Polyol Dispersions Research Articles

Magnetic properties of smart textile fabrics through a coating method with NdFeB flake-like microparticles

Coatings were prepared by using NdFeB flake-like microparticles with aqueous polyurethane polyol dispersions and were coated onto the surface of textile fabrics in order to obtain textile fabrics with good magnetic properties. X-ray diffraction and energy dispersive spectroscopy analysis showed that there was no significant oxidation and magnetic decline in the samples after 6 months. The surface morphologies of the textiles were characterized using scanning electron microscopy and optical microscopy. The results showed that the crack density (the number of cracks per unit area) increased with increasing magnetic microparticle content, which can be attributed to two reasons: on one hand, the stress concentration at areas of high powder concentrations fractured more easily; on the other hand, the expansion coefficients of magnetic microparticles and polymer materials are different. Three kinds of textile fabrics with different microparticle concentrations were magnetized by means of a magnetizing machine. It was found that the cotton knitted fabrics had the highest average surface magnetic induction intensity, reaching 19 mT when the content of magnetic microparticle was 50 wt%. It was considered that this was related to the magnetic field distribution, due to the surface friction coefficient of the textile fabrics and the positions/angles of the flake-like microparticles. The hysteresis loops were measured using a vibrating sample magnetometer, and the results showed that the higher the concentration of magnetic microparticles, the higher the magnetization of the fabric. In short, this method can be used to prepare fabrics with high magnetization required under special conditions.

Thermostability and flame retardance of green functional two-component waterborne polyurethane coatings with nanoparticles

A new kind of green and functional two-component flame-retardant waterborne polyurethane and its coating were synthesized through adding polyurethane polyol dispersions, hydrophilic nanoTiO2 and hydrophilic curing agent. The properties and analysis were characterized via FTIR, laser particle analyzer, rheometer, TEM, TGA, TGA-FTIR, LOI tester, SEM, UV–vis spectrum, water and solvent resistance. The results showed the tensile strength counld reach 22.3 MPa. And the nanoTiO2 delayed speed of thermal decomposition to improve thermostability of two-component waterborne polyurethane. Larger quantities of hydrophilic nanoTiO2 did not produce a larger unbroken carbon yield surface or thicker carbon layers, but effectively produced a condensed phase flame-retardant effect with OP550 during burning. Besides, LOI and UL-94 also reached over 29.4% and V–0 respectively. The UV and visible light shielding noticeably increased with the adding nanoTiO2. The 0.5% content of nanoTiO2 had the optimal properties in green and functional two-component waterborne polyurethane coatings.

Preparation and properties of high storage stability polyester polyol dispersion for two-component waterborne polyurethane coating

A new type of polyester polyol dispersion with good storage stability was prepared based on a hydrophilic monomer 5-sodium sulfodimethyl isophthalate (5-SIPM), and frequently-used monomers such as neopentyl glycol (NPG), dimethyl terephthalate (DMT), dimethyl phthalate (DMP) and trimethylolpropane (TMP) by the transpolycondensation and polycondensation method. The polyester polyol dispersion was characterized by FTIR and GPC. The proper content of these monomers were determined by the performance of polyester dispersion: the content of TMP was 15wt%, the content of NPG was 7.5wt% and the hydrophilic monomer 5-SIPM content was 5wt%. Two-component waterborne polyurethane (2K-WPU) coatings were prepared by Bayhydur® XP2487/1 and polyester polyol dispersions, which were stored before and after at 40 ° for 6 weeks, the prepared films have no differences in drying time, adhesion, pencil hardness, gloss and chemical resistance, the result also reveals that the polyester polyol dispersion have excellent storage stability resistance.

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.

Preparation and characterization of a polydimethylsiloxane‐modified, epoxy‐resin‐based polyol dispersion and its crosslinked films

ABSTRACTWaterborne polydimethylsiloxane‐modified epoxy‐resin‐based polyol dispersions were synthesized by the reaction of 2,4‐toluene diisocyanate with 2,2‐bis(hydroxymethyl) propionic acid, hydroxypropyl‐terminated polydimethylsiloxane (HTPDMS), and bisphenol A epoxy resin based polyol. These HTPDMS‐modified polyol dispersions exhibited a small particle size and an excellent dispersion stability. Two‐component waterborne polyurethane (2K‐WPU) was prepared from the HTPDMS‐modified polyol dispersion and a hydrophilic‐modified polyisocyanate. The structure of the HTPDMS‐modified polyol and its crosslinked 2K‐WPU films (SEFs) were characterized with Fourier transform infrared and NMR spectroscopies. The effects of the HTPDMS content on the mechanical and thermal properties of the resulting SEFs were investigated. The results show that the thermal stability of the crosslinked SEFs was enhanced with increasing HTPDMS content, whereas the modulus, tensile strength, and pencil hardness values of the films decreased with increasing HTPDMS content. Siloxane segments migrated onto the surface during the film‐formation process. The contact angle of the films increased from 71 to 96 °, and the water absorption ratio of the films decreased from 6.6 to 5.0% when the HTPDMS content in the films increased from 0 to 10%. These results indicate that the water resistance of the films was enhanced by the introduction of HTPDMS into the 2K‐WPU networks. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44342.

