CA2264719A1 - Fluoropolymer dispersion coatings from modified thermoplastic vinylidene fluoride based resins - Google Patents

Abstract

A paint base for dispersion coatings substrates comprising an acrylic modified fluoropolymer, paints and varnishes derived therefrom, coatings derived therefrom and articles coated with said coatings are disclosed. The coatings have improved gloss, flex, crack resistance and other improved use properties.

Description

1015W0 99/01505CA 02264719 1999-02-24PCT/US98/13734FLUOROPOLYMER DISPERSION COATINGS FROM MODIFIEDTHERMOPLASTIC VINYLIIDENE FLUORIDE BASED RESINSIR 3501 NPThis application claims priority from U.S.Provisional Application Serial No. 60/051,642 filedJuly 2, 1997.EE£EJL£&LJHE_lNIENIIQNThis invention relates to compositions of matterclassified in the art of chemistry as seed polymersbased on fluoropolymers, more specifically homopolymers of vinylidene fluoride (VDF) and copolymersof vinylidene fluoride with comonomers selected fromhexafluoropropylene (HFP) tetrafluorethylene (TFE),chlorotrifluorethylene (CTFE), trifluoroethylene(TrFE), and/or vinylfluoride (VF), in combination withpolymers based on acrylic acid, acrylic acid esters,methacrylic acid and/or methacrylic acid esters(acrylic polymers), to compositions containing them,more specifically to liquid coating compositions-1-10152025W0 99/01505CA 02264719 1999-02-24PCT/U S98/ 13734containing them, and to processes for the preparationand use of the compositions containing the seedpolymers of fluoropolymers and acrylic polymers andfor the use of the fluoropolymers and acrylic polymerscombinations themselves.EACKGRQHND_£ELJ3flLJ1DHflIEEflNCoatings made through use of paint binders andpaint vehicles formulated from polyvinylidene fluoride(PVDF) polymer resins are known to provide goodsolvent resistance, chemical resistance, weatherresistance, heat stability, strength and resilience.However, there is a desire for further improvement,particularly in exterior durability in harshenvironments. In addition, the mechanism of filmformation in conventional polyvinylidene fluoride(PVDF) based dispersion coatings and the industrialconditions under which these coatings are applied leadto medium gloss coatings, typically 30 to 40 asmeasured with 60 degree gloss geometry. The nature ofconventional PVDF dispersion paints is a mixture ofdiscrete PVDF particles into a homogeneous acrylicsolution phase or discrete PVDF particles and discreteacrylic particles in an aqueous phase. These systemsmay or may not contain pigments and other additives aswell. It is known in the art that in order to developoptimum properties from this type of paint system, thePVDF and acrylic phases must mix during filmformation. In the case of coil coating, which is onecommon application of this type of coatings system,10152025WO 99/01505CA 02264719 1999-02-24PCT/U S98/ 13734film formation times of 30 to 60 seconds are typical.Short bake cycles offer little time for complete PVDFand acrylic mixing.It has been found that the formulation ofvehicles and binders for paints and varnishes from thecombinations of PVDF homo and copolymers and acrylicpolymers described more fully below provides coatingswith higher gloss levels than conventional prior artPVDF acrylic blended resin paint systems. Inaddition, the mechanical flexibility of the coatingsprovided by the present invention is improved overprior art blended systems under certain formulationand baking conditions. Accelerated ultraviolet light(UV) resistance testing by standard methods indicatesthat coatings provided by the present invention haveimproved UV resistance compared to prior art blendedresin systems as shown by improved gloss retention.ERIQB_ARIThere are numerous published patents and patentapplications worldwide which describe the use ofparticles in a latex of polyvinylidene fluoride hom-or co—polymers as seeds for the polymerization ofvarious acrylic monomers to form latices from whichaqueous based paints and other coatings materials areformed directly without isolation of the polymers fromthe latices. See, for example, U.S. Patent 5,439,980,4,946,889, 5,034,460; European Patent Applications 0670 353 A2, 0 736 583 Al, 0 360 575 A2; JapaneseApplications 6-335005 (8-170045), 4-97306 (S—2713S9),10152025W0 99/01 505CA 02264719 1999-02-24PC T/U S98/ 1 37343—355973 (5-170909), 3—l24997 (4-325509), 7~63l93 (8-259773); PCT Applications WO 95/08582, and thefollowing abstracts — Chem. Abstr. 1994: 702216, Chem.Abstr. 