Film Defects,
`
`Obvious defects can result from incomplete coverage during application of a coating,
`resulting in thin spots or holes, often called skips or holidays. Many other types of
`defects and imperfections can develop in a film during or after application. In this
`chapter we deal with the most important defects and to the extent possible, discuss the
`causes of the defects and approaches for eliminating or minimizing their occurrence-
`Unfortunately, the nomenclature for many defects is not uniform. Reference ll] provides
`definitions for coating terms, including those for film defects.
`
`24.1 . SURFACE TENSION
`
`
`
`Many defects are related to surface tension phenomena. Surface tension occurs because _;
`the forces at an interface of a liquid differ from those within the liquid, due to the unsym-
`metrical force distributions on the surface molecules. The surface molecules possess-
`higher free energy, equiva nt to the energy per unit area required to remove the-
`
`surface layer of moleculesfihe dimensions of surface tension are force exerted in the
`
`surface perpendicular to a line; SI units are newtons per meter or millinewtons per
`meter {mN m").
`[Older units,
`still commonly used, are dynes per centimeter
`(I mN in" = l dyne crn”').]
`imilar surface orientation effects are present in solids,
`which have surface free ener
`s expressed in units of free energy per unit area, rnillijoules
`per square meter (ml rn"2) that are numerically and dimensionally equal to mN nfl.
`Frequently, people speak of the surface tension of the solids; although not formally
`correct, errors do not result, because the values are identical. Reference {2} is an excellent
`discussion of surface and interfacial properties, including data on many polymers.
`
`Organic Coatings: Science and Technology. Third Edition, by Zeno W. Wicks, }r., Frank N. Jones,
`S. Peter Pappas, and Douglas A. Wicks
`Copyright (C) 2007 John Wiley & Sons, lnc.
`
`490
`
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:43)(cid:16)(cid:25)
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`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:44)(cid:16)(cid:20)
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`#
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`L}: DH QC!-1.:-If'gg_‘
`
`fi_m-.L;¢-
`
`Declaration of Robert A. Iezzi, Ph.D.
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`APPENDIX I-2
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:44)(cid:16)(cid:21)
`
`
`
`Wavelock
`
`
`
`
`
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`
`
`
`
`
`
`
`
`
`Exhibit 1017
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`Page 153
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`
`104
`
`CAM
`
`CAM.
`
`See Psocsssme, COMPUTER CONTROL.
`
`CAOUTCHOUC.
`
`See RUBBER, NATURAL.
`
`CAPROLACTAM POLYMERS.
`
`See POLYAMIDES.
`
`CARBAMATES, POLYMEREC.
`
`See POLYURETHANES.
`
`CARBANSONIC POLYMERIZATION.
`F'OL.Yl¥‘IERlZA'l‘lON.
`
`See Amomc
`
`CARBOCATIONIC POLYMERIZATION.
`CATIONIC POLYMERIZATIQN.
`
`See
`
`CARBODI IMIDES, POLY-.
`POLYMERS.
`
`See ISOCYANATE-DE.RlV'E‘.D
`
`CARBOHYDRATES.
`
`See PQLYSACCHARIDES.
`
`CARBON
`
`Carbon is a nonrnetallic element occurring in the native state
`and is also obtained industrially in varying states of order and
`purity. Unlike the other two forms of elemental carbon, dia~
`mond and graphite, carbon black is not found in the native
`state; it has been synthetically produced for several millennia.
`Carbon black is the generic name for the family of materials
`consisting essentially of elemental carbon in the form of sphe-
`roidal colloidal particles and coalesced particle aggregates of
`colloidal size obtained by the thermal decomposition of hydro-
`carbons. Carbon black is the only form of carbon that is used
`
`extensively in polymersj
`
`CARBON Bi.ACl(
`
`Properties
`
`Morphology and Microstructure. With the exception of coarse
`thermal carbon, carbon blacks rarely exist as individual sphe-
`
`roidal particles. Instead, particles exist in c
`aggregates forming a coherent unit. The carb=
`also referred to as a domain or nodule, consi
`imperfect graphitic layer planes.
`Surface Area. Surface area is inversely 1-:
`size for smooth-surface carbon blacks and aft
`ance of carbon-blackwfilled polymers. Surfat
`erally determined by nitrogen adsorption 2
`standard test method.
