Polyurethane-acrylate Emulsion Research Articles

Synthesis and properties of waterborne polyurethane acrylate emulsions with high bio‐based content

Synthesis and properties of waterborne polyurethane acrylate emulsions with high bio‐based content

A Novel Polyfunctional Polyurethane Acrylate Derived from Castor Oil-Based Polyols for Waterborne UV-Curable Coating Application.

Because of its unique molecular structure and renewable properties, vegetable oil has gradually become the focus of researchers. In this work, castor oil was first transformed into a castor oil-based triacrylate structure (MACOG) using two steps of chemical modification, then it was prepared into castor oil-based waterborne polyurethane acrylate emulsion, and finally, a series of coating materials were prepared under UV curing. The results showed that with the increase in MACOG content, the glass transition temperature of the sample was increased from 20.3 °C to 46.6 °C, and the water contact angle of its surface was increased from 73.85 °C to 90.57 °C. In addition, the thermal decomposition temperature, mechanical strength, and water resistance of the samples were also greatly improved. This study not only provides a new idea for the preparation of waterborne polyurethane coatings with excellent comprehensive properties but also expands the application of biomass material castor oil in the field of coating.

Waterborne polyurethane acrylate emulsion with dangling chain structure: Simultaneously showing wide damping temperature range and excellent hydrophobic performance

AbstractWaterborne polyurethane (WPU) damping material has been drawing much attention in academic field because of its low toxicity compared with polyurethane (PU) damping material. In order to expand the application range of WPU damping materials, it is necessary to further improve the hydrophobicity and damping properties of WPU. A novel dangling chain polyol‐n (DCP‐n, n expressed as average molecular weight of MPEG) was synthesized from methoxypolyethylene glycol (MPEG), isophorone diisocyanate (IPDI) and 1,1,1‐tris (hydroxymethyl) propane (TMP). Subsequently, a series of dangling chain‐n‐waterborne polyurethane acrylate (DC‐n‐WPUA, n expressed as average molecular weight of MPEG) emulsions were synthesized using DCP‐n as the chain extender. The increase of DCP‐n length will fill in free volume, hinder the entry of water molecules. Therefore, improve the hydrophobic performance. In addition, the increase of DCP‐n length will lead to more intermolecular friction, which can increase the dissipation of energy, and improves the damping performance of DC‐n‐WPUA. The test results show that the hydrophobicity of DC‐n‐WPUA film is improved, and the maximum static water contact angle can reach 110.6°. Dynamic mechanical analysis testing data showed that DC‐500‐WPUA has the best damping performance, and its effective damping temperature range was 77.9°C (−32.0 ~ 45.9°C). The carbamate group on DCP‐n will produce hydrogen bonds to restrict the movement of the chain segments, and the hydrogen bond breakage requires more energy. This ameliorates the thermal stability and mechanical properties of DC‐n‐WPUA. Thus, the initial modulus of DC‐n‐WPUA larger than the initial modulus of WPUA. Therefore, the DC‐n‐WPUA have the potential to be applied to hydrophobic damping coatings in the future.

Preparation and Properties of UV and Aziridine Dual–Cured Polyurethane Acrylate Emulsion

For the UV–curable waterborne polyurethane acrylate (WPUA) emulsion, the free carboxylic groups in the molecular chains introduced by hydrophilic monomers are the inherent disadvantage. We prepared UV and aziridine dual–cured WPUA (UV/AZ–WPUA) emulsion that the carboxylic groups can be crosslinked by the trifunctional aziridine crosslinking agent, trimethylolpropane tris(2-methyl-1-aziridinepropionate) (Sac–100). The effects of Sac–100 content on the gel fraction, tensile properties, hardness, wear resistance, water resistance, and surface morphology of the cured films and coatings were investigated. The results show that, with the increase of the Sac–100 content, the gel fraction, tensile strength, elongation at break, and toughness of the films increase first and then decrease and the wear weight loss and water absorption ratio gradually decrease; in addition, Sac–100 also has an effect on the surface roughness of the coatings. Through comprehensive evaluation, it is considered that the optimum Sac–100 content is 4 wt% in UV/AZ–WPUA system. With the optimum Sac–100 content, the gel fraction of the coating film is 89.78 wt%, the tensile strength is 34.58 MPa, the elongation at break is 343.64%, the toughness is 65.08 MJ/m3, the wear loss is 4.7 mg, and the equilibrious water–absorption ratio is 11.63 wt%. Compared with the UV–cured film without Sac–100, the tensile strength, toughness, and hardness of the dual–cured films increase by 155.4%, 129.3%, and 25.7%, respectively, and the water absorption ratio decreases by 27.1%.

