Aqueous Polyurethane Dispersions Research Articles

New dispersions for pigment printing binders in the manufacture of light industry goods

Pigment printing using screen technology has certain problems associated with the limited use of domestic raw materials. The expansion of the range of printing inks fills the need for small-circulation production of textile products with original artistic and color design and the use of modern printing equipment. In this work, the possibility of using new aqueous polyurethane dispersions as binders in pigment printing was explored for the first time. This will expand the range of thickeners through the use of polyurethane dispersions, ensuring the production of strong and elastic polymer films during low-temperature processing. Such dispersions are environmentally friendly products, since toxic solvents are not used. We propose the application of new polyurethane thickeners in compositions with polyurethane dispersions as a rheological modifier. The rheological parameters of printed compositions and the physical and mechanical properties of films of polyurethane dispersions were determined and it was found that the dispersions used are capable of forming a soft and plastic film. This confirms the suitability of these film-forming preparations for use in pigment printing. The new binders based on polyurethane dispersions make possible to create effective printing compositions, to improve the quality of prints and to impart improved performance properties.

STUDY OF THE ANTISTATIC PROPERTIES OF MATERIALS TREATED WITH COLLOIDAL COMPOSITIONS BASED ON METAL NANOPARTICLES

The article provides a short overview of the application of metal nanoparticles in the textile indus- try, describes their properties and application`s fields. The definitions of electrification, electrostatic field, electric charge density are given. The application of processing of fabrics by polyurethane dispersion and metal nanoparticles in technological processes of textile materials finishing is justified. The objects of the study are cotton fabric`s samples with addition of synthetic fibres, colloidal solutions of silver and copper nanoparticles, aqueous polyurethane dispersion. The antistatic properties of the fabrics have been studied. The electrostatic field intensity of the samples was measured on the device ST-01, with the density of the electric charge calculating according to the intensity values. It has been experimentally established, that the processing of fabrics by solutions of nanoparticles of metals contributes to reduction of intensity of their electrostatic field to 65 %, compared with the initial samples. It is noted that treatment of fabrics by polyure- thane dispersion in combination with copper nanoparticles gives no clear antistatic properties to the blended fabrics.

Waterborne polyurethane dispersions based on polypropylene glycol/polycarbonate diol: Evaluation of their use as wood protective coatings

AbstractWhen exposed to the open air, the wood can change its physical and structural properties due to the combined effect of ultraviolet radiation, oxygen, humidity, atmospheric pollutants, and microorganisms. The demand for durable coatings with application to wooden structures or pieces is always a relevant topic. Waterborne polyurethane (WPU) dispersions as wood protective coatings might be attractive, especially outdoors. In this work, WPU dispersions have been synthesized from isophorone diisocyanate and different ratios of polypropylene glycol and polycarbonate (PC) diol. Synthesized polyurethanes were applied to wood surfaces as a coating. The results showed that the partial and total replacement of polypropylene glycol (PPG) by PC influences the mechanical, thermal, and structural properties of the films obtained from aqueous polyurethane dispersions. In addition, a simple and promising methodology based on Fourier‐transform infrared (FTIR) spectra was proposed to determine the polycarbonate content in poly(carbonate‐ether‐urethane). The synthesized coatings reduced water absorption by the wood, especially the one with a 25:75 polycarbonate to PPG ratio. The applied coating does not impact the final color of the wood, allowing a natural aging effect. Polyurethanes are promising for use as coatings for wood.

Synthesis and application of flame retardant self‐matting aqueous polyurethane dispersion

AbstractTo address the issues of insufficient film smoothness, and flammability of aqueous polyurethane dispersions (PUD) prepared by adding matting agents, two hydrophilic chain extenders, dimethylolpropionic acid (DMPA) and sodium 2‐[(2‐aminoethyl)amino] ethanesulphonate (A95), were used to regulate the particle size of the emulsion while using FRC‐6 flame retardant as a small molecule chain extender to prepare a self‐matting and flame retardant PUD. Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, and atomic force microscopy were used to structurally characterize the latex films. The results showed that as theR‐value (NCO/OH molar ratio) and soft segment content decreased, the prepolymer viscosity increased, making it difficult to emulsify and reducing the glossiness of the film. Moreover, an initial increase in DMPA content led to a decrease in film glossiness, followed by an increase. Increasing the molar ratio of A95 sulfonic acid salt‐based chain extender to EDA affected the glossiness of the film, with a 2:8 molar ratio of A95: ethylenediamine (EDA) resulting in a glossiness of the film of 6.5%. The addition of reactive flame retardant diethyl bis (2‐hydroxyethyl) aminomethyl phosphonate (FRC‐6) increased the branching content in the prepolymer, improved the flame retardancy of the film, and reduced its glossiness. As a result, the self‐prepared PUD had a flat film with a glossiness as low as 6.0% and a flame retardancy rating of level 4.