`Surface Activity and Chemistry. The surface
`black is a function of the degree of heterogem
`surface and the nature and number of che
`
`groups on the edges of the graphitic layer pl
`carbon content ranges from ca 80 to +99 wt
`the manufacturing process and the aftertrea
`The interaction between carbon black ant
`
`physical or chemical in nature, and probably”
`are frequently involved. The microstructure
`inant factor in the interaction with most ela
`
`Manufacture
`
`Carbon black has been produced by five proc-
`impingenient, acetylene, thermal, and furna
`furnace process is the dominant worldwide r
`
`Economic Aspects
`
`Worldwide carbon-black capacity was estim.
`t in 1983; approximately 98% was made by th
`The US. furnace-carbon capacity represents a}
`of the world capacity.
`
`Applications
`
`In 1982, approximately 1.02 X 10“t of carbc
`sumed in the United States, 63% of which w
`products for transportation (mainly tires and
`30% in industrial rubber products (belting, i
`products} and 7% in inks, coatings, plastics,
`plications. About 93% of carbon-black prod
`elastomers, mainly to improve strength proper
`is the principal pigment in ink, and excels
`prevent damage to polymers from uv radiati
`
`Table 1. Properties of Carbon Blacks
`
`Process grade
`furnace
`rubber
`ink
`paint
`plastics
`color
`conductive
`lampblack replacement.
`other
`thermal
`larnpblack
`acetylene
`
`1983 US.
`production, 10” t
`
`954
`38
`as
`
`29
`6.8
`1.4
`13
`18
`1.6
`6.8
`
`Particle
`diameter
`d, nm
`
`1?~1 10
`18+'l0
`nine
`
`18-70
`l5~30
`69~90
`15-70
`i5U—5l}0
`lO0—l30
`35-50
`
`Porosity,
`52 of total
`surface
`
`:12
`-<8
`«<45
`
`<36
`I--35 <95
`0
`‘:75
`0
`0
`0
`
`Declaration of Robert A. Iezzi, Ph.D.
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`APPENDIX I-3
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:44)(cid:16)(cid:22)
`
`
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`Wavelock
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`Exhibit 1017
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`Adhesion Aspects of
`Polymeric Coatings
`
`by
`
`Jamil A. Baghdachi
`
`Q-fixes for 500? .
`Ca“
`61¢
`
`'
`
`-:2
`if»
`
`.;5~
`5%’
`
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:45)(cid:16)(cid:20)
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`&
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`
`F57/€2‘(/fiozz
`
`32*/‘/'65 012
`,.
`A
`.
`_
`. 0://Wigs
`2'12-7"/zzzir;/ogjtf
`
`Adhesion Aspects of
`mic Ccaiingg
`
` 0337
`
`Publisned by
`
`FEDERATION OF SOON-ETIES FOR COATENGS TECHNOLUC-fi(
`492 Nomstown Road
`Blue Bell, PA 19422-2350 USA
`
`Declaration of Robert A. Iezzi, Ph.D.
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`APPENDIX J_2
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:45)(cid:16)(cid:21)
`
`December 1996
`
`
`
`Wavelock
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`Exhibit1017
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`Table 2-Surface Tensions of Typical Solvents Used in Coatings
`
`_
`
`Solueni
`........ ..
`\sVeiLi-:1‘ ......
`Etliyienc glycni
`l"i'lip_\_’it_‘|‘aL'
`,=.;l‘y'=::il ,,,,,,,
`(}—X'_v'lCJ‘lC ....... .,
`Toluene
`nviiut}-‘i .-icctate.
`n-Btitniioi
`....... ..
`..... ..
`l\'lii'1t'Z1';1lF‘.pil.'i‘rS ,,,,
`Metliyl isuliL1i\_=l ltctnne
`Mctlizuml
`\"7\*“:bT;l’ ii::1':lii'ii;1
`ii--{)t;t2uie ........... ,.
`Lncml spitiis ..
`1i—Hex:iric- ._
`
`
`
`................. ..
`
`,,
`
`Surface Tension cly_nesi'cn_i__
`71.7
`:1
`56.0
`.301
`
`}_Q
`
`0.8 ._r
`I
`
`L‘
`
`\
`
`l
`
`*"—T
`‘en
`
`-\
`
`‘~,
`
`I
`
`I
`
`.