Influence of the composition of macromolecular diols on the rheology and water absorption of polyurethane acrylate emulsions

AbstractWaterborne modified polyurethane (PU) dispersions with different macromolecular diols as soft segments were prepared by the self‐emulsifying method, and then compounded with the acrylate monomers, the polyurethaneacrylate composite emulsion (PUA) with the core‐shell structure was prepared by emulsifier free emulsion polymerization. The effects of the type and ratio of macromolecular diols in the soft segment on the particle size and distribution, rheological properties, adhesion, water absorption and thermal properties of the PUA emulsion were studied. The results showed that the particle size of PUA decreased, and the shear resistance and heat resistance of PUA were enhanced with the addition of polypropylene glycol. According to the water absorption rate of PUA emulsion, it was found that adding poly‐1,4‐butanediol adipate glycol and poly(caprolactone) diol with more hydrophobic groups could improve the water resistance of PUA dry film, and the minimum water absorption value was 0.68%.

Preparation and properties of UV-curable waterborne silicon-containing polyurethane acrylate emulsion

The non-toxic and environmental protection characteristics of water-based coating make it has a good development prospect, but its poor water resistance and stability have attracted widespread attention. A type silicon-containing polyurethane acrylate core-shell structure emulsion was prepared by using in-situ self-emulsification, and it was applied to fabric-based substrates to study the influence of the different distribution of groups on the surface of the coating on the interfacial properties of the fabric-based coating. The silicon-containing polyurethane acrylate was synthesized by grafting unsaturated double bond with silane coupling agent which was characterized by FTIR and 1H NMR. The stability of the emulsion was tested by dynamic light scattering technique. The distribution of latex particles and the core-shell structure were observed by transmission electron microscopy (TEM). After the introduction of vinylsiloxane, the particle size of polyurethane acrylate emulsion decreased from 180.3 nm to 111.7 nm, and the emulsion samples could be stored for 6 months stably. The surface properties and morphology of the cured polyurethane acrylate film samples were evaluated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The thermal stability of cured film was analyzed by thermogravimetry (TG). In addition, emulsion samples with different silicone contents were coated on different fabric-based substrates (cotton fiber, PET and PP), and the fabric based coatings were cured quickly by utilizing the characteristics of fast UV curing and low energy consumption. The low surface energy organosiloxane was easier to migrate to the surface of the material, which increased the surface tension of the fabric based coatings. The water contact angles of the coatings interface were greater than 100°, showed good hydrophobic performance. In addition, the emulsion was dipped into the fabric-based substrate and it was found that the content of polar groups (-COO−) on the surface of the fabric-based coatings gradually increases along with increase of the concentration of the emulsion and the number of dips, and the organosiloxane originally on the surface of the coating was coated on the inner layer, made the hydrophobic performance of the coating decreased and when the emulsion concentration increased to 0.5 g/mL or the dip coating reached 5 layers, the interfacial performance of the coating changed from hydrophobic to hydrophilic. And the fabric based coatings with adjustable interfacial properties were obtained.

Hydroxyl‐terminated polybutadiene based waterborne polyurethane acrylate emulsions: Synthesis, characterization, and damping property

AbstractA new kinds of waterborne polyurethane acrylate (WPUA) dispersions were synthesized based on isophorone diisocyanate (IPDI), hydroxyl‐terminated polybutadiene (HTPB), 1, 4‐butanediol (1, 4‐BDO), polytetramethylene ether glycol (PTMG), dimethylolpropionic acid (DMPA), 2‐ethylhexyl acrylate (EHA), and methyl methacrylate (MMA) as main raw materials. The influence of the HTPB content on the particle size, storage stability of the WPUA dispersions and the damping property of cured films were studied by using dynamic light scattering (DLS), dynamic mechanical analysis (DMA), respectively. It can be found the WPUA dispersions have a good stability and the damping temperature range of loss tangent (tan δ) >0.3 reaches a maximum (−26.6–79.14°C) when the content of HTPB is 20%. The HTPB based WPUA could be applied to damping material.

A reactive hydrophobically modified ethoxylated urethane (HEUR) associative polymer bearing benzophenone terminal groups: Synthesis, thickening and photo-initiating reactivity

Hydrophobically modified ethoxylated urethanes (HEURs), as a representative class of associative polymers, are widely used as rheology modifiers in waterborne systems such as coatings, emulsions, inks etc. due to their unique associative network structure and finite relaxation behavior in solution. However, conventional HEURs are non-reactive and generally stay free in final cured films, which may induce some damages to the performance of the coatings. To solve the problem, a new concept of reactive HEUR has been proposed. That is, a reactive HEUR should bear reactive hydrophobic end-groups which can chemically crosslink with matrix resins during the curing process of waterborne coatings. In this work, with the help of the hydrogen abstraction photo-initiating reactivity of benzophenone (BP) group, a reactive HEUR (BPC11HEUR) end-functionalized by a photo-initiator BP moiety has been prepared. In aqueous solution, as demonstrated by steady shear measurement, an exponential increment of solution viscosity along with the increasing of polymer concentration (C) was found when C surpassed its critical percolation concentration (Cp ≈ 23.6 g/L). Besides, ultraviolet (UV) light induced photolysis in aqueous solution manifested a typical photochemical reaction behavior of BPC11HEUR polymer with a final photolysis degree (D) of approximate 78% after 300 s of irradiation. In situ 1H NMR and rheological measurements collectively revealed the efficient photo-initiating reactivity of BPC11HEUR for waterborne UV monomers or resins. Further, rheological measurements demonstrated that the emulsion zero/low shear viscosity can be greatly enhanced by ca. 50 folds for a commercially available waterborne UV polyurethane acrylate emulsion when the addition amount of BPC11HEUR varied from 0 to 1.0 wt%. These results shown that the reactive BPC11HEUR polymer can not only be used to efficiently modify the rheological properties of solutions or emulsions but also can chemically crosslink with waterborne UV acrylic monomers or resins by light irradiation. The work may be of interest for development of reactive HEURs used in waterborne UV coatings, inks, and adhesives, etc.

