Incorporation of surfactants in the formulation will help you to improve the coating appearance. Apply a sufficient amount of coating suspension. Reduce the amount of hygroscopic excipient such as disintegrant. Select a more flexible coating Contamination Dirt Pickup: NEUTRALIZING CHARGES ON THE FILM WEB If static charges on the film web can be controlled to a low level, most electrostatic related problems can be eliminated. So much so that when vinyl films and overlaminates are rolled up on a roll, the films can pick the impression of backside of the release liner. Adhesive Film defects can ruin protective and aesthetical properties of coatings. The drying Air temp and the velocity is critical. Cracking in conformal coating is where a smooth surface fractures into sections with the cracks in the coating leaving the area below exposed to potential contaminants. The last critical step in the tablet production cycle is tablet coating after solving problems in core tablet manufacturing. Opposite polarities will attract. Avoid the use of sorbitol with HPMC (Hydroxy Propyl Methyl Cellulose), HPC (Hydroxy Propyl Cellulose), Cellulose ethers, and Methyl Cellulose. Spraying coating formulations once the required inlet temperature has been reached instead of prewarming the tablets (a process that usually involves some tablet motion without any coating being applied). Formulation of paracetamol suspension seems very easy to formulate. The problem may also be a consequence of spraying coating liquids with excessively high viscosities such that effective atomization is difficult to achieve. Especially this problem has happened with the presence of inappropriate logo. Coating and core have different thermal expansion properties. New Delhi: CBS Publishers & Distributors Pvt. Separation or pulling apart of wet film to Expose underlying Finish or substrate. Tablet coating defects and remedies are the crucial concern of a pharmaceutical formulation scientist. Reducetheamountofhygroscopicexcipient such asdisintegrant. Insufficient plasticization or too much pigmentation. A substrate having low surface energy is called hydrophobic, implying that the surface of the substrate is not able interacting strongly with a material brought on top of it. Use of sorbitol in coating formulation which causes major fall in the thermal gelation temperature of the HPMC (Hydroxy Propyl Methyl Cellulose), HPC (Hydroxy Propyl Cellulose), Cellulose ethers, and Methyl Cellulose. In other words, it is the fading or dulling of a coated tablet color after a prolonged period of storage at a high temperature. Electrostatic charges develop on surfaces of film webs as they are transported through various converting processes such as Coating, Laminating , rewinding, slitting. A lot of hustle can be prevented by using available knowledge that is simple and easy. Adhesive Oozing / Bleeding Blistering Setting appropriate drying temp is a key to get raid of Blisters. The second important aspect is the rheology of the Adhesive. Ankit, Gupta & Bilandi, Ajay & Kataria, Mahesh & Neetu, Khatri. It is a coating defect where tablets stick together especially when two tablets stick together. Use appropriate drying (inlet air) temperature. In other words, pitting is the deformation of the core of the tablet without any visible signs of disruption of the film coating. Cracking of applied film coating can be microscopic or macroscopic in nature. Permeability to moisture 4. It occurs when the internal stress (that develops within the film as it dries) exceeds the tensile strength of the film. Loading and unloading tablets from the coating pan. The strong electrostatic fields associated with these charges attract dust particles, fibers, bugs and hair resulting in surface contamination. They may be electrically operated, passive, or may use radioactive materials as the ion generation source. Peeling refers to the formation of uneven or rough irregularities on the surface of a coating film applied on a core tablet surface. Your email address will not be published. Especially this problem has happened with the presence of inappropriate logo. It is a coating defect where tablet surfaces erode as tablets tumble during the coating process. Logo In-filling /Break Lines In-filling, IV Bolus vs IV Infusion of Parenteral Drug Product, Difference between Bioavailability and Bioequivalence. In spite of its relative longevity, it remains a complex process in which all technical issues and their impact are not always fully appreciated with the result that potential problems continue to arise with all too frequent regularity. [Rodger Talbert] Paint Technology Handbook(b-ok.org), Coating materials for electronic applications: polymers, processes, reliability, testing, COATING INSPECTOR PROGRAM Level 2 Student Manual Jan 2014, Coating Inspector Program Level 1 Student Manual, DETERMINATION OF THE VARIOUS DEFECTS ATTRIBUTED TO THE MANUFACTURE, SURFACE