Waterborne Polyurethane Resin Research Articles

Flexibility and abrasion tolerance of superamphiphobic coatings with rigid core–shell particles

Superamphiphobic coatings maintain surfaces clean even facing severe oil contamination, which is crucial for ensuring the lifespan of materials in highly polluted environments. Achieving excellent wear resistance and flexibility individually on superamphiphobic surfaces is relatively simple, but simultaneously obtaining both properties is challenging and often requires compromises. In this study, we develop an innovative approach inspired by “overcoming firmness by gentleness” to create superamphiphobic composite coatings with flexibility and abrasion tolerance. This innovative strategy combines a soft polyurethane resin with rigid diatomite/aluminum hydroxide (core–shell) particles, resulting in a coating structure resembling karst topography. Depositing aluminum hydroxide enhances the reactivity and content of hydroxyl groups on diatomite particles, simultaneously improving the hardness and 1H,1H,2H,2H-Perfluorodecyltrichlorosilane (FDTS) grafting degree of the core–shell particles. Residual hydroxyl groups on the semi-fluorination core–shell particles chemically bond with the isocyanate groups in the waterborne polyurethane resin, leading to enhanced crosslinking density and improved wear resistance of the coating. The top coating of F-SiO2 particles leads to a reduction in the surface energy of the core–shell coating. The obtained core–shell coating demonstrates excellent oil resistance even after 800 cycles of Taber abrasion under a load of 250 g and 1000 cycles of 360° bending, demonstrating remarkable wear resistance and flexibility simultaneously. This approach provides valuable insights for developing superamphiphobic composite coatings with flexibility and abrasion tolerance and opens new possibilities for their applications in flexible electronics and droplet manipulation.

Preparation and Dispersion Performance of Hydrophobic Fumed Silica Aqueous Dispersion.

Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. A series of experiments were conducted on the HFS-dispersing technology in this study. The size and structure of HFS primary particles were observed via transmission electron microscopy (TEM). The measurement results of the TEM were D50 = 13.6 nm and D90 = 19.7 nm, respectively. The particle size and dispersion performance of HFS were tested via dynamic light scattering (DLS). Additionally, the HFS aqueous dispersion was prepared and compounded with waterborne polyacrylic latex and polyurethane resin. The elemental distribution of the coatings was characterized using energy dispersive spectroscopy (EDS). The results show that the HFS in a non-ionic polymer dispersant had the best dispersion performance. The particle size of the HFS in the aqueous dispersion is related to the dispersion conditions. Under optimized conditions, the HFS aqueous dispersion can be prepared with a particle size of D50 = 27.2 nm. The HFS aqueous dispersion has stable storage stability. Even after storage for 47 d, the particle size still did not change significantly.

A simple surface engineering to develop the potential of carbon nitride nanosheets in high-performance polymer nanocomposites conducted by first-principles calculations

The incompatible interface between carbon nitride (CN) nanosheets and polymer resin is a huge challenge to develop high-performance polymer/CN nanocomposites. Recently, the complicated surface functionalization methods reported severely hinder the commercial production and practical application of polymer/CN nanocomposites. Herein, conducted by the first-principles calculations, a simple surface engineering is put forward to change the surface characteristic of CN nanosheets by rapidly introducing oxygen atoms with a chemical oxidation method. Presented by the first-principles calculations, it is found that the introduction of oxygen atoms can enhance the adsorption energy between oxygen-doping carbon nitride nanosheets (OCN) and waterborne polyurethane (WPU) resin. As a result, a stronger interfacial interaction and better dispersion state are presented in WPU/OCN nanocomposites, thus laying the foundation for the properties enhancement. Further, effective suppression effects for thermal pyrolysis and fire hazards of WPU resin are demonstrated by OCN nanosheets. As presented by cone calorimeter results, the peak values of heat release rate and total heat release in WPU/OCN-2 are decreased to 806 kW/m2 and 43.3 MJ/m2, significantly less than those of pure WPU (1028 kW/m2 and 55.9 MJ/m2). Meanwhile, more char residue, lower signal intensity of pyrolysis gas, and a prolonged time for signal peak also confirm that the addition of 2.0 wt% OCN nanosheets can hinder the thermal degradation behavior of WPU resin. In addition, the introduction of oxygen atoms promotes the formation of hydrogen bond interactions between OCN nanosheets and WPU matrix, thus enhancing interfacial compatibility and overcoming the re-stack problem. As a result, break strength and elongation at break of WPU/OCN-2 are up to 621% and 24.4 MPa, respectively. The combination of first-principles calculations and surface engineering opens a new approach for designing and developing high-performance polymer nanocomposites.