`non—H—bondmg
`liquids
`
`K
`
`\ \
`
`\\
`
`A
`
`\
`
`$ 0.5 -
`
`\
`
`0.4 1-
`
`O 2 _
`'
`i
`._
`
`u
`
`Hsbonding A
`liquids
`
`A
`
`A
`
`I
`40
`
`I
`50
`
`l
`60
`
`30
`
`Surface tension (niN!rn)
`
`A
`\
`A‘
`?0
`
`Al
`
`i
`
`L
`_
`
`Figure 16—Comparison of Zisman plots of H~bonding and non~H—
`bonding liquids on polystyrene. (Data taken from reference 25)
`
`
`
`Table 3-“Surface Tensions of Typical Polymers and Additives
`Used in Ccatings
`
`Surface Tension tfyneslcm
`
`.
`
`
`
`.
`
`__l_”F_’l5"‘l“’,‘.
`i\-'lui;m1inc msiii ........................................ .
`l’<iiy\~'iiiyl lmtyi';il
`l3cn:ogLmJ.1a1i'iine resin
`
`
`PM ?[he "1il1i‘3[i1}~‘lt3l]L’ :iLli]i;iiT1is.lCl,
`Epon H7
`Urea 1‘Csi11,.
`..
`l"nl)”c.~_'-.te1'i'nel:imi'iie film
`T‘nl'\‘t—ti13‘leiit: oxide tlinl MW 6,000 .
`Pol\'stv1'er1e .......... .,
`l‘ril',\"vin'_y'l L‘l1i(}l'lLiL‘
`Pnlyinethyl iiietliacryltite ..... ..
`<’w3’i.-. Suyzi FA rilkyti ............... ..
`iilfliy‘.-‘i]‘l)i ;’.L'L‘L-'li'{'
`........................... .. A. ..
`l11L‘[i}:iCi"_»-'l2ltC ............ .,
`. 3.1.6
`i-’rilyl‘nL-rtyl
`
`l’vJl}'i,ii-liLit}'l :-iciyiiitel Mn .7
`_,G[i[J
`33,7
`. 3
`ivlutiuiiciw
`PUivtetrziflutirisetEiyie <2 Mw i,l)R5
`Pi.'ii‘)"Liil1‘lL'1.'il}‘i silnxanc Mn 1,100 .
`
`
`i‘talf\'rtiimcLii<,»'1
`iimzziiie Mn 102
`
`
`
`rs
`
`..
`
`'.)1\’.';'—'i».v
`
`_._.i_.
`
`J./_
`
`
`
`
`
`Wavelock
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Exhibit1017
`
`
`
`
`
`
`
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`
`
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`Page157
`
`13
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`&
`
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`
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`
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`Declaration of Robert A. lezzi,
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`APPENDIX J-3
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:45)(cid:16)(cid:22)
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`Trends in Plastics Coatings
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`Page 1 of 12
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`Coating Plastics - Some Important Concepts from a Formulators Perspective
`
`lntrod uction
`
`Lawrence C. Van lseghern, President
`Van Technologies, Inc.
`
`In the automobile industry, the trend is to produce less expensive, lighter, and stronger components that appeal to
`the aesthetic tastes of the consumer. Appliance manufacturers produce units that have non-metallic casings and
`components that provide superior durability and function relative to their older counterparts. Composite materials
`are currently used to manufacture furniture including the use of laminate sheeting that provides the beauty and
`feel of real wood. Cassettes and enclosures are manufactured for the safe storage of static sensitive electronic
`components. Eyeglass lenses are produced and sold to wearers that are lighter, safer upon impact, and highly
`resistant to scratching. From automobiles, to appliances, to furniture, to electronics, to eyeglasses, and beyond,
`plastics represent materials that increasingly impact many facets of everyday life.
`
`Often, plastic materials will require coatings or markings to enhance their function or appeal. Designers and
`manufacturers of technical coatings routinely experience unique challenges when dealing with plastics due to
`their chemical and physical nature.
`
`This discussion will present concepts pertaining to the coating of plastics including the nature of plastic surfaces,
`wetting and adhesion, and adhesion promotion. With increased awareness of these topics, the forrnulator of
`coatings for plastic materials will be better able to design coatings having superior properties.