PREPARATION AND APPLICATION OF TEXTURED PAINTS, Interactions and penetration of polymers and nanolatexes into wood: An overview, PAINTING INSPECTION GRADE 3/2 (ATC88) TWI Ltd, Training and Examination Services WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY, File ID 86440 Filename Thesis SOURCE (OR PART OF THE FOLLOWING SOURCE): Type Dissertation Title Coating strategies for the protection of outdoor bronze art and ornamentation Author L, A review on self-cleaning and multifunctional materials, Robust hybrid elastomer/metal-oxide superhydrophobic surfaces, Coating Inspector Program Level 2 Student Manual, Designation: D3276 151151 Standard Guide for Painting Inspectors (Metal Substrates) 1, E99154 b863 489a 8ad5 cb1e5c0c6780 150331011256 conversion gate, A E.48, [THE GRAPHIC STANDARDS GUIDE TO ARCHITECTURAL FINISHES], Architectural Specification Issued For Construction, Study of Separation of Pigments in Paints for Development of Multicolor Paint, .Current Opinion in Colloid & Interface Science 6 2001 383401 Capillary forces and structuring in layers of colloid particles, 9076Emulsions Foams and Suspensions - Fundamentals and Applications, Observation and Modelling of Fluid Transport into Porous Paper Coating Structures, A review on aqueous film coating technology, The conservation of panel paintings and related objects, Wallpaper 1x1 A Textbook for Craftsmen and Those who wish to Be, Jasa P A S A N G Wallpaper Tangerang - 081338236055, Manufacturing Technology for Aerospace Structural Materials This Page is Intentionally Left Blank Manufacturing Technology for Aerospace Structural Materials, European Coatings Tech Files Coatings Formulation 2 nd Revised Edition, Manufacturing Technology for Aerospace Structural Materials - F.C. Please feel to write to me for any specific problem you might be facing . The most ideal temps for drying zone wise beginning from First to last zone should be set. It a defect where tablets break apart during pan loading or while tumbling in the pan or during the coating process, or during unloading of the coating pan. Higher internal stresses in the film than the tensile strength of the film. Use high molecular weight of plasticizer. Tiny deep holes exposing substrate A small , sunken area that forms on a coating film after a bubble ruptures. PEOPLE ALSO READ:SOP for Operation and Cleaning of Vibrosifter. It is a coating defect where peels off the tablet during or after the coating process. Inadequate coating or migration of soluble dyes-plasticizers and other additives during drying. Although problems encountered during film coating process can fall into a broad range of categories, by far the largest category is that associated with visual defects, often purely cosmetic in nature, which rarely impact the efficacy of the finished dosage form, except in the sense that they might lead to reduced patient confidence. It is a coating defect where the coating becomes dull immediately or after prolonged storage at high temperatures. It is a coating defect where pits appear on the surface of a tablet core without any visible disruption of the film coating. Adhesive Coating is a simple process There are various methods available for the same. It is possible to minimise conformal coating cracking effects by Lowering the initial cure temperature Allowing an initial drying time at room temperature before exposure to elevated temperature Reducing the coating thickness to avoid CTE mismatch issues Select a coating with a wider temperature range performance. As progressing technology allows faster production speeds, static related problems are also increasing, hampering production and affecting product quality. The plasticizers that make films soft, also make them very impressionable. Causes and Remedies of Chipping/ Edge Erosion. Entrapment of gases or vapor in or under the film due to overheating either during spraying or at the end of the coating. It is defect of film coating whereby volcanic-like craters appears exposing the tablet surface. Your email address will not be published. Also, I liked your pictures. Add alcohol or use spray nozzle capable of finer atomization. Scrape or sand substrate to remove wrinkled coating. Be aware that the use of defoamer, being an approach that cannot always be prevented, increases the risk of cratering , as well as reduction in Peel adhesion values. It is a coating defect where tablet surfaces erode as tablets tumble during the coating process. It is a coating defect where coating bridges formed across a logo or break line. Learn how your comment data is processed. Tablet cores having high friability values, worn or damaged tablet tooling (that produce flashing on the tablet edges), minor lamination problems (with the tablet cores) that exacerbate edge erosion problems, brittle film coatings that offer insufficient protection to tablet edges, excessive mechanical stress imparted in the coating process, excessive