Phosphated polyurethane-acrylic dispersions: synthesis, rheological properties and wetting behaviour

Phosphated polyurethane-acrylic dispersions were prepared by a new method that is free from organic solvents and requires a very low dispersion force. After the carboxylic acid groups of the phosphated polyurethane were neutralised by suitable bases, water was added to form the phosphated polyurethane seed dispersion. Polyurethane-acrylic dispersions were obtained from the phosphated polyurethane seed by emulsion copolymerisation. The polyurethane seed polymer was found to be stable over the initiator concentration used and the rheological properties of the polyurethane acrylics were found to follow Newtonian behaviour under the prescribed experimental conditions. This is a good indication that the dispersions may be used as pigment wetting media. The dynamic contact angle study showed the poor wettability of the phosphated polyurethane-acrylic dispersion films, indicating good hydrophobicity.     

Stability and properties of waterborne polyurethane/clay nanocomposite dispersions

Factors that can affect the stability of waterborne polyurethane (WBPU)/clay nanocomposite dispersions are reported. It is suggested that the dispersion stability depends on the carboxyl acid salt content, clay content, sonication (mechanical forces), and clay surface structure. It was observed that the dispersion stability increased with increasing carboxyl acid salt content after applying sonication (mechanical forces) in clay with OH groups (Cloisite 30B) up to 23.58 mol% DMPA. Encapsulated (WBPU20-30B4-M and WBPU23-30B5-M) clay in PU particles was formed using the above combination. The dispersion with clay encapsulated in PU particles had the longest storage time of all of the dispersions. The zeta potential, particle size, particle size distribution, and viscosity of the dispersions also depend on carboxyl acid salt content, clay content, sonication (mechanical forces), and clay surface structure.     

Effect of melamine on the foam kinetics of polyurethane model system. I. Surface properties in the absence and presence of melamine particles

The dynamic and equilibrium surface tension of a polyurethane model system with and without melamine particles was investigated. It is concluded that the diffusion is the rate-determining factor in the adsorption process. Greater dynamic surface tension is found for the melamine-containing dispersion than for the corresponding solution in the absence of particles. A possible explanation is given by the presence of attractive interactions between the particles. The adsorption of the surfactant on the melamine surface, wetting properties of the particles by the investigated system, and the rheological behavior of the dispersions are discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1729–1738, 1998     

超高固含量水基聚氨酯分散体的合成理论与实践

综述了超高固含量聚氨酯分散体合成的理论和实践,以球状物体堆积密度数学模型分析了高分子乳液和分散体的极限浓度,以高分子分散体粒子存在水溶胀层的实验分析了分散体体积浓度和固含量的区别,从理论的角度分析了合成超高固含量聚氨酯分散体采用内乳化结合外乳化及采用连续瞬间分散工艺的必需性,简单介绍了国外超高固含量聚氨酯分散体的合成工艺。     

Study of ionic/nonionic polyurethane dispersions with high solid content and low viscosity using a complex hydrophilic chain-extending agent

An ionic/nonionic polyurethane dispersion with high solid content and low viscosity with a complex hydrophilic chain-extending agent was prepared using isophorone diisocyanate as a hard segment and propylene oxide glycol as a soft segment. The complex hydrophilic chain-extending agent consisted of DPSA and BDSA. The effects of the molar ratio of DPSA/BDSA on the properties of the resultant polyurethane dispersions were studied. The morphologies and properties of the ionic/nonionic PU dispersions were examined using particle-size, TEM, and viscosity analyses. It was found that the ionic/nonionic dispersions possessed wide particle-size distributions due to the addition of the complex hydrophilic chain-extending agent. The ionic/nonionic PU dispersions possessed higher solid content than conventional WPU dispersions because the number and volume percentage of the large particles and small particles of the ionic/nonionic dispersions met the requirements for high solid content. It was observed that the solid content of the ionic/nonionic dispersion increased and then decreased with an increasing molar ratio of DPSA/BDSA. When the ratio ranged from 4:10 to 5:10, the solid content of the ionic/nonionic PU dispersion reached up to 55%. It was also noticed that the apparent viscosity of the ionic/nonionic polyurethane dispersion decreased with an increasing molar ratio of DPSA/BDSA. The complex hydrophilic chain-extending agent consisting of DPSA and BDSA enhanced the solid content and decreased the viscosity of the ionic/nonionic dispersions, which are very important for improving the properties and expanding the applications of PU dispersions. In addition, the ionic/nonionic polyurethane dispersion had good electrolyte-resistance properties, stability at both high and low temperatures, and storage stability.     