Preparation and optimization of WPU dispersion from polyether/polyester polyols for film and coating applications

BackgroundCastor oil and polytetramethylene ether glycol (PTMG) are used as polyester and polyether polyols. The waterborne polyurethane (WPU) resin is synthesized from polyether/polyester polyols following a ketone and catalyst-free pre-polymerization process. MethodsWPU resins are prepared from PTMG/castor oil with various hydroxyl molar ratios, such as 1/0, 3/1, 1/1, 1/3, and 0/1. Significant findingsThe results indicate that the WPU dispersions has a long shelf-life, high colloidal stability, and narrow distribution of molecular size. The addition of castor oil can increase the proportion of the cross-linking density, hard segments and hydrogen bonds of the WPU molecular chain. The addition of PTMG/castor oil increases from the molar ratio 1/0 to 1/1, the tensile strength of WPU film increases from 17.1 MPa to 25.6 MPa; the T5% increases from 250°C to 262°C; the water swelling ratio at 24 h decreases from 33.2 g/g to 19.4 g/g. The results indicate the using PTMG/castor oil can improve the mechanical strength, water resistance, and thermal stability of WPU film. The WPU could be applied to wood coatings with high properties. This study provides a cleaner process for optimizing the performance of WPU resin, which can replace conventional ketone- and organotin-based films and coatings.

Drag reduction in internal turbulent flow by fabricating superhydrophobic Al2O3/waterborne polyurethane coatings

Nowadays, increasing the CO2 emissions are one of the inevitable challenges in the world. In addition, in many industries, fossil fuels are the main source of energy demands which worsen the problem. Since in most applications, the performance and energy loss are highly affected by the drag force, many investigations have been proposed to improve the surface properties to moving surface against the water, and consequently, increasing drag reduction. To this end, one effective way is utilizing superhydrophobic coatings. In this study, we prepare two different superhydrophobic coatings using Al2O3 nanoparticles (NPs) modified by HMDS (1,1,1,3,3,3-Hexamethyldisilazane) and PDMS (Hydroxy-terminated polydimethylsiloxane), which are named HS and PS, respectively, in a waterborne polyurethane (WBPU) resin. The coated substrates show a significant water repellency and the measured contact angles are 158.6° and 153.2° for HS and PS coatings, respectively. Furthermore, the results indicate that the drag reduction is improved up to 18.771% and 16.141% for PS and HS coatings, respectively. Besides, it is observed that the friction coefficient in the superhydrophobic pipes decreases significantly. Also, to show the durability of the resultant surfaces, immersion tests in pure water, sea-water, alkaline, and acidic solutions are used.

Preparation of single-layer coating polyester cotton composites with electric loss of their electromagnetic properties

In this paper, single-layer coated polyester–cotton composites were prepared using PU-2540 waterborne polyurethane resin as the adhesive, graphite and silicon carbide as functional particles, and adopting a coating technology on the plain polyester–cotton fabric. First, the single-layer graphite-coated polyester cotton composite was prepared with graphite as the functional particle, and the influence of graphite content on the reflection loss and shielding effectiveness was studied. When the applied electric field frequency is 1610 MHz and the graphite content is 40 wt%, the minimum reflection loss is −26 dB; when the applied electric field frequency is 39.9 MHz and the graphite content is 50 wt%, the maximum shielding effectiveness is 12 dB. Then the single-layer silicon carbide-coated polyester–cotton composite was prepared with silicon carbide as the functional particle, and the influence of silicon carbide content on the reflection loss and shielding effectiveness was studied. With the applied electric field in the range 500∼3000 MHz the greater the content of silicon carbide, the smaller the reflection loss, the better the wave-absorbing ability, the larger the shielding effectiveness, and the better the shielding performance. Finally, the single-layer graphite/silicon carbide-coated polyester–cotton composites were prepared by doping graphite and silicon carbide in different proportions, and the influence of doping ratio on dielectric properties, reflection loss, and shielding effectiveness was investigated. The real part of the dielectric constant of the material was highest – that is, the polarization ability of the material was best when there were only graphite particles in the doping medium and the silicon carbide content was 0. The imaginary part of the dielectric constant and the tangent of loss angle of the material were the highest – that is, the loss and attenuation ability of the material were best – when the doping ratio of graphite to silicon carbide is 4:1. With the applied electric field in the range 500∼3000 MHz and with increasing graphite content, the reflection loss of the material became smaller, showing an enhanced wave-absorbing property, and the shielding effectiveness of the material increased, showing an enhanced shielding performance.