1993, 474687, Derwent 93: 278324, Derwent 91:329278, Derwent: 90: 317958, Derwent 87: 082345,Derwent 86: 213626, Derwent 94: 107015/13, Derwent 93:365288/46, Derwent 93: 365461/46, Derwent 96: 049627,Derwent 93: 397686, Derwent 94: 808169 and thereferences cited in these publications. None of thesepublications teach or suggest isolation of the solidsfrom the seed polymerization latex and subsequentredispersion of the recovered solids in aqueous ornonaqueous solvents to form dispersion type paints andvarnishes.There are a number of patents and publicationswhich teach dispersion type paint and varnishcompositions based on polyvinylidene fluoride polymersand copolymers physically mixed with acrylic polymers.See, for example, U.S. Patent 3,324,069, U.S. Patent4,128,519, PCT Application WO 93/13178 and EuropeanPatent Application 0 670 353 A2 and the referencescited therein. Nothing in any of these referencessuggests the improved properties provided to paint andvarnish applied coatings by the compositions of theinstant invention.DEEINIIIQNSAs used herein and in the appended claims, theterms "paint base" or "paint vehicle" comprehend thecombination of paint binder and thinner into which10152025W0 99/01505CA 02264719 1999-02-24PCT/U S98/ 13734pigment is mixed to form a paint. As used herein andin the appended claims, the term "varnish" comprehendsa liquid composition which is converted to a-transparent solid after application as a thin layer.A paint base or paint vehicle without added pigmentcan be a varnish.As used herein and in the appended claims, theterms "binder" or "paint binder" comprehend the non-volatile portion of a paint base or paint vehicle. Itholds pigment particles together and the paint film asa whole to the material on which it is applied.As used herein and in the appended claims,"thinner" comprehends the portion of paint (orvarnish) which volatilizes during the drying process.It includes any solvent (aqueous or non-aqueous).As used herein and in the appended claims,"acrylic modified fluoropolymer" ("AMF") means thesolid resin (particles or agglomerated) prepared bypolymerizing ethylenically unsaturated monomersselected from the group acrylic acid, acrylic acidesters, methacrylic acid, methacrylic acid esters andmixtures thereof in the presence of a latex ofvinylidene fluoride homo- or copolymers as describedin more detail below and isolating, if necessary, theresin from the latex resulting from its preparation.As used herein and in the appended claims"dispersion coating" means a coating where the paintbase or vehicle is made from substantially dry resin,isolated from the latex resulting from itspreparation, dissolved or suspended in thinner.l0152025W0 99/01505CA 02264719 1999-02-24PCT/US98/13734Thus, a paint base for a dispersion coating willbe one wherein the paint base will containsubstantially only resin isolated from any latex it—was initially formed in, if necessary, andsubstantially dried.SDMARX_QE_IHE_lHEENlQNThe invention provides in a first compositionaspect, a paint base or paint vehicle for dispersioncoating which comprises in an amount of from 10% to90% by weight of the dry resin content, an acrylicmodified fluoropolymer resin.Special mention is made of embodiments of thefirst composition aspect of the invention wherein thethinner for the paint base or paint vehicle issubstantially non-aqueous.Still further special mention is made ofembodiments of the first composition aspect of theinvention wherein the thinner for the paint base orpaint vehicle is aqueous based.The invention provides in a second compositionaspect a paint comprising the paint base or paintvehicle of the first composition aspect of theinvention and a pigment mixed therein.The invention provides in a third compositionaspect, a coating derived by applying a paint asdefined in the second composition aspect of theinvention or a varnish consisting essentially of apaint base or paint vehicle as defined in the firstcomposition aspect of the invention to a surface on10152025W0 99/01 505CA 02264719 1999-02-24PCT/U S98/ 13734which a coating is desired and evaporating the solventcontained in said paint or varnish.The invention provides in a fourth compositionaspect, an article of manufacture comprising anarticle having adhered on at least one surface thereofa coating as defined in the third composition aspectof the invention.The invention provides in a process aspect, aprocess for applying an improved acrylic modifiedfluoropolymer binder containing coating on a surfacewhich comprises applying a paint as defined in thesecond composition aspect of the invention or avarnish consisting essentially of a paint base orpaint vehicle as defined in the first compositionaspect of the invention to said surface andevaporating the thinner from said paint or varnish.DEIAILED_DESCRlEIIQN_QE;IfiE_lNMENIlQNThe invention will now generally be describedwith reference to preferred embodiments thereof so asto enable one of skill in the art to make and usesame.The vinylidene fluoride homo- and copolymeremulsions employed as a starting material are known,as are their methods of preparation. See, forexample, Humphrey and Dohany, Vinylidene FluoridePolymers, Encyclopedia of Polymer Science andEngineering, 2nd Edition, Vol. 17, pp. 532 to 548,1232, John Wiley and Sons, and the references citedtherein. See also U.S. Patents 3,857,827; 4,360,652;10152025W0 99/01505CA 02264719 1999-02-24PCT/U S98/ 137344,569,978; 3,051,677; 3,178,399; 5,093,427; 4,076,929,-S,543,217; Moggi et al., Polymer Bulletin, 1, pp 115to 122, (1982), Bonardelli et al., Polymer, 21, pp.905-909 (1986), Pianca, et al., Polymer, 25, PP 224 to230 (1987), and Abusleme et al., European PatentAppln. No. 650,982 A1. The latices so prepared may behomopolymer PVDF or copolymer PVDF with suitablemonomers for copolymerization with VDF being selectedfrom HFP, TFE, TrFE, VF or mixtures thereof. HFP is apreferred comonomer.Up to about 30% by weight comonomer(s) may beincorporated in PVDF copolymers with from about 0% toabout 25% by weight being preferred.Seed particles having Tg less than 25°C arepreferred for this invention. Techniques forcontrolling Tg are well known in the art and are notper se part of this invention. The most common methodof control of Tg for fluorocopolymers is by control ofthe fluorocopolymer composition.It is also preferred that the seed particle sizeshould be less than 250 nm. in order to obtain a finalAMP polymer particle size of less than 350 nm.Use of emulsion or suspension polymerization invertical or horizontal reactors in batch, semi-continuous or continuous mode is contemplated by theinvention.The acrylic and methacrylic monomer that are seedpolymerized in the presence of the fluoropolymer latexare acrylic acid, acrylic acid alkyl esters,methacrylic acid and methacrylic acid alkyl esters10152025WO 99/01505CA 02264719 1999-02-24PCT/US98/ 13734wherein the alkyl group in the ester portion of themolecule is from 1 to about 10 carbon atoms, with from1 to about 4 carbons being preferred.Suitable acrylic esters include, withoutlimitation, ethylacrylate, methylacrylate,butylacrylate, propylacrylate, isobutylacrylate,amylacrylate, 2—ethylhexylacrylate, and hexylacrylate.Suitable methacrylic acid esters include withoutlimitation, ethyl methylacrylate, methyl methacrylate,butyl methacrylate, propyl methacrylate, isobutylmethacrylate, amyl methacrylate, 2-ethylhexylmethacrylate and hydroxyethyl methacrylate. Preferredmonomers are acrylic acid methacrylic acid, ethylacrylate, methyl acrylate, butyl acrylate, methylmethacrylate and glycidyl methacrylate. The acrylateand methacrylate ester monomers may be used singly orin combination.For fine tuning properties of the final formedpaint films, small quantities of other copolymerizablemonomers and/or oligomers may be copolymerized withthe acrylic and/or methacrylic acid and estermonomers. These include, without limitation,acrylonitrile, conjugated dienes, such as, 1,3-butadiene and isoprene, fluoroalkyl acrylates,fluoroacrylalkyl methacrylates, aromatic alkenylcompounds, such as, styrene, N-methylstyrene, styrenehalides and divinyl hydrocarbon compounds, such as,divinyl benzene. Reactive emulsifiers, such as thoseavailable under the tradenames, Burenna, Eliminol, NKester, may be used.10152025W0 99/01505CA 02264719 1999-02-24PCT/US98/13734The total amount of acrylic acid, acrylic esters,methacrylic acid, methacrylic acid esters or mixturesthereof should be 80% or greater, preferably 90% orgreater by weight of the total monomer mixture.The total monomer mixture for polymerization orcopolymerization in the presence of the fluoropolymerseed particles should be 10 to 200 parts by weight,preferably 20 to 80 parts by weight per 100 parts byweight of seed particles.The seed polymerization can be carried out underthe same conditions as for conventional emulsionpolymerizations. The desired acrylic and/ormethacrylic monomer(s) and a polymerization initiatorand, optionally, a surfactant, a chain transfer agent,a pH regulator, and, also optionally, eventually asolvent and a chelating agent, are added to the seedlatex, and reaction is carried out under atmosphericpressure, 0.5 to 6 hours at temperatures of 20 to90°C, preferably 40 to 80°C.The emulsion polymerization using thefluoropolymer as a seed can be performed according tostandard methods:Batch polymerization, wherein the monomer(s), theinitiator and the other ingredients, if required, areadded to the aqueous fluoropolymer dispersion from thebeginning;Semi-continuous polymerization,_wherein a part orall of one of the ingredients is fed continuously orbatch-wise during the reaction;10152025W0 99/01505CA 02264719 1999-02-24PCT/US98/13734Continuous polymerization, wherein all theingredients and the aqueous fluoropolymer dispersionare simultaneously fed into a reactor.The ingredients may be added to the reactor neat,solubilized in a suitable solvent (organic or aqueous)or as a dispersion in a suitable solvent.Use of all types of polymerization reactors(stirred tank, tubular, loop) is contemplated by theinvention. A stirred tank reactor operating in thesemi—continuous mode is preferred because of itsconvenience and flexibility.The process used to manufacture the products ofthe invention involves at least two stages. At leastone stage is required for the emulsion polymerizationof the fluoropolymer and at least one is required forthe seeded emulsion polymerization of the acrylicmonomer(s).These stages can be performed in the same reactoror different reactors. Each stage may contain itsspecific monomers, surfactant, initiator, chaintransfer agent, pH regulator, solvent and/or