Maleopimaric acid‐modified two‐component waterborne polyurethane for coating applications

ABSTRACTMaleopimaric acid (MPA), an important rosin derivative, was used to partially substitute isophthalic acid for the preparation of an anionic polyol (MPP) dispersion. The MPP dispersion was then applied to prepare a novel maleopimaric acid‐modified two‐component waterborne polyurethane (MPP‐2K‐WPU). The influences of NCO:OH molar ratio on the thermal properties, water absorption, surface free energy, and application properties of MPP‐2K‐WPU films were investigated. With increasing NCO:OH molar ratio, the thermal stability, pencil hardness, and ethanol resistance of MPP‐2K‐WPU films were improved, but the water resistance was enhanced firstly and then weakened. The surface free energy of MPP‐2K‐WPU films mainly depended on the dispersion interaction which was related to the structure of macromolecules. In addition, compared with the control sample of PP‐2K‐WPU(1.5:1) film, the MPP‐2K‐WPU(1.5:1) film exhibited improved thermal stability, water resistance, gloss, pencil hardness, and ethanol resistance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43292.

Preparation and properties of maleopimaric acid-based polyester polyol dispersion for two-component waterborne polyurethane coating

Abstract An anionic polyol (MPP) dispersion was prepared by introducing maleopimaric acid (MPA) into polyester polyol chain through esterification reaction. The influences of catalyst content, molar ratio of alcohol to acid, 5-sulfoisophtalic acid sodium salt (5-SSIPA) content and MPA content on particle size, stability and rheological property of MPP dispersion were investigated. The optimized conditions for the synthesis of stable MPP dispersion were identified as 1 wt% catalyst content, 1.4:1 molar ratio of alcohol to acid, 2.86 wt% 5-SSIPA content, and 15 wt% MPA content. The MPP dispersion was then applied to the preparation of a novel maleopimaric acid-based two-component waterborne polyurethane (2K-WPU) coating. Incorporating MPA into MPP dispersion leaded to the maleopimaric acid-based 2K-WPU coating with improved tensile strength, gloss, pencil hardness, water resistance and ethanol resistance. The results suggested that MPP dispersion provided a potential application in the field of 2K-WPU coating.

Preparation and properties of waterborne polyurethane/epoxy resin composite coating from anionic terpene-based polyol dispersion

An anionic polyol (T-PABA) dispersion was prepared by modifying terpene-based epoxy resin with para-aminobenzoic acid. Then T-PABA dispersion was crosslinked with a hexamethylene diisocyanate (HDI) tripolymer to prepare waterborne polyurethane/epoxy resin composite coating. The rheological properties and particle size distribution of the composite system were characterized by rotary rheometer and laser particle size analyzer. The crosslinked composite product has good thermal resistant properties, with glass-transition temperatures (Tg) about 40% and 50% weight loss temperatures (Td) in the range of 400–420. The smooth and transparent film obtained from the composite product has good flexibility, adhesion, impact strength, antifouling and blocking resistance properties. The impact strength, pencil hardness, water-resistant and thermal-resistant properties of the composite products increased with the molar ratio of isocyanate group to active hydrogen of T-PABA.

Evaluation of the crosslinking reaction kinetics of cationic polyol dispersions with differential scanning calorimetry and dielectric analysis

The crosslinking reaction kinetics of two-component waterborne polyurethanes (2K-WPUs) composed of cationic polyol dispersions and hydrophilically modified hexamethylene diisocyanate (HDI) tripolymer were investigated by differential scanning calorimetry (DSC) and dielectric analysis (DEA) techniques. DSC data fit for the 2K-WPUs was carried out with Málek's mechanism function method. The kinetic parameters and kinetic models of crosslinking reaction were determined by the kinetic analysis with Málek's method. The result showed that the crosslinking process of the reaction followed an autocatalytic reaction. Sestak–Berggren model (S–B model) could favorably describe the crosslinking reaction process of the studied 2K-WPUs. The reaction rate curves derived from the experimental data showed a good agreement with the theoretical calculation under 5–20°Cmin−1 heating rate. Isothermal DSC and DEA of the crosslinking process of the 2K-WPUs were used to confirm the obtained kinetics equations. The conversion–time curves from isothermal DSC matched favorably with the calculated curves from the obtained kinetic equations, and the log ion viscosity–time curves from isothermal DEA matched roughly with the conversion–time curves from DSC.