pan speed and inadequate tablet design (shape) all contribute to this overall problem. This is a typical defect when adhesive is sprayed , or coated by pickup rollers. However, the resulting hole possibly can not level out when the viscosity of the film is too high. Enter the email address you signed up with and we'll email you a reset link. First, foam bubbles can be stabilized by additives having a surfactant (soap) structure. Common Tablet Defects:Causes and Remedies, Advantages and Disadvantages of Pharmaceutical Emulsions, Problems Encountered During Trituration and Possible Solutions, Mechanisms Involved in the Mixing of Pharmaceutical Powders, Mixing of Pharmaceutical Powders in Small-Scale Operations, 9 Reasons Why Customers Choose Your Competitors Products Over Yours, Common Medical Abbreviations and Their Meaning, Understanding the Various Types of Hepatitis Virus, Six Reasons for the Importance of Primary Care for the Elderly, National Agency for Food & Drugs Admin & Control, Journal of Pharmaceutical Development and Industrial Pharmacy, Coated product performance and functionality, Processing efficiencies and manufacturing costs, Optimizing spray rate and/or drying air temperatures and volumes to achieve better atomization of the coating liquid and improve drying, Thinning of coating solution with additional solvent to reduce viscosity and thus improve atomization. At first, the use of surfactants should be minimized. You can download the paper by clicking the button above. Examples of suspension (Chemistry, Food & Pharmaceuticals), Difference between Drug Design and Drug Development, Tablet Compression Machine: Types, Functional Parts, List of tablet coating defects and remedies, 7. Academia.edu no longer supports Internet Explorer. Larger the tablets and the denser the core formulation. Decrease in viscosity of coating suspension. When air temperature is too high, droplets lose more solvent and dry out before they can flow and level properly. Excessive foaming of the coating solution. High molecular weight polymeric blends or polymers. Use coating formulation with increased hiding power. Pan loading with insufficient amount of core tablets. Refurbishing or replacement of damaged/worn tooling. The use of surfactants in adhesive formulation will avoid pinholes to appear on the dry paint film. This manifests in aerosol or spray gun application where the coating is applied too far away from the substrate and the coating is too "dry" on the surface to level out. Static electricity is the cause of many problems encountered in the transporting and converting of film webs in today's modem machinery. Two aspects strongly dominate the formation, stabilization and release of foam. Application of higher rate of the coating solution. Inappropriate drying (inlet air) temperature. It is defect where isolated areas of film are pulled away from the surface when the tablet sticks together and then part. Chipping/ Edge Erosion: a common tablet coating defect, 11. It is a coating defect in which the film either cracks across the crown of the tablet (cracking) or splits around the edges of the tablet (Splitting). Decrease the spray rate and use optimum drying conditions. These problems are, of course, totally unacceptable for products where the applied coating is a major factor in modifying drug-release characteristics. Addalcoholorusespraynozzlecapableof fineratomization. Reduction of the surface tension is required to avoid fish-eyes. Coating over contaminated surface (e.g., dirt or wax). Although some degree of roughness is always evident with film-coated tablets, coating process adjustments that might allow this characteristic to be kept to a minimum such that it is not readily visible to the naked eye include: Although the adjustments listed above may fall outside compliance with the registered process, they likely should be considered to be part of the original process design process. Insufficient film strength to provide resistance to edge damage. Dirt Pickup: Accumulation of dirt, dust particles , fiber and hair , on the adhesive film; may be a major problem. Increase spray rate and/or reduce processing temperatures. Causes and remedies of Core Erosion/ Surface Erosion. In other words, it is a defect in the films coating results in craters appearing on the tablet which in turn results in the exposure of the tablets surface. Inadequate distribution of the coating suspension. Adhesive coated during extremely hot weather or cool damp weather, which causes the adhesive film to dry faster on top than on the bottom. In other words, it is a haziness or appearance of white specks in the film coated tablet. Film webs tend to develop high charges; 30 kV to 40 kV is common. Scuffing is appeared when tablets are more sliding rather than trembling. This process-related problem may be resolved by reducing liquid application rate or increasing drying air temperature and air