19 -6 Coatings Technology Handbook, Third Edition 19.5 Die Adjustment as It Relates to Manifold Design Precise coating weight control depends on the stability of the total system and on operator experience. Die performance will be at its best when a balance of pressure and flow is reached at the lip area. This balance is hard to define; changes in materials and rate will affect it. We can best describe this through the voice of an operator when he talks about the die being “jumpy or nervous” in one case and “lazy or unresponsive” in the other. In the case of the “jumpy” adjusting die, the pressure balance is too high; with the “lazy” one, pressure is too low. We will refer to this performance parameter as the operating window. When a die must be profiled excessively to improve end flow, the operating window will vary across the die; therefore, the die adjusting characteristics will differ (e.g., jumpy center, lazy ends). This effect is magnified in automatic control. When a die is set up at 0.010 in. opening in the center and 0.020 in. at ends to achieve balanced flow, a 3% change in opening at the ends is 0.0006 in., and in the center it is a 0.0003 in. change. As we develop more dynamic computer programs to respond faster or to predetermine a target point, uniform die response becomes very important. 19.6 Coat Weight Adjustment Base coat weight is controlled by pump and line speed. Transverse area coat weight is a function of the lip gap adjustment. It is important to remember that the pump will always deliver a given amount of fluid to the web. When the operator adjusts the lip, material is not taken away — it is only moved from one place to another. This difference between roll or knife coating and slot die coating is often overlooked by the operator. 19.7 Adhesive Selection Adhesives formulated for roll coating, in some cases, are not compatible with slot die heads. This is because roll coaters are high shear devices, whereas slot dies develop low shear. Any fluid that requires very high shear to create smoothing will not perform well on a low shear coating head. The shearing device or lip face can be modified to change shear level in two ways: changing the face-to-web gap (see the shear level, as frequent changes of adhesive and formulation are common. 19.8 Die Steel and Piping Selection Recent developments and reformulations of adhesives have led to highly corrosive or aggressive fluids. The die steel or plating must be carefully selected to ensure chemical compatibility, machinability, and reasonable cost. We find the majority of problems centering around highly acidic adhesives. A pH level of 4 will severely attack a chrome-plated die and render it unusable in a matter of 2 to 3 months. Several stainless steels offer reasonable prices and a highly corrosion-resistant makeup. 19.9 Proximity versus Contact Coating Tr aditional die designs require being pushed into the backup roll to produce even coating distribution (contact coating). Utilizing modern manifold technology, we can reduce the roll contact pressure signif- icantly and, therefore, reduce roll damage and lip wear. Most important, when this application technique is chosen, the flex lip concept can be used. In any system, it is of utmost importance to have inserts that are quickly replaceable, a lip step differential that can be easily changed, and the capability to increase the shear without having the infeed DK4036_book.fm Page 6 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Figure 19.6) and changing the face length (Figure 19.7). Provision should be made for ease of changing lip rotate into and make contact with the web and roll (Figure 19.8). Slot Die Coating for Low Viscosity Fluids 19 -9 2. The angle of contact depends on lip profile, die-to-roll gap, roll hardness, roll diameter, lip step difference, lip profile, and material spreading tendency. It is impossible to predict this angle without all these factors and in-depth experience. 3. Reduced contact pressure is necessary to reduce roll and die lip damage. 4. Because roll deflection is very hard and expensive to eliminate, a die that can be deflected or bent to conform to roll variance is required if roll deflection is a problem. It is common to use a steel roll backing up the elastomer roll to lessen the deflection problem, and with heated adhesives to help cool the elastomer roll. 5. for the best and most reproducible coating surface. 