Development of biocompatible aqueous polyurethane dispersions using chitosan and curcumin to improve physicochemical properties of textile surfaces

The present research work aims to synthesize a blend of chitosan (CSN) and curcumin (CRN) based aqueous polyurethane dispersions (CSN-CRN APUDs) for the modification of textile surfaces. A series of anionic CSN-CRN APUDs were prepared by the reaction of isophorone diisocyanate (IPDI) with polyethylene glycol (PEG) and extended with chain extenders (CSN and CRN). Structural characterizations of prepared materials were examined through a fourier transformed infrared (FTIR) spectrophotometer. The performances of coated CSN-CRN APUDs on the colorfastness properties (washing, rubbing and perspiration) and the mechanical properties like tensile strength and tearing strength of plain weaved poly/cellulosic textiles (dyed, printed and white) were examined before and after the application of CSN-CRN APUDs. The findings showed that the mechanical and colorfastness properties of all the CSN-CRN APUDs treated poly/cellulosic textile samples were improved significantly as compared with untreated poly/cellulosic textile samples. The newly synthesized CSN-CRN APUD coating materials are sustainable and greener products, particularly derivatized from bio-resources. These coating materials can be utilized as outstanding eco-friendly substitutes for poly/cellulosic textile coatings for surface modifications.

The role of the electrical percolation threshold on the anticorrosion performance of an aqueous polyurethane dispersion containing polyaniline

In this study, the anticorrosion properties of a waterborne polyurethane dispersion (WPU) containing polyaniline (PAni) were investigated and discussed considering the electrical percolation threshold (EPT) of this mixture. For that, easily dispersible poly(styrene sulfonic acid)-doped PAni (PAni:PSS) was incorporated into an anionic WPU at contents ranging from 1 to 8 wt%. Free-standing films of PAni:PSS/WPU reached the EPT at 6 wt% (4.8 v.%) of PAni:PSS. The mixtures remained stable and without signs of PAni dedoping. Based on the electrical behavior curve, PAni:PSS/WPU coatings were prepared below (1, 2, 3 wt%), close to (5 wt%), at (6 wt%) and above the EPT (8 wt%). The coatings were applied on ground low-carbon steel panels and evaluated regarding their contact angle, adhesion, and anticorrosion performance in electrochemical tests. The coatings prepared below the EPT presented higher hydrophobicity, good wet adhesion, and higher open circuit potential (OCP) and impedance modulus in the low frequency range (|Z|10 mHz). The best overall performance was achieved at 3 wt% of PAni:PSS which presented OCP values in the range of 34 ± 11 mV for 144 h and initial |Z|10 mHz of 108 Ω.cm2. These coatings also presented a colorimetric feature of changing color as the corrosion progressed. Meanwhile, the coatings containing PAni:PSS quantities close, at and above the EPT, i.e., at 5, 6 and 8 wt% presented high porosity, poor wet adhesion, and intense blistering. They also presented OCP values in the region of active corrosion and impedance spectra typical of coatings with poor barrier properties. These results indicate that, the formation of conducting networks within the insulating matrix is not necessarily a condition that must be met for a coating containing PAni achieve an optimal anticorrosion performance.

Bio-based castor oil and lignin sulphonate: aqueous dispersions and shape-memory films

