6 -1 6 Adhesion Testing 6.1 Fundamentals of Adhesion 6- 1 6.2 Standardization of Adhesion Tests 6- 3 6.3 Delamination Procedures 6- 4 6.4 Local Debonding Systems 6- 7 6.5 Flaw Detection Methods 6- 10 6.6 Outlook 6- 12 References 6- 13 6.1 Fundamentals of Adhesion Without sufficient adhesion, a coating of otherwise excellent properties in terms of resistance to weather, chemicals, scratches, or impact would be rather worthless. It is therefore necessary to provide for good adhesion features when paint materials are formulated. There must also be adequate means for controlling the level of adhesion strength after the coating has been spread and cured on the substrate. Moreover, methods should be available that allow for the detection of any failure in the case of the dissolution of the bond between coating and substrate, under any circumstances whatsoever. 6.1.1 Components at the Interface In chemical terms, there is a considerable similarity between paints on one side and adhesives or glues in this chapter to concentrate on the behavior of paint materials. Adhesion is the property requested in either case, though perhaps with different emphasis on its intensity, according to the intended use. Such a coating is, in essence, a polymer consisting of more or less cross-linked macromolecules and a certain amount of pigments and fillers. Metals, woods, plastics, paper, leather, concrete, or masonry, to name only the most important materials, can form the substrate for the coating. It is important, however, to keep in mind that these substrate materials may inhibit a rigidity higher than that of the coating. Under such conditions, fracture will occur within the coating, if the system experiences external force of sufficient intensity. Cohesive failure will be the consequence, however, if the adhesion at the interface surpasses the cohesion of the paint layer. Otherwise, adhesive failure is obtained, indicating a definite separation between coating and substrate. Ulrich Zorll Forschungsinstitut für Pigmente and Lacke DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Components at the Interface • Causes of Failure • Measures of Cross-Cut Test • Tensile Methods Adhesion Scratch Technique • Indentation Debonding • Impact Tests Ultrasonic Pulse-Echo System • Acoustic Emission Analysis • Knife-Cutting Method • Peel Test • Blister Method Thermographic Detection of Defects on the other (Figure 6.1). Both materials appear in the form of organic coatings; thus, it is appropriate 7 -1 7 Coating Calculations 7.1 Introduction 7- 1 7.2 Resins 7- 1 7.3 Pigments 7- 2 7.4 Solvents 7- 2 7.5 Additives 7- 2 7.6 7.7 Calculations 7- 2 7.8 Converting to a 100 Gallon Formulation 7- 4 7.9 Cost 7- 4 7.10 Coverage 7- 5 7.11 Computer Use 7- 5 Bibliography 7- 5 7.1 Introduction Coatings are defined as mixtures of various materials. The questions arise as to how much of which materials, and how do these things relate. The materials fall into four general categories, as follows: •Resins • Pigments •Solvents •Additives 7.2 Resins These are the generally solid, sticky materials that hold the system together. They are also called binders, and when in a solvent, they are the vehicles for the system. They may come as a “single-package” or “two- package” system. Single package is just the liquid resin or the resin in solvent. Two package means that an “A” part was blended with a “B” part to cause a chemical reaction. In both systems, we need to know the amount of solid resin present. This dry material divided by the total of the dry plus the solvent is frequently called a “resin solid.” With the two-package systems, we need to know not only the solids but also the ratio of these solids to form the desired film. This ratio may be designated