volume. Blisters will occur as a result of humidity testing on test panels, indicating moisture penetration through the film. Sorry, preview is currently unavailable. Useefficient andoptimum drying conditions. It is a coating defect of the film where volcanic-like craters appear on the tablet surface. SOP for Calibration of Shimadzu HPLC (Prominence i LC 2030), Column Cleaning, Regeneration and Storage of Silica Based Columns, USP 2021 (United State Pharmacopeia 44 - NF 39), Method Validation in Pharmaceutical Analysis A Guide to Best Practice, Dexamethasone: First Drug in Corona Virus. The use of air ionizers is the most common, cost effective method of controlling static charges on the film web. IRJP. 50-58. Use of sorbitol in coating formulation which causes major fall in the thermal gelation temperature of the HPMC (Hydroxy Propyl Methyl Cellulose), HPC (Hydroxy Propyl Cellulose), Cellulose ethers, and Methyl Cellulose. A neutral material will have no electric field so induction charging, particle attraction and most ESD events will not occur. During drying, the film may shrink and pull away from the sharp corners of an intagliation or bisect, resulting in a bridging of the surface. It is defect in which the film either cracks across the crown of the tablet (cracking) or splits around the edges of the tablet (Splitting). Substrate treatment is often applied to plastics prior to coating. 3. It a defect where tablets break apart during pan loading or while tumbling in the pan or during the coating process, or during unloading of the coating pan. During film formation Adhesive should transform a liquid into a closed, solid film called coating. These occurrences become especially evident in converting operations such as sheeting, bag making and die-cutting where the film is no longer under the control of the mechanical structure of the web and its transport system. Small to large broken or unbroken bubbles Broken edge craters and small blister-like spots can be caused by oil, grease or contamination on the substrate. Even when the surface energy of the substrate is relatively high, wetting may become a critical factor if highly dynamic application processes are involved. However addition of around 0.5 to 1.0 % of Defoam / Anti Foam is generally followed . Wrinkling: A rough, crinkled adhesive surface, which occurs when uncured adhesive forms a "skin.".
The resultant coating is rough with numerous areas of localized thick coatings. Use coating formulation which is less tacky. On fast-running printing presses or roller-coater application, for example, wetting must be very fast to obtain good results. Wetting becomes more critical when the surface energy of the substrate is low and/or when the surface tension of the liquid Adhesive is high. Reducing pan speed throughout the coating process (or at least until sufficient coating has been applied so that the tablets receive some protection from the applied coating). Temperature of the tablet core is greater than the melting point of the materials used in the tablet formulation. London: Pharmaceutical Press. Pin holing is one of the most common surface issues especially in sprayed application. Other possible cause of picking may include inadequate atomization, poor product movement or poor distribution of spray. 2020-22 PharmaEducation, All Rights Reserved. Causes and Remedies of Scuffing of Film-coated Tablets. Crawling can be prevented in a number of ways. (2013). Use high molecular weight of plasticizer. Lachman, L., & Liebermann, H. A. Get the Information Regarding Medicines and Diseases, Operation and Cleaning of Fluidized Bed Dryer, Ten Tips to Prevent an Accidental Overdose. Improper flash or recoat time between coats. Use of a low-grade, highly pigmented paint. These problems can be avoided by increasing the nozzle air pressure (or the atomization air volume), increasing pan speed and optimizing the uniformity of solution delivery through the spray gun respectively. A charged film of either polarity will attract to uncharged surfaces of insulators or conductors. Cleanliness of the surface for adhesion 2. Uneven surface formation -much like that of the skin of an orange -which results from poor coalescence of atomized paint droplets. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. Entrapment of gases in or underneath the film due to overheating either during spraying or at the end of the coating run. Although such problems may under many circumstances be purely cosmetic, cohesive failure of the coating certainly detracts from many of the functional qualities of the coating. Appearance is similar to that of an orange. Remington: The science and practice of pharmacy. Now, this article titled as tablet coating defects and remedies may help to solve the following questions: How was the article about tablet coating defects and remedies? Unmodified plastics, for example, are a group of materials having low surface energy. Required fields are marked *. Compatibility between the coating and the surface adhered to due to surface energies mismatch 3. Commonly flat surfaces along the edgesofcapsule-shaped tablets. But a pharmacist make it less . It is a coating defect where the film becomes chipped or worn away and dented usually at the edges of the tablet as the coating is being applied. Your email address will not be published. Especially during Gravure or Kiss roller coating , air can be brought into the adhesive . A small , dome like bulge in the coated film or a small recess in a coating film. Inadequate distribution of the coating suspension. Raising relative humidity is sometimes used to increase surface conductivity of some normally insulate materials in an effort to reduce static charging. Use film coating formula with higher solids. recessed area in a coating film with a raised area in the middle , is nothing but Fish eyes. Cracking is the term used to describe a condition in which the continuity of the film is disrupted. High degree of attrition related to the coating process. the substrate is changed from hydrophobic to hydrophilic. Use high quality adhesive which will allow good flow and appearance coat an appropriate primer before using such Adhesive over the surface. Unequal distribution of coating suspension. It is well known that defects and imperfections pre-existing on the substrate surface can be easily duplicated and magnified in the hot-dipping stage, resulting in defective coatings. Selection of different tablet core design/ surface profile. The attritional effects in the typical film-coating process cannot be overemphasized. Coating and core have different thermal expansion properties. Use coating formulation which is less tacky. The most common ionizers used in film transport systems are static bars and ionized air blowers. Coating droplets are over-dried before contacting tablet surface, increasing tablet surface roughness and filling the logo. This causes obvious quality problems in printing, coating and laminating and cleanliness problems with food, medical and pharmaceutical packaging films. Solutions to bridging involve improving film adhesion and/or reducing stress within the film, and usually require some reformation of either the tablet core or the film coating solution. Pinholes are typically larger and less abundant across a coating's surface than solvent pops. Tablet Coating techniques: Concepts and recent trends. Use proper composition with improved mechanical strength. Decrease in viscosity of coating suspension. Use a coating formula that provides enough protection from moisture. Factors that can cause orange peel effect include: 1. This article will focus on identifying the most common defects in film coating process, along with typical causes and possible solutions. Increasing viscosity of coating solution. This problem is caused by the high surface tension of the adhesive applied on a polymer surface, such as a plastic films. This defect can be so severe that the monogram or bisect is completely obscured. It is a coating defect where the surface of the applied film coating is extremely rough and nonglossy, often taking on the appearance of the skin of an orange. Cure temperature too high Conformal coating heat cured too quickly without allowing enough time for room temperature (RT) drying Film thickness too great causing coefficient of thermal expansion (CTE) mismatch and cracks occurring in the coating Operating temperature too high or too low causing the conformal coating to flex too much & crack. Adjusting the type and concentration of plasticizer. Causes and Remedies of Sticking and Picking. Less protection by film from moisture during storage. A huge amount of time and money is invested in preventing and resolving defects. Pan fill with sufficient amount of core tablets. Pharmaceutics: The science of dosage form design. Foam can already be present in the adhesive before application starts. Entrapment of gases or vapor in or under the film due to overheating either during spraying or at the end of the coating. Details discussion on the tablet coating problems and remedies: It is local detachment of film from the substrate forming blister. A coated defect characterized by a ring like blotch with a light colored area in the center of the ring. Discuss some common tablet coating problems and solutions. Pan loading with insufficient amount of core tablets. Foam and Bubble formation because of air spraying of a polymer solution. Precipitation of coating polymer due to use of a poor solvent or high coating temperature. Increase the hardness of the film by increasing the molecular weight of the coating polymer. Precipitation of coating polymer due to use of a poor solvent or high coating temperature. Reduce coating solids to facilitated equal coating distribution. Finally, the rheology of the system should be such that the air that was introduced can