Process optimization for spray coating of poly (D, L-lactic acid) films (original) (raw)
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Relation between surface roughness of free films and process parameters in spray coating
European Journal of Pharmaceutical Sciences, 2011
A novel spraying apparatus was developed to obtain reproducible free sprayed films. Aqueous solutions of PolyVinyl Alcohol PVA 4-98, HydroxyPropyl MethylCellulose HPMC 603 and HPMC 615 were used as reference coating materials. The apparatus is composed by a spraying system, a closed chamber containing a rotating Teflon cylinder, a pressured air supply system, a spray solution supply system, and a computerized control system. The spraying air pressure, the cylinder rotation speed, and the cylinder-spray nozzle distance were tailored in such a manner that the roughness of the obtained free films was similar to that from reference coated particles. Optimum spraying process conditions were found for all three coating materials using design of experiments. The morphology of the sprayed films obtained using the optimum conditions is evaluated by means of scanning electron microscopy (SEM), and atomic force microscopy (AFM), and then compared with those from corresponding cast films and coating layers on particles. A match was found between the morphology of sprayed films and that from the corresponding coating layer on the particle surface. The spray apparatus produced reproducible sprayed films with tuneable roughness and/or smoothness depending on the set of processing parameters.
Material consumption and dry film thickness in spray coating process
Procedia CIRP, 2014
Material consumption and dry film thickness are the two main indicators for identifying the efficiency of spray coating process. Using a proper spray condition, less material consumption could be obtained as per a given dry film thickness. This paper presents the influences of supplyingair pressure, spray time and nozzle size of spray gun on the weight of material used per shot and the dry film thickness obtained. A highvolume-low-pressure type spray gun was used to atomize and deliver a liquid solution of Teflon depositing on a flat work surface. The experimental results showed that low spray time, large nozzle size and low spray pressure were responsible for the increased material consumption and dry film thickness. The optimization was performed, where the material consumption was minimized and the dry film thickness was set within a specified standard. Based on the geometric interaction between the spray gun and work-piece, a spray coating model in this application, which is considered unique was also developed and discussed in this paper. Moreover, this paper demonstrates a determination of the coefficient of spray coating process (k) through a relationship between coating thickness and material consumption using data obtained from the experiment. As a result, a relationship among the dry film thickness and positions of the spray gun was established and it can be used to predict the coating thickness. In conclusion, the optimal conditions in the spray coating process was determined to minimize material consumption whereas the developed spray coating model predicts the coating thickness related to the position of the spray gun. This model will substantially reduce spray gun setup time during production in order to obtain required dry film thickness.
Preparations of Poly(lactic acid) Dispersions in Water for Coating Applications
Polymers, 2021
A green, effective methodology for the preparation of water-based dispersions of poly(lactic acid) (PLA) for coating purposes is herein presented. The procedure consists of two steps: in the first one, an oil-in-water emulsion is obtained by mixing a solution of PLA in ethyl acetate with a water phase containing surfactant and stabilizer. Different homogenization methods as well as oil/water phase ratio, surfactant and stabilizer combinations were screened. In the second step, the quantitative evaporation of the organic provides water dispersions of PLA that are stable, at least, over several weeks at room temperature or at 4 °C. Particle size was in the 200–500 nm range, depending on the preparation conditions, as confirmed by scanning electron microscope (SEM) analysis. PLA was found not to suffer significant molecular weight degradation by gel permeation chromatography (GPC) analysis. Furthermore, two selected formulations with glass transition temperature (Tg) of 51 °C and 34 °C...
Observation of the Coating Process in Spray Coating
2017
Spray coating is a facile coating and deposition process with numerous existing and emerging applications. However, it is a stochastic process comprising impingement of many droplets, which upon impact on a heated substrate may dry individually or coalesce first to make a thin liquid film and then dry to make a thin solid film. There is very limited knowledge on how this process occurs; therefore in this work, high speed imaging is used to visualize the spray coating process. Two model solutions including food-dye with properties similar to those of water, and PEDOT:PSS, a polymeric solution, are sprayed onto glossy paper and regular glass substrates. Substrates are kept at room temperature and elevated temperature of 80 °C. In some cases, a vertical ultrasonic vibration is imposed on the substrate to study its effect on the coating process. In conclusion, it is observed that the spray coating process is highly random and stochastic. A higher substrate temperature results in better ...
Film Coating Technology: Past, Present and Future
Film coating has evolved with time keeping in pace with the demands of the Pharmaceutical industry. There has been tremendous and necessary modification like improved production equipment and the development of highly efficient filmcoating formulations and polymers which has accelerated the acceptance of film-coating technology. Film coating has taken over sugar coating owing to the broader flexibility and additional functionalities in former. There has been state of the art level improvisation in methodology and technique exemplified by solvent or water based and dry coating. The main focus of this literature review is to summon up the different types of coating technologies and various parameters and variables that play a major role during the entire process. Commentary on future direction is also provided.