as a simple ratio of 1 to 1. Or it may be based on 1 or 100, as 0.3 to 1, or 30 parts per hundred, or a total of 100 as 43 to 57. These ratios determine the film properties. We will also need to know the density (weight per unit volume, usually as pounds per gallon) of the resin or vehicle to help calculate volume. Arthur A. Tracton Consultant DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Formulation Weight • Formulation Volume • Formulation Density • Formulation of “Nonvolatile by Weight” • Ratio (Weight) • Pigment Volume Content (Volume) Conventions 7-2 Formulation “Nonvolatile by Volume” • Pigment to Binder Coating Calculations 7 -3 TA B LE 7.1 Paint Formulation Calculations No. Constants Calculations Material lb/gal gal/lb %NV Cost, $/lb Weight Volume Dry Weight Dry Volume #/100 gal gal/100 gal Cost/gal 1Titanium Dioxide 34.99 0.029 100 $1.15 100 2.86 100 2.86 196.00 5.6 2.25 2 Phthalocyanine Blue 12.99 0.077 100 $10.55 50 3.85 50 3.85 98.00 7.5 10.34 3Acrylic Resin Solution 9.05 0.11 50 $1.09 300 33.15 150 16.58 588.00 65.0 6.41 4Toluene 7.55 0.132 0 $0.28 20 2.65 0 0.0 39.20 5.2 0.11 5Butoxyethanol 7.51 0.133 0 $0.75 30 3.99 0 0 .0 58.80 7.8 0.44 6Methyl Ethyl Ketone 6.71 0.149 0 $0.55 30 4.47 0 0 .0 58.80 8.8 0.32 7 8 9 10 Total X X X X 530 50.97 300 23.29 1038.8 99.9 19.88 Factor = 1.96 On Total Formulation a% Nonvolatile Weight 56.60 b% Nonvolatile Volume 45.69 c Pigment/Binder Ratio 2 to 3 d Pigment Volume Content 28.81 eDensity, lb/gal 10.4 fsquare feet/gal @ 1 mil dry 733 DK4036_book.fm Page 3 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 7 -6 Coatings Technology Handbook, Third Edition TA B LE 7.2 Paint Formulation Constants Calculations No.Material lb/gal gal/lb %NV % Solvent % Water Cost, $/lb Weight Gallons Dry Wt Dry Vol #/100 gal gal/100# Cost/ 100 gal Water Solvent 1 Gloss Varnish 8.43 0.118623962 1 0 0 $0.00 75 8.896797153 75.00 8.896797153 347.76 41.25 $0.00 0 0 2Resin @ 40% in BCarbAc 8.71 0.114810563 0.4 0.6 0 $0.00 25 2.870264064 10.00 1.148105626 115.92 13.31 $0.00 0 69.55284525 3Titanium Dioxide 10.5 0.095238095 1 0 0 $0.00 95 9.047619048 95.00 9.047619048 440.50 41.95 $0.00 0 0 4Antiskin Agent 13 0.076923077 1 0 0 $0.00 0.1 0.007692308 0.10 0.007692308 0.46 0.04 $0.00 0 0 5Butyl Carbitol Acetate 10.8 0.092592593 0 1 0 $0.00 7.4 0.685185185 0.00 0 34.31 3.18 $0.00 0 34.31273699 6Cobalt Drier, 6% 17.83 0.05608525 0.5 0.5 0 $0.00 0.253 0.014189568 0.13 0.007094784 1.17 0.07 $0.00 0 0.586562328 7Lead Drier, 12% 8.5 0.117647059 0.5 0.5 0 $0.00 0.379 0.044588235 0.19 0.022294118 1.76 0.21 $0.00 0 0.878684278 8 0.00 0 0.00 $0.00 0 0 9 0.00 0 0.00 $0.00 0 0 10 0.00 0 0.00 $0.00 0 0 Total X X X X X 203.132 21.56633556 180.42 19.12960304 941.89 100.00 $0.00 0 105.3308289 Total Formulation factor = 4.63685635 cost/gal lb/gal 9.42 $0.00 % Nonvolatile weight 88.817 % Nonvolatile volume 88.701 for loss $@95$ Pigment/Binder Ratio 0.51 $0.00 wt pigment 95 wt binder 90 Pigment Volume Content 0.22 vol pigment 2.87 vol binder 10.05 vol pigment + binder % Water 0.00 VOC = 1.05 lbs/gal % Solvent 11.18 DK4036_book.fm Page 6 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 8 -1 8 Infrared Spectroscopy of Coatings 8.1 Introduction 8- 1 8.2 Principles 8- 1 8.3 8.4 Data Collection 8- 3 8.5 Data Interpretation 8- 5 8.6 Applications 8- 6 References 8- 7 8.1 Introduction Infrared (IR) spectroscopy is a most useful technique for characterizing coatings, a very cost-effective and efficient means of gathering information. If not the final answer, IR studies can point the way to other information or techniques needed to solve a problem. Ease of sample preparation is one advantage of IR. There are numerous ways of presenting the coating sample to the infrared spectrometer. The wide