chelatingagents. It is preferred that the same reactor beemployed for the various stages.The final latex may be composed of dispersedparticles, homogeneous in size and composition, or ofdispersed particles having several populations of sizeand/or of composition. Latex having a homogeneouscomposition distribution of the dispersed particles ispreferred. A broad particle size distribution, or amulti-modal particle size distribution allowing10152025W0 99/01 505CA 02264719 1999-02-24PCT/US98/13734efficient packing of the particles, may be preferredto—a homogeneous particle size distribution.The final latex particles may be composed of one,two or more phases of various morphologies such assingle phase morphology, core—shell, half—moon,inverse core shell, strawberry, snow ball men,interpenetrating network and the like, all of whichare well known in the art as are the techniques ofobtaining same. The preferred morphologies arefluoropolymer cores/acrylic shells, latex particlesand homogeneous latex particles. A single phase latexparticle morphology can be obtained with misciblefluoropolymer/acrylic polymer pairs or withinterpenetrating networks.The surfactant that can be used includes anionicsurfactants, cationic surfactants, non-ionicsurfactants and amphoteric surfactants. They can beused separately or in combinations of two or more,with the proviso that obviously incompatible typescannot be combined. They can be mixed with the seedlatex, or with the monomer mixture, or in any suitablecombination with other polymerization ingredients.The anionic surfactant includes esters of higheralcohol sulfates (e.g. sodium salts of alkyl sulfonicacids, sodium salts of alkyl benzene sulfonic acids,sodium salts of succinic acids, sodium salts ofsuccinic acid dialkyl ester sulfonic_acids, sodiumsalts of alkyl diphenyether disulfonic acids).Suitable cationic surfactants are an alkyl pyridiniumchloride or an alkylammonium chloride. The non-ionic10152025W0 99/01505CA 02264719 1999-02-24PCT/US98/ 13734surfactant includes polyoxyethylene alkyl phenylethers, polyoxyethylene alkyl ethers, polyoxyethylenealkyl esters, polyoxyethylene alkyl phenyl esters,glycerol esters, sorbitan alkyl esters, andderivatives thereof. A suitable amphoteric surfactantis lauryl betaine. Reactive emulsifiers, which areable to copolymerize with the above-mentionedmonomers, can also be used (e.g. sodium styrenesulfonate, sodium alkyl sulfonate, sodium aryl alkylsulfonate). The amount of surfactant usually used is0.05 to 5 parts by weight per 100 parts by weight oftotal fluoropolymer particles.Any kind of initiator which produces radicalssuitable for free radical polymerization in aqueousmedia, for temperatures from 20 to 100°C, can be usedas the polymerization initiator. They can be usedalone or in combination with a reducing agent (e.g.sodium hydrogenobisulfite, sodium L-ascorbate, sodiumthiosulfate, sodium hydrogenosulfite). For example,persulfates, hydrogen peroxide, can be used as water-soluble initiators, and cumene hydroperoxide,diisopropyl peroxy carbonate, benzoyl peroxide,2,2'azobis methyl butanenitrile, 2,2’-azobisisobutyronitrile, 1,l'azobiscyclohexane-1-carbonitrile, isopropylbenzenehydroperoxyde can beused as oil-soluble initiators. Preferred initiatorsare 2,2'azobis methylbutanenitrile and1,1'azobiscyclohexane—1—carbonitrile. The oil-solubleinitiator could be dissolved in a small quantity ofsolvent if desired. The amount of initiator used is10152025W0 99/01505CA 02264719 1999-02-24PCT/U S98/ 137340.1 to 2 parts by weight per 100 parts by weight ofthe monomer mixture added.There are no limitations in the type of chaintransfer agents that can be used, as long as they donot excessively slow down the reaction. The chaintransfer agents that can be used include for examplemercaptans (e.g. dodecyl mercaptan, octylmercaptan),halogenated hydrocarbon (e.g. carbon tetrachloride,chloroform), xanthogen (e.g. dimethylxanthogendisulfide). The quantity of chain transfer agent usedis usually 0 to 5 parts.by weight per 100 parts byweight of the monomer mixture added.A small quantity of solvent can be added duringthe reaction in order to help swell the seed particle.The quantity of solvent added should be in such rangesthat workability, environmental safety, productionsafety, fire hazard prevention, are not impaired.The quantity of pH adjusting agents (e.g. sodiumcarbonate, potassium carbonate, sodiumhydrogenocarbonate) and chelating agents (e.g.ethylene diamine tetraacetic acid, glycine, alanine)used are 0 to 2 parts by weight and O to 0.1 per 100parts by weight of the monomer mixture added,respectively.Additional amount of surfactants or pH adjustingagents can be added to the final latex. This usuallyhelps in improving storage stability:5A further description of preferred methods ofsynthesis of AMF polymers and of the monomers whichmay be used therein is given in European Patent 0 36010152025W0 99/01505CA 02264719 1999-02-24PCT/U S98/ 13734575 B1 and Japanese Patent Application 4—97306.Isolation of the acrylic modified fluoropolymerresin