escape in a short period of time during the first stage of film formation. Under static conditions, the contact angle Q of a liquid drop placed on a given substrate determines whether wetting is good or poor. Use lower molecular weight polymeric blends or polymers. The problem is commonly seen with nutraceutical products. This could be that the flash off zone before heat curing is inadequate or the oven profile is incorrect. coating of top coat of adhesive to insufficiently cured primer. Low the viscosity of the coating solution. Peeling refers to the formation of uneven or rough irregularities on the surface of a coating film applied on a core tablet surface. As a matter of fact a temp gradient setting is essential. In doing so, legibility of the logo can be significantly reduced. Fish-eyes can be caused by oily spots or silicone particles and/or by air-borne droplets that are deposited on the coated surface. It is a coating defect where part of film of tablets momentarily stick together or stick to the pan, often just after they pass through the spray zone, and then sticked area being detached from the tablet surface. This condition relates to inadequate spreading of coating solution before drying thereby causing a bumpy or orange peel effects on the coating. Required fields are marked *. This allows the entire thickness of the wet adhesive film warm up uniformly. Peeling: Loss of bond due to poor adhesion. In other words, it is the fading or dulling of a coated tablet color after a prolonged period of storage at a high temperature. Campbell, Myers d surfaces interfaces and colloids principles and appl, Durable and flexible graphene composites based on artists paint for conductive paper applications, Robust Fluorine-Free and Self-Healing Superhydrophobic Coatings by H 3 BO 3 Incorporation with SiO 2 Alkyl-Silane@PDMS on Cotton Fabric, ATMOSPHERIC PLASMA TREATMENTS IN CONVERTING AND TEXTILE INDUSTRIES. Insufficient plasticization or too much pigmentation. Causes and Remedies of Orange Peel (Roughness). Process conditions such as low spray rates coupled with excessive drying conditions (high processing temperatures and airflows) and use of excessive atomizing air pressures (for air-spray systems) which accentuate premature drying of the droplets of coating liquid are likely to cause this inherent roughness to become visible. Because of the catastrophic nature of film cracking, the most effective approaches involve designing tablet core formulations that minimize or eliminate the risk of significant expansion behaviour occurring and creating film-coating formulations that are flexible enough to withstand any tablet core expansion that might occur. After being flattened in temper rolling, these areas reflect light differently, appearing as either dark or bright spots depending on the lighting condition. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. In other words, it is a haziness or appearance of white specks in the film coated tablet. While cohesive failure is often associated with brittleness of the coating, the problem is certainly exacerbated by thermal expansion effects particularly when significant differences exist between the thermal expansion coefficients for the core and coating, respectively. It is a coating defect where tablets stick together especially when two tablets stick together. Read Also: Common defects in sugar-coated tablets. Please feel free and leave your comments regarding tablet coating defects and remedies. It is a coating defect where the engraved logo or break line filled with either particle of dried polymer or solidified foam. Methods such as modifying the surface of the material to give it some degree of conductivity or the use of air ionization must be employed. Adhesive might be too viscous ( high viscosity ) Or The coating nip is too tight solvent evaporation too fast Origin and Potential Causes: Improper gun adjustment and techniques. Higher internal stresses in the film than the tensile strength of the film. Because tablet edges are often exposed most to these attritional effects, fracture at this point is not uncommon and results in parts of the tablet surface being chipped and dented. Selecting coating formulations with increased mechanical strength and/or increased film flexibility. In some cases the substrate must be modified in such a way that the surface energy of the substrate is raised, i.e. If first coats of enamel are allowed to become too dry, solvent in the paint droplets of following coats will be absorbed into the first coat before proper flow is achieved. Low the viscosity of the coating solution. As more coating is applied to tablet surfaces, the stresses that develop within the coating as it dries overcome the forces of attachment of the coating to the tablet surface, causing the coating to pull away within the logo or break line, making either less visible.
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