Preparation and properties of urethane/acrylate composite by emulsion polymerization technique

Aqueous polyurethane–acrylic hybrid emulsions were prepared by semibatch emulsion polymerization of a mixture of acrylic monomers (styrene, butyl acrylate and acrylic acid) in the presence of polyurethane dispersion. Equivalent physical blends were prepared by mixing acrylic emulsion and polyurethane dispersion. The weight ratio between acrylic and polyurethane components was varied to obtain enhanced performance properties and microphase structure of hybrid latexes. The synthesized emulsion hybrids and physical blends were characterized by fourier transform infrared spectroscopy, thermogravimetric analysis. The experimental results indicate better acrylic–polyurethane compatibility in hybrid emulsions than in physical blends, resulting in improved chemical and mechanical properties. The blend ratio 50:50% (w/w) exhibited synergistic effects between the two polymers and revealed remarkable improvement in various coating properties over other blend ratios and the individual resin components.     

Comparison of properties of acrylic–polyurethane hybrid emulsions prepared by batch and semibatch processes with monomer emulsion feed

Aqueous acrylic–polyurethane hybrid emulsions were prepared by batch and semibatch polymerization of acrylic monomer mixtures (butyl acrylate, methyl methacrylate and acrylic acid) in the presence of polyurethane dispersion. The acrylic component was introduced in the monomer emulsion feed. The weight ratio between acrylic and polyurethane components was varied to obtain different emulsion properties, microphase structure and mechanical film properties. Scanning electron microscopy, average particle size and molecular weight measurements were performed to characterize the latex systems. Mechanical properties were examined by measuring Koenig hardnesses of dried films. The average particle size increased with the acrylic/polyurethane ratio. Particles of larger than average size and, to some extent, higher than average molecular weights by batch process were formed. Koenig hardnesses decreased with increasing acrylic/polyurethane ratio. Properties of emulsions synthesized by semibatch processes were compared with the results reported for a different polyurethane dispersion. Copyright © 2003 Society of Chemical Industry     

Waterborne polyurethane/acrylate: Comparison of hybrid and blend systems

Polyurethane/acrylate hybrid composites in a broad range of composition (10, 30, 50, 70 and 90 wt.% of acrylic content), were obtained by emulsion polymerization of acrylic monomers (methyl methacrylate/n-butyl acrylate/acrylic acid mixture) in the presence of preformed polyurethane chains with polymerizable terminal vinyl groups. Blends with the same acrylic content were also prepared by mixing polyurethane and acrylic dispersions. Samples were characterized by SEC, DLS, FTIR, UV, TEM, AFM, SAXS/WAXS and gel fraction content. Mechanical properties, Buccholz and pencil hardness, surface roughness and water contact angle of films were also determined. The effect of the acrylic content on morphology and film properties was also evaluated. Hybrids are crosslinked systems showing changes in the particle and film morphologies with increasing acrylic content. The properties of hybrid films show a non-linear behavior with the increase of the acrylic component, while physical blends exhibit a gradual behavior from PU to AC. FTIR results indicate better acrylic-polyurethane compatibility in hybrid systems than in physical blends. Hybrid composites with up to 70 wt.% of acrylic component are homogeneous by SAXS. On the other hand, AFM results show that blends are phase segregated systems at all composition levels.     

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

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

Preparation and properties of emulsifier‐/solvent‐free polyurethane‐acrylic hybrid emulsions for binder materials: Effect of the glycidyl methacrylate/acrylonitrile content

To obtain binder materials, emulsions of emulsifier‐/solvent‐free waterborne polyurethane‐acrylic hybrids with a fixed acrylic monomer content (30 wt %) were prepared in this study. This study focused on the effect of glycidyl methacrylate (GMA)/acrylonitrile (AN) wt % on the shelf stability, mean particle size and viscosity of hybrid emulsion samples, water swelling %/dynamic mechanical thermal properties/mechanical properties of hybrid film samples, and the failure mode and adhesive strength of binder materials prepared in this study. Characterization of the chemical structures of prepolymers, hybrid materials (binder materials), and atmospheric pressure plasma‐treated polyethylene (PE) has been performed by means of Fourier transformed infrared spectroscopy to determine the presence/disappearance/peak intensity change of functional groups. Various properties such as mean particle size, viscosity, T_g, water swelling %, hardness and mechanical properties, and failure mode and adhesive strength for leather/leather, control PE/leather, and plasma‐treated PE/leather were found to be significantly dependent on the weight ratio of GMA/AN. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44497.     