Tailoring of Durable Conductive and UV-Shielding Properties on Cotton and Polyester Fabrics by PEDOT:PSS Screen-Printing.

In the present study, cotton (Co) and polyester (PES) fabrics were screen-printed with a conductive poly3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) printing paste along with a commercially-available screen-printing binder (SFXC) or waterborne polyurethane resin (WPU), in order to enhance wash and wear durability, and to improve some functional properties, without essentially influencing the physical–mechanical properties of the base material, as well as the introduced fabrics’ conductivity. The application of a conductive polymer coating reduced transmittance in the whole UV region drastically, indicating good UV-shielding ability in the treated fabrics. Moreover, the employed binders improved the fabrics’ protection against harmful solar UV radiation significantly, depending on the type of fibre and binder. Furthermore, the SFXC binder intensified the hydrophobicity of Co as compared to the WPU binder, and, on the other hand, WPU reduced the hydrophobicity of PES. Finally, the screen-printed fabrics were washed up to 20 cycles and rubbed up to 20,000 cycles, and characterised by means of mass loss determination and electrical resistivity measurement. Both binders enlarged polymer stability against the effect of washing and rubbing, depending on the number of cycles, the type and amount of employed binder, the type of fibres, and the thickness and uniformity of coatings.

Preparation of robust antistatic waterborne polyurethane coating

In this study, a novle robust antistatic waterborne polyurethane (WBPU)-ZrO2 nanoparticle (NP) coating is specially designed using sol-gel process. For this purpose the effective parameters on resin performance and surface resistivity of the synthesized coating investigated and optimized. The WBPU composite containing 6 wt% ZrO2 NPs, dissipates electrostaic charges with surface resistivity of 9.1 × 109 Ω sq−1 and also improves adhesion strength about 30 % compared with neat resin. Moreover, the homogenous distribution of modified ZrO2 NPs provides a surface roughness of 27.0 nm which can avoid the absorption of dust on the surface. Facile fabrication of robust WBPU–ZrO2 coating with considerable antistatic properity provides a pathway to the development of environmental friendly antistatic surfaces. The improved properties of synthesized WBPU–ZrO2 coating are mainly due to (i) stable adhesion of ZrO2 NPs into WBPU resin after cross-linking with resin matrix, (ii) formation of a rough structure on the coating surface, and (iii) modification of resin performance that provides film hemogenity.

Graphene Oxide-Loaded Zinc Phosphate as an Anticorrosive Reinforcement in Waterborne Polyurethane Resin

Graphene Oxide-Loaded Zinc Phosphate as an Anticorrosive Reinforcement in Waterborne Polyurethane Resin

Enhanced corrosion resistance of waterborne polyurethane containing sulfonated graphene/zinc phosphate composites

Compared with solvent-based resins, waterborne resins still have defects such as insufficient anti-corrosion efficiency. In this paper, the sulfonated graphene/zinc phosphate composites were prepared as an anti-corrosion filler and doped into waterborne polyurethane resin. The morphology of composites is different from pure zinc phosphate. The optimal corrosion resistance can be obtained by adding 0.5 wt% sulfonated graphene/zinc phosphate fillers characterized by Potentiodynamic polarization curves and EIS analysis The corrosion current density (icorr) was 0.4252 μA/cm2 and the charged transfer resistance (Rct) was up to 10.937 × 103 Ω cm2, which show a good potential as anti-corrosive fillers in waterborne coatings system.

Synthesis and properties of quick-drying UV-curable hyperbranched waterborne polyurethane coating

Ultraviolet light (UV)-curable hyperbranched waterborne polyurethane (UVHWPU) resins were synthesized using polypropylene glycol (PPG)-1000, dimethylol propionic acid (DMPA), trimethylol propane (TMP), isophorone diisocyanate (IPDI) as core moiety, and 2-hydroxyethyl methacrylate (HEMA) as capping agent. The preparation methods of the UVHWPU resins were studied and an optimum recipe was given by selecting the proper dosage of DMPA, PPG-1000 and TMP. The structure of hyperbranched resins was characterized by C13-NMR spectra and Fourier transform infrared (FTIR) spectroscopy. The type and dosage of photoinitiator were determined, and the properties of UVHWPU coating with excellent performance were examined.

