactant influences on color development and viscosity

A matrix of coating variables, nonassociative versus associative thickeners, different latex median particle sizes, individual surfactants and colorants [carbon black (CB), red, and yellow pigments], was examined for their influence on variances in coatings rheology and color development. Within the different coating groups, the variable of interest in this study was the surfactant added to the colorant formulation. In all three colorant formulations, sodium dodecyl sulfate (an anionic surfactant) provided poorer color development (CD) than in applied formulations containing an equivalent nonylphenol oxyethylene (EO) surfactant. In CB formulations, nonionic surfactants with higher EO content provide improved color development at low (2 mM) concentrations, but near equality in CD is achieved with low EO surfactants at higher concentrations. In contrast to CB formulations, red and yellow colorants exhibit good color development with high EO content nonionic surfactants only at low nonionic surfactants concentrations. This variance appears to be related to the interactions of surfactants with inorganic pigments (talc and laponite) in the colorant formulation. The coating’s rheology is related to latex, thickeners, and surfactant components of the paint, as has been noted in previous studies, but not to the nature of the color pigment. The viscosity of the hydroxyethyl cellulose (nonassociative type) and HEUR (associative type) thickened paint decreased with colorant addition due to dilution effects. There were no unusual deviations with the NP(EO)_x surfactants, except when a large hydrophobe nonionic surfactant [e.g., C₁₈H₃₇(EO)₁₀₀] is added. In HEC thickened coatings, the viscosity decreases when C₁₈H₃₇-(EO)₁₀₀ is in the colorant due to that surfactant inhibiting depletion flocculation. In the C₁₈H₃₇(EO)₁₀₀ coatings containing the HEUR thickener, significant increases in viscosity were observed, above the dilution values observed with the colorant addition. This is related to the viscosity maximum in the low concentration of HEUR with the C₁₈H₃₇(EO)₁₀₀ surfactant. Color development is independent of the viscosity profile of the coating. Presented in part at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 13–14, 2003 in Philadelphia, PA.     

Study of the rheology of aqueous radiation curable polyurethane dispersions modified with associative thickeners

The chemistry of radiation curable polyurethane dispersions is outlined with an emphasis on the microstructure of the aqueous polymer dispersion and the possible interactions with associative thickeners. The steady-shear flow was studied for two model dispersions prepared from the same unsaturated polyurethane but showing significantly different particle size distributions. A hydrophobically modified ethoxylated urethane (HEUR) associative thickener with a linear structure was incorporated at different amounts to the dispersions with varying particle volume fractions. The steady-state viscosity at 25 and 10 °C was always reached quickly after instant flow rate changes so that no significant thixotropic effects were reported within the experimental timescale. Without thickener, the flow curves of the two model dispersions exhibited a Newtonian behavior except at the highest volume fractions where shear thinning became apparent. The maximum packing values determined from the Krieger–Dougherty relationship were essentially the same for the two systems. In the presence of thickener, the flow curves were characterized by a Newtonian plateau followed by a marked shear thinning region even at low particle volume fractions. This behavior typically suggests the formation of a physical network between polyurethane particles and thickener molecules partly adsorbed onto the polymer surface. The zero-shear viscosity of the two dispersions was compared with respect to: (i) particle volume fraction and (ii) particle surface area at different HEUR concentrations. At a given volume fraction, the particle size affects the viscosity of thickened models. As a corollary, a relationship is found between the particles size and the level of thickener required to reach a target viscosity. This study offers practically relevant data in terms of application conditions and provides a better insight into the thickening protocol.     

The crosslinking directing dynamic behavior of polymer latex under the investigation toward waterborne damping coatings