聚氨酯-丙烯酸酯复合乳液的合成及力学性能

采用三乙胺水溶液中和乳化法制备了用己二酸二酰肼封端的PU水分散体,并以此为种子,加入甲基丙烯酸甲酯、丙烯酸丁酯和双丙酮丙烯酰胺用双引发剂进行乳液聚合得到复合乳液。动态力学测试结果表明该复合乳液材料为相分离体系,组分有一定的相容性并依赖于组成比。拉伸实验结果表明随硬组分甲基丙烯酸甲酯含量的增加,抗拉强度增加,材料由橡胶向脆性塑性转变;复合乳液比乳液混合物有较高的强度和伸长率。     

Water‐based crosslinkable coatings via miniemulsion polymerization of acrylic monomers in the presence of unsaturated polyester resin

Hybrid miniemulsion polymerization was performed with a three‐component acrylic system of methyl methacrylate, butyl acrylate, and acrylic acid in the presence of a Bayer® Roskydal TPLS2190 unsaturated polyester resin. Latexes were obtained in which the polyester resin was grafted to the acrylic polymer, forming a water‐based crosslinkable coating. Grafting between the resinous component and the acrylic polymer is a feature different from the work of others who have attempted to combine the properties of both systems in water‐based blends. Both emulsions and latexes were shelf‐stable for over 6 months, shear‐stable, and resistant to at least one freeze/thaw cycle. Resin‐to‐monomer ratios were studied as high as 1 : 1 (wt : wt), and total emulsion solids, as high as 45%. Monomer droplet and latex particle sizes were similar, suggesting evidence of the preponderance of droplet nucleation. A high level of crosslinking (>70%) during polymerization was observed in this particular hybrid system in contrast to those involving alkyd or polyurethane resins (<5%). Films, both homogeneous and hard, were achieved with exceptional adhesion. Electron microscopy showed the hybrid particle morphology to have internal domains of polyester resin in an acrylic matrix. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 916–927, 2000     

Preparation,properties, and applications of acrylic–polyurethane hybrid emulsions in extinction electrophoresis

Aqueous acrylic–polyurethane hybrid emulsions (PUA) were fabricated by semibatch emulsion copolymerization using a mixture of acrylic (AC) monomers in the presence of an isocyanate terminated polyurethane (PU). The effects of PU content on the morphology of the hybrid emulsions and film properties were here investigated in detail using FT‐IR, UV, TEM, and SEM. TEM images clearly showed that hybrid emulsions exhibited a core‐shell structure before neutralization. However, after neutralization with N,N‐dimethylethanolamine, the typical particles exhibited phase inversion, producing particles with irregular hemispheres shapes and diameters about 0.5 μm. SEM images showed that the film surface became rougher as PU content increased, peaking at 10 wt %, the gloss of this film was 23.1 (60°). The UV transmittance spectra of the PUA hybrid emulsion within a wavelength range 700–200 nm decreased as PU content increased. This was consistent with the changes in the surface roughness of the film. Electrophoresis took place on an aluminum alloy surface and the product was dried at 120°C. The film exhibited excellent mechanical performance due to curing reaction between the N?C?O group on PU and hydroxyl group on the AC copolymer. The gloss of the film was found to be as low as 4.0 after electrophoresis testing. These films may be useful in practical extinction electrophoresis. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40078.     

Polyurethane‐acrylic hybrid emulsions with high acrylic/polyurethane ratios: Synthesis,characterization, and properties