from the seed polymer latex may be accomplished-by standard methods well known in the art such as,drying of the latex, coagulation by high shear mixing,centrifugation, and/or altering the ionic balanceand/or freezing followed by filtration and optionalwashing and the like.The paint base or paint vehicle composition maybe left unpigmented to form a varnish, or it may bemixed with one or more pigments to form a paint. Thesame pigments useful in other PVDF based coatings maysatisfactorily be used in the practice of the presentinvention. The pigments include, for example, thosepigments identified in U.S. Patent No. 3,340,222. Thepigment may be organic or inorganic. According to oneembodiment, the pigment may comprise titanium dioxide,or titanium dioxide in combination with one or moreother inorganic pigments wherein titanium dioxidecomprises the major part of the combination.Inorganic pigments which may be used alone or incombination with titanium dioxide include, forexample, silica, iron oxides of various colors,cadmiums, lead titanate, and various silicates, forexample, talc, diatomaceous earth, asbestos, mica,clay, and basic lead silicate. Pigments which may beused in combination with titanium dioxide include, forexample, zinc oxide, zinc sulfide, zirconium oxide,white lead, carbon black, lead chromate, leafing andnon—leafing metallic pigments, molybdate orange,-15-10152025W0 99/01505CA 02264719 1999-02-24PCT/US98/13734calcium carbonate and barium sulfate.The preferred pigment category is the ceramicmetal oxide type pigments which are calcined.Chromium oxides and some iron oxides of the calcinedtype may also be satisfactorily utilized. Forapplications where a white coating is desired, a non-chalking, non-yellowing rutile-type of titaniumdioxide is recommended. Lithopones and the like areinadequate as they suffer from lack of chalkresistance and/or from inadequate hiding. AnastaseTiO2 is similarly not recommended.The pigment component, when present, isadvantageously present in the composition in theamount of from about 0.1 to about 50 parts by weightper 100 parts of resin component. While for mostapplications the preferred range is from about 25 toabout 35 parts by weight pigment per 100 parts ofresin component, for white and light colored pigmentthe amount of pigment is generally in the higherranges of the preferred amount, and may be as high as35 parts by weight per 100 parts of resin component orhigher.Clear metallic pigmented coats will have very lowamounts by weight of pigment.As paint bases or paint vehicles, thecompositions of the invention with be in liquid form.The binder comprising the fluoropolymer resin and anyoptional other resins contained therein will be,dispersed, partially or completely dissolved in athinner which may comprise either aqueous or non-10152025CA 02264719 1999-02-24W0 99/01505 PCT/US98/13734aqueous based solvents. Such solvents may either besingle solvents or mixtures of solvents. Suitableaqueous based solvents are described in U.S. Patent‘4,128,519. Suitable non—aqueous based solvents aredescribed in WO 93/13178 and U.S. Patent 3,324,069.The solvents employed are not per se part of thisinvention and any conventional solvent or mixture ofsolvents including latent solvents conventionallyemployed in PVDF resin based paints is contemplated assuitable by the invention.Other conventional paint components, such assurfactants, dispersants, waxes, crosslinking agents,UV absorbers, flatting agents, thickeners and the likemay also be included in the paint base or paintvehicle and the paint and varnish compositions of theinvention.Standard techniques, well known to those of skillin the art, may be employed to mix the ingredientscontained in the paint base or paint vehicle and thepaint and varnish compositions contemplated by thepresent invention.The paint and varnish compositions of thisinvention may be applied to a wide variety ofsubstrates including plastics, wood, metals, ceramics,glass and the like by conventional coating methods,such as spraying, brushing, dipping, casting, knifecoating, coil coating, reverse roll coating, draw downand other methods known in the art.After application, solvent based paints andvarnishes having the resins in solution are air—dried10152025W0 99/01505CA 02264719 1999-02-24PCT/US98/13734to remove the thinner, including the solvent, atambient temperatures, 15° to 50°C, and other aqueousand non—aqueous solvent based paints and varnishes arebaked or heated to evaporate the thinner, includingthe solvent, and coalesce the coating. The heatingtemperatures will range from about 125° to about 300°C,preferably from about 175° to about 275°C. Obviouslyfor coating substrates sensitive to the highertemperature range, solvent based paints and varnisheshaving the resin totally dissolved should be employed.Although adherence of the polymer film formed ondrying the paint and varnish compositions to thesubstrate is normally more than adequate, increasedadhesion may be obtained by first priming thesubstrate surface with a compatible coating