Latex polymers with precisely designed dynamic mechanical behavior are the key for waterborne damping coatings, which are widely desired in noise and vibration reduction with additional environmental benefits. In this work, we synthesized series of polymer latexes with various crosslinking agents (CA) and network distributions through the control on emulsion polymerization processes. We have revealed that the variation on crosslinking can significantly direct the latex behavior under dynamic conditions as well as its films. The variables involve the CA composition, the functionality, the crosslinking manner, the hydrophilic-hydrophobic feature as well as the feeding method. Although all the latex films showed the damping peaks locating in the range from −10 to 70°C, their damping behaviors were quite different. Suggested by the empirical parameters of LA and TA, the product from sequential monomer feeding method tended to give good extensional damping performance. Especially when the crosslinking of diacetone acrylamide (DAAM)/adipic dihydrazide was applied, there was a linear increase on LA with the increasing dosage of DAAM from 0 to 10 mmol in the final monomer addition batch. Meanwhile, good constrained layer damping is expected on the products from the power monomer feeding method with the maximum CA dosage shown below 7.5 mmol. The best TA was achieved when the CA of divinylbenzene was used in the dosage of 5 mmol. These results would be valuable to be referenced in the engineering on organic damping materials toward modern industrial and vehicles applications.     

水性丙烯酸酯汽车涂料树脂的制备与粘度的研究

合成了用于配制水性汽车罩光清漆的丙烯酸酯涂料树脂,研究了丙烯酸单体、含芳香酯基团单体、引发剂、链转移剂和聚合温度对树脂水溶性和粘度的影响,并用红外光谱表征了树脂的结构。结果表明,增加丙烯酸单体的用量会提高丙烯酸酯树脂的水溶性和粘度,而增加含芳香酯基团的甲基丙烯酸苄酯（BNMA）单体、引发剂和链转移剂的用量和提高聚合温度可降低树脂的粘度。该树脂与氨基树脂（HMMM）固化剂配制的漆膜性能优良,可以用作汽车原厂漆（OEM）。     

Influence of coalescing aids on the latex properties and film formation of waterborne coatings

Coalescing aids are organic solvents that are widely used to accommodate the film formation of waterborne coatings. The influence of the volatility, hydrophilicity, and amount of coalescing aids on the properties of waterborne dispersions and the dynamics of film formation was investigated. The results show that coalescing aids increased the viscosity through particle swelling and solvation, with the effect being stronger with more hydrophilic solvents. The results obtained with electrochemical impedance spectroscopy (EIS) and indentation tests show that hydrophilic coalescing aids were more efficient because of the partitioning on the particle interfaces but they could temporarily decrease the water resistance. The ease of coalescence was countered by solvent retention, which complicated the dynamics of film formation. EIS was used to optimize a real‐world coating formulation and identify the pitfalls arising from the complex dynamics of film formation. The best resistance to humidity was obtained with a combination of hydrophobic and hydrophilic coalescing aids. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45142.     

疏水缔合型两性聚丙烯酰胺增稠剂的制备及性能研究

以司班-80、OP-10为复配乳化体系,N,N′-亚甲基双丙烯酰胺(甲叉)为交联剂,丙烯酸十八酯(ODA)为长碳链疏水单体,用过硫酸钾引发丙烯酰胺(AM)、丙烯酸(AA)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)进行反相乳液聚合,制备了疏水缔合型两性增稠剂。探讨了增稠剂的交联结构、交联剂用量、长碳链疏水单体用量,DMC用量以及所得产品的耐盐性、流变性和耐稀释性。结果表明:当交联剂占单体量0.17%,长链疏水单体为0.6%,DMC为13.8%时,其综合增稠效果最佳。     

Parameters influencing the spray behavior of waterborne coatings

The influence of liquid pressures and orifice diameters on the sprayability of non-Newtonian, waterborne latex coatings, that vary in latex particle size and thickener composition are examined in this study. It is observed that the higher the dynamic uniaxial extensional viscosities (DUEVs, η_e) of the coatings, the larger the Sauter mean diameters (SMDs) of the spray droplets and the broader the droplet size distributions. The shear viscosities at high shear rates and the parameter reflecting shear elasticity, the storage moduli, at low deformation rates do not correlate with the droplet sizes and the distributions observed. In addition to these observations, the Sauter mean diameters of spray droplets decrease with increasing spray pressures and with decreasing orifice diameters; however, with increasing pressures, pulsations in the fluid due to turbulence create areas of high and low droplet density. The relationship of the SMD to orifice diameters using fan nozzles is defined by the relationship: The experimental results associated with each of these parameters are discussed in the text. Presented at the 1998 Annual Meeting of the Federation of Societies for Coatings Technology, on October 15, 1998, in New Orleans, LA. Polymers and Coatings Department, Fargo, ND 58105. Research Development Center, Lancaster, PA 17604.     