`
`The Nature of Plastics as Coating Substrates
`Although, the term, “plastic"' denotes materials that can be deformed, shaped, or molded, it is more common
`today to apply the term to synthetic high polymers that are thermally deformable.
`lt is also quite common to see
`references to various thermosetting polymers and synthetic composites within the context of plastic materials.
`Plastics, therefore, encompasses 21 diverse family of polymeric materials.
`
`For successful coating design, the coatings formulator must consider the physical and chemical characteristics of
`the polymer substrate or plastic surface to be coated. Surface tension, modulus. coefficient of thermal expansion,
`response to coating drying and cure, as well as the chemical structure and conformation of the polymer are just a
`few factors that influence the type of coating required for a particular application. The following will discuss
`these factors and offer some insight into their management.
`
`A. Surface Tension:
`
`Surface tension will directly influence a coating’s ability to wet out, to penetrate, and to adhere to the porous
`structure of a surface . Although plastics may be present in a porous structure (as used in filtration media), details
`discussed below will be limited to the phenomenon of wetting and adhesion and the role that surface tension
`plays.
`
`It is generally seen that the lower the surface tension, the more problematic it is to coat the surface uniformly with
`good adhesion. Within the family of plastic materials, there is a considerable range of surface tension that the
`formulator must consider when examining various types of polymers (Table 1.).
`It is also noteworthy that the
`surface tension of a given polymer or plastic material will vary upon changes in molecular weight and
`temperature. Fortunately, once the molecular weight (MW) of a polymer reaches approximately 2000 — 3000, the
`surface tension will reach within 1 dyne/cm of the surface tension at infinite molecular weight. As temperature
`fluctuates between 10° C and 50° C (normal process temperatures), the surface tension is fairly constant but is
`seen to decrease at significantly elevated temperatures. It is not uncommon to see a reduction in surface tension
`of20‘/o to 30% at 150" C for particular plastic material. Therefore, for practical considerations, the formulator
`need not be overly concerned with polymer molecular weight, but should consider any elevated process
`temperatures that may impact surface tension factors especially when applying thermoset coatings]. Table 1.
`illustrates the surface tensions of various polymers.
`
`TABLE 1. Surface Tension of Various Polymeric Materialsl
`
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
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`http://www.vtcoatings.com/plastics.htm
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`Trends in Plastics Coatings
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`Page 2 of 12
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`Surface Tension (dyne/em)@ 20° C
`
`Polymer
`
`Cellophane
`Cellulose
`Cellulose acetate
`
`Cellulose acetate butyrate
`Epoxy Resins
`Ethylcellulose
`nitrocellulose
`
`Nylon l2
`
`Nylon 6
`Nylon 6,6
`Phenoxy Resins
`Poly(2—ethyll1exylacrylate)
`Poly(acrylamide)
`Poly(ac1'yl0nitrile)
`Poly(butadiene)
`P0ly(butadiene—acryl0nitrile)
`Po ly(chl0roprene)
`P0ly(ethylacrylate)
`Pol)/(ethylene)
`Poly(etl1ylene—acrylic acid)
`Poly(ethylene—propylene)
`Poly(ethylene—propylene—hexadiene)
`Poly(etl1ylene-vinyl acetate)
`Pol}/(ethyleneterephthalic acid)
`Poly(ethylrnethac1'ylatc)
`Poly(hydroXyethylmetliacrylate)
`
`Polyfisoprene)
`Poly(methacrylonitrile)
`Poly(methylmethacrylate)
`Poly(oxyethylene)
`Poly(propylene)
`
`Pol)/(styrene)
`Poly(styrene—acrylonitrile)
`Poly(tet1‘afluoroethylene)
`Pol)/(vinyl acetate)
`Poly(vinyl alcohol)
`
`Poly(vinyl butyral)
`
`Poly(vinyl but}/rate)
`P0ly(vinyl chloride)
`Poly(vinylidene chloride)
`Poly(vinylidene fluoride)
`Polycarbonate of bisphenol A
`Polyimides
`
`Polyimines
`Polysiioxanes
`Polysulfone
`Polyurethanes
`Starch
`
`Declaration of Robert A. Iezzi, Ph.D.
