Novel hyperbranched resins for coating applications

Hyperbranched polycondensates derived from AB_x-type monomers have been generally recognized as the cheaper and economically more feasible counterparts of the well-known other members of the dendritic macromolecule family, the perfectly branched dendrimers. Since they can be manufactured more quickly and easily in a one-step polymerization procedure, their significantly lower cost price puts them in a much more favourable position to be industrially applied as coating resins. The conceptual design of a branched macromolecule is ideally outlined for film forming applications. The viscosity in relation to their molecular weight is kept low due to their compact morphology hampering chain entanglements, while on the other hand, the large number of functional end groups enable efficient cross-linking.

Standing apart from the standard AB_x approaches, optionally employing a B_x starter molecule, DSM has now developed a new type of hyperbranched polyesteramides derived from cyclic carboxylic anhydrides and dialkanolamines. In a one-pot procedure, the dialkanolamine molecules react preferentially via the secondary amine group with the cyclic anhydride, forming in situ a bis(hydroxyalkyl)amide group (AB₂) containing carboxylic acid. Because of the known high reactivity of 2-hydroxyalkylamide groups towards esterification with carboxylic acids, a fast and efficient polycondensation at temperatures of 140–200°C without the addition of a catalyst can be performed. Using the dialkanolamine component in molar excess over the anhydride, gel formation is excluded and a predictable and stable melt viscosity is obtained.

The resulting hydroxyl functional resins have been applied successfully as powder coatings binder components. In addition, the presence of the reactive hydroxyl groups makes these hyperbranched polymers very suitable materials for further modifications. By letting them react with aliphatic and/or aromatic monoacids, for example, polymers with different properties could be synthesized which have been found very suitable for a number of coating applications, for example, air drying topcoats and primers and two-pack urethane lacquers. A combination of favourable properties, including high hardness and early drying, high solids content and weatherability was observed.     

Novel bi-layered nanostructured SiO2/Ag-FHAp coating on biodegradable magnesium alloy for biomedical applications

In this study, a novel bi-layered nanostructured silica (SiO₂)/ silver-doped fluorohydroxyapatite (Ag-FHAp) coating was deposited on biodegradable Mg-1.2Ca-4.5Zn alloy via physical vapor deposition (PVD) combined with electrodeposition (ED). The nano-SiO₂ underlayer had a compact columnar microstructure with thickness of around 1 µm while the Ag-FHAp overlayer presented large plate-like crystals accompanied with small rounded particles with thickness about 10 µm. Potentiodynamic polarization test exhibited that the double layer SiO₂/Ag-FHAp coated Mg alloy has superior corrosion resistance compared to uncoated and single layer SiO₂ coated samples. Contact angle measurement showed that Ag-FHAp coating over nano-SiO₂ layers significantly increased surface wettability which is favorable for the attachment of cells. Cytotoxicity tests indicated that the nanostructured SiO₂/Ag-FHAp coating enabled higher cell viability compared to nano-SiO₂ coating and uncoated samples. In addition, bi-layer and single-layer coatings considerably improved the ability of cell attachment than that of the uncoated samples. The cell viability of coated and uncoated samples increased with increasing incubation time. The double layer SiO₂/Ag-FHAp coated biodegradable Mg alloy possessed high corrosion resistance and cytocompatibility and can be considered as a promising material for implant applications.     

Bio-based semi-aromatic polyesters for coating applications

Linear and branched bio-based semi-aromatic (co)polyesters were evaluated as resins for solvent-based and powder coatings. Dimethyl-2,5-furandicarboxylate (DMF), 2,3-butanediol and various multifunctional comonomers were used to synthesize amorphous hydroxyl-end-capped (co)polyesters. The resins were cross-linked using the ?-caprolactam blocked trimer of isophorone diisocyanate. Both the solvent-based and powder coatings proved to be hard but brittle, which was a result of the very stiff molecular structure of the formed network. This was corroborated by the T_g values obtained for the coatings, which exceeded 100 °C for both the solvent-based and powder coatings. The poly(ester urethane) coatings prepared from the branched copolyesters show a reasonable solvent resistance. However, swelling occurred during the solvent treatment, indicating an insufficient network formation. The solvent-based and powder coatings exhibit similar mechanical and physical performance, showing that in this study there was no significant influence of the preparation method. In view of the obtained results it can be concluded that DMF-based branched polyesters are interesting candidates for solvent-based and powder coating applications.     

Onshore applications for intumescent coating systems

Conclusions  1. Thin-film intumescents are virtually unaffected by dry interior environments. 2. Exterior durable intumescents can give long term fire protection to structural steelwork in an exterior environment provided they are overcoated with suitable finishing coats. 3. Thin-film intumescents are not suitable for hot condensing environments. Caution has to be exercised in using exterior exposure data obtained in the UK for intumescents that are going to be exposed in hot humid climates. 4. Infrared analysis can be used to monitor the durability of intumescent coatings in situ.     