19.10.2 Lip Profiling Lip shape and the relative position of the lead and trailing wipers to each other are of utmost importance in today’s coating technology. In some cases, using today’s high technology coatings, a uniform and proper level of wiping action is required to produce satisfactory coating. As a result of the shear thinning characteristics in today’s more difficult adhesives, proper profiling and angle to attack will produce a smooth and even coating. Any variance in lip profile will create differential wiping, causing an uneven appearance. Because, with modern coating heads, uniform distribution is not a function of the lip face, we can confine the lip face to a single function — namely, creating a proper environment at lay-down. No hard data are available on lip face design as the interrelation between roll diameter, roll hardness, line speed, substrate, lip design, and adhesive viscosity characteristics come into play. There seem to be two technical camps. One group adheres to the flat, fixed wiping lip, with a differential step between the infeed lip and the wiping, or outfeed, lip. The other group tends to favor a rotating or fixed rod in the wiping area. This rod style design is as old as die coating, and several patents have been issued. 19.10.3 Die Support Design and Operation The interrelationship of die and mounting require that the two units act as one, both being equally important. Absolutely necessary to the successful operation of a slot coating head are the items in the Application and utilization of existing equipment designs will determine the best die-to-roll position. Operator convenience and the ability to view the point of laydown are very important. It is our opinion The support bed must be completely rigid and vibration-free. Any sag or bow in the die will create problems in the die-to-roll alignment. For this reason, we do not recommend that the die be supported from its ends. On heated dies, the designer must also allow for thermal growth while maintaining die straightness. 19.10.4 Support and Adjustment System Design Specifications Item 1 in Figure 19.10 : The die should be supported on precision-ground pads, with die straightness (contouring) adjustments for roll warp correction. On heated dies, insulation should be provided between die frame, and allowance made for die growth. Item 2 in Figure 19.10 : A heavy-duty rectangular tubing cross frame should be used for maintaining straightness during operation and adjustment. Item 3 in Figure 19.10 : An “X” in/out adjustment utilizing machine tool slideways, with fast air actuation and hydraulic soft stop cushions is used. A micro stop correction adjustment with dial indicator or LVDT should be provided for each end. Item 4 in Figure 19.10 : This “Y” adjustment is provided for roll axis position alignment. DK4036_book.fm Page 9 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Angle of attack of the die to roll must be pivoted around the pivot point indicated in Figure 19.8 series of design specifications indicated in Figure 19.10 and explained in Section 19.9.4. that mounting position A in Figure 19.9 is the most advantageous, and position B is the least. Slot Die Coating for Low Viscosity Fluids 19 -11 arrangement, with indicator markings in degrees. Note that the angle of attack movement is centered at the die lip (coating contact) point. 19.10.5 Die-to-Roll Positioning Flexibility and repeatability are primary requirements. Difficult adhesives, speeds, and substrates will require different setup positions, and the ability to vary the die-to-web position easily with exact repeat- ability is of prime importance. The support frame must allow in/out movement and angle of attack adjustment (see Figure 19.10). In/out adjustment will have two functions: (a) fast movement with 5 to 8 in. (130 to 200 mm) of travel, allowing lip cleaning; and (b) micro in/out to fine-tune roll-to-lot gap distance. This adjustment should allow differential end-to-end gapping. The in/out adjustment must be on a straight line, always moving directly at the roll centerline. (Pivot- style mountings are not recommended.) 19.10.6 Angle of Attack Position Adjustment To create different shear levels for proper film forming at varying speeds, the angle of attack must be adjustable. This movement should be accurate and smooth, and movement should cover about ± 5 ° . It is important that when one positioning point is adjusted, the other roll-to-die relationships remain 19.10.7 Lip Opening Setup Depending on materials and laydown, a 0.008 to 0.012 in. even lip opening gap (Figure 19.11) should be set before start-up and adjusted for proper flow and laydown after start-up. The lip opening setting adjusts coat weight thickness, not die-to-roll gap. Roll coaters will have difficulty with this, as they have traditionally used roll-to-roll gap as the coat weight adjustment. FIGURE 19.11 Lip opening setup. lip opening DK4036_book.fm Page 11 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Item 5 in Figure 19.10: This is an angle of attack positioning adjusted through a rack-and-pinion gear unaltered. Angle of attack adjustment must pivot about the point indicated in Figure 19.8. 