variety of sampling accessories or attachments, which can easily be swapped in and out of most spec- trometers, enables the study of liquids and solids under a wide range of conditions. There is large body of literature on infrared methodology, 1,2,3 and there are extensive collections of reference spectra available. Almost all components of coatings can be identified by IR; it is especially useful for polymers. IR spectroscopy can monitor changes, such as drying, curing, and degradation, which occur to coatings. Quality control of raw materials and process monitoring during coating synthesis and formulation can be done by IR spectroscopy. Most important to the identification of coatings and the study of their properties is the skill of the analytical scientist. This factor is often overlooked because the trend in analytical instrumentation in recent years has been increasing computer control and automation. Even when these systems are at hand, they have little value without a well-trained and experienced analytical scientist behind them. The individual with a coatings problem or application is well advised to seek the services of an experienced spectroscopist. 8.2 Principles The atoms of any molecule are continuously vibrating and rotating. The frequencies of these molecular motions are of the same order of magnitude (10 13 to 10 14 cycles per second) as those of IR radiation. When the frequency of molecular motion is the same as that of the IR radiation impinging on that Douglas S. Kendall National Enforcement Investigations Center, U.S. Environmental Protection Agency DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Infrared Microscopy • Imaging Separation • Transmission Spectra • Attenuated Total Depth Profiling • Other Sampling Methods Instrumentation 8-2 Reflectance (ATR) • Infrared Photoacoustic Spectroscopy and 8-8 Coatings Technology Handbook, Third Edition 38. D. Lin-Vien, N. B. Colthup, W. G. Fateley, and J. G. Grasselli, The Handbook of Infrared and Raman Characteristic Frequencies of Organic Molecules. New York: Academic Press, 1991. 39. B. J. Kip, T. Berghmans, P. Palmen, A. van der Pol, M. Huys, H. Hartwig, M. Scheepers, and D. Wienke, Vib. Spectrosc., 24, 75 (2000). 40. J. R. Ferraro and K. Krishnan, Eds., Practical Fourier Transform Infrared Spectroscopy: Industrial and Laboratory Chemical Analysis. New York: Academic Press, 1989. 41. B. Schrader and D. Bougeard, Eds., Infrared and Raman Spectroscopy: Methods and Applications. Weinheim, Germany: VCH Publishers, 1995. 42. W. Sueteka and J. T. Yates, Surface Infrared and Raman Spectroscopy: Methods and Applications. New York: Plenum Press, 1995. 43. A. M. Millon and J. M. Julian, in ASTM Spec. Tech. Publ., Anal. Paints Relat. Mater., STP 1119, 173 (1992). 44. J. K. Haken and P. I. Iddamalgoda, Prog. Org. Coat., 19, 193 (1991). 45. S. V. Compton, J. R. Powell, and D. A. C. Compton, Prog. Org. Coat., 21, 297 (1993). 46. R. L. De Rosa and R. A. Condrate, Glass Researcher, 9, 8 (1999). 47. A. R. Cassista and P. M. L. Sandercock, J. Can. Soc. Forensic Sci., 27, 209 (1994). 48. J. A. Payne, L. F. Francis, and A. V. McCormick, J. Appl. Polym. Sci., 66, 1267 (1997). 49. G. A. George, G. A. Cash, and L. Rintoul, Polym. Int., 41, 162 (1996). 50. J. L. Gerlock, C. A. Smith, E. M. Nunez, V. A. Cooper, P. Liscombe, D. R. Cummings, and T. G. Dusibiber, Adv. Chem. Ser., 249, 335 (1996). 51. A. A. Dias, H. Hartwig, and J. F. G. A. Jansen, Surf. Coat. Int., 83, 382 (2000). 52. R. J. Dick, K. J. Heater, V. D. McGinniss, W. F. McDonald, and R. E. Russell, J. Coat. Technol., 66, 23 (1994). 53. M. W. Urban, C. L. Allison, G. L. Johnson, and F. Di Stefano, Appl. Spectrosc., 53, 1520 (1999). 54. D. J. Skrovanek, J. Coat. Technol., 61, 31 (1989). 