MXPA99002578A - Fluoropolymer powder coatings from modified thermoplastic vinylidene fluoride based resins - Google Patents

Abstract

An improved blend suitable for powder coating comprising an acrylic modified fluoropolymer and pigment, processes for its preparation and use and coated articles produced therefrom are disclosed. Use of unpigmented acrylic modified fluoropolymers to form powder coating and objects so coated are also disclosed.

Description

COATINGS OF FLUOROPOLYMER POWDER OF RESINS BASED ON THERMOPLASTIC VINYLIDENE FLUORIDE MODIFIED FIELD OF THE INVENTION This invention relates to compositions of matter classified in the chemical art as seed polymers based on fluoropolymers, more specifically homopolymers of vinylidene fluoride (VDF) and copolymers of vinylidene fluoride with selected comonomers of hexafluoropropylene (HFP) tetrafluoroethylene (TFE) chlorotrifluoroethylene (CTFE), trifluoroethylene (TrFE) and / or vinyl fluoride (VF for its acronym in English), in combination with polymers based on acrylic acid, esters of acrylic acid, methacrylic acid and / or esters of methacrylic acid (acrylic polymers), to compositions containing them, more specifically to powder coating compositions containing them and processes for the preparation and use of the compositions containing the seed polymers of fluoropolymers and acrylic polymers and for the use of a combination of fluoropolymer and acrylic polymer Lico for themselves. BACKGROUND OF THE INVENTION There are a number of patents and publications disclosing powder coatings based on homopolymers and copolymers of PVDF made by fluoropolymer alloys with acrylics. In all cases, the fluoropolymer, acrylics and pigments are mixed by melting and the mixed product is milled by melting. See, for example, Patent of U.S.A. No. 5,346,727 and references cited therein. The present invention, avoiding the need to melt-mix the fluoropolymer, the acrylic polymer and the pigment, provides a powder coating composition that already has the desired uniform particle size or that can be comminuted to the desired relatively uniform particle size. without the need for cryogenic grinding or low temperature. There are a number of patents and patent applications published worldwide that describe the use of particles in a homo-or copolymer latex of polyvinylidene fluoride as seed for the polymerization of various acrylic monomers from which the paints Water-based and other coating materials are formed directly without isolating the lattice polymers. See, for example, US Patents. Nos. 5,439,980, 5,034,460, 4,946,889 and 5,523,346, PCT application WO 95/08582, EP 0736583A1, EP 0360575A2, Japanese applications 6-335005 (8-170045), 3-124997 (4-325509), 3-355973 (5- 170909), 4-97306 (5-271359), 7-63193 (8-259773) and the following abstracts - Chem. Abstr. 1994: 702216, Chem. Abstr. 1993, 474687, Derwent 94: 080169, Derwent 94: 062223, Derwent 93: 397686, Derwent 94: 107015/13, Derwent 93: 365288, Derwent 93: 365461, Derwent 93: 278324, Derwent 91: 529278, Derwent 87: 082345 , Derwent 86: 213626 and references cited in these publications. None of these publications teaches or suggests the isolation of solids from the seed polymerization latex and subsequent use of the solids to form powder coating compositions. The present invention provides a more economical way to prepare fused powder coatings having physical properties equal to or better than those of the prior art of powder coatings. DEFINITIONS As used herein and in the appended claims, "modified acrylic fluoropolymer" ("AMF") means the solid resin (particulate or agglomerated) prepared by polymerizing the ethylenically unsaturated monomers selected from the group of acrylic acid, acid esters acrylic, methacrylic acid, methacrylic acid esters and mixtures thereof, in the presence of a homo- or co-polymer latex of vinylidene fluoride as described in greater detail below. COMPENDIUM OF THE INVENTION The invention provides in a first aspect of the composition, an improved polymer mixture based on polyvinylidene fluoride, acrylic polymer and pigment useful for powder coatings wherein the improvement comprises the polymer based on polyvinylidene fluoride and the acrylic polymer being combined as an acrylic modified fluoropolymer. Special mention is made of tangible embodiments of the first aspect of the composition of the invention wherein the pigment is combined with the acrylic modified fluoropolymer when the modified fluoropolymer is suspended with acrylic as a latex. Special mention is made of tangible embodiments of the invention wherein the pigment combines the modified fluoropolymer with acrylic by mixing both ingredients as a dry powder. The tangible embodiments of the first aspect of the composition of the invention have the characteristic of inherent applied use of being suitable for forming powder coatings on substrates, providing good uniform coatings with uniform distribution of pigment and good adhesion while avoiding the need for step of cryogenic grinding or similar in its preparation. The invention provides in a first aspect of the process, a method for forming a composition of the first aspect of the composition of the invention which comprises dispersing the pigment in a modified fluoropolymer latex with acrylic to create a first mixture; coating the solids of the first mixture to obtain the first aspect of the composition of the invention as a powder; and, if necessary, recovering the first aspect of the composition of the invention as a powder on the desired particle size scale by a selected particle size selection process of grinding, screening or a combination of the same. .