19 -12 Coatings Technology Handbook, Third Edition 19.10.8 Die-to-Roll Gap Setup The distance from die to roll or substrate is, in general, determined by web thickness and the viscosity of the fluid to be applied. The more clearance that can be maintained, the less damage there may be due to positioning or start-up mistakes. We suggest, as a rule of thumb, that a clearance equal to the substrate thickness be set between substrate and infeed lip face. This distance may be less for materials of very low viscosity or for hard roll to lip face. 19.11 Backup Roll Design Processors and equipment manufacturers alike would like to utilize steel backup rolls to improve runout (T.I.R.) and to mitigate heat transfer problems. In some cases on lab or narrow production systems, steel rolls have been successful. In most cases, however, steel rolls are not as forgiving as an elastomer roll and therefore have not yet been accepted for production. We expect this to change as the technology matures. Elastomer rolls have improved over the past several years to allow the precise roll-to-lip conformation absolutely required for proximity coating. When specifying an elastomer roll, the following items must be carefully considered: •Runout tolerance •Release characteristics •Heat transfer •Hardness •Hardness uniformity •Roll deformation (bow) •Resistance to attack by the coating or cleaning agent We see the use of rolls covered with urethane or Viton being most evident with diameters of around 300 mm and hardness of up to 90 durometer, Shore A. Runout tolerances of 0.0005 in. and better are being achieved. The elastomer roll will be deformed by a given width web, and rolls must be provided to match web width changes. Spare rolls are also necessary, as damage often occurs. 19.12 Automatic Control 19.12.1 Die Control All commercially acceptable automatic die adjustment systems available today use flexible lip and heated does not seem to be greatly affected. The greatest confusion surrounds the effect of pure mechanical response time and how it relates to process analysis and its relation to response. All systems to date simply read the variation from target and make a corrective response. Polymer lot-to-lot differences, temperature changes, in-plant drafts, and many other factors that affect gauge have made it impossible to anticipate flow changes. Anticipation-based programs can be used in product changes, however, if known effects will happen over a relatively fixed period or on start-up. During a production run, if a variance is seen, make sure that it is not a short-term effect, gone in the time it would take to make a change. We also may want to determine the variance trend. Only after careful analysis of the problem can we make a die adjustment. The time from discovery until an adjust- ment takes effect varies from line to line, however start-up to ± 5% control, assuming the total system has reached some stability, will be 10 to 20 min, and ± 3% control in 15 to 30 min. DK4036_book.fm Page 12 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC to smooth materials. Make sure the gap is from web to lip face, as shown earlier (Figure 19.6), not from bolt arrangements (see Figure 19.12). Minor disagreements exist on details, but total overall performance 19 -14 Coatings Technology Handbook, Third Edition Thickness variations are converted to lip opening correction by increasing or decreasing power to the individual lip bolt control blocks to trim variations to a minimum. The key to the transverse thickness control is a microprocessor-based controller that is tied into the conventional computer control system. On ambient operation dies, care must be taken to isolate the heat from the Autoflex bolts from the die body. 19.12.2 Die-to-Roll Position Adjustment System The ability to repeat the original roll-to-die setup position is critical during start-ups and normal web splice coating interruption. During operation, minor changes in die position may have to be made to accommodate roll expansion, changes in adhesive viscosity and smoothability, and substrate thickness variance. An automatic posi- tioning device is available that will allow continuous adjustment, if necessary, of the web to the lip face. This is accomplished through a device similar to the Autoflex die bolt adjustment system. A heating and cooling device is installed in the manual adjustment system (U.S. Patent 3,940,221) for die-to-roll gap setup. Heating or cooling of this device will expand or contract the steel block and increase or decrease the die-to-roll gap. A usable method for monitoring smoothing must be employed and interfaced with the Autoflex computer. 