Blocked polyisocyanates containing monofunctional polyhedral oligomeric silsesquioxane (POSS) as crosslinking agents for polyurethane powder coatings

Blocked polyisocyanate crosslinkers for powder coatings were synthesized using alicyclic diisocyanates (TMDI and IPDI), formic acid, (methylaminopropyl)hepta(isobutyl)Si₈O₁₂ (POSS), ?-caprolactam, dibutyltin dilaurate as well as triethylamine as catalysts. The chemical structures of these compounds were characterized by means of IR, ¹H NMR and ¹³C NMR spectroscopy. The three-dimensional surface topography and surface chemical structure of the resulting powder coatings were investigated by using confocal microscope and ATR FT-IR. The values of surface roughness parameters were calculated. The surface topography was correlated with the chemical structure of the coatings and macroscopic surface behaviour: surface free energy, abrasion resistance, hardness, adhesion to the steel surface and impact resistance. Thermogravimetric analysis was employed to assess the hardening property of powder coatings and the thermal decomposition processes.     

Polyurethane powder coatings crosslinked with allophanate structures containing polyisocyanates

With the use of alicyclic diisocyanates, aliphatic alcohols and dibutyltin dilaurate as well as triethylamine as a catalysts internally‐blocked polyisocyanate crosslinkers which contained allophanate bonds were synthesized. The chemical structure of those compounds were characterized by IR, ¹H‐NMR, and ¹³C‐NMR spectroscopy. Their molecular weight distribution (MWD) parameters were determined by gel permeation chromatography (GPC). Those blocked polyisocyanates were used for the production of ecological lacquer compositions and coatings. The unblocking and curing reactions were investigated on the DTA, TG, and DSC thermograms. The resulting powder lacquers exhibit an excellent appearance; they are transparent, smooth, and nonyellowing. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Linking of oligoesters hydrolysis to polyurethane coatings

The hydrolytic stability of a series of oligoesters comprised of three and four different monomers was evaluated. The hydroxyl terminal oligoesters were prepared from adipic acid (AA) and isophthalic acid (IPA), with six different diols and one triol, which included: 1,4‐butanediol, 1,5‐pentanediol, 1,6‐hexanediol, neopentyl glycol, 2‐methyl‐1,3‐propanediol, trimethylolpropane, and 2‐butene‐1,4‐diol. The hydroxyl terminated oligoesters were reacted with phenyl isocyanate to form telechelic urethane groups. Hydrolysis rate constants were obtained from plots of acid number vs. time. It was observed that ternary oligoester systems had lower hydrolysis rates than quaternary systems. In addition to investigating the hydrolytic stability of the synthesized oligoesters, polyurethane coatings were produced by reacting the hydroxyl‐terminated oligoesters with an aliphatic polyisocyanate (1,6‐hexanediisocyanate trimer). Model oliogester hydrolysis was then correlated to the weatherability of a crosslinked polyurethane film. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40198.     

含氟聚氨酯树脂涂料的制备及应用

本文介绍了可溶性的带痉基含氟烯烃的合成及含氟聚氨酯涂料的制备，含氟聚氨酯涂料具有优异的耐候性，保色性及耐热，耐腐蚀，耐化学性，可用于建筑，储罐，船舶和飞机等领域。     

Effect of oleic acid content and chemical crosslinking on the properties of palm oil‐based polyurethane coatings

Polyurethanes (PU) were prepared by reacting palm oil‐based polyols and aromatic diisocyanate (toluene 2, 4 diisocyanates). The content of oleic acid was varied in the polyester polyols and the hydroxyl value was fixed to be 140 mg KOH g^?1. The NCO/OH ratios were varied to 1.2, 1.4, and 1.6. Crosslinking density of the PU was measured by swelling in toluene at room temperature. It was found that the crosslinking increased with decreasing oleic acid content and increasing NCO/OH ratio. The samples were assessed by thermogravimetric analysis, differential scanning calorimetric, and short‐term creep measurements. The highest rupture strength of the PU films was 36 MPa and thermostability improved as the oleic acid content and the NCO/OH ratios were increased in the sample. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and properties of UV‐curable fluorinated polyurethane acrylates containing crosslinkable vinyl methacrylate for antifouling coatings