An Optimization Of Spray Coating Process To Minimize Coating Material Consumption
ECMS 2017 Proceedings edited by Zita Zoltay Paprika, Péter Horák, Kata Váradi, Péter Tamás Zwierczyk, Ágnes Vidovics-Dancs, János Péter Rádics, 2017
In cookware industry, interior spray coating process is an important process to protect the cookware product from the corrosion. In this process, the coating material "TEFLON" is used to spray to cover all the part's surface. If a pot or pan is not too deep, one spray gun is enough to spray to cover all the interior surface. However, for the high side-wall pot, two spray guns must be used to spray at two different areas. The first area is at the bottom and its corner. The second area is around the top rim of the pot or pan. Note that the spray pattern is of fan-type. Thus, the sprayed area will be covered by the mentioned two spray guns. Consequently, the large amount of coating material is consumed to meet the dry film thickness (DFT) requirement. In this paper, the optimization of spray coating process is studied aiming to minimize the material usage. The experimental design technique is applied to determine the optimal spray coating parameters. The parameters used in this study include angle, spray time, fan pattern, and air pressure. The relationship models of coating material volume and DFT are presented in this research. The optimal parameters of the two spray guns are presented.
An Effect of Coating Parameters to Dry Film Thickness in Spray Coating Process
Key Engineering Materials, 2016
In cookware manufacturing industry, spray coating process plays an important role both in function and appearance quality of a product. Typically, Teflon (PTFE) is used for interior coating to increase corrosive and nonstick. Practically, nozzle size and spray time are crucial variables to dry file thickness (DFT) in the process. In mass production, a product is mounted on a rotating spindle which installed on the conveyor and moves pass the spray guns. Thus, the rotating speed is also a potential variable to the DFT. Thus, the objective of this paper is to explore a relationship of these abovementioned three variables i.e. nozzle size, spray time, and rotational speed to dry film thickness After that the optimal condition such that the required DFT is met will be determined. To achieve this goal, the experimental design technique including analysis of variance (ANOVA) is employed in this study. It is found that each of the three variables affects the DFT. The higher of spray time, ...
A model for film thickness using direct spray coating
Proceedings of the 5th Electronics Packaging Technology Conference (EPTC 2003), 2003
This paper presents a model for film thickness using direct spray coating. The model reflects the dependence of film thickness on several parameters such as the solids content of the solution, the dispensed volume, the scanning speed of the spray head and the substrate's dimension. The model is verified with experimental data using spray coating of photoresist on 4"silicon wafers. A direct spray coating system (EVG 101) is used to perform the coating experiments. The model has been a great means to predict the thickness of the deposited layers, as well as to control and to understand the spray process.
International Journal of Applied Pharmaceutics, 2023
Objective: The objective of this study is to present the main screening parameters for the development of Spray Film-Forming Systems (SFFSs) using the design space. The focus is on characterizing the different phase states of SFFSs during application and establishing appropriate methods for determining the range of parameters. Methods: In this study, various methods were used to determine the range of SFFS parameters. These include contact angle determination, pH test, viscosity measurement, drying rate estimation, spray pattern determination, tensile strength test, and washability. The methods used were evaluated and found to be effective in assessing the quality parameters of liquid concentrates, aerosols, and films of commercially available SFFS samples. Results: Three states (liquid, aerosol, and solid) of commercially available SPSFs were evaluated using the techniques mentioned above. The applicability of the techniques and variability was discussed in comparison with similar studies. The results showed that the mean pH ranged from 5.43±0.02 to 6.63±0.05, the bioadhesion of liquid concentrates was in a narrow range of 4.49±0.52, the highest index of dynamic viscosity was 0.33±0.04, values of the spray pattern ranged from 6.19±1.97 to 17.46±2.72 cm2, bioadhesion values of the films ranged from 3.87 to 4.06 N, average values of film formation time were in the range of 65.55±12.65) s. 3 of the 4 samples had resistance to skin cracking, the tensile load of the commercial SFFS films varied from 2.91±0.3 to 5.11±0.65 N, and the tensile strength from 1.07±0.11 to 1.20±0.3 mPa. All films were not washed off with water. Conclusion: The findings of this study demonstrate the successful application of tested methods in determining the range of parameters for SFFSs. The established values for indicators of liquid concentrates can serve as a basis for the further development of SFFSs. Overall, this research contributes to the understanding and standardization of Spray Film-Forming Systems for wounds, enabling their effective development and application in local skin treatments.
A Novel Hybrid Spraying Method for Obtaining High Quality Coatings
Engineering Transactions, 2016
The aim of this study is to present the development of the hybrid method, and its possible applications, advantages and limitations. The new elaborated method of spraying can be applied for the production of coatings working in an aggressive environment. In the paper, the corrosion-erosion resistance of coatings obtained by the hybrid method is presented. The structure and chemical composition of coatings are obtained by the scanning electron microscopy (SEM). The made samples were subject to cyclic corrosion test in air and at high temperature of 650°C. The changes in mass of samples in time were measured and the curve of the course of corrosion processes was specified. In this paper, the results of abrasion test on T07 stand and erosion tests under a load of 200 g in ambient and elevated temperature are presented. The presented results confirm the correctness of chosen parameters of a new, elaborated and innovative hybrid method.