Novel precursors suitable for RIM polyurethane networks

The synthesis and development of novel, furan-based diisocyanates (FDI) and myrcene-based polyols (PM) with potential for polyurethane production are presented. Pure FDI compounds, similar in structure to 4,4'-methylenediphenylene diisocyanate (MDI) were prepared unambiguously from fur-furylamine as liquids of low volatility, stable down to 0° C. making them particularly suitable for RIM. Comparative kinetics studies with n-butanol show the FDIs to behave as benzylic compounds with reactivities intermediate between those of aryl and alkyl diisocynates. Studies were made on segmented copolyurethanes prepared from FDI and polyol mixtures of 1,4-butane diol (BD) and polytetrahydrofuran (Mn. 1010). Hydroxyfunctional polymyrcenes were prepared from myrcene in n-butanol at 100° C using hydrogen peroxide as initiator. The liquid rubbers formed (M_n, 2000-4000; with f_n, 2.3-1.3 respectively) were shown by n.m.r. to comprise mainly substituted 1,4-butadiene units and are similar to the commercially available polybutadienes (PB). Copolyurethane elastomers were prepared from polyol blends of PM and 1,4-butane diol reacting with MDI. Both series of FDI-and PM-based copolyurethanes were shown by d.s.c. d.m.a. and tensile measurements to possess properties comparable to analogous materials formed from, respectively, MDI- and PB-based systems. In addition to their suitability for RIM, the results show the feasibility of deriving polyurethane feedstocks from naturally-occurring, non-oil based sources.     

Waterborne nanocomposite resins for automotive coating applications

Organic acrylic polymers in aqueous dispersed form are binders that can be used for the production of environmentally friendly coatings. The film properties have been improved by adding small amounts of fully dispersed inorganic hard phases in the form of needle shaped Boehmite, disc shaped Laponite and Montmorillonite platelets. Depending on the location and structure of the nanoparticles in the emulsion, after application and curing of the nanocomposite binder various morphologies are found in the transparent and flexible films. Hydrophilic nanoparticles at the interfaces of the polymer droplets and hydrophobic nanoparticles completely or partially located inside the polymer droplets yield dramatically increased stiffness of the cured film as well as adjustable rheology of the binder.     

Rheology of plastisol formulations for coating applications

A plastisol is a suspension of PVC particles and mineral fillers in a liquid phase composed of plasticizer and adjuvants. Plastisol formulations are commonly used in coating processes for flooring application. In the knife‐over‐roll process, they are subjected to a wide range of shear rates (0–10⁵ s^?1). They are adjusted in order to fulfil the target end‐use properties but their processability depends on their rheology. Plastisol based on three PVC resins with or without mineral filler have been investigated using a Couette device and a capillary rheometer. Results show a high impact of PVC particle content, particle sizes and distribution on rheology: a polydisperse formulation displays a shear‐thinning behavior in the whole shear rates range and exhibits yield stress; a monodisperse formulation shows a shear thinning behavior at low shear rate, followed by a Newtonian plateau, then a more or less pronounced dilatancy peak depending on plasticizer rate and finally another shear‐thinning behavior; a bidisperse resin stands in between. Filler content also impacts the rheology: shear thickening effects at intermediate shear rates decrease or even disappear; however, the viscosity increase is important for low shear rates and depends on the filler particle size and particle size distribution. POLYM. ENG. SCI., 57:982–988, 2017. © 2016 Society of Plastics Engineers     

Comb-like liquid crystalline polymers for coating applications

Comb-like liquid crystalline (LC) acrylic copolymers were synthesised by inserting flexible spacer between polymer backbone and mesogenic group. The incorporation of mesogenic group was confirmed by IR, 1H-NMR and polarizing photomicroscopy techniques. Thermal behaviour was studied using DSC and TGA. An in-depth study of coating properties in terms of drying time, hardness, adhesion, flexibility, viscosity and chemical resistance of acrylic copolymers and LC acrylic copolymers were carried out.     

Bio-based hyperbranched polyurethanes for surface coating applications

High performance vegetable oil based hyperbranched polymers are not only interesting but also very useful with respect to current scenario of advanced coating materials. So in the present study hyperbranched polyurethanes have been synthesized from the monoglyceride of Mesua ferrea L. seed oil, poly(?-caprolactone)diol, 2,4-toluene diisocyanate and glycerol without using any catalyst by a two-step one pot A₂ + B₃ approach. The linear analog (neglecting little possible branching due to different components of monoglyceride) of the hyperbranched polyurethane has also been prepared by the same method without using glycerol, just to compare with hyperbranched polymer. The formation of polymers was confirmed by FTIR, ¹H NMR, UV and SEM studies and measurements of hydroxyl value, solubility and viscosity. TGA results indicated the high thermal stability of hyperbranched and linear polymers (210–220 °C). The properties like tensile strength, impact strength, hardness, adhesion, flexibility, gloss, elongation at break and chemical resistance were influenced by the hard segment content of the polymers. The hyperbranched polyurethane with 30% hard segment content showed the optimum properties. The values of hydrodynamic diameter of hyperbranched polymers compared to the linear analog support the hyperbranched formation. Thus it confirms the formation of mechanically strong and thermally stable hyperbranched polyurethane coating materials from a vegetable oil.     