19.13 Deckling Deckling may be necessary to reduce die width or to make stripe coatings. Be careful when attempting this, to make sure that shim materials are soft. We recommend Teflon/filled, Teflon/aluminum, foil/ aluminum shim stock, or soft brass. For room-temperature applications, an adhesive/foam/adhesive mounting tape works very well. does not clamp into the lip and can be changed very quickly. If excessive force is applied when the deckle is clamped into the lip, the lip will distort, causing lip wear or uneven coating at this point (Figure 19.14B). Deckling or stripe coating cannot be used in a system featuring the rotating rod lip design. 19.13.1 Air Entrapment behind Deckling When the die ends are deckled in, it is common for air to become trapped in this area. This air is slowly released, causing voids in the coating at the edges. A purge port with shutoff valve should be installed at the die ends to eliminate this problem. 19.14 Die Cleanup In most cases, it is important to change coatings or coating formulation frequently. Therefore, it is necessary to be able either to purge out the system or to clean the die completely. This holds true for the complete system, including pump filters and piping. Purging is the easiest and most common method; but extreme care is necessary to streamline all flow areas to eliminate dead areas. The opening and cleaning of a die can be an easy 30 min experience or a 3 to 4 day nightmare. Slot die designs differ greatly; some are simple two-piece designs, while others have complex assemblies. It is common to have a dual pumping and piping system, allowing quick changeover from one coating to the next, cleanup then taking place after the line is up and running. DK4036_book.fm Page 14 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC In many applications, a rake-type device may be used for stripe coating (Figure 19.14A). This device 20 -1 20 Extrusion Coating with Acid Copolymers and Lonomers 20.1 Product Considerations 20- 1 20.2 End-Use Considerations 20- 3 20.3 Processing Conditions 20- 5 20.1 Product Considerations Acid copolymers and ionomers are high-performance resins that offer adhesion, heat seal, and barrier acrylic and methacrylic acid copolymers, the two types of acid copolymer commercially available in the United States at this time. The presence of the methyl side group in the methacrylic acid copolymers results in some subtle differences between the two resin types, but they can be regarded as equivalent after allowing for the difference in molecular weight of the comonomers. For example, a 10 wt% acrylic acid copolymer is equivalent to a 12 wt% methacrylic acid copolymer in carboxyl group content. group with either sodium or zinc ions. Because the neutralization reaction results in a substantial increase in melt viscosity, it is commonly referred to as ionic cross-linking. In both acid copolymers and ionomers, the melt and solid state properties are strongly influenced by are almost 10 times stronger than the intramolecular forces in the nonpolar polyethylenes. The ionomers are distinguished by the combination of hydrogen bonding and interchain ionic forces perhaps an order of magnitude stronger than the hydrogen bonds. As a consequence, the ionomers have a wide spectrum of melt and solid state properties, including better hot tack and grease resistance than acid copolymers of equivalent acid content. With the acid copolymers, melt index and acid content are the major variables available to the resin producer. Because melt index is a measure of melt viscosity, it is related primarily to the processing characteristics of the resin. The resins now used for extrusion coating applications fall in the 5 to 15 melt index range to accommodate a broad field of processing needs. Resins with acid contents of 3 to 15% are currently available on the market. The effects of increasing acid content are as follows: • Better foil adhesion • Better hot tack Donald L. Brebner E. I. du Pont de Nemours & Company DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Foil Adhesion • Heat Seal Characteristics Melt Temperatures • Other Considerations properties markedly superior to those of conventional polyethylenes. Figure 20.1 shows the structure of Ionomers (Figure 20.2) are derived from acid copolymers by partial neutralization of the carboxyl intramolecular hydrogen bonding, as illustrated in Figure 20.3. The forces involved in hydrogen bonding 20 -4 Coatings Technology Handbook, Third Edition Hot tack strength is the ability of a heat seal to remain together when a force is applied while it is still in the molten state. This is a critical property in vertical form-fill-seal applications, in which the product is loaded immediately after the seal is made. It is also critical in any high speed packaging operation in which the package is exposed to some form of abuse before the seal