Structure and surface properties of a novel bulk-matte waterborne polyurethane coating composite

This paper reports on a novel self-matte or bulk-matte waterborne polyurethane coating composite with inherently extremely low gloss. The coating composite was comprised of a siloxane-containing waterborne polyurethane (SPU) resin and a crosslinked waterborne polyurethane (CPU) resin. The CPU resin was mainly responsible for fabricating the micro-rough surface of the film, which was achieved by a crosslinking reaction between the waterborne polyurethane and bisphenol A-type epoxy E-44 resin. The SPU resin was used to improve the comprehensive properties of the film, which was ascribed to the addition of silane coupling agent KH792. Compared with traditional matte coatings, this coating composite made it possible to avoid high loadings of matting agent and to arrive at highly flexible low-gloss finishes. Gloss levels of as low as a few tenths of a percent, even at high incidence angles, have been achieved with zero loading of extraneous dulling agent. The chemical structures of the SPU and CPU resins were characterized by FTIR-ATR and NMR spectra. The micro-rough topographies and surface rough degrees of the SPU, CPU and their 50%/50% composite films were measured by SEM and MSP, respectively. The particle sizes and particle morphologies of the SPU and CPU resins were imaged by TEM. Finally, the comprehensive properties of the SPU, CPU and their 50%/50% composite resins were evaluated, including the water contact angle, film transparency, tensile strength and storage stability.

Preparation and characterization of a novel low gloss waterborne polyurethane resin

A novel waterborne polyurethane (WPU) resin with low gloss and micro-roughness was synthesized by the prepolymer and self-emulsification method. It was achieved by introducing multi-hydroxyl castor oil and reactive bisphenol A-type epoxy E-44 or E-51 resin to polyurethane prepolymer to form a cross-linking network structural waterborne polyurethane emulsion, which demonstrated the distinctive characteristic of the shear-thinning pseudoplastic fluid with a yield stress. The chemical structures and rough surface morphologies of the WPU films were characterized by FTIR-ATR, LCRS, AFM, SPMS and SEM, respectively. The specular gloss values at 20°, 60° and 85° incident angles were measured, and the values of different kinds of roughness parameters were obtained. The relationship between the gloss and the castor oil content was also discussed in detail. In general, this WPU resin endowed the film with micro-roughness, moderate hardness and good adhesive strength, making it very prospective in substitution for the traditional low gloss coatings.

Waterborne polyurethane molecular structure designed and its acetic acid and ammonia absorption efficiency

In this study, waterborne polyurethane (WPU) resins consisted of carboxylic acid and side-chained EO (ethylene oxide) functional groups were prepared via a prepolymer ion-hybrid reaction process. After dipping the WPU on fabrics, the dipped fabrics showed promising deodorization properties for both basic and acidic odors and also showed good wash durability because of the presence of those characteristic groups. Basic odors were neutralized via carboxylic acid groups on the WPU, whereas acidic odors were absorbed by the EO groups through hydrogen bonding. Fourier transform infrared spectroscopy (FT-IR) was used to examine the functional groups of carboxylic acid and EO groups, before and after dipping the WPU on the fabrics. The deodorization properties of the dipped fabrics were associated with the content of the functional groups existing on the WPU molecular chain. Scanning electron microscope (SEM) analysis also revealed that the dipped fabrics had a promising wash durability and deodorization properties after 5 times of laundering because WPU particles were still strongly adhered to the fabrics. More side-chain EO groups, more acetic acid molecules were absorbed; while more-COOH groups in polymer chain, more ammonium molecules were absorbed. Table 2 shows that the synthesized WPU’s possess very highly washed durability.