Novel synthesis of low VOC polymeric dispersions and their application in waterborne coatings

A new approach for the synthesis of reactive solvent-free polyurethane dispersions is discussed in detail. A powerful tool is introduced by incorporating β-ketoester groups in the polymer chain. β-Ketoesters have two different reaction sites. On the one hand the keto groups can react with nucleophiles like polyamines. On the other hand the carbon atoms of the activated CH₂ groups are centers for the attack of electrophiles like aldehydes and isoyanates. Polymers functionalized in this way are interesting new intermediates in chain extension reactions for aqueous polyurethane dispersions. Another advantage of the functionalized polyurethane dispersions is the possibility of additional crosslinking with melamine resins or blocked isocyanates.     

MDI型水性聚氨酯膏化和黏度影响因素

采用四氢呋喃均聚醚(PTMEG-1800),2,2-羟甲基丙酸(DMPA)和二苯基甲烷二异氰酸酯(MDI-50)等为原料合成聚氨酯预聚体,加入乙二胺(EDA)等后扩链得到水性聚氨酯乳液(WPU).WPU乳液黏度的影响因素主要有搅拌速率、-NCO/-OH的量比值(R值)、乳胶粒子粒径大小等,合理控制黏度可以避免乳液膏化现...     

Unifying model for associative thickener influences on waterborne coatings: II. Competitive adsorption of nonionic surfactants and HEUR thickeners on titanium dioxide pretreated with inorganic stabilizers and organic oligomeric dispersants

Size exclusion chromatography in tandem with UV absorbance of the surfactant is used to separate and quantify the amount of nonionic surfactant and model hydrophobically modified ethoxylated urethane (HEUR) thickeners adsorbed on different organic oligomeric polyacid, metal oxide-treated TiO₂ surfaces. The isoelectric point imposed on TiO₂ by the metal oxide surface treatment determines the amount of organic dispersant adsorbed. The size of the α-olefin on the maleic acid dispersant is also important in the adsorption of the dispersant. The size of the α-olefin on the organic acid dispersant, in turn, determines the amount of surfactant and HEUR thickener adsorbed. The surfactant, unlike the HEUR thickener, exhibits a dependence on the metal oxide treatment in neutral media, independent in several aspects of the amount of organic dispersant adsorbed. The adsorption dependence of HEUR thickeners and nonionic surfactant on the hydrophobe size of the HEUR is discussed. Presented at the 69th Annual Meeting of the Federation of Societies for Coatings Technology, on October 23, 1996 in Chicago, IL Polymers and Coatings Dept., Dunbar Hall, Fargo, ND 58105. Chestnut Run, Building 709, Wilmington, DE 19898.     

Effects of inorganic fillers on the shear viscosity and fire retardant performance of waterborne intumescent coatings

In the present work, the effects of inorganic fillers on the fire retardant performance of waterborne intumescent coatings are investigated by thermogravimetry (TG), capillary rheometer, X-ray diffraction spectroscopy (XRD) and fire retardant test, etc. The TG results indicate that the thermal stability of vinyl acetate-vinyl ester of versatic acid copolymer (hereafter VAc-VeoVa) in VAc-VeoVa/Si–Al powder composite or in VAc-VeoVa/Halloysite nanometer-tube (HNTs) composite is improved mainly due to the release of the crystal water in Si–Al powder or HNTs. Capillary rheometer analysis results demonstrate that the VAc-VeoVa/HNTs composite melt possesses the highest shear viscosity, because of the large specific surface area of HNTs and the strong interaction force between HNTs and VAc-VeoVa. Weight loss difference (ΔT) of filler/ammonium polyphosphate (APP) composites show antagonism effects at 300 °C < T < 650 °C and synergistic effects at T > 650 °C. The fire retardant test results show the coatings using TiO₂/Si–Al powder/HNTs (8/1/1) as multiple fillers obtains an intumescent char layer with intumescent ratio of 28.14 and presents excellent fire retardant performance (3327 s). It is found that the high melt viscosity, resulted from the effect of inorganic filler, immobilizes the relaxation and rotation of polymer chain, restricts the intumescent behavior of the coatings, which leads to the formation of an intumescent char layer with lower intumescent ratio and the shortening of the fire retardant time. Moreover, the antagonism effect between filler and APP reduces the catalytic dehydration efficiency of pentaerythritol (PER) and VAc-VeoVa, which, as a result, also affects the final fire retardant performance of coatings.     