To obtain highly effective antifouling coatings, a series of UV‐curable polyurethane acrylates containing diluents [heptadecafluorodecyl methacrylate (PFA, 6 wt %)/isobornyl acrylate (IBOA, 34 wt %)/methyl methacrylate (MMA, 20‐5 wt %)/vinyl methacrylate (VMA, 0–15 wt %)] were prepared. This study examined the effect of bulky MMA (20‐5 wt %)/crosslinkable VMA (0–15 wt %) weight ratio on the properties of the UV‐curable polyurethane acrylates. The fluorine concentration in UV‐cured film surface increased with increasing VMA content up to 9 wt % and then decreased. The T_gα, transparency, elasticity, and mechanical properties of the UV‐cured film samples increased with increasing VMA content. The water/methylene iodide contact angles and surface tension of samples increased from 107/79 to 121/91° and decreased from 17.8 to 12.7 mN/m with increasing VMA content up to 9 wt % and then decreased/increased, respectively. From these results, it was found that the optimum VMA content was 9 wt % to obtain a high‐performance antifouling coating. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42168.     

Dimeric isocyanates in polyurethane powder coatings

Internally-blocked polyurethane crosslinkers based on the uretdione of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) will be introduced. The principal structures and the performance properties of different products will be described. Besides the use in conventional high-gloss coatings, the possibilities will also be pointed out for special uretdione adducts for coatings with greater chemical resistance, specifically solvent resistance, or in the preparation of matte surfaces.     

Bamboo tar‐based polyurethane wood coatings

Bamboo tar is a natural resource of aromatic polyol obtained from a residue of by setting or distilling crude bamboo vinegar. In this study, the two‐packed polyurethane (PU) coatings were prepared by blending bamboo tar and castor oil varying with different weight ratios and polymeric toluene diisocyanate (PTDI) was used as a hardener at the NCO/OH molar ratio of 1.0. Six kinds of PU coatings were formulated and the viscosity, pot‐life, drying time, mechanical properties (hardness, tensile strength, impact resistance, adhesion, and abrasion resistance), gel content, durability, lightfastness, FTIR, thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) were characterized. The results indicated that the bamboo tar containing PU film appearance is semitransparent yellow‐brown color and the wood texture could be kept after finishing. All PU films possessed excellent adhesion as well as durability. The increase in bamboo tar content led to shorten drying time of coatings and to increase in hardness, tensile strength, lightfastness, and thermal stability of films. From these results and due to a light smell flavor, it is suggested that the bamboo tar‐based PU coatings is suitable to be used as an exterior wood coatings. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of polyurethane urea based on fluorine‐containing bisphenoxydiamine

A fluorine‐containing bisphenoxydiamine, 2,2‐bis[4‐(4‐aminophenoxy)phenyl]hexafluoropropane (BAPF₆P), was synthesized and characterized by means of Fourier transform infrared spectrometry (FTIR), NMR, and elemental analysis. The obtained BAPF₆P was used as a chain extender to prepare polyurethane urea (PUU), whose morphology and properties were measured through FTIR, differential scanning calorimetry, thermogravimetric analysis, tensile measurements, and atomic force microscopy. The results show that the PUU elastomers based on BAPF₆P exhibited good mechanical properties and thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1863–1869, 2006     

Polyurethane powder coatings containing polysiloxane

In this study, blocked polyisocyanate crosslinkers (PIC) for powder coatings were synthesized using isophorone diisocyanates (IPDI), formic acid, poly(dimethylsiloxane), ?-caprolactam, dibutyltin dilaurate as well as triethylamine as catalysts. The chemical structures of these compounds were confirmed by means of IR and NMR spectroscopy and the molecular weight distributions were investigated using gel permeation chromatography (GPC). Polyurethane powder coating systems consisting of polyester resin and synthesized polyisocyanate were examined. The surface structure of powder coatings was investigated with confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The surface structure was correlated with the chemical structure of the coatings and macroscopic surface behavior: contact angle, surface free energy, gloss, abrasion and scratch resistance, hardness as well as adhesion to steel surface.     