Polyampholyte acrylic latexes for tablet coating applications

Polyampholyte latexes can exist within a certain pH range as low‐viscosity aqueous dispersions, while upon a pH shift to the vicinity of the isoelectric point they undergo ionic coacervation. Three classes of coacervation latexes were synthesized and evaluated for their suitability for use in tablet coating applications. Pharmaceutical tablet coatings are commonly based on hydroxypropyl methyl cellulose, poly(vinyl alcohol), and acrylic polymers. Because of the high viscosity of their aqueous solutions, and to the consequent required low concentrations of the tablet coating polymers in the coating solutions to enable sufficiently low viscosity for effective spray application, the current commercial pharmaceutical tablet coating technology requires the removal of large amounts of water during the manufacturing process. In this work, films prepared from high‐solids, low‐viscosity coacervated acrylic latexes showed good hardness, very low tackiness, an excellent combination of optical properties, and very low water vapor permeability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40049.     

新型共聚聚酯在医疗器械上的应用

2013年2月,每年一届的美国西部医疗器械设计博览会(MD&MWest)如期在美国加利福尼亚州阿纳海姆(Anaheim)会展中心举行.总部位于田纳西州金斯波特的伊士曼化工有限公司展出了两款新型商用共聚聚酯和共聚聚酯弹性体. 腹腔镜镜头内部清洁系统(LLICS).LLICS作为外科手术器械在微创手术中用于原位清洗腹腔镜镜头.该器械手柄(如图)来自科罗拉多州博尔德医药有限责任公司Melicor的发明,是伊士曼Ecdel共聚聚酯TPE和EastarPETG共混成型制品.     

Organic/inorganic composite materials for coating applications

A new organic/inorganic coating material based on the modification of a conventional melamine/polyol system has been developed. Polyhydroxyethylmethacrylate functionalized with alkoxysilane group was mixed with hexamethoxymethylmelamine. Upon heating under an acid catalyzed condition, both sol–gel reaction and melamine/polyol reactions occurred simultaneously, leading to highly crosslinked hybrid composites. The synthesis and characterization of the hybrid materials are reported. The organic/inorganic material was also coated and cured on polycarbonate substrates. The coated/cured samples exhibited excellent optical property. Surface scratch and abrasion resistance of the samples was found better than those of pristine polycarbonate substrate. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1341–1346, 1999     

Perspective: green polyurethane synthesis for coating applications

Polyurethanes exhibit excellent coating properties for many applications. Facing the continuous growth of the polyurethane coating market, in the last few years many scientists have addressed the safety and sustainability of their production. This paper highlights the efforts that have been pursued in this direction from both the academic and industrial perspectives and covers aspects ranging from the substitution of petroleum‐based monomers by biobased equivalents to the development of novel synthetic pathways for the production of polyhydroxyurethanes. © 2018 Society of Chemical Industry     

Polysiloxaneurethanes: new polymers for potential coating applications

Polysiloxaneurethanes (PSUR) are block copolymers containing polysiloxane and urethane (or polyurethane) segments and showing very interesting mechanical, dielectric and surface related properties. Brief reviews of investigations that have been carried out so far on PSUR are presented with special reference to coating applications of them. The properties of the novel moisture-curable PSUR (MCPSUR), tested before and after moisture curing, are discussed in connection with their chemistry and structure. The properties of aqueous dispersions of PSUR (ADPSUR) synthesised in ICRI are also reviewed. The preliminary results of some coating tests made for MCPSUR and ADPSUR are presented.     

Bimodal dispersions in coating applications

This paper describes a study of several model bimodal particle size distribution latex systems produced by blending large and small particle size anionically stabilised latices over a wide range of blend ratios. Minimum film forming temperature (MFT), drying rate, tensile and water uptake measurements were carried out. At a 80/20 weight ratio large/small particles a minimum was observed in the MFT and also in the extent of water absorption of latex films with short drying times, although for films dried for longer periods no such minimum in water absorption was observed. Drying profiles fit well with existing models, except for the 80/201/s blend which exhibits more complex drying behaviour. Low shear rate viscosity of selected blends was measured over a range of latex solids contents. The Theological data were fitted by the Krieger-Dougherty equation which was used to calculate the maximum volume packing fraction. An 80/20 blend (large/small) was found to exhibit a higher maximum volume fraction than that of either pure component of the blend, demonstrating the better packing achievable in blending. A theoretical treatment of the coalescence of bimodal particles is presented in an appendix to the paper.