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`APPENDIX K-2
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:46)(cid:16)(cid:21)
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`http://wwwvtcoatings.corn/plasticslitm
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`Trends in Plastics Coatings
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`Page 3 of 12
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`It is possible to enhance a coatings performance through chemical modification of the plastic surface. Chemical
`modification will alter the surface tension of the plastic material, and is generally done by positioning polar
`groups on the surface such as pendant hydroxyl, chloro, amino, and carboxyl groups. Notice in Table l. the
`influence that polar functionality has on surface tension. Compare, for example, the relatively high surface
`tension of epoxy resins with that of poly(propylene). These two materials will exhibit different properties with
`the same coating fluid.
`
`B. Modulus:
`The modulus characterizes the stiffness or resistance to deformation of a material. It is common to examine
`modulus through the relationship between the stress imposed on a material and the resulting strain exhibited by
`the material. A material of low modulus exhibits deformation with minimum force applied, whereas a material of
`high modulus exhibits significant resistance and is typically hard and brittle. A material having an elastic
`modulus will show relative ease in elongation with recovery, provided the elongation has not been taken to the
`break point. Figure l. iliustrates various types of materials and their stress/strain behavior. Plastic materials are
`seen to respond, typically, according to scheme “B” but higher and lower modulus plastics do occur.
`
`Figure 1.
`
`Stress
`
`
`
`A = High Modulus
`(hard, brittle)
`
`B = Med. Modulus
`(softer, yield point)
`
`C = Low Modulus
`
`(soft, elastic)
`
`Strain
`
`1n the design of quality coatings, the stress/strain behavior of the coating composition when dry and/or cured
`should be consistent with that of the substrate material. Even though this is true under ideal circumstances, it is
`often the case that: a.) high modulus coatings are applied to lower modulus substrates, b.) low modulus coatings
`are applied to higher modulus substrates.
`
`1. High modulus coatings on lower modulus substrates:
`For decorative coatings and other application, it is generally not advised to apply a coating when the
`modulus of the cured coating is substantially higher than that of the substrate as failure may occur in the
`form of cracking and/or loss of adhesion. This statement must be qualified, however, since the formulator
`must consider the range of stress imposed on the coated product or article during its specified life cycle.
`To illustrate this point, take for example the relationship of a very high modulus hardcoat composition
`used for polycarbonate and other plastic molded articles. Although the modulus of the hardcoat
`composition is significantly higher than that of the substrate, during the normal use of the coated article
`the stress imposed may never be enough to result in failure. Therefore, the formulator must balance the
`modulus of the dry and/or cured coating with that of the substrate and the expected stress that will be
`imposed on them during use.
`
`2. Low modulus coatings on high modulus substrates:
`Many applications occur where a coating composition that exhibits softness and flexibility is applied to a
`Declaration of Robert A. Iezzi, Ph.D.
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
`APPENDIX K-3
`(cid:36)(cid:51)(cid:51)(cid:40)(cid:49)(cid:39)(cid:44)(cid:59)(cid:3)(cid:46)(cid:16)(cid:22)
`
`http://wwwytcoatings.com/plastics.htm
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`Wavelock
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`Exhibit 1017
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`Trends in Plastics Coatings
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`Page 4 of 12
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`surface that is hard and brittle. Recent developments in “soft feel” urethane coatings illustrate this point
`quite well. The bulk mass of the substrate plastic material will support the dimensional stability of the
`coating and permit adequate performance in use. Under certain circumstances, low modulus coatings on
`a high modulus substrate may provide impact resistance. A good example of this behavior is seen with
`glass chemical storage containers that have a chemically resistant vinyl protective coating.
`
`C. Coefficient of Thermal Expansion:
`Plastics exhibit various coefficients of thermal expansion and it is important to consider the temperature range
`that the coated product or article will be exposed to during its life cycle. A disparity in the coefficient of thermal
`expansion between the coating and the substrate can result in poor interfacial stability as temperature fluctuates.
`It is, therefore, common to cycle coated articles through extremes of temperature. Failure, when it occurs, will
`usually take the form of checking, crazing, cracking, and loss of adhesion. Other non—fatal flaws can also occur.
`such as curl and wrinkling. Most often, problems are witnessed when a coating of high modulus and low
`coefficient of expansion is applied to a plastic of moderate to low modulus and a relatively high coefficient of
`expansion.