Aqueous polyurethane dispersions based on castor oil and lignin sulphonate (LS) were successfully synthesized in homogenous solution with nanoscale PU-lignin particle sizes as small as 35 nm. The particles size was found to be LS independent, while the dispersion viscosity increases dramatically with increasing the LS content. The increase in viscosity with increasing LS content was explained based on the chemical structure of LS. The LS is a water-soluble material and chemically reacted with diisocyanate to become a part of the dispersion particle (i.e., the nanoparticles is in fact a mixture or copolymer of castor oil-based polyurethane and lignin dispersed in water). The affinity of the PU-LS nanoparticle towards water could be increased with increasing the content of LS. Therefore, the PU-LS nanoparticle can adsorb thick water layer with increasing the LS content. According to this suggestion, the free water in the dispersion would significantly decrease and consequently the dispersion viscosity increases considerably. The cross-link density was also increase with increasing the LS content of the thin films obtained from dispersion cast. The PU-LS thin films obtained from dispersion cast showed an excellent shape-memory effect and the shape recovery was found to be strongly LS dependent. Furthermore, the supper critical CO2 solution was used successfully to create three-dimensional porous structure of PU-LS with cell size depends on LS content. The temporary folded shape of PU-LS with 5 wt.% LS changed to its permanent shape (plane stripe) within just 17 s once the sample was immersed in a water bath at the programing temperature.

Mathematical modelling of flow field in 3-dimensional additive printing

The distribution of flow field caused by squeegee movement exercises a crucial influence over the transfer of aqueous polyurethane dispersion (PUD) in the 3-dimensional (3D) additive printing for warp knitted vamp. So, the current study's goal is to develop a mathematical model for flow field related to printing parameters, where analytical solution of squeegee deformation is crucial. This paper presents an analytical procedure to deduce the deformation equation of wedge squeegee with variable section based on the semi-inverse method from elastic mechanic. Then a mathematical model of 3D additive printing is obtained using lubrication theory, leading to non-dimensional velocity as well as the integral expression of hydrodynamic pressure that is solved by the Romberg integration algorithm. Further analysis reveals the similarities and differences between flow field studied in this paper and Couette flow. More importantly, the hydrodynamic pressure near the squeegee tip plays a crucial role in PUD transfer. Then, the sensitivity analysis is carried out to quantify the impacts of process parameters on hydrodynamic pressure. Among printing parameters, the printing angle has the greatest influence on hydrodynamic pressure, which is often neglected in traditional engineering studies. The theoretical calculations are compared against the simulations of finite volume method, showing good agreement for the distribution of velocity and pressure. This work paves the way for adjustment of process parameters and mechanism study of PUD transfer.

Rheological experiment and fractional derivative model for aqueous polyurethane dispersion

AbstractRheology of aqueous polyurethane dispersion (PUD) has a significant influence on the industry process. In this study, the aqueous PUD used in warp knitted vamp printing was characterized by Fourier transform infrared (FTIR) spectra, dynamic light scattering and laser Doppler electrophoresis. Characterization results reveal that aqueous PUD shows bimodal and broad particle size distributions as well as negative surface charges. Aiming at studying the influence of rheological property on industrial applications of aqueous PUD, dynamic oscillating shear experiments were performed, and its constitutive equation was deduced. Experimental results suggest that temperature has no distinct effect on the linear viscoelastic range, in which aqueous PUD shows a solid‐like behavior. In view of advantages of fractional order constitutive equation describing the viscoelasticity of fluid, this paper optimize the fractional order element to derived fractional Zener (FZ) and Poynting‐Thomson models, and FZ model performs the better. Furthermore, the application and analysis of fractional order model provide theoretic guide for industrial process in warp knitted vamp printing.

Synthesis of novel curcumin-based aqueous polyurethane dispersions for medical textile diligences with potential of antibacterial activities

Synthesis of novel curcumin-based aqueous polyurethane dispersions for medical textile diligences with potential of antibacterial activities

Photothermal Waterborne Polydopamine/Polyurethanes with Light-to-Heat Conversion Properties

A polydopamine-polyurethane (PDA-WPU)-based polymeric matrix with efficient light-to-heat conversion properties that can initiate light-activated temperature elevations is presented. The polymerization of dopamine monomer in a pre-synthesized aqueous polyurethane dispersion resulted in hybrid polyurethane-polydopamine particles via the coating of discrete waterborne polyurethane (WPU) particles with photothermal polydopamine. The resulting polydopamine-polyurethane (PDA-WPU) dispersions presented a unimodal particle-size distribution and particle sizes that increased as a function of the initial dopamine concentration and polymerization time. Films cast from PDA-WPU dispersions were black-colored and presented a homogeneous morphology with contact angles that decreased with increasing PDA content. While the thermal decomposition behavior and thermal conductivity values of hybrid PDA-WPU films were improved relative to neat WPU films, the glass transition temperatures remained unaffected and the films presented acceptable mechanical properties. PDA-WPU films prepared with the highest amount of polydopamine reached 105.8 °C when irradiated with solar light at 3 sun for 20 min. Five min of irradiation with NIR laser light at 800 mW/cm2 elevated the temperatures of the PDA-WPU films from room temperature to 138.6 °C. Moreover, PDA-WPU dispersions were molded in the form of a container to investigate their potential in solar-driven water-evaporation applications. The hybrid PDA-WPU polymer matrix prepared via a facile postsynthesis modification of WPU dispersions with polydopamine synergistically possesses the features of both components and presents strong photothermal activity along with its easy-to-apply, nanoparticle-free, and environmentally friendly nature; thus, this matrix can be viewed as a promising candidate for a wide range of photo-driven applications.