55. M. L. Mittleman, D. Johnson, and C. A. Wilke, Trends Polym. Sci., 2, 391 (1994). 56. M. Irigoyen, P. Bartolomeo, F. X. Perrin, E. Aragon, and J. L. Vernet, Polym. Degradation and Stability, 74, 59 (2001). 57. H. Kim and M. W. Urban, Polymeric Mater. Sci. and Eng., 82, 404 (2000). 58. B. W. Johnson and R. McIntyre, Prog. Org. Coat., 27, 95 (1996). 59. M. R. Adams, K. Ha, J. Marchesi, J. Yang, and A. Garton, Adv. Chem. Ser., 236, 33 (1993). 60. L. J. Fina, Appl. Spectrosc. Rev, 29, 309 (1994). 61. T. Buffeteau, B. Besbat, and D. Eyquem, Vib. Spectrosc., 11, 29 (1996). 62. N. Dupuy, L. Duponchel, B. Amram, J. P. Huvenne, and P. Legrand, J. Chemom, 8, 333 (1994). 63. M. W. C. Wahls, E. Kentta, and J. C. Leyte, Appl. Spectrosc., 43, 214 (2000). 64. J. E. Dietz, B. J. Elliott, and N. A. Peppas, Macromolecules, 28, 5163 (1995). 65. T. A. Thorstenson, J. B. Huang, M. W. Urban, and K. Haubennestal, Prog. Org. Coat., 24, 341 (1994). 66. B. W. Ludwig and M. W. Urban, J. Coat. Technol., 68, 93 (1996). 67. E. Kientz and Y. Holl, Polym. Mater. Sci. Eng., 71, 152 (1994). 68. G. C. Pandey and A. Kumar, Polym. Test., 14, 309 (1995). DK4036_book.fm Page 8 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 9 -1 9 Thermal Analysis for Coatings Characterizations 9.1 Introduction 9- 1 9.2 Characteristics 9- 1 9.3 Techniques 9- 1 9.4 Applications 9- 2 Bibliography 9- 3 9.1 Introduction The evaluation of substances and finished materials by thermal analysis will be discussed as a tool that the paint chemist can use to help evaluate coating properties. These properties are those that change as a function of temperature. 9.2 Characteristics Substances change in a characteristic manner as they are heated. Thermal analysis (TA) monitors these changes. TA procedures are generally used to characterize various substances and materials that change chemically or physically as they are heated. These changes in properties as a function of temperature have been used to help characterize the interrelationship of a coating’s composition and performance. TA methods or techniques measure changes in properties of materials as they are heated or at times cooled. A TA evaluation entails subjecting a small sample of from a few milligrams to 100 mg to a programmed change in temperature. The resulting change in property is detected, attenuated, plotted, and measured by a recording device. The instrumentation consists of an analysis module, a heating or cooling source, a measuring device, and a system for reporting the results, usually as an X – Y plot. A computer is used to program and control the procedure and analyze and store the results. 9.3 Techniques The techniques of prime importance in coatings’ characterization and analysis include differential scan- ning calorimetry (DSC), differential thermal analysis (DTA), thermogravimetric analysis (TGA), ther- momechanical analysis (TMA), and dynamic mechanical analysis (DMA). Each of these will be discussed, with examples of the information derivable from each procedure. William S. Gilman Gilman & Associates DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC . 34 .99 0.029 10 0 $1. 15 10 0 2.86 10 0 2.86 19 6.00 5.6 2.25 2 Phthalocyanine Blue 12 .99 0.077 10 0 $10 .55 50 3. 85 50 3. 85 98.00 7.5 10 .34 3Acrylic Resin Solution 9.05 0 .11 50 $1. 09 30 0 33 .15 15 0 16 .58. 2.870264064 10 .00 1. 14 810 5626 11 5.92 13 . 31 $0.00 0 69.55284525 3Titanium Dioxide 10 .5 0.095 238 095 1 0 0 $0.00 95 9.047 619 048 95.00 9.047 619 048 440.50 41. 95 $0.00 0 0 4Antiskin Agent 13 0.0769 230 77 1 0. # /10 0 gal gal /10 0# Cost/ 10 0 gal Water Solvent 1 Gloss Varnish 8. 43 0 .11 86 239 62 1 0 0 $0.00 75 8.89679 715 3 75.00 8.89679 715 3 347.76 41. 25 $0.00 0 0 2Resin @ 40% in BCarbAc 8. 71 0 .11 4 810 563