has cooled. One method of measuring hot tack strength is the Du Pont spring test. A series of springs of different thicknesses and widths at the narrowest point provides varying levels of spring tension (Figure 20.5). pressure of 40 psi. The 3 sec dwell time allows an accurate measurement of the interfacial seal temperature by using a very fine thermocouple hooked up to a rapid response recorder. When the heat seal bars are released, the springs apply an instantaneous force to the seal. The separation of the 1 in. wide seal is measured to the nearest tenth of an inch. The results are plotted as the force required to obtain 20% seal separation as a function of temperature. content in comparison with LDPE. LDPE, a completely nonpolar material, has very low hot tack strength. FIGURE 20.4 Heat seal strength versus bar temperature (1 mil coatings on 30 lb kraft paper). FIGURE 20.5 Spring for Du Pont hot tack tester. 2000 1500 1000 500 Seal Separation Force, gms/in 200 220 240 260 280 9% Acid Ionomer 9% Acid Copolymers LDPE Seal Interface Temperature, °F 8" 1" 3" DK4036_book.fm Page 4 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Figure 20.6 shows how the spring is located inside the sample. The sample is heat sealed for 3 sec at a Figure 20.7 shows the hot tack characteristics of an ionomer and acid copolymers of equivalent acid 21 -1 21 Porous Roll Coater 21.1 Introduction 21- 1 21.2 Extrusion Porous Roll System 21- 1 21.1 Introduction Recent progress had been made in silicone-coated products that are curable by electron beam (EB) and products, in which the release levels range between 25 and 50 g per 25 mm wide strip, typical viscosities of the materials tested are in the range of 500 to 1000 cp at room temperature. These silicone products are manufactured by Th. Goldschmidt, in West Germany, and Lord Corporation, in Pennsylvania, and other companies. The UV products are either one-part premixed/ready-to-use materials, or two-com- ponent products that require nitrogen inerting to overcome surface smear and to achieve a complete cure at web speeds up to 30 m/min per each UV lamp. A schematic diagram of the nitrogen inerting lamp). The EB products are also premixed/ready-to-use, and as with the UV chemistries, they also require nitrogen inerting to obtain a full cure at typical web speeds of 200 m/min. The energy dosage is 21.2 Extrusion Porous Roll System 21.2.1 Development One recently developed extrusion roll coating system incorporates a slot nozzle coating head, located transferred to an adjacent “applicating roll,” which in turn, contacts the coating web for fluid transfer. The relative speed ratio between the “nozzle roll” and the “applicating roll” is approximately 1:30. Reports on trials have noted that the curable coatings possess poor shear properties and that the speed ratio between the rolls is somewhat dependent on this limitation. The shear properties can be improved by heating the rolls, but this method is not always productive, with the result that the coated web has the appearance of small blotches, 1 to 2 mm or larger, or lateral bands (chatter) of coating, rather than a smooth, uniform coating. Likewise, conventional roll coaters that contain multiple rolls experience a and dilatant characteristics. Viscosity of dilatant fluids increases with increasing shear rate, as shown in surface conditions, silicone product properties, and the method of applications. Most coating processes are able to apply these coatings between 1.3 to 1.6 g/m 2 within industry standards; however, the type of web material greatly influences the final coating weight. Our research to reexamine the current methods for applying curable silicones enabled us to develop an alternative method Frederic S. McIntyre Acumeter Laboratories, Inc. DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Development • Details and Disadvantages ultraviolet (UV). Advantages of UV and EB converting processes are shown in Table 21.1. Of these new process is shown in Figure 21.1. The UV lamps used for curing are rated at 300 W/in. (120 W/cm per approximately 2 megarads (Mrad). A schematic diagram of an EB processor is shown in Figure 21.2. adjacent to a slow speed “nozzle roll” (see Figure 21.3). The fluid is coated onto the “nozzle roll” and similar effect (see Figure 21.4). This phenomenon is associated with fluids that have poor flow properties Figure 21.5. The actual coat weight applied in either case is influenced by the web substrate material, Porous Roll Coater 21 -5 FIGURE 21.6 Porous roll coater. FIGURE 21.7 Diagram of a porous roll. FIGURE 21.8 Rotary screen printer. Web Laminating Roll Applicating Roll Web Reference Pickup to Synchronize Pump Speed to Web Speed 3-Way Valve Digital Pump Drive Filter Positive Displacement Metering Pump Supply Feed Return Feed Rotary Union Porous Roll Hopper Reservoir Cavity Outer Wall Reservoir Cavity Inner Supply Roll Single Supply Port and Rotary Union Porous Stainless Steel Sintered Metal Outer Shell Surface Preparation which Determines Application Pattern End Cap Single Width Rotary Screen Cylinder Interior Doctor Blade Printing Fluid Ink DK4036_book.fm Page 5 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC [...]