Incidence of the polyol nature in waterborne polyurethane dispersions on their performance as coatings on stainless steel

Three waterborne polyurethane dispersions derived from polyester, polyether and polycarbonate diols with molecular weight of 1000 Da were synthesized by the acetone method and used as coatings on stainless steel 304 plates. The properties of the dispersions and the polyurethane films were influenced by the polyol nature. The polyurethanes obtained with polyether or polyester showed higher degree of phase separation between the soft and the hard segment. The higher adhesive strength under shear stresses was obtained in the joints produced with the waterborne dispersion obtained with polycarbonate diol. The properties of the polyurethane coating obtained with polycarbonate diol on stainless steel 304 were significantly higher as compared with the others. Improved performance of coatings obtained with polycarbonate diol was ascribed to the higher polarity of the carbonate groups that contributed to additional hydrogen bond formation between soft segments with respect to those obtained with polyether or polyester     

高粘度乳液的研究及其应用

作者通过对高粘度乳液聚合进行的研究，介绍了高粘度乳液聚合的配方和工艺，讨论了影响乳液粘度的诸因素和高粘度乳液在涂料和粘合剂领域中的应用。     

Waterborne latex coatings of color: I. Component influences on viscosity decreases

For almost two decades, it has been known that the addition of colorants to a waterborne latex coating thicknened with an associative thickener will result in a viscosity loss. The influence of surfactants on viscosity variations in waterborne latex coatings, as discussed in our most recent JCTCoatingsTech article,¹ is the source of the viscosity decreases. To evaluate this problem, aqueous solutions containing large quantities of five different surfactants, and the smallest particle size of the colorants, carbon black (CB), were prepared. Large quantities of surfactant were used to allow for adsorption on, and stabilization of, CB. When traditional associative polymers (HMHEC, HASE, and a telechelic HEUR) were used to thicken carbon black dispersions, viscosity decreases were not observed, for most of the surfactnat is adsorbed on the CB’s surface. There is enough surfactant, however, to promote viscosity decreases in comb-HEUR thickened CB dispersions. Moving beyond the colorant dispersions, the CB, yellow, or red colorants were then added to a commercial latex paint that contains many surfactants, glycol ether, and coalescing aids, and significant viscosity decreases were observed. The decreases were very dramatic as the colorant concentration was increased to obtain deeper color tones, due to the additional excess surfactant added to the coating. Reduction in total surfactant levels in the colorant was an obvious solution, but this led to rub-up incompatibility. The conflict between viscosity retention and rub-up incompatibility was resolved when the surfactant concentration was reduced by adding to the colorant formulation compositionally different hydrophobically-modified poly(oxyethylenes) and hydrophobe-modified maleic acid co-oligomers. Presented in part at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 13–14, 2003 in Philadelphia, PA     

High performance waterborne coatings based on dispersions of a solid epoxy resin and an amine-functional curing agent

A novel, waterborne epoxy system comprised of non-ionic stabilized dispersions of a solid epoxy resin and an amine curing agent has been designed for ambient-cure coatings. The performance characteristics of coatings formulated from the new system have been compared to a standard system. The new system produced formulated coatings with robust performance over a wide range of amine-to-epoxy stoichiometries (65 to 130%). At 100% stoichiometry, the new system was found to have lower VOC, faster hardness development, better gloss, and higher impact resistance than the standard system. The new formulations also exhibited superior water and salt spray resistance, and a definitive viscosity rise at the end of potlife. Unlike the standard system, coating morphology of the new waterborne system was found to be similar to a solvent-based coating. For the new system, good coalescing solvents, as judged by gloss and gloss potlife, were found to have low solubility parameters and high boiling points. Presented at the 76th Annual Meeting of the Federation of Societies for Coatings Technology, on October 15, 1998, in New Orleans, LA. P.O. Box 1380, Houston, TX 77251-1380.