New intumescent flame‐retardant agent: Application to polyurethane coatings

The first part of this investigation focused on the synthesis and characterization of a new type of intumescent flame‐retardant (IFR) agent. Four steps were used in the synthesis process. The structure was characterized by FTIR, magic‐angle spinning nuclear magnetic resonance (MAS‐NMR) ¹³C spectroscopy, and elemental analysis. The addition of an IFR agent into polyurethane (PU) varnish led to an improvement in its carbonization and flame‐retardant (FR) properties. The second part focused on the evaluation of such characteristics as FR property, thermal stability of IFR/PU‐based coatings, rheology of IFR/PU‐based coating solutions, and mechanical properties such as hardness, adhesion, and flexibility of IFR/PU‐based dry coating films. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1193–1206, 2004     

Biobased dimer fatty acid containing two pack polyurethane for wood finished coatings

Novel two pack polyurethane wood finished coatings are prepared from renewable sources, such as vegetable oil based fatty acid and dimer fatty acid. In actual experimental part oleic acid was reacted with diethanolamine to obtain amide which was on condensation polymerization with dimer fatty acid converted into the polyesteramide polyol. These are all being used to prepare polyurethanes. The functional and structural elucidation of dimer fatty acid based polyesteramide and diethanolamide were carried out by end group analysis, spectral studies such as FTIR and ¹H NMR. Average molar masses of the polyesteramide were estimated by gel permeation chromatography (GPC). The polyesteramide was used in the preparation of wood finished polyurethane coatings by reacting it with aromatic diisocyanates. Thermogravimetric analysis (TGA) was used to study the thermal behavior of coatings. Physico-chemical and coating properties of the coatings were investigated by using standard methods. The results indicated that the bio-based wood finished PU coatings provided good mechanical, weather resistance as well possessed adequate coating properties for wood surface protections.     

Fully biobased polyester polyols derived from renewable resources toward preparation of polyurethane and their application for coatings

Renewable resources such as isosorbide and dimer acid were used to prepare fully biobased polyester polyols and polyurethane (PU) coatings. The structural features of polyester polyols were studied by end-group analysis and spectroscopic methods. Then polyols were utilized in the preparation of PU coatings by reacting with diisocyanate. The prepared PU coatings were tested for both mechanical and chemical testings, which involved gloss, cross-cut adhesion, pencil hardness, anticorrosion performance by immersion and Tafel plot methods, and chemical resistance against water, solvent, and acid media. The prepared PUs were also tested for their thermal stability using a thermogravimetric analyzer and surface morphology by a scanning electron microscopy. Tested mechanical properties, chemical resistance, and thermal stability results demonstrated that the renewable sources used in the preparation of PU coatings can be good substitutes over petroleum resources. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47558.     

Catalyst effect on the crosslinking kinetics of a fluorine containing polyurethane network

A bicomponent fluorinated polyurethane coating was obtained by crosslinking a bifunctional, OH terminated perfluoropolyether oligomer with a fluorinated polyisocyanate based on the isophorone diisocyanate (IPDI) cyclic trimer. Three different tin containing catalysts (dibutyltin dilaurate (DBTDL), dibutyltin dimercaptide (DBTDM), tin octoate (TO)) were evaluated during the crosslinking reaction through gel time measurements and IR spectroscopy at various temperatures from +15 to +45°C. Both the methods showed a substantial higher activity of the first two catalysts, tin octoate being almost ineffective (latent) at ambient temperature. The spectroscopic measurements allowed the determination of apparent second‐order kinetic constants (k) of the crosslinking reaction. The activation energies E_a in the temperature range considered were obtained from the corresponding Arrhenius plot, showing a temperature dependence higher for DBTDM than DBTDL (8.5 vs. 7.0 kcal/mol). Finally, the conversion of the crosslinking reaction on the dry polymer film was estimated to be around 60–80% after 8 h at ambient temperature for DBTDM and DBTDL, but only 20–25% for TO catalyzed reactions. The formation of a hard urethane phase having a glass transition temperature T_g higher than the crosslinking temperature was considered as the main limiting factor of the overall reaction rate.     