layer.For example, for wood, a useful primer is a layer ofpigmented acrylic acid ester polymer as described inU.S. Patent 3,234,039 and in U.S. Patent 3,037,881.For metal coatings, for aqueous based paint andvarnish compositions, a preferred primer layer isdescribed in U.S. Patent 3,111,426 that is an epoxybased primer. More generally, acrylic based primerssuch as described in U.S. Patent 3,526,532 and theprimers of U.S. Patent 4,179,542 based on mixtures ofpartially fluorinated halogenated ethylene polymers,epoxy resins, powdered metallic pigments and wetground mica are also useful on metalsi For coatingson glass, as well as glass cloth, glass fibers orother flexible substrates, woven or non-woven, knownadhesion promoters may be used. In particular, glass1015202530WO 99/01505CA 02264719 1999-02-24PCT/U S98/ 13734fiber may first be treated with a silane couplingagent as described by I.L. Fan and R. G. Shaw, RubberWorld, June 1971, page 56.Air drying of the solvent based paints andvarnishes of the invention having the resins insolution on substrates such as paper, glass fiber,glass cloth, and non-woven textiles may beaccomplished at ambient temperatures with dryingperiods of from about 3 to 24 hours. However, withforced air drying at about 50°C the films will dry in10 to 15 minutes. At 60°C about 5 to 10 minutes areadequate using forced air drying. After application,other aqueous and non—aqueous based systems aresubjected to heat to evaporate the thinner, includingthe solvent, and subject the polymers to coalescence.As stated above, the heating temperatures will rangefrom about 125°C to about 300°C, preferably betweenabout 175°C and 275° and most preferably between about215°C and 250°C.Alternatively, the paints and varnishes of theinvention may be cast and subjected to heating toobtain a free film of the composition. In all cases,coatings are smooth, glossy, uniform and adheretenaciously to the substrate. The films and coatingsare also hard, creep resistant (that is dimensionallystable), flexible, chemically resistant and weatherresistant. Smoke generation resistance andhydrophobicity are also provided by the films andcoatings.The following examples further illustrate thebest mode contemplated by the inventors for thepractice of their invention and should be considered-19-10152025WO 99/01505CA 02264719 1999-02-24PCT/US98/ 13734as illustrative and not in limitation thereof.The following examples demonstrate that AMFresins provide coatings with higher gloss levels than-conventional PVDF/acrylic blended paint systems. Inaddition, the flexibility of the AMP coatings areimproved over blended systems under certainformulation and baking conditions. Accelerated UVtesting indicates that the AMP based coatings havingimproved UV resistance as shown by improved glossretention as compared to blended systems.Example_1;__flhiLe_gQatifigs at 70/30 PVDF/acrvlic ratioFormulations A, B, and C were prepared containingcomponents outlined in Table I. For each formulation,the components were charged into a grinding containerand 4 mm glass beads were added to each formulation inthe amount of 1.25 times the total formulation weight.The paint formulations were milled for one hour. Thebase resin used in formulation A was an AMF containinga PVDF to acrylic weight ratio of 80/20, andformulations B and C used two different PVDFhomopolymers. Secondary acrylic resin was added toeach formulation such that all formulations were at afinal fluoropolymer to acrylic weight ratio of 70/30.Note that toluene was added only to formulation A toaccount for toluene added into formulations B and Cwith the Acryloid B—44S.CA 02264719 1999-02-2410152025W0 99/01505 PCT/U S98/ 13734Table IWeight Percent of Formulation ComponentsFormulation A Formulation B Formulation C_ Base Resin 25.6 20.5 20.5(AMFl@PVDF/ (PVDF 1) (PVDF 2)Acrylic=80/20)Ti—Pure R-960** 15.8 15.8 15.8Acryloid B-448* 9.1 21.9 21.9(40% solids intoluene)Toluene 7.7 —- --Isophorone 41.8 41.8 41.8Total 70/30 70/30 70/30F1uoropolymer/Acrylic Ratio*Copo1ymer of methyl methacrylate and ethyl acrylate (Rohm and HaasCo., Phila., PA).**Ti—Pure is a registered trademark of DuPont for their titaniumdioxide grades.A wire drawdown applicator was used to apply eachpaint to aluminum panels, and the coated panels werebaked at 525°F for 90 seconds. After baking, panelswere post treated either by immediate immersion inroom temperature water, quenched, or a secondary bakeat 140°C for 24 hours, annealed. Table II shows glossand flexibility test results for these panels. AMFformulation A has a higher gloss than both PVDFformulations B and C when quenched or annealed. Also,the high flexibility of the quenched coatings ismaintained only by formulation A. Formulations B andC both loose some degree of flexibility uponannealing. Surface SEM photos of quenched coatingsprepared from formulations A and C were examined. TheSEM photos clearly show that the AMF coating has a_ 21 -8UBS'l'|TUTESHEE'l'(RULE§§_)10152025W0 99/01505CA 02264719 1999-02-24significantly smoother surface than the