Effects of the NCO/OH molar ratio and the silica contained on the properties of waterborne polyurethane resins

Waterborne polyurethane resins (WPUs) were synthesized with polytetramethylene ether glycol (PTMG), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI), triethylamine (TEA) and ethylenediamine (EDA) as the raw materials of polyol, internal emulsifier, isocyanate, neutralizer and chain extender, respectively. The NCO/OH molar ratios used for the pre-polymerization were set as 1.6/1, 1.8/1 and 2.0/1. Furthermore, tetraethoxysilane (TEOS) was added to the WPUs to prepare the WPU/silica organic-inorganic hybrids by the sol-gel process. The characteristics of WPUs prepared with different NCO/OH molar ratios, and the properties of WPU and WPU/silica films were investigated. The results show that WPUs prepared with higher NCO/OH molar ratios have suspensions with lower viscosity, smaller average particle size and smaller average molecular weight, and lead the films to have more urea and amide structure, better solvent resistance, higher tensile strength, modulus and break energy, lower molecular chain activity, and smaller damping peak height, but weaker thermal resistance. The network structure of silica can limit the activity of the soft-segment, increase the stiffness of the hard-segment and enhance the thermal resistance of WPUs films.

Synthesis and surface analysis of self-matt coating based on waterborne polyurethane resin and study on the matt mechanism

Self-matt coating of waterborne polyurethane (WBPU) was synthesized by combining prepolymer and self-emulsification methods. The emulsion was fabricated from both hydroxy carboxylic acid and aminosulfonic acid types of hydrophilic chain-extending agents, in which the 2-[(2-aminoethyl) amino] ethane sulphonate sodium (AAS salt) was produced in laboratory. This emulsion demonstrated an excellent matt performance without the addition of extra matting agents after filming. Four different kinds of surface properties were measured on the film: the specular gloss (60° gloss meter), the contact angle (CA), the surface roughness degree (3D Surface Profilometer), and the topography of the coatings surface (SEM). The results showed that tons of spherical particles with diameter in a few micrometers were aggregated on the film surface. The effect of the roughness parameters (R a and R q ) and the average particle size of the emulsions on the specular gloss degree were probed. The research indicated that the emulsion with average particle size in the range of 2.5–3.0 µm and, meanwhile, the film with roughness parameters R a and R q both greater than 1 µm could attain the best matt effect. The WBPU emulsions showed good physical and mechanical properties, and were introduced into wood varnish for matting purpose.

Synthesis and assessment of novel anticorrosive polyurethane coatings containing an amine-functionalized nanoclay additive prepared by the cathodic electrophoretic deposition method

Cathodic electrophoretic deposition (CEPD) was utilized to cover a mild steel cathode in an aqueous solution consisting of a newly synthesized two-component one-pack waterborne polyurethane resin.

Synthesis and characterization of solvent-free waterborne polyurethane dispersion with both sulfonic and carboxylic hydrophilic chain-extending agents for matt coating applications

Self-extinction and solvent-free waterborne polyurethane resin without the addition of extra matting agents.

Gas transport properties in waterborne polymer nanocomposite coatings containing organomodified clays

Nanostructured composite coatings, consisting of phylosilicates embedded within polymer matrices, were prepared and characterized. Waterborne acrylic and polyurethane resins were employed as matrix, and hydrophilic or organically modified nanoparticles of montmorillonite as reinforcement. Emphasis in this article is put on the preparation of the coating. An overview of the major steps involved is presented. The choice of a suitable solvent for the preparation stage is based on the values of the solubility parameters of the constituents. The characterization techniques that are used include X-ray diffraction analysis, gas permeation measurements, and IR spectroscopy. The results highlight the significance of the selection of appropriate ingredients and the knowledge of the interactions between the clay particles, the organic matrix, and the solvents used for the preparation of the coating.

Preparation, Structure and Properties of High Performance Silver-Filled UV-Curable Polyurethane Acrylate Conductive Inks

In this paper, polyethylene glycol thioglycolate was prepared by esterfication. Spherical silver nanoparticles were formed from silver nitrate solution by liquid chemical reduction method with hydrazine hydrate as reducant. Based on the previous two steps, the nanoAg was absorbed by the polyethylene glycol thioglycolate trough the deposition. Metal nanoparticles were absorbed by polyethylene glycol thioglycolate with M-S bond to form polymer modified nanoparticle powder. The conductive inks were prepared using modified nanoparticles, other filler and laborator self-made water-borne polyurethane resin as the bonding material. Then the ink was coated on the PET film surface to mold. Catalyst, temperature and time effected esterfication. The esterfication rate was about 55% at 110°C for 3 hours. XRD indicated that the nanoAg prepared were cubic crystals, TEM showed that the size of modified nanoAg was less than 10nm. Metal nanoparticles with M-S bond effectively reduced the surface energy and had better compatibility with organic materials. Cross-cutting tests showed that adhesion between the ink and PET films was well and the conductive inks also showed good wet resistance and thermostability.