Waterborne anionomeric polyurethane–ureas from functionalized fluoropolyethers

A family of anionomeric segmented polyurethane–ureas made from α‐ω dimethylol‐terminated perfluoropolyethers (M_n = 1000–2000), isophorone diisocyanate, dimethylol propionic acid, and ethylenediamine was obtained in form of stable aqueous dispersions. The dispersions were characterized by viscometry and dynamic laser light scattering. The main compositive parameters explored were the amount of COOH groups and the length of the fluorinated macromer. The new polyurethane–ureas were characterized by dynamic mechanical analysis obtaining information on modulus, thermal transition, and phase segregation. Surface properties and chemical resistance were estimated through measurements of static contact angles and spot tests with different solvents. Although surface hydrophobicity was not affected by composition, water‐sorption behavior was sensitive to the ionic character (COOH level) of the polymer. Diffusion and permeability coefficients of polymer films, having different carboxyl contents, were estimated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 136–144, 2004     

Curing behavior of anionic poly(urethane urea) dispersions crosslinked with partially methylated melamine formaldehyde

A rigid‐body pendulum rheometer was used to observe the isothermal cure behavior of an anionic poly(urethane urea) dispersion crosslinked with different amounts of partially methylated melamine formaldehyde (PMMF). In this experiment, the anionic poly(urethane urea) dispersion had a large number of >N? H crosslinking or branching sites in urethane and urea groups per molecule, which allowed a large amount of PMMF to couple with the elastic polyurethane (PU) backbone. The test results showed that the cure response of the PU dispersion crosslinked with PMMF was a function of the concentration of PMMF and indicated that 30 phr PMMF could be the optimum amount of the crosslinking agent and that 120°C was the optimum temperature for the curing process. In addition, PMMF self‐condensation could take place during the curing process. The self‐condensation of PMMF also was monitored by a thermogravimetric method. Moreover, the dynamic mechanical properties of PMMF‐crosslinked PU films were affected by the concentration of PMMF. From the curing behavior and dynamic mechanical analysis test results, it was reasonable to assume that highly PMMF branched PUs with partial crosslinking structures could be formed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Polyurethan-dispersionen durch schmelz-dispergierverfahren

Following a survey of polyurethane ionomers, their technical importance, methods of preparation and characteristics, the methods of preparation of aqueous polyurethane dispersions are presented. Dispersion by strong shearing forces and emulsifiers is compared to the spontaneous dispersion of polyurethane ionomers from organic solution or as liquid isocyanate prepolymers. As a new method for the preparation of polyurethane dispersions, the spontaneous dispersion of ionomer melts with following poly-condensation in two-phase systems is described. The principle is that molten ionic modified polyester or polyether prepolymers containing terminal -NCO groups are reacted with urea to give bisbiuret, methylol groups generated by aqueous formaldehyde in a homogeneous phase, and the plasticised melt of methylolised ionic oligourethane bisbiurets so obtained dispersed in water at 50-130 °C. Thereafter, a formaldehyde poly-condensation forming high-molecular polyurethane polybiuret is achieved by lowering the pH of the dispersion. The reaction takes place in the dispersed phase. The procedure yields from the monomers, simply and without complicated apparatus, emulsifier free aqueous dispersions of ionic polyurethanes. The reactions occurring in the process are discussed.     

