Design of water-based polyvinyl alcohol coatings using a drying modifier to minimize the residual solvent and coating defects

Rawat, Mamta; Ahuja, Sanjeev

doi:10.1007/s13726-021-01019-3

Cited by 5 publications

(13 citation statements)

References 44 publications

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“…The results of the present work employing PEG‐6000 are first compared with an earlier work employing a surfactant Capstone FS‐63 (FS) 47 . Both drying modifiers act by plasticization.…”

Section: Resultsmentioning

confidence: 96%

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Design of low cost waterborne polyvinyl alcohol coatings using plasticizer polyethylene glycol to minimize the residual solvent and coating defects

Rawat

Ahuja

2022

J of Applied Polymer Sci

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Waterborne coatings provide nontoxicity and flame-retardance but exhibit inefficient drying. The literature on drying enhancers is limited for the want of residual solvent minimization study. Here, we use polyethylene glycol-6000 (PEG), a low cost biodegradable plasticizer, to minimize the residual solvent in polyvinyl alcohol (PVA)-water coatings. Coatings were prepared at different PEG loadings (0, 0.50, 1.00, 2.50, 5.00, and 7.50 wt%) and initial conditions.The maximum drop in the residual solvent was 87% at 0.50 wt% PEG loading in the coating of initially 5% PVA and 1000 μm thickness. The effect of doubling the initial wet thickness from 500 to 1000 μm was first examined. The minimum residual solvent significantly reduced from 1.30% to 0.59%, and occurred at the same PEG loading of 0.50 wt%. However, the drying time increased and drying rate slowed down remarkably. SEM results also revealed that at the optimum PEG loading a smooth and dense coating was obtained. Thermogravimetric analysis/derivative thermogravimetric studies showed improved thermal stability and differential scanning calorimetry showed little decrease in T g at optimized PEG loading. When the initial polymer concentration was doubled from 5% to 10%, the optimum PEG loading lowered from 0.50 to 0 wt%. Simultaneously, a marked increase in the minimum residual solvent from 1.30% to 3.27% occurred, caused by the hydrophilicity of PVA and enhanced solution viscosity. On comparison with a fluorosurfactant (FS) modifier, PEG yields significantly better maximum reduction in residual solvent at substantially lower optimum loading by employing higher wet film thickness. Furthermore, PEG is significantly lower in cost and environmentally friendly than FS.

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“…The results of the present work employing PEG‐6000 are first compared with an earlier work employing a surfactant Capstone FS‐63 (FS) 47 . Both drying modifiers act by plasticization.…”

Section: Resultsmentioning

confidence: 96%

“…The results of the present work employing PEG-6000 are first compared with an earlier work employing a surfactant Capstone FS-63 (FS). 47 Both drying modifiers act by plasticization. The earlier study was also performed on PVA-water system under the same set of initial and drying conditions and modifier loadings.…”

Section: Comparison With Available Studiesmentioning

confidence: 99%

Design of low cost waterborne polyvinyl alcohol coatings using plasticizer polyethylene glycol to minimize the residual solvent and coating defects

Rawat

Ahuja

2022

J of Applied Polymer Sci

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“…The conventional method is to simply apply the coating on the surface of the material and wait for the volatilization and drying of the solvent. Aqueous-phase coating, which is environmentally friendly, has a large latent heat of evaporation and hence, a long drying time [ 12 ]. Conversely, the organic phase coating with a short drying time pollutes the environment [ 13 ].…”

Section: Discussionmentioning

confidence: 99%

“…Spraying and brushing have good coating capability for flat and regular surfaces, but they do not effectively produce uniform coating for objects with complex and irregular surfaces and internal complex spatial structures. Organic paints can be rapidly and conveniently applied and have relatively short drying times; however, they have a high content of volatile organic compounds (VOCs), resulting in severe environmental pollution [ 10 , 11 , 12 , 13 ]. The use of water-based paints can mitigate the pollution problem, but the large latent heat of water vaporization results in an excessively long drying time, which is not conducive to rapid large-scale production.…”