PVDF/acrylicblended coating. This is also in agreement with thehigher gloss of the AMF coating.Table I IPCT/US98/13734Coating PropertiesFormulation A Formulation B Formulation C60 Degree Gloss of 68 41 45Quenched Coating60 Degree Gloss of 42 37 35Annealed CoatingT—Bend Flexibility 0eT O—T 0—Tof Quenched Coat ingT—Bend Flexibility 0—T 4-T 2-Tof Annealed CoatingE J 2_ m. . EWZCEEEE: J. .Formulations D and E were prepared containingcomponents outlined in Table III. For eachformulation, the components were charged into agrinding container and 4 mm glass beads were added toeach formulation in the amount of 1.25 times the totalformulation weight. The paint formulations weremilled for one hour. The base resin used informulation D was an AMF containing a PVDF to acrylicweight ratio of 80/20, and formulation E base resinwas PVDF homopolymer. Secondary acrylic resin wasadded to formulation E such that both formulationswere at a final fluoropolymer to acrylic weight ratioof 80/20. Note that toluene was added intoformulation D only to account for toluene added intoSUBSTTIIHESHEEHRULEE5}101520W0 99/01 505CA 02264719 1999-02-24formulation E in the Acryloid B-44S.Table IIIPCT/U S98/ 13734Weight Percent of ComponentFormulation D Formulation EResin 29.2 23.4(AMF1@PVDF/ (PVDF 2)Acrylic=80/20)Ti—Pure R-960 - 15.8 15.8Acryloid B—44S —- 14.6(40% solids in toluene)Toluene 8.8 --Isophorone 46.2 46.2Total Fluoropolymer/Acrylic 80/20 80/20RatioA wire wound drawdown applicator was used toapply each paint to aluminum panels, and the coatedpanels were baked at 525°F for 90 seconds. Afterbaking, panels were post treated either by immediateimmersion in room temperature water, quenched, or asecondary bake at 140°C for 24 hours, annealed. TableIV shows gloss and flexibility test results for thesepanels. AMF formulation D has a higher gloss thanPVDF formulation E when quenched or annealed. In thiscase, the high flexibility of the coatings ismaintained for both formulations underaboth posttreatment conditions.SUBSTlTUTESHEE|' (RULE 25)101520W0 99/01 505CA 02264719 1999-02-24PCT/US98/13734Table IVCoating PropertiesFormulation D Formulation E60 Degree Gloss of 68 34Quenched Coating60 Degree Gloss of 47 28Annealed CoatingT-Bend Flexibility of O-T O-TQuenched CoatingT-Bend Flexibility of O-T O-TAnnealed CoatingExample 3Formulations F and G were prepared containingcomponents outlined in Table V. For each formulation,the components were charged into a grinding containerand 4 mm glass beads were added to each formulation inthe amount of 1.25 times the total formulation weight.The paint formulations were milled for one hour. Thebase resin used in formulation F was an AMF containingPVDF to acrylic weight ratio of 70/30, and formulationG base resin was PVDF homopolymer. Secondary acrylicresin was added to formulation G such that bothformulations were at a final fluoropolymer to acrylicweight ratio of 70/30._ 24 -3U'5a"'mU1'E8l-iEET(RUL.‘Eg6)10152025CA 02264719 1999-02-24W0 99/01505 PCT/U S98/ 13734Table VWeight Percent of ComponentFormulation F Formulation G.Resin 29.2 20.5(AMF2@PVDF/ (PVDF 3)Acrylic=70/30)Ti~Pure R-960 15.8 15.8Acryloid B-44S -- 21.9(40% solids in toluene)Isophorone 55.0 41.8Total Fluoropolymer/Acrylic 70/30 70/30RatioOriginal 60 Degree Gloss - 56 36Quenched60 Degree Gloss of Coating 58 22after 15,000 hours of QUV-BExposurePercent Gloss Retention of 104 61Coating after 15,000 hoursof QUV-B ExposureA wire wound drawdown applicator was used toapply each paint to aluminum panels, and the coatedpanels were baked at 550°F for 90 seconds andimmediately quenched into room temperature water. Asshown in Table V, AMF formulation F gives a higheroriginal gloss than PVDF formulation G. After 15,000hours of fluorescent UV—B exposure, the AMF coatingalso maintains a higher percentage of the originalgloss.b_asss1_AMEA 100 g paint batch was prepared from Formulation_25_SUBSTITUTESHEET (RULE26)10152025W0 99/01505CA 02264719 1999-02-24PCT/US98/13734H by charging components 1 to 6, in the ratios shownin Table VI, into a grinding container with 100 g of 4mm glass milling beads. The mixture was milled for 2hours and strained through a coarse filter to removethe milling media. Component 7 and 8 were added tothe strained mixture, and the mixture was rolledslowly for approximately 2 hours. The paint wasapplied to aluminum panels with a wire wound drawdownapplicator chosen to produce 20-25 micron drycoatings. Coated panels baked at 450°F for 10 minutesproduced smooth continuous coatings. The coatingspassed 0-T flexibility testing, 100% crosshatchadhesion, and 60 inch-pounds (the maximum load whichdoes not produce substrate rupture) of direct orreverse impact without cracking.Table VI: Formulation HComponents Weight Percent1) AMP‘ Resin 44.0(VDF-HFP/Acrylic=62-8/30)2) Deionized Water 44.03) Dipropylene glycol 3.54) Tripropylene glycol methyl 3.5ether5) Ethylene glycol butyl ether 1.06) Rhone—Poulenc Col1oid® 643* 0.57) N—methyl pyrrolidinone 3.58) Dimethyl amino ethanol amount needed,to adjust pH to 8-9*= Proprietary