Application of statistical experimental strategies to the process optimization of waterborne polyurethane

A modified acetone process for the preparation of aqueous polyurethane (PU) dispersion is investigated. PU dispersions were prepared by polyaddition of isophorone diisocyanate (IPDI) to poly(tetramethylene ether glycol) (PTMG) and dimethylolpropionic acid (DMPA), followed by neutralization of pendant COOH groups with triethylamine (TEA). The resulting prepolymer chain was then extended through reaction with an ethylenediamine (EDA) derivative bearing sulfonate groups. The effect of such preparation conditions as catalyst (dibutyltin dilaurate, DBTDL) concentration, the acetone/PU ratio, phase-inversion temperature, agitation rate, and water-addition rate on the average particle size of aqueous PU anionomer dispersions is systematically studied using fractional factorial design and response surface methodology. Fractional factorial analysis indicates that the effects of the acetone/PU ratio, phase-inversion temperature, water-addition rate as well as the two factor interactions of DBTDL concentration and phase-inversion temperature, of the acetone/PU ratio and phase-inversion temperature, and of acetone/PU ratio and agitation rate are the key variables influencing average particle size of PU dispersions. Empirical models for average particle size are fitted and plotted using central composite experimental design as contour diagrams in order to facilitate examination of the average particle size results. The results show that for a 100 g PU anionomer containing 0.311 wt % COOH and 1.51 wt % SO₃H groups, a minimum number-average particle size of the dispersion ～ 25 nm can be obtained under an acetone/PU ratio, water-addition rate, phase-inversion temperature, catalyst concentration, and agitation rate of 3.65, 2 mL/min, 50°C, 150 ppm and 350 rpm, respectively.     

Preparation and stability of aqueous acrylic polyol dispersions for two-component waterborne polyurethane

In this study, aqueous acrylic polyol dispersions with high stability for a two-component waterborne polyurethane were prepared. To improve the stability of acrylic dispersions, the influence of the acrylic acid (AA) addition method, neutralization, water addition rate during the dilution process, and dispersion equipment on the stability of the aqueous acrylic polyol dispersion was studied using dynamic light scattering and a thermal storage experiment. The acrylic resins’ structure was examined using Fourier transform infrared spectra, and the water resistance of the resultant films was investigated by electrochemical measurements and a water-swelling experiment. The dispersions prepared by two-step AA addition exhibited better particle size distribution, viscosity, and thermal storage compared with those prepared by one-step AA addition. Furthermore, the acrylic resin prepared by two-step AA addition was observed to possess a higher acid value. The corrosion currents of films based on dispersions prepared by two-step AA addition decreased to a smaller extent after 24 h of immersion in water. The dispersions afforded smaller particles when larger amounts of neutralizer and slower water addition rates were used. The dispersions prepared using a sawtooth disk dispersion machine displayed better performance than that prepared using a homogenizer dispersion machine.     

Waterborne polyurethane dispersions obtained by the acetone process: A study of colloidal features

Waterborne polyurethane (PU) dispersions were prepared from isophorone diisocyanate (IPDI), 2‐bis(hydroxymethyl) propionic acid (DMPA), 1,4‐butane diol (BD), poly(propylene glycol) (PPG), and triethylamine (TEA) by means of phase inversion through the acetone process. Changes in DMPA content, initial PU content in acetone, phase‐inversion temperature, evaporation conditions, and solvent nature were found to have a great impact on dispersion properties. Using a DMPA concentration of 0.30 mmol/g_pol, stable PU dispersions could only be obtained when the initial PU content in acetone was at least 60 wt %, and phase‐inversion temperature was lower than 30°C. However, when increasing the PU content to 75 wt %, stable dispersions were obtained using DMPA concentrations three times lower. Finally, viscosity curves during the water addition step as well as a phase diagram were determined to understand the particle formation mechanism. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.     