Modification with tertiary amine catalysts improves vermiculite dispersion in polyurethane via in situ intercalative polymerization

In situ intercalative polymerization is an environmentally-friendly process to produce polymer-clay nanocomposites with good clay dispersion. In this work, quaternary ammonium salts with tertiary amine groups were synthesized to modify clay as catalytically active modifiers for polyurethanes. Polyol dispersions with the catalyst-modified vermiculites were prepared by ultrasonication and examined by X-ray scattering and rheology. In the polyurethane elastomers synthesized from the above dispersions in a solvent-free process, X-ray scattering showed that the clay was highly intercalated/exfoliated without noticeable peaks for d < 9 nm, and TEM images revealed that the local dispersion of clay sheets was affected by the structure of the modifier. Addition of the modified clay to the polyurethane elastomers had only a small effect on the phase separation between hard and soft segments as deduced from DSC, FT-IR and DMA results. Thermo-mechanical and barrier properties of the composites were evaluated, and with one modifier, the nanocomposites showed a 390% increase in tensile modulus at 25 °C and a 40% reduction in CO2 permeability at a loading of 5.3 wt% of catalyst-modified clay.

Crosslinking reaction and properties of two‐component waterborne polyurethane from terpene‐maleic ester type epoxy resin

AbstractA two‐component waterborne polyurethane (2K‐WPU) is prepared with the terpene‐maleic ester type epoxy resin‐based polyol dispersion and a hydrophilically modified hexamethylene diisocyanate tripolymer. Laser particle size analyzer and transmission electron microscopy are used to characterize the particle size distribution and the micromorphology of the 2K‐WPU. Crosslinking reaction kinetics of the 2K‐WPU is examined by fourier transform infrared spectrometry (FTIR) spectra. In the preliminary stage of the crosslinking reaction, it shows a very good fit with a second order reaction kinetics, and the apparent activation energy is 94.61 kJ mol−1. It is also shown from the FTIR spectra that the complete crosslinking reaction of the 2K‐WPU needs 7 h at 70°C. The crosslinked products of the 2K‐WPU have good thermal resistant properties, with glass‐transition temperatures (Tg) in the range of 35–40°C and 10% weight loss temperatures (Td) in the range of 275–287°C. The films obtained from the crosslinked products have good water‐resistance, antifouling, blocking resistance properties and impact strength of &gt;50 cm, flexibility of 0.5 mm, adhesion of 1 grade, pencil hardness of HB‐2H. The pencil hardness and thermal‐resistant properties of the crosslinked products increase with the molar ratio of isocyanate (NCO) group to hydroxyl (OH) group. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of isocyanate to hydroxyl index on the properties of clear polyurethane films

Clear polyurethane films were made from aqueous polyurethane pre-polymer dispersions and water-dispersible aliphatic isocyanate pre-polymer, varying the amount of isocyanate used to cure the films. Film series were made from one of two polyol dispersions; the control XP-7110 having a higher molecular weight and containing 10wt.% n-methylpyrrolidone (nmp) was compared to a zero-volatile organic compound (VOC) lower molecular weight alternate polyol XP-2591. Increasing the relative number of isocyanate groups to hydroxyl groups in these films provided an increase in glass transition temperature (Tg), tensile strength, elastic modulus and improved barrier properties to dimethyl methylphosphonate (DMMP) for both polyols in this study. At all indices in this study XP-7110 films achieved slightly higher Tg and slightly better resistance to permeation by DMMP than the XP-2591 films. Water resistance of the films was not improved at higher indices nor was there any difference between the polyols. Yet, the experimental results suggest that it is possible to produce polyurethane binders with acceptable film properties while reducing the VOC content of the formulation by using t-butyl acetate as the isocyanate reducing solvent. The zero-VOC polyol achieved better tensile properties with higher indexing than the current polyol containing 10wt.% VOC. While the zero-VOC polyol did not perform as well as the baseline polyol in some tests, the differences in performance were small and thus there may be an opportunity to use the zero-VOC polyol as a partial or even a complete replacement of the current material.