Section: Introductionmentioning

confidence: 99%

Rapid Preparation of Flame-Retardant Coatings Using Polyurethane Emulsion Mixed with Inorganic Fillers

Wang

Liu

et al. 2023

Polymers

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The traditional aqueous flame-retardant coating faces the problem of slow solvent evaporation rate in the preparation process. It is an urgent problem to ensure that the function of the membrane is not destroyed while accelerating the solvent volatilization. Herein, we fabricated films on the metal substrate surface by a totally novel method: demulsification-induced fast solidification to rapidly obtain the flame-retardant coating. The environmentally friendly flame retardants aluminum hydroxide and red phosphorus were mixed with the commercial water-based polyurethane 906 emulsion to explore the optimal mixing ratio, where the adhesion of the flame-retardant reached the Grade 3 standard, the sample remained intact after the 100 cm drop hammer test and the limiting oxygen index value reached 30.4%. In addition, compared with the traditional process, this method, with the advantages of rapidly drying, environmentally friendly, uniformly prepared coatings on the surface of any shape substrates, as well as accurate and controllable coating thickness, can be widely applied in the flame-retardant field.

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“…Recently, plasticizers have also shown high potential to act as drying enhancers in minimizing the residual solvent and coating defects. [4][5][6][7]21,[36][37][38][39][40][41] Rawat and Ahuja 6 have lately used plasticizer TPP in polystyrene-p-xylene films and carried out a detailed design study to investigate the effects of several operating conditions on the drying characteristics, and on thermal, morphological, and mechanical properties. The conditions varied were wet film thickness, concentration of polymer/solvent/ enhancer, molar mass of polymer, and temperature.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the performances of different drying enhancers for waterborne polyvinyl alcohol films

Ahuja

2023

J of Applied Polymer Sci

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Waterborne polyvinyl alcohol (PVA) films show lower environmental impact but render high residual solvent on account of hydrophilicity of PVA and low volatility of water. Plasticizers have shown high potential to act as drying enhancers in some recent studies. Plasticizers triphenyl phosphate (TPP) and polyethylene glycol (PEG400) with their favorable chemical structures and relatively low molar masses are promising options. Their performances in drying waterborne PVA films are compared with the plasticizers used in earlier works, at different initial wet film thicknesses, polymer contents, enhancer contents, and enhancer molar masses. Films were solvent casted by drying PVA‐water solutions in a substrate. TPP causes maximum lowering of the residual solvent and does this at high drying rate corresponding to low initial wet film thickness and PVA content. The least value of residual solvent is 0.20% at optimum TPP loading. The next best residual solvent results of 0.21% and 0.59% are, respectively, exhibited by PEG400 and PEG6000, but at low drying rate for high wet film thickness, for both the enhancers; however, at high drying rate for low wet film thickness anomalous skinning increased the residual solvent. At 0.51%, Capstone FS‐63 also gives good results and at high drying rate. Their relative performances are correlated to the viscosity of cast solutions, glass transition temperature of films (DSC), and chemical structures of the polymer and enhancers. TPP thus proved to be most effective. SEM showed dense films and disappearance of defects with optimum loading of TPP, and TGA/DTG showed thermally stable coatings. In spite of the higher cost of TPP it can have useful specialized applications that exploit its excellent flame retardance features.

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Design of water-based polyvinyl alcohol coatings using a drying modifier to minimize the residual solvent and coating defects

Cited by 5 publications

References 44 publications

Design of low cost waterborne polyvinyl alcohol coatings using plasticizer polyethylene glycol to minimize the residual solvent and coating defects

Design of low cost waterborne polyvinyl alcohol coatings using plasticizer polyethylene glycol to minimize the residual solvent and coating defects

Rapid Preparation of Flame-Retardant Coatings Using Polyurethane Emulsion Mixed with Inorganic Fillers

Comparison of the performances of different drying enhancers for waterborne polyvinyl alcohol films

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