Castor oil-based waterborne hyperbranched polyurethane acrylate emulsion for UV-curable coatings with excellent chemical resistance and high hardness

Synthesis, characterization, and coating performance of castor oil (CO)-based waterborne hyperbranched polyurethane acrylate (WHPUA) emulsions are highlighted in this work. Herein, a second-generation CO-based hyperbranched polyester (C20) was synthesized by introducing the renewable CO as a B3 core and dimethylolpropionic acid as an AB2 monomer via a pseudo-one-pot condensation procedure. Three types of CO-based WHPUA emulsions were prepared through the addition of the hyperbranched C20 with maleic anhydride (MA) and the isocyanate-bearing semiadduct (IPDI-HEA) at different MA/IPDI-IH molar ratios without the addition of any emulsifiers. The prepared emulsions were further formulated into UV-curable coating formulations and exposed to a medium-pressure mercury lamp. Consequently, the obtained UV-cured coatings exhibited outstanding adhesion performance, excellent transparency, and an acceptable degree of final double bond conversion. Owing to a relatively low concentration of hydrophilic units and a large number of acrylate functionalities in the waterborne oligomer, the obtained films were endowed with high crosslinking density and low hydrophilic nature, thus producing enhanced tensile strength, pencil hardness, water resistance, and chemical resistance. Due to their combination of renewable materials, a waterborne system and a UV-curing technique, these CO-based WHPUA emulsions offer promising opportunities to be used as environmentally friendly coatings.

Preparation and Properties of High Solid Content and Low Viscosity Waterborne Polyurethane-Acrylate Emulsion with a Reactive Emulsifier.

High solid content waterborne polyurethane-acrylate (WPUA) emulsions have been successfully synthesized in two steps. Firstly, we prepared a waterborne polyurethane emulsion, then reacted it with acrylate monomer by emulsion polymerization using the semi-continuous seeded method. The effects of the type and amount of emulsifier, the amount of dimethylolpropionic acid (DMPA), the choice of capping group, the ratio of PU/PA, and the method of adding a water-soluble monomer to the properties of the composite emulsion were investigated. The reactive emulsifier replaced the traditional emulsifier and there were no metal ions introduced to the reaction, whether by the emulsifier or the initiator. Through a variety of tests, we proved that the prepared emulsion has the advantages of small particle size, narrow distribution, good stability, good performance of the film, and solid content of 46%.

Preparation and properties of UV‐curable waterborne polyurethane–acrylate emulsion

ABSTRACTPolyurethane–acrylate oligomer terminated with multiple unsaturated bonds was prepared using isophorone diisocyanate, (IPDI), methylene diphenyl diisocyanate, and polyols as monomers, using 2,2‐dimethylol propionic acid as hydrophilic chain extender, together with pentaerythritol triacrylate (PETA) as end‐capper. The UV‐curable waterborne polyurethane–acrylate (UV‐WPUA) composite emulsion was obtained by mixing the PUA oligomer with certain content of reactive diluents and then dispersing the mixture in water. The molecular structure of the polyurethane prepolymer, PUA oligomer, and UV‐cured polymer was investigated by Fourier transform infrared spectroscopy. The influence of the composition and content of the diluents and end‐capper on UV‐WPUA properties, including the emulsion stability, thermal property, water resistance, adhesion, hardness, glossiness of polymer film were studied. The results show that the WPUA emulsion has excellent stability, and the UV‐cured film features good hardness and remarkable water resistance when PETA is used as end‐capper and the end‐capping ratio of the polyurethane prepolymer is 70% and dipentaerythritol hexaacylate/dipropylene glycol diacrylate (mass ratio 1:1) is used as diluent. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45208.

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

ABSTRACTStable 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.

Polyurethane-Acrylate Composite Emulsion Applying to the Pre-Coated Adhesive Film

This paper studied on the application mechanics and characteristics of the polyurethane-acrylate composite emulsion applying to the pre-coated adhesive film of paper and plastic laminating. The formula design and synthesis method of the polyurethane-acrylate composite emulsion was researched, and the physical properties of the copolymer emulsion was tested by infrared spectroscopy (IR), particle size analysis, gel permeation chromatography (GPC). According to mix the waterborne polyurethane acrylate emulsion to the waterborne rosin emulsion, the hot melt pre-coated adhesive was obtained. The experimental results based on the physical properties and image analysis of the pre-coated adhesive film of paper and plastic laminating showed that: the adhesive film coated by this hot melt adhesive had a high gloss and adhesive force, it improved the application performance of the pre-coated adhesive film of paper and plastic laminating in the printing and packaging industry.