Kinetics of the crosslinking reaction of nonionic polyol dispersion from terpene-maleic ester-type epoxy resin

The bulk crosslinking reaction kinetics of a novel two-component waterborne polyurethanes (2K-WPUs) composed of a bio-resin-based polyol dispersion and a hydrophilically modified hexamethylene diisocyanate tripolymer are investigated by freeze–drying and differential scanning calorimetry (DSC) technique at different heating rates. The data fit for the above two components is implemented with the nth-order kinetics equation and Malek’s mechanism function method, respectively. The kinetic parameters of crosslinking reaction are determined by the kinetic analysis of the data obtained from the thermal treatment, and then the kinetic model is built. The results indicate that the nth-order model deduced from Kissinger and Crane equation has great distinction with the experimental data, while the Malek analytic mechanism shows that the crosslinking process of the crosslinking reaction follows an autocatalytic reaction. The two-parameter (m and n) autocatalytic model (S–B model) can well describe the crosslinking reaction process of the studied 2K-WPU. The DSC curves derived from the experimental data show a good agreement with the theoretical calculation under 5–20 °C min−1 heating rate. The results provide theoretical basis for the choice of the manufacturing process and the optimization of processing window.

Synthesis and Properties of Vermiculite-Reinforced Polyurethane Nanocomposites

Natural vermiculite was modified by cation exchange with long-chain quaternary alkylammonium salts and then dispersed in polyether-based polyols with different structures and ethylene oxide/propylene oxide ratios. The dispersions were evaluated by X-ray scattering and rheology. In all polyol dispersions tested, polyols were intercalated into the vermiculite interlayers. Also, significant shear thinning behavior was observed. A large interlayer spacing of ∼90 Å was achieved in one polyol suitable for polyurethane elastomer synthesis. In polyurethane made with this polyol, clay platelets were extensively intercalated or exfoliated. The composites showed a >270% increase in tensile modulus, >60% increase in tensile strength, and a 30% reduction in N(2) permeability with a loading of 5.3 wt % clay in polyurethane. Differential scanning calorimetry and dynamic mechanical analysis revealed that the nanoclay interacts with the polyurethane hard segments.

Synthesis of gold nanoparticles in hyperbranched polyol dispersions

AbstractIn this study, a series of different generation hyperbranched poly(amine‐ester) with hydroxyl as terminal group were synthesized and used as protectants to synthesize gold nanoparticles with a facile and highly reproducible method. The effect of hyperbranched poly(amine‐ester) generation on size and their distribution of gold nanopartciels were discussed. The results of ultraviolet visible absorption spectroscopy, Transmission electron microscopy and scanning electron microscopy showed that the mean diameter were 24.3 ± 2.6 nm, 18.2 ± 2.1 nm, and 13.6 ± 1.5 nm corresponding to the different generation hyperbranched poly(amine‐ester), and the synthesized gold nanoparticles were almost monodisperse with a narrow size distribution. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation and properties of nonionic polyol dispersion from terpinene‐maleic ester‐type epoxy resin

AbstractA nonionic epoxy‐based polyol (NTP) which can be used in place of the commonly used polyol dispersions to prepare two‐component waterborne polyurethanes was synthesized with terpinene‐maleic ester‐type epoxy resin (TME), polyethylene glycol (PEG), and trimethylopropane (TMP) in the presence of sulfuric acid as catalyst. The synthesis process was tracked with gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) by investigating the changes of molecular weight and glass transition temperature (Tg) of the product. FTIR was used to characterize the chemical structure of NTP. Major technical parameters of NTP were as follows: hydroxyl value 100 mg/g, hydroxyl group content 3.04%, Tg 4.03°C, and viscosity 150 mPa s (40% solid content). Effect of molecular weights and dosages of PEG on stability of NTP dispersion was examined by particle size analyses. It was found that stable dispersion was obtained when using PEG6000 as hydrophilic chain and its dosage ≥8% by the weight of TME. The average particle size of the prepared dispersion was about 200 nm from particles size and TEM analyses. The NTP dispersion showed characteristic of shear thinning, which indicated it was a pseudoplastic fluid. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