`
`The fonnulator should recognize that expansion in "volume is a three dimensional phenomenon. An applied
`coating at equilibrium is fixed in two dimensions by the surface area of the substrate. The third dimension is
`determined by the application thickness (Figure 2). As the temperature changes to induce expansion, the coating
`and substrate will respond accordingly. Flexible substrates and coatings usually respond to stresses by exhibiting
`curl (Figure 2a. and 2b.). In the case of more rigid substrates and hard, non—flexible coatings, differing
`coefficients of expansion will cause significant internal stress to be localized at the interface of the two layers.
`This may result in failure of the coating as shown in Figure 3.
`
`Figure 2.
`
`Coating
`
`Substrate
`
` 5
`
`-.2 ...,..-'. =.i.vi.-xix.’ —
`
`.41..
`
`.
`
`i_.-.
`
`The expansion due to applied heat under idealicircumstances will occur in three dimensions, but with thin film flexible
`substrates, a mismatch in the coefficient of thermal expansion will result in interfacial stress causing curl.
`
`a.) Case 1. The coating has a higher coefficient of thermal expansion vs. the substrate:
`
`_.ix-,s--....._]
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`2"‘
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`http://www.vtcoatings.com/plastics.htm
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`Trends in Plastics Coatings
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`
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`Figure 3.
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`Coatings of relatively higher modulus may respond to interfacial stress to the extent that any substrate thermal
`expansion will cause cracking, crazing, and loss of adhesion. Such failure may not occur until the system has been
`repeatedly cycled through extremes of temperature.
`
`I). Response to Coating Drying and Cure:
`The action of the drying and cure of a coating composition on the surface of a plastic is also very important for
`the formulator to consider.
`In many aspects, the elements presented in the previous section (Coefficient of
`Thermal Expansion) will apply to the concepts of drying and cure. This is due to the fact that shrinkage is the
`primary phenomenon to control. Coatings that are less than 100% non-volatile will experience shrinkage. Again.
`since this is a volume relationship, three dimensional forces will be active. Not only does the thickness change
`from wet thickness to dry, but stress will be imposed on the coating interface due to shrinkage forces in the plane
`of applied coating. This usually results in curl as shown in figure 2b.
`in dealing with this situation, higher solid
`coatings are preferred, soft flexible coatings work reasonably, and at times the plastic can be back coated.
`
`Curl can also occur due to the cure of a coating composition, especially if by a condensation type reaction.
`Addition reactions show better resistance to curl. Back coating on the opposite side of the plastic may be
`necessary or the plastic may need to be thicker or supported to maintain flatness.
`
`E. Chemical Structure and Conformation:
`1. Structure:
`
`As indicated above, the chemical structure of a polymer will influence the ability of a coating to wet out
`and adhere to the polymer surface uniformly. The adage that, “Like — Likes - Like” applies, however,
`many instances require coatings of dissimilar chemistry to be applied to a piastic surface. Knowledge of
`the plastic in both its structure as well as conformation will guide the formulator to successfully develop
`coatings.
`
`Polar functionality, when present in a polymer structure will promote ease in coating application. For
`example, it is typical for the formulator to find that epoxy resin products show better coating application
`properties versus polyolefin products, given the same coating formulation. The presence of polar
`functionality is especially beneficial when working with waterborne coatings. Not only does water tend
`to wet out more readily due to surface tension forces, but polar groups will promote adhesion through
`
`(cid:39)(cid:72)(cid:70)(cid:79)(cid:68)(cid:85)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:53)(cid:82)(cid:69)(cid:72)(cid:85)(cid:87)(cid:3)(cid:36)(cid:17)(cid:3)(cid:44)(cid:72)(cid:93)(cid:93)(cid:76)(cid:15)(cid:3)(cid:51)(cid:75)(cid:17)(cid:39)(cid:17)(cid:3)
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`http://wwwvtcoatings.com/plasticshtm
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`Trends in Plastics Coatings
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`Page 6 of 12
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`potential hydrogen bonding of suitable functionality of the coating polymer composition.
`
`The converse situation is also important to recognize, where polar functionality present in the chemistry
`of the coating composition will influence the performance of the final coated product. The higher the
`p