Surface properties of fluorinated hybrid coatings

A commercial perfluoropolyether containing alkoxysilane functionalities was employed to prepare organic–inorganic hybrid coatings by using the sol‐gel process in the presence of tetraethoxysilane. Contact angle analysis revealed a strong hydrophobic and oleophobic character of the coatings almost independently from the molecular weight of the starting fluorinated oligomer. Surface tension values were in the range of 14–16 mN/m, suggesting a preferential segregation of fluorinated segments onto the surface of the coating. Atomic force microscopy showed the presence very smooth surfaces permitting to neglect the contribution of the surface roughness to wettability. Friction coefficient values were markedly lower with respect to the value of uncoated glass substrate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1483–1488, 2006     

Degradation of polyurethane coating materials from liquefied wheat straw for controlled release fertilizers

Polyurethane (PU) was synthesized by liquefied wheat straw and isocyanates for controlled release fertilizers (CRFs). CRFs coated by PU were buried in soil for 12 months. The degradation degree and mechanism of PU coating materials were observed by thermogravimetric analysis (TGA), Atomic Force Microscope (AFM), differential scanning calorimetry (DSC), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Fourier transform infra‐red spectroscopy (FTIR). Significant microscopic morphology of PU exhibited many small chips or stereovision holes caused by biodegradation or hydrolytic degradation due to the presence of natural polymer wheat straw. AFM results depicted the plane and height topography changes of PU before and after 12 months burial time, showing the swelling morphology of buried PU. TGA and FTIR results confirmed the disintegration of PU polymer due to the presence of isocyanates monomers in the PU12. XPS revealed an accumulation of biofilm on the surface of buried PU, providing the evidence of biodegradation mechanism. Pot experiment indicated the resin residual coating has a positive effect on soil quality. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44021.     

多重交联紫外光固化水性聚氨酯涂料

通过环氧树脂改性以及多元醇内交联、六甲撑二异氰酸酯(HDI三聚体)交联改性、固化剂交联和紫外光交联等四重交联,并加入季戊四醇三丙烯酸酯(PETA)作为接枝化合物,合成了紫外光固化水性聚氨酯丙烯酸酯分散体(WPUD)。研究了环氧树脂改性以及PETA含量对漆膜性能的影响。结果表明,经过环氧改性,采用2.5%的HDI三聚体和13.6%的PETA合成的水性聚氨酯丙烯酸酯分散体,其漆膜吸水率为6.3%,耐丙酮擦洗360次,摆杆硬度0.79。所得漆膜达到或超过了溶剂型紫外光固化涂料的要求。     

Structural variation in soft segment of waterborne polyurethane acrylate nanoemulsions

High solid content waterborne polyurethane acrylate (WPUA) nanoemulsions are prepared as textile finishes. Two structurally different soft segments, that is, polyether and polyester are used with isophorone diisocyanate, 2‐hydroxyethyl methacrylate, and butyl acrylate. Structural variations are investigated in features of nanoemulsions and their coatings. Physical properties of nanoemulsions, such as average particle size, stability, solid content, and viscosity, are investigated. Nanoemulsions with high solid content, that is, 40–47% are produced without any internal emulsifier. Average nanoparticle size, that is, <100 nm is confirmed by dynamic light scattering and atomic force microscopy (AFM). Fourier transform infrared spectroscopy proved synthesis of proposed WPUA products. Synergistic effect of polyurethane and acrylate is observed in chemical and water resistance of WPUA. Differential scanning calorimetry (DSC) and thermogravimetric analysis indicate stable uniformly cross‐linked network of WPUA. Application of nanoemulsions on 100% cotton fabric shows a significant improvement in tear strength, which is more pronounced for polyester‐based WPUA. Scanning electron microscope images of treated fabric samples show good adhesion of nanoemulsions on cotton surface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41706.     

Fullerene containing polyurethane nanocomposites for microwave applications

Novel flexible polyurethane (PU) composite films containing nano‐barium hexaferrite (BaF) and nano‐barium titanate (BT) have been synthesized and characterized. The PU nanocomposites were synthesized from fullerenol and prepolymer of hexamethylene diisocyante and polytetramethylene glycol by adding 1–3% each of BaF (high permeability) and BT (high permittivity). The incorporation of the nanopowders was confirmed by X‐ray diffraction (XRD), transmission electron microscopy, and energy dispersive X‐ray diffraction (EDX). Study of thermal properties by thermogravimetric analysis and dynamic mechanical analysis revealed enhanced thermal stability of the nanocomposites. Study of mechanical properties showed that the tensile strength had increased remarkably in the nanocomposites. The electromagnetic‐absorbing properties were studied by measuring the complex permeability and permittivity in the frequency range of 8.2 to 12.4 GHz. The good reflection loss of the nanocomposites at such low filler content suggests its potential applicability as a radar absorber. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013