Highly absorbent hydrogels comprised from interpenetrated networks of alginate\u2013polyurethane for biomedical applications

Developing new approaches to improve the swelling, degradation rate, and mechanical properties of alginate hydrogels without compromising their biocompatibility for biomedical applications represents a potential area of research. In this work, the generation of interpenetrated networks (IPN) comprised from alginate–polyurethane in an aqueous medium is proposed to design hydrogels with tailored properties for biomedical applications. Aqueous polyurethane (PU) dispersions can crosslink and interpenetrate alginate chains, forming amide bonds that allow the structure and water absorption capacity of these novel hydrogels to be regulated. In this sense, this work focuses on studying the relation of the PU concentration on the properties of these hydrogels. The results indicate that the crosslinking of the alginate with PU generates IPN hydrogels with a crystalline structure characterized by a homogeneous smooth surface with high capacity to absorb water, tailoring the degradation rate, thermal decomposition, and storage module, not altering the native biocompatibility of alginate, providing character to inhibit the growth of E. coli and increasing also its hemocompatibility. The IPN hydrogels that include 20 wt.% of PU exhibit a reticulation index of 46 ± 4%, swelling capacity of 545 ± 13% at 7 days of incubation at physiological pH, resistance to both acidic and neutral hydrolytic degradation, mechanical improvement of 91 ± 1%, and no cytotoxicity for monocytes and fibroblasts growing for up to 72 h of incubation. These results indicate that these novel hydrogels can be used for successful biomedical applications in the design of wound healing dressings.

Bio-based polyurethane aqueous dispersions

Abstract With the advances of green chemistry and nanoscience, the synthesis of green, homogenous bio-based waterborne polyurethane (WPU) dispersions with high performance have gained great attention. The presented chapter deals with the recent synthesis of waterborne polyurethane with the biomass, especially the vegetable oils including castor oil, soybean oil, sunflower oil, linseed oil, jatropha oil, and palm oil, etc. Meanwhile, the other biomasses, such as cellulose, starch, lignin, chitosan, etc., have also been illustrated with the significant application in preparing polyurethane dispersions. The idea was to highlight the main vegetable oil-based polyols, and the isocyanate, diols as chain extenders, which have supplied a class of raw materials in WPU. The conversion of biomasses into active chemical agents, which can be used in synthesis of WPU, has been discussed in detail. The main mechanisms and methods are also presented. It is suggested that the epoxide ring opening method is still the main route to transform vegetable oils to polyols. Furthermore, the nonisocyanate WPU may be one of the main trends for development of WPU using biomasses, especially the abundant vegetable oils.

Development of coalescents for paints and varnishes based on ionic liquids – the products of diethanolamine and inorganic acids interaction

This paper reports the synthesis of ionic liquids through the interaction between diethanolamine and orthophosphate and boric acids in order to establish the possibility of replacing volatile coalescents in a formulation for paints and varnishes with ionogenic compounds. The results from studying the influence of polymeric coalescents based on ionic liquids on the rheological properties of water-dispersion paints and varnishes of different nature are presented. It has been established that the synthesized coalescents could be used to modify the properties of paints and varnishes based on polyurethane and styrene-acrylic aqueous dispersions. It has been shown that the product of the interaction between diethanolamine and boric acid in aqueous solutions forms an ionogenic complex compound with a unipolar conductivity in terms of ОН─ ions. It was also established that when introduced to the formulation of water-dispersion paints and varnishes, the solutions of modifiers produce a diluting action. The influence of ionic liquids on the process of film formation of aqueous dispersions of polymers and pigmented paints and varnishes based on them was investigated. It was established that the synthesized ionogenic compounds are not inferior, in terms of their effectiveness, to the widespread conventional industrial coalescents of the Texanol→ type. Therefore, there is reason to assert the possibility of replacing the industrial coalescent Texanol→ in the formulation of pigmented water-dispersion paints and varnishes based on styrene-acrylic and polyurethane dispersions with fundamentally new synthesized ionogenic modifiers. Thus, the coatings with a coalescent based on ion liquid of diethanolamine borate have a higher level of conditional hardness, which exceeds by 17 % the hardness index of the paint made on the basis of the conventional Texanol→ type coalescent, without changing its decorative properties, such as color and shine