Fabrication of electrospun fibers from a waterborne soy-based polyurethane employing polyethylene oxide as a coformer

The fabrication of electrospun fibers made from aqueous dispersions of polyurethane obtained from renewable sources is an eco-friendly method to produce porous membranes for different applications. Polyethylene oxide (PEO) has been already employed in formulations for allowing fiber formation, but its role was not yet completely understood. In this work the fabrication of electrospun fibers made from biobased polyurethane aqueous dispersion with PEO in order to obtain regular fibers is performed. The role of PEO was studied by thermal analysis, infrared and Raman spectroscopy, rheology, and fiber morphology. Polyurethane fibers were obtained only when PEO was added, otherwise the dispersion is electrosprayed and particles are formed. It was observed that PEO modifies the rheology of dispersion and assists coalescence of polyurethane particles. On the other hand, polyurethane fibers conserved their diameter and their homogeneous structure after removal of PEO by immersion in water, which indicates that the distribution of both polymers was even within the fibers. This work provides both an insight on the role of PEO and a route for the fabrication of eco-friendly biobased polyurethane microfibers from aqueous dispersions.     

Aqueous polyurethane dispersions derived from polycarbonatediols

Aqueous polyurethane dispersions derived from polycarbonatediols, isophorone diisocyanate, and carboxylic diols including dimethylol propionic acid and dimethylol butyric acid were prepared. The effect of dispersing procedure is investigated by FT IR, GPC, and the tensile film properties. The polyurethane dispersions prepared by a standard procedure exhibit lower molecular weights due to the overhydrolysis of the NCO groups. The polyurethane dispersions prepared by a modified procedure exhibit significantly higher molecular weights due to more effective chain extension, and their cast films exhibit higher tensile strength. The particle size, tensile properties, thermal properties, and dynamic mechanical properties are investigated. The chemical structure of the polycarbonatediols seems to affect the tensile strength. The glass transition temperature of the soft segments, T_g(S), of the polyurethane dispersions can be seem from the DSC and DMA data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1723–1729, 2004     

负离子型聚氨酯离聚体水分散过程的相反转

用异佛尔酮二异氰酸酯、聚己二酸新戊二醇酯和二羟甲基丙酸（DMPA）合成了负离子型聚氨酯离聚体．研究了该类离聚体在水分散过程中的相反转变化,讨论了DMPA质量分数和水分散温度对相反转过程的影响。结果表明,DMPA质量分数增加或水分散温度提高,可使相反转所需的时间缩短,分散液粒子粒径变小,粒径分布更均匀,黏度增大。水分散温度的作用较DMPA更为明显。差示扫描量热分析表明,水分散过程破坏了亲水性硬链段的有序性。傅里叶变换红外光谱分析表明,聚氨酯水分散液用乙二胺扩链后．脲羰基的氢键化程度随DMPA质量分数的增加、水分散温度的提高而提高。     

Structure and property characterization of nanograde core‐shell polyurethane/polyacrylate composite emulsion

Anionic aqueous polyurethane dispersion was synthesized through self‐emulsifing method from cycloaliphatic isophorone diisocyanate (IPDI) and dimethylolpropionic acid (DMPA). The carboxyl acid group in DMPA was used to make the polyurethane dispersible. The polyurethane/polyacrylate (PU/PA) composite particles were also prepared by seeded surfactant‐free emulsion polymerization; the cycloaliphatic polyurethane aqueous dispersion was used as seed particles. The structures and properties of the composite emulsion as well as the physical mixture of polyurethane dispersion and polyacrylate emulsion were characterized by FTIR, DSC, dynamic light scattering, TEM, X‐ray photoelectron spectroscopy (ESCA), and electronic tensile machine. The results showed that the synthesized PU/PA composite emulsion was found to form inverted core‐shell structure with polyacrylate as the core and with polyurethane as the shell, and its diameter of particles is in the range of nanograde, the crosslinking reaction was existed in composite emulsion. The intimate molecular mixing of crosslinking polymers are also claims to result in a superior balance of properties compared to physical blends of polyurethane dispersion and acrylate emulsion. The crosslinking mechanism of PU/PA composite emulsion was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