2.1 VOC solvent borne 2K clear coats based on star oligoethers

The European product directive 2004/42/CE on 2K (2-component) car repair coatings forces the customers to use 3.5 lbs/gal volatile organic compounds (VOC) products for topcoats and clear coats as of 2007. There will be a new discussion on solvent emission levels as of 2008 in view of actual technologies available and the EC commission may come up with more stringent proposals. The main binders used in 3.5 VOC 2-pack refinish topcoats and clear coats are acrylic polyols sometimes combined with polyester based diluents which are cross-linked with 1,6-hexamethylene diisocyanate trimer (HDI-trimer). This technology will not allow formulating substantial lower VOC products (e.g. 2.1 lbs/gal) at an acceptable overall balance of potlife, overall drying, appearance and durability. It is believed today that those emission levels and product performance can only be reached: - In solvent borne systems with oligomers if reactive functional groups, like hydroxyl or amine, are blocked. The blocking of the functional groups result in sufficient long potlife and unblocking takes place upon hydrolysis during film formation. - In water borne systems with standard polyol dispersions and emulsions. Both solutions will have limitations as far as paint application conditions because of the dependence of either the hydrolysis reaction (in solvent borne) or the evaporation of water (in water borne) on air humidity. Other issues related to water borne are the reactivity of the polyisocyanate with water causing foaming and film defects remain unsolved. Technologies depending on a fast hydrolysis reaction with water will probably also be limited to unpigmented formulations. It would therefore be an advantage if a standard hydroxyl–isocyanate binder system could be developed that can be used in low VOC pigmented and unpigmented 2K formulations. In this paper we will discuss hydroxyl functional, branched polyethers that allow formulating regular 2K clear and top coats at 2.1 lbs/gal VOC with an acceptable overall balance of potlife, appearance, durability and productivity impossible or difficult to obtain with acrylic or polyester polyols. The structure of the polyether oligomer has to be branched (at least four functional) to get the overall property balance. The polyether oligomers are prepared by ring-opening polyetherification giving narrow functionality and molecular weight distributions and a favorable solids/viscosity relation. The ratio of mono epoxyester to polyol and type of polyol will determine functionality, molecular weight ( M w) and hydroxyl number (OH#) of the polyether oligomer. The paper will comment on relation solids/viscosity with glass transition temperature ( T g), functionality ( F) and M w, all-important factors to get the property balance. We will show how final clear coat properties correlate with some initial oligomer/cross-linker properties in view of M w, T g and F of oligomer and type of polyisocyanate hardener.

Preparation and properties of microcapsule with EVA core‐PU shell structure

AbstractMicrocapsule with poly(ethylene‐co‐vinylacetate) (EVA) core‐polyurethane (PU) shell structure was synthesized by interfacial polymerization in aqueous polyol dispersion with ethylene diamine as the chain extender of toluene diisocyanate in poly(vinyl alcohol) aqueous solution as the stabilizing agent. The effects of polyol constituent on the average particle size and distributions, morphologies, color strength, and friction fastness of core‐shell particles were investigated to design microcapsule. The friction fastness of printed fabrics with EVA core‐PU shell microcapsules became the increase to 4–5 grades. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 893–902, 2007

Stabilization and growth of silver nanocrystals in dendritic polyol dispersions

The chemical and physical properties of metal nanoparticles are governed critically by their size, shape, and morphology. In this work, we present results of the growth of silver nanocrystals in a dispersion medium that allows nanocrystallization comparable to conventional crystal growth from saturated solutions. Dendritic polyol dispersions in an ethanol/water mixture are shown to be dynamic, nanoscopic templates for the growth of silver nanoparticles. Nanocrystals with well-defined shapes in the size range of 10–600 nm are grown using this method.

Preparation and characterization of polyurethane-carbon nanotube composites.

Well-dispersed and long-term stable carbon nanotubes/polyol dispersions were prepared by a mechanochemical approach with the aid of dispersing agent. Polyurethane (PU)-carbon nanotube nanocomposites were prepared by further polymerization. Multi-walled carbon nanotubes (MWNT) can be dispersed individually. Fourier transform infrared (FTIR) spectra suggested that the addition of carbon nanotubes improved the degree of phase separation of polyurethane. Dynamic mechanical analysis (DMA) suggested that glass transition temperature () of polyurethane decreased with increasing carbon nanotube content slightly. Tensile test suggested that MWNT is more helpful to improve the modulus than single-walled carbon nanotube (SWNT), which is more favourable to improve the elongation of polyurethane. The different reinforcing effects of MWNT and SWNT on PU were correlated to the shearing thinning exponent and the shape factor of carbon nanotubes in polyol dispersion. Raman shift of SWNTs can reflect the dispersion state of SWNT in polyol or in PU, and the interaction between polymer and SWNT. Both SWNT and MWNT can improve the thermal stability of polyurethane and thermal conductivity.