Sustainable Polyurethane–Lignin Aqueous Dispersions and Thin Films: Rheological Behavior and Thermomechanical Properties

Sustainable aqueous polyurethane (PU) dispersions derived from castor oil and lignosulfonate (LS) have been successfully synthesized with stable nanoscale morphology and average particle sizes as s...

Analysis and Modeling of Viscosity for Aqueous Polyurethane Dispersion as a Function of Shear Rate, Temperature, and Solid Content.

Aqueous polyurethane dispersion (PUD) has attracted increasing attention in a wide range of industrial applications because of their versatile properties as well as ecofriendly nature. In this study, the aqueous PUD used in warp-knitted vamp printing was characterized by Fourier transform infrared spectra, dynamic light scattering, and laser Doppler electrophoresis. The mean diameter and zeta potential are 206.6 nm and −18.3 mV, respectively. The rheological behavior of aqueous PUD as a function of shear rate, temperature, and solid content was investigated experimentally. Besides, a new correlation model was proposed based on the Carreau equation and Arrhenius relation. The resulting model has high accuracy in viscosity estimation under complex conditions according to the prediction interval of 95%. Furthermore, the reasonable ranges of parameters were proposed theoretically for successful printing.

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

AbstractThe 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.

Fundamental insight into anionic aqueous polyurethane dispersions

Abstract Aqueous Polyurethane Dispersions (APUD) have been at the epicenter of the coating industry & research, devising greener solutions to modern coating problems. The formulation of APUDs involves many components namely, polyols, isocyanates, chain extenders, and ionic centers which enable the Polyurethane to be dispersed in water. This reduces the dependence on solvent-based coatings, providing a better and eco-friendly replacement for existing systems. Advantages like ambient temperature curing and excellent adhesion further reinforce the case for APUD. This review encompasses the synergistic effect of said components while painting a vivid picture of how they would affect the final properties of the coating.

Polyurethane coated non-woven: A Promising Solution for Building Insulation

The aim of this work is to evaluate the potential application of textile and polyurethane aqueous dispersion in insulation application in the form of a nonwoven polyurethane composite. Based on their properties, nonwoven are promising insulation solution for buildings. However, the major disadvantage is their flammability and their low mechanical property. The main purpose of this research is to improve physical, thermal and acoustical properties of these materials, by using a thin layer of polyurethane. According to the experimental results, it can be concluded that the PU layer enhanced the barrier properties of textile nonwoven. Moreover, it has a great effect on the sound absorption coefficient and thermal conductivity. The results of this study provide an effective solution for insulation application. Indeed, these alternative materials will contribute to the cost advantage as well as the green building initiative.

Effect of DMPA Content on Colloidal Stability of Jatropha Oil-based waterborne Polyurethane Dispersion

Driven by the increase of oil price in the market as well as environmental concerns by the society, a renewable raw material such as vegetable oil becomes the alternative to produce bio-based polyol to replace non-renewable polyols in polyurethane production. The recent development of aqueous polyurethane dispersion proves that environmentally waterborne PUD offers an efficient alternative to the solvent-borne PUD for the application in ink, adhesives, and coatings. In this study, the jatropha oil has been successfully functionalized to polyol (JOL) by epoxidation and oxirane ring opening steps. Jatropha oil-based waterborne polyurethane (JPU) dispersions were produced by polymerizing the JOL with isophorone diisocyanate (IPDI) and dimethylolpropionic acid (DMPA). The colloidal stability of JPU dispersions was studied in terms of particle size and zeta potential. Varying DMPA content from 5.0-7.0 wt.% resulted in small average particle size of dispersion from 39.40 nm to 133.2 nm. High zeta potential obtained in a range of -52 mV to -65 mV indicates the particles in the dispersion are sufficiently separated and therefore stable. Eventually, the study provides an overview of vegetable oil-based waterborne polyurethane dispersion with good stability for surface coating application.