Allyl polyoxyethylene ether (APEE) was used as coupling agent between polyurethane (PU) and acrylic polymer (AC) to synthesize stable waterborne polyurethane‐acrylic (PU‐AC) hybrid emulsions with high AC/PU weight ratio ranged from 45/55 to 70/30. The effect of the AC/PU weight ratio and the acrylate type including methyl methacrylate (MMA), butyl acrylate (BA) and mixture of them on the properties of the synthesized emulsions and resultant films were investigated. The research results showed that the colloidal particle of the emulsions behaved core‐shell structure, and the copolymers were not crosslinked. An increase in the AC/PU weight ratio led to an increase in the average particles size and the particle size distribution, but decrease in the viscosity of the emulsions. Meanwhile, the molecular weight distribution of the copolymers became wide, and the tensile stress, shore A hardness, storage modulus, glass transfer temperature, water resistance, and water contact angle of the resultant films increased, except that the films of PU‐BA were too soft to determine their mechanical properties. MMA and BA can provide the PU‐AC hybrid emulsions with very different properties, and which can be adjusted according to the special application. It was suggested that APEE can not only built up chemical bonds between PU and AC, but also increase the self‐emulsifying ability in the emulsion polymerization due to its hydrophilic ethylene oxide and carboxylic groups, resulting in that PU‐AC hybrid emulsions with high AC/PU ratio can be obtained by this method. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44488.     

Effect of nanosilica content on properties of polyurethane/silica hybrid emulsion and its films

Polyurethane/silica hybrid emulsion (PUSi) was synthesized by the reaction of isophorone isocyanate, polyether polyol, hydrophilic nanosilica (A200), dimethylol propionic acid, trimethylol propane, and 3‐aminopropyltriethoxysilane (KH550). The films of the waterborne polyurethane (WPU) were prepared. The structure of the polyurethane was characterized by Fourier transform infrared spectrometer (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). The particle size distribution and morphology of emulsion were examined. Influence of nanosilica content on the mechanical properties and solvent absorption of the cast films were also measured quantificationally. FTIR indicates that  NH₂ of KH550 reacted with  NCO of polyurethane. TG analysis indicates that nanosilica can improve thermal stability of polyurethane. There is no clear effect of nanosilica on the glass transition of soft segments. It was found that greater mechanical properties of WPU were obtained when chemical networks were formed by sol‐gel process. As the nanosilica content increases, water absorption and ethanol absorption decreased. The particle size increases with increase of A200 content. PUSi hybrid emulsions are endowed with pseudoplasticity. The apparent viscosity of emulsions increased and then decreased with addition of A200. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

聚氨酯-丙烯酸酯复合乳液的合成与性能

采用甲基丙烯酸甲酯(MMA)与水性聚氨酯乳液共聚反应制备聚氨酯-丙烯酸酯(PUA)复合乳液,研究了MMA添加量、引发剂种类和聚合温度对PUA复合乳液及涂膜性能的影响,确定了PUA复合乳液合成的工艺参数。用傅立叶红外光谱(FTIR)测定反应产物的结构。研究发现油溶性引发剂比水溶性引发剂更适合PUA体系的乳液聚合。随着MMA添加量的增大,PUA复合乳液胶粒粒径增大,黏度减小,涂膜光泽度下降,机械性能增强,耐水性增加。     

Waterborne oil‐modified polyurethane coatings via hybrid miniemulsion polymerization

As part of a wider effort to develop a new class of waterborne coatings, hybrid miniemulsion polymerization was carried out with acrylic monomers (methyl methacrylate, butyl acrylate, and acrylic acid) in the presence of oil‐modified polyurethane resin. Latexes with different ratios of resin to acrylic monomers were synthesized. The monomer emulsions prepared for hybrid miniemulsion polymerization showed excellent shelf‐life stability (>5 months) and the polymerization was run free of coagulation. Solvent extraction indicated that the grafting efficiency of polyacrylics was greater than 29% for all the samples produced. A ¹³C solution NMR spectrum showed that a substantial fraction of the original carbon double bonds (>61%) in oil‐modified polyurethane remained after polymerization for film curing. Films obtained from the latexes presented good adhesion properties and fair hardness properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 105–114, 2000     

Preparation and properties of poly(siloxane‐ether‐urethane)‐acrylic hybrid emulsions