膦磺酸型阻垢剂结构与性能探讨

探讨了６种不同官能团结构膦磺酸的阻磷酸钙垢及稳定锌的性能，对膦磺酸、有机膦及磺酸共聚物进行阻垢分散性能比较，结果表明：分子中膦酸基增多可增强阻垢分散的效果，４ｍｇ／Ｌ膦甲基磺酸或膦乙基磺酸的阻碳酸钙性能优于ＡＴＭＰ、ＨＥＤＰ和磺酸共聚物。结果还表明：亚甲基磺酸基或乙基磺酸基能增强有机膦酸阻磷酸钙垢，稳定锌和分散氧化铁的性能。     

Polyurethane dispersions derived from polycarbonatediols and m‐di(2‐isocyanatopropyl)benzene

Aqueous polyurethane dispersions derived from various polycarbonatediols, m‐di(2‐isocyanatopropyl)benzene(TMXDI), and various carboxylic diols including dimethylol propionic acid (DMPA), dimethylol butyric acid (DMBA), and a carboxylic polycaprolactonediol (Placcel 205BA) were prepared by a method in which the dispersing procedure was modified to enhance the molecular weight. The NH₂/NCO ratio during chain extension affected the molecular weight of the polyurethanes, significantly, and an optimum ratio of 0.67:1.0 was used. The molecular weight, particle size, tensile properties, and thermal properties of the polyurethane dispersions were investigated. The effect chemical structure of the polycarbonatediols on the properties shows no obvious trend, but the polyurethane dispersions derived from the carboxylic polycaprolactonediol exhibit smaller particle size and softer tensile properties when compared with those derived from DMPA and DMBA. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Synthesis and Properties of Aqueous Polyurethane/Polytert-butylacrylate Hybrid Dispersions

Aqueous polyurethane/polytert-butylacrylate (PU/Pt-BA) hybrid dispersions were prepared by polymerizing tert-butyl acrylate monomers that were emulsified by the waterborne polyurethane dispersions. The waterborne polyurethane dispersions, which contained no volatile solvent, were prepared by the prepolymer mixing process. The structure characteristics and properties of the hybrid dispersions were studied. A particle sizer and a viscometer were used to examine the physical characteristics of the dispersions. A Fourier transform infrared spectrophotometer and a gel permeation chromatograph were used to examine the structure of the hybrid composites. The thermal and mechanical properties were examined by a dynamic mechanical analyzer, a thermogravimetric analyzer, and an abrasion resistance tester. When the amount of ionic PU emulsifiers maintains constant, the average particle diameter and viscosity of the PU/Pt-BA hybrid dispersion become larger as more t-BA monomer was added and polymerized. As compared to the pure PU and Pt-BA polymers, the shifting of two T_gs in the composite toward each other may imply the improved compatibility between PU and Pt-BA through the hybridization process used in this study. The Pt-BA enhances the thermal and abrasion resistances of the PU/Pt-BA composites.     

Emulsifyable air drying urethane alkyds

A novel monomer, acrylamido (A) tertiary (T) butane (B) sulfonic (S) acid (ATBS) a commercially available ionic moiety was used as a replacement of dimethylol propionic acid (DMPA) in synthesis of polyurethane dispersion. IR technique was used to confirm the chemical structure and formation of polyurethane dispersions. Polyurethane dispersions were investigated for various coating properties, such as drying times, pencil hardness, adhesion, chemical and solvent resistance. Polyurethane dispersion based on ATBS showed better thermal, chemical and coating properties than those prepared by DMPA anionomer.