... Taylor & Francis Group, LLC DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM 24 Flexography 24. 1 Introduction 24- 1 Historical Development of the Aniline and Flexographic Printing Process • The Flexo Process 24. 2 Flexo Press Systems 24- 2 End Printers • Stack Presses • In-Line Systems • Central Impression Machines 24. 3 The Most Important Flexo Deck System 24- 5 Three-Roller System (Fountain... combination with paper bag machines to permit printed paper bags to be produced in a single pass From the early 1920s until approximately 1 940 , aniline 24- 1 © 2006 by Taylor & Francis Group, LLC DK4036_book.fm Page 10 Monday, April 25, 2005 12:18 PM 24- 10 Coatings Technology Handbook, Third Edition consist of colorants (dyes or pigments), binding agents (natural resins, artificial resins, or plastics), and... Three-Roller System (Fountain Roller Color Deck) • Two-Roller or Fountainless Printing Deck 24. 4 Printing Forms or Plates 24- 7 Rubber and Photopolymer Plate Making • Printing Plate Mounting and Proofing Richard Neumann Windmöller & Hölscher 24. 5 Print Substrates and Printing Inks 24- 9 Print Substrates • Flexo Inks 24. 1 Introduction Throughout the printing industry, flexography, or flexo, has established... Module Coatings Technology Handbook, Third Edition Dual Unwind Module Laminating Roll DK4036_book.fm Page 10 Monday, April 25, 2005 12:18 PM 21-10 Coating Applicator, Hot Melt Extrusion Coating (Paper/Film) Dual Turret Rewind/Slitter Module U V Blower Module Refrigeration Unit for Hot Melt and U V Chill Rolls Hot Melt Control Console Corona Treatment Module CL-300 Series Coater Laminator (171 mm– 340 mm)... Coating • Overall Paste Coatings • Foam Coatings 22 .4 Advantages 22 -4 22.1 Introduction Not long after the introduction of multicolor printing machines, the one-color printing unit was also introduced, which through the years has found its way to a wide range of application areas such as wall cover printing, production of hard floor covering, technical coatings, artificial leather production,... of the paste • The squeegee setting with regard to the counter-pressure roller 22.3 Products The coatings that can be applied by rotary screen are discussed in Sections 22.3.1 through 22.3 .4 22-1 © 2006 by Taylor & Francis Group, LLC DK4036_book.fm Page 5 Monday, April 25, 2005 12:18 PM 22-5 FIGURE 22 .4 Screen coating line © 2006 by Taylor & Francis Group, LLC oo C ling om R W pe oll in ns er di a... Screen Coating DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM 23 Screen Printing 23.1 Introduction 23-1 23.2 Geometry of the Printing Screen 23-2 The Rotary Screen Timothy B McSweeney Screen Printing Association International 23.3 The Stencil 23-3 23 .4 Dynamics of the Squeegee 23-3 23.5 Coating Transfer 23 -4 23.6 Converting the Applied Coating 23 -4 23.7 Conclusion... porous roll coating systems, located on either Single Width Multiple Width FIGURE 21.10 Pattern printing with porous roll © 2006 by Taylor & Francis Group, LLC DK4036_book.fm Page 8 Monday, April 25, 2005 12:18 PM 21-8 Coatings Technology Handbook, Third Edition Component B Component A Hopper Hopper Material A Filter Material B Filter Return A Digital Pump Drive Positive Displacement Metering Pump...DK4036_book.fm Page 6 Monday, April 25, 2005 12:18 PM 21-6 Coatings Technology Handbook, Third Edition Standard Shell Porosity Greater Porosity Shell FIGURE 21.9 Porous roll applicator porosity porous roll having larger openings, depending on... DK4036_book.fm Page 11 Monday, April 25, 2005 12:18 PM Corona Power Supply Porous Roll Coater U V Power Supply HMHT-IMP Hot Melt Adhesive Delivery System DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM 22 Rotary Screen Coating 22.1 Introduction 22-1 22.2 Equipment 22-1 22.3 Products .22-1 F A Goossens Stork Brabant Pattern-Type Coatings • Dot Coating • Overall Paste Coatings . 24 -1 24 Flexography 24. 1 Introduction 24- 1 24. 2 Flexo Press Systems 24- 2 24. 3 The Most Important Flexo Deck System 24- 5 24. 4 Printing Forms or Plates 24- . 23- 3 23 .4 Dynamics of the Squeegee 23- 3 23.5 Coating Transfer 23- 4 23.6 Converting the Applied Coating 23- 4 23.7 Conclusion 23- 4 References 23- 4 23.1 Introduction . copolymers by partial neutralization of the carboxyl intramolecular hydrogen bonding, as illustrated in Figure 20.3. The forces involved in hydrogen bonding 20 -4 Coatings Technology Handbook,