Poly(siloxane‐ether‐urethane)‐acrylic (PU‐AC) hybrid emulsions were prepared by introducing different hydroxyethoxypropyl‐terminated polydimethylsiloxane (PDMS) content into the acrylic‐terminated poly(ether‐urethane) backbone and then in situ copolymerizing with methyl methacrylate and butyl acrylate via emulsion process. The effects of PDMS on the particle size and viscoelastic behavior of the hybrid emulsions were investigated. Meanwhile, the hydrogen bonding, mechanical and thermal mechanical properties, water resistance, the surface gloss, and wettability of the resultant hybrid films were also studied. The results showed that all the hybrid emulsions showed shear‐thinning behaviors, and the introduction of PDMS resulted in the formation of the hybrid emulsions with increased average particle size and decreased viscosity. The chemical bonds built between PU and AC yielded higher than 73% crosslinking fraction in all the hybrid materials, but this value decreased with increasing PDMS content because PDMS reduced the hydrogen bonding interactions and enhanced the phase separation. As a result, an increase in the PDMS content led to an increase in the elongation, water resistance, surface roughness, and water hydrophobic of the films, but the tensile strength, hardness, storage modulus, and glass transitions temperature decreased. It is suggested that introduction of PDMS can provide the hybrid materials with the improved flexibility, water resistance, and surface hydrophobicity, which has potential application value in the fouling‐release coatings, biomaterials, and surface fishing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44927.     

Synthesis and properties of grafted latices from a soybean oil‐based waterborne polyurethane and acrylics

A novel soybean oil‐based vinyl‐containing waterborne polyurethane (VPU) dispersion has been successfully synthesized from toluene 2,4‐diisocyanate, dimethylol propionic acid and a 90 : 10 mixture of chlorinated soybean oil‐based polyol and acrylated epoxidized soybean oil (AESO). Then, a series of VPU/acrylic grafted latices have been prepared by emulsion graft copolymerization of acrylic monomers (40 wt % butyl acrylate and 60 wt % methyl methacrylate) in the presence of the VPU dispersion, using potassium persulfate as an initiator. The structure, morphology, and thermal and mechanical properties of the resulting latices, containing 15–60 wt % soybean oil‐based polyols as a renewable resource, have been investigated by Fourier transform infrared spectroscopy, solid state ¹³C NMR spectroscopy, transmission electron microscopy, thermogravimetric analysis, dynamic mechanical analysis, and mechanical testing. The results indicate that graft copolymerization of the acrylic monomers onto the VPU network occurs during emulsion polymerization, leading to a significant increase in the thermal stability and mechanical properties of the resulting miscible grafted latices. This work provides new environmentally‐friendly latices from a renewable resource with high performance for coating applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

水性聚氨酯的改性研究

分别采用丙烯酸酯、环氧树脂合成2种不同的改性水性聚氨酯,比较了改性前后及2种不同的改性水性聚氨酯在乳液、涂膜性能及粘接性能方面的差异。结果表明,改性后的水性聚氨酯综合性能明显提高,其中环氧树脂改性水性聚氨酯(EPU)在固化交联后涂膜的耐水、耐溶剂及力学性能又明显好于丙烯酸酯改性水性聚氨酯(PUA),其粘接强度与溶剂型聚氨酯相当;而采用丙烯酸酯改性的水性聚氨酯PUA乳液稳定性好于EPU乳液。     

Urethane/acrylic composite polymer emulsions

Blends of waterborne urethane and acrylic polymer systems were studied to obtain a composite emulsion that would have all of the advantages of the two polymers without their associated disadvantages. An approach to achieve extensive polymer-polymer interactions through crosslinking reactions was studied to optimize the positive aspects of each polymer. The crosslink system used an acrylic polymer emulsion containing keto or aldo groups and a polyurethane dispersion incorporating a hydrazine group. The degree of crosslinking was determined by FT-IR Single package, ambient temperature crosslinking emulsions were obtained by using this system. In addition to the excellent properties these two polymers normally possess, the crosslinked blends exhibit synergistic effects in film properties, such as good solvent resistance and low heat sensitivity over a wide range. Composite polymers of this type could be useful in applications where high durability is required: tennis court coatings, floor coatings, laminating adhesives. and paper and textile finishes.     

Performance properties of acrylic and acrylic polyol–polyurethane based hybrid system via addition of nano‐caco3 and nanoclay

Thermosetting acrylic (TSA) resin was prepared by solution polymerisation of acrylic acid and methyl methacrylate (MMA). Hybrid polymer consisting of acrylic polyol–polyurethane was prepared by addition of hydroxy ethyl acrylate and hexamethylene diisocyanate (HMDI). Incorporation of Functionalised nanocalcium carbonate and bentonite nanoclay were accomplished by in situ method during the synthesis of both the polymers. Loading of nano‐CaCO₃ and nanoclay was varied from 0 to 4 wt.% to investigate variation in mechanical, optical and high performance properties. The superiority of nanoclay in enhancing the mechanical and performance properties like the salt spray and humidity resistance in comparison to that of nano‐CaCO₃ was clearly established. It was also observed that, addition of nanomaterials in hybrid resins system shows superior results compared to neat acrylic system and in situ additions of these nanomaterials improve the dispersion and stability in the matrix.     