DefoamerT-Bend formability was determined according toASTM D 4145-83 (Reapproved 1990) a Standard Test-25-SUBSTlTUTESH’EET(F-‘ULE252-10152025W0 99/01505CA 02264719 1999-02-24PCT/US98/13734Method for Coating Flexibility of Prepainted Sheet.In this test, prepainted coated panels are bent 180°around progressively more thicknesses of metal orlarger diameter dies, the end point being whenfailures no longer occur. The panels are examined atlow magnification (5 to 10x) after each bend forfracture of the coating (cracking) and, for loss ofadhesion (pickoff), by means of a tape pull off test.60° Gloss was determined according to ASTM D523-89 a Standard Test Method for Specular Gloss. Thistest measures the specular (mirror) reflectance from areference in comparison to a black glass standard.The 60° angle is used for medium gloss specimens andwas used for the specimen tests reported in thisapplication.Adhesion and impact resistance are a StandardTest Method for Measuring Adhesion by Tape Testdetermined by ASTM D 3359-90 and NCCA TechnicalBulletin II-6 a Specification for Evaluation of FilmAdhesion by "Cross Hatch" Tape Test After ReverseImpacting respectively. In the ASTM test, a latticepattern with either six or eleven cuts in eachdirection is made in the film to the substrate,pressure sensitive tape is applied over the latticeand removed. In the NCCA Technical Bulletin II-6test, the painted test sample is subjected to reverseimpact force by the Gardner Variable Impact Testerusing forces up to that required to rupture thesubstrate of the test specimen. Scotch adhesive tape#610 is applied to the deformed area, air bubbles are-27-SUBSTITUTESHEET (RULE26)10152025W0 99/01505CA 02264719 1999-02-24removed by rubbing and the specimen is allowed to setto return to room temperature (but no more than 10minutes). The tape is removed with a quick pull atright angles to the test surface._ h _ _D. . : .Table VIIComnongnts e1' crht PercentAMF Resin (PVDF/Acrylic = 80/20) 39.6Ti—Pure R-960 19.8Glyceryl tripopionate 19.8VM & P Naphtha** 19.8BYK 182 (45% active)* 1.0Total Weight Solids 59.9*BYK 182 is a dispersant from BYK—Chemie**Aliphatic hydrocarbon solvent 119°C to 139°C boiling rangeAll components were combined, charged into agrinding container with 4 mm glass grinding beads, andthe formulation was milled for one hour. Theresulting paint was a homogeneous fine dispersion withlow viscosity (<lOO0cPs). A wire wound drawdownapplicator was used to apply the paint over chromatedaluminum panels. Bake schedules of 550°F for 45seconds, 450°F for 10 minutes, and 350°F for 20 minutesall produced smooth continuous films with 100%crosshatch adhesion.In the foregoing examples, the vinylidenefluoride polymer and the acrylic modified-28-SUBSTITUTE SHEET (RULE 26)PCT/US98/1373410152025CA 02264719 1999-02-24W0 99/01505 PCT/US98/13734fluoropolymers employed in formulating the paintvehicles employed are identified as follows:PVDF polymers were all commercially available VDFhomopolymers sold by Elf Atochem North America, IncC)- Iunder the KYNAR trademark.PVDF 1 was KYNAR 500+PVDF 2 was KYNAR 500PVDF 3 was KYNAR 500AMF polymers were all based on PVDF polymerlatices synthesized in accordance with procedures usedfor commercially available PVDF polymers sold by ElfAtochem North America, Inc., under the KYNARtrademark. The AMF polymers were made as described inthe specification. The PVDF type polymer in the seedpolymer latices and the acrylic monomers and theirrelative percentages by weight are as follows:Acrylic AcrylicAME Elmiiaad Mmxmrs mmnm@LJ¢i2AMF 1 KYNAR 730 M.A./EA 70/30AMF 2 KYNAR 500 MMA/EMA/BMA so/40/1oAMF (Ex. 4) KYNAR Flex 2800 MMA/EA/MAA 65/32/3AMF (Ex 5) KYNAR 730 MMA/EA 70/30Acrylate monomer abbreviations:MMA = methyl methacrylateEA = ethylacrylateEMA = ethyl methacrylateBMA = butyl methacrylateMAA = methacrylic acid-29-SUBSTITUTESHEEHRULEBG)

Claims (8)

The subject matter which applicants regard as their invention is particularly pointed out and distinctly claimed as follows:
We claim:

1. A paint base for dispersion coating which comprises in an amount of from 10% to 90% by weight of the dry resin content an acrylic modified fluoropolymer resin.

2. A paint base as defined in claim 1 wherein the thinner in said paint base is substantially non-aqueous.

3. A paint base as defined in claim 1 wherein the thinner in said paint base is aqueous based.

4. A paint comprising a pigment mixed with a paint base as defined in claim 1.

5. A coating derived by applying a paint as defined in claim 4 to a surface on which a coating is desired and evaporating the thinner of said paint.

6. A coating derived by applying a paint base as defined in claim 1 as a varnish on a surface on which a coating is desired and evaporating the thinner of said paint base.

7. An article of manufacture comprising an article having adhered on at least one surface thereof a coating as defined in claim 5.

8. An article of manufacture comprising an article having adhered onto at least one surface thereof a coating as defined in claim 6.