Synthesis and characterization of crosslinking waterborne fluorinated polyurethane‐acrylate with core‐shell structure

Crosslinking core‐shell emulsions of waterborne fluorinated polyurethane‐acrylate (WFPUA) were successfully synthesized using a solvent‐free method. The crosslinkers of diacetone acrylamide and adipic dihydrazide were introduced into the WFPUA emulsions. The physical properties of hybrid emulsions such as the average particle size, stability, and viscosity were characterized. The core‐shell of crosslinking WFPUA emulsion synthesized in this study was observed by transmission electron microscopy. Then, the results of Fourier transform infrared spectroscopy, atomic force microscopy, and X‐ray photoelectron spectroscopy indicated that the fluorinated monomer (FA) had been polymerized into the crosslinking waterborne polyurethane‐acrylate polymer, and the fluorinated groups have evident enrichment on the film‐air surface with the increase of FA content. At the same time, the thermal properties, water repellent/antifouling properties, and mechanical properties were measured. Moreover, the thermal properties and the elongation are raised but tensile stress and shore hardness are decreased with the increase of FA content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40970.     

Preparation and properties of emulsifier/N‐methylpyrrolidone‐free crosslinkable waterborne polyurethane–acrylate emulsions for footwear adhesives. I. Effect of the acrylic monomer content

Stable emulsions of emulsifier/N‐methylpyrrolidone‐free crosslinkable waterborne polyurethane–acrylates (C‐WBPUAs) with various acrylic monomer contents (0, 10, 20, and 30 wt %) for footwear adhesive materials were successfully prepared in this study. The effects of the acrylic monomer content on the shelf stability, mean particle size, and viscosity of the C‐WBPUA emulsions; the tensile properties and dynamic mechanical thermal properties of the C‐WBPUA film samples; and the adhesive strengths between the upper (synthetic leather) and the sole (ethylene vinyl acetate rubber) in both the dry and wet states of the formulated adhesives (C‐WBPUA emulsion–thickener–hardener) were examined. The adhesive strengths of the formulated adhesives for footwear (leather–sole) in both the dry and wet states increased with increasing acrylic monomer content up to 20 wt %; after this, they almost levelled off. Thus, C‐WBPUA20 and C‐WBPUA30, where the number indicates the acrylic monomer content, can be recommended as high‐performance adhesive materials for footwear. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43758.     

Kinetic investigations of acrylic–polyurethane composite latex

The effect of various reaction parameters on the rate of polymerization, R_p, and on the particle size and morphology of aqueous acrylic–polyurethane hybrid dispersions, prepared by semibatch emulsion polymerization, was investigated. The particles of polyurethane dispersion were used as seeds during the polymerization of acrylic component: methyl methacrylate (MMA), butyl acrylate (BA), and a mixture of MMA and BA with the ratio of 1:1. These emulsions were found to form structured polymer particles in aqueous media using scanning electron microscopy. The kinetics of the emulsion polymerization was studied on the basis of Wessling's model. The influence of emulsifier and initiator concentrations, including the monomer feed rates, R_m, on the rates of polymerization and on the properties of the resulting dispersions were studied. The number of particles and the particle size were also measured during the polymerization process. The final values were found to be independent of the concentration of the emulsifier, initiator and the monomer feed rate in monomer starved conditions. In the steady‐state conditions, during the seeded semibatch hybrid emulsion polymerization, the rate of polymerization and the monomer feed rate followed the Wessling relationship 1/R_p = 1/K + 1/R_m. The dispersions MMA/PU, BA/PU, and MMA/BA/PU have K values of 0.0441, 0.0419 and 0.0436 mol/min, respectively. The seeded BA/PU hybrid polymerization proceeded according to Smith‐Ewart Case I kinetics, while the MMA/PU hybrid emulsions demonstrate Case II of the Smith‐Ewart kinetic model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2639–2649, 2002