The invention provides in a second aspect of the process, a process for the preparation of a composition of the first aspect of the composition of the invention comprising; recovering the solids of an acrylic-modified fluoropolymer latex as a coarse dry powder; if necessary converting the coarse dry powder to a powder having a desired particle size by a selected process of grinding, screening or a combination thereof; and combining said dry powder in the desired particle size with pigment particles in the desired particle size to obtain the first aspect of the composition of the invention. The invention provides in a third aspect of the process, a process for the preparation of a composition of the first aspect of the composition of the invention comprising: combining the dry resin coated with an acrylic-modified fluoropolymer latex, the resin having the size of desired particle, with pigment particles in the desired particle size. The invention provides in a second aspect of the composition, an article of manufacture comprising a substrate coated with at least one surface thereof with a coating derived from the first aspect of the composition of the invention. The invention provides in a fourth aspect of the process, a process for the preparation of a modality of the second aspect of the composition of the invention comprising applying at least one surface area of the substrate on which a coating is desired, a layer of a composition of the first aspect of the composition of the invention and making the layer to a fixed coating by the application of heat. The invention provides in a third aspect of the composition, an article of manufacture comprising a substrate having at least one surface thereof a coating derived from a fluoropolymer modified with non-pigmented acrylic. The invention provides in a fifth aspect of the process, a process for the preparation of an embodiment of the third aspect of the invention composition comprising applying a layer of a powder coating composition of fluoropolymer modified with non-pigmented acrylic to the surface of the substrate on which the coating is desired and the layer is coalesced to a fixed heat coating application. A non-pigmented acrylic-modified fluoropolymer powder coating composition means an acrylic-modified fluoropolymer or an acrylic-modified fluoropolymer prepared as described in the Description portion.

Detailed of the invention of the specification but without the pigment incorporation. DESCR I I ION DETAILS OF THE I NVENC TION The invention will now be described generally with reference to the preferred modalities thereof in a way that allows someone skilled in the art to make and use it.

The emulsions of homo- and co-polymer of vinylidene fluoride used as starting materials are known, as are their methods of preparation. See, for example Humphrey and Dohany, Vinylidene Fluoride Polymers, Encyclopedia of Polymer Science and Engineering, 2a. Edition, Vol. 17, pp. 532 to 548, 1989. John Wiley and Sons, and references cited therein. See also the Patents of E.U.A. Nos. 3,857,827; 4,360,652; 4,569,978; 3,051,677; 3,178,399; 5,093,427; 4,076,929; 5,543,217; Moggi et al., Polymer Bulletin, 7, pp. 115-122, (1982), Bonaderdelli et al., Polymer, 27, p. 905-909 (1986), Pianca, et al., Polymer, 28, p. 224-230 (1987) and Abusleme et al., European Patent Application No. 650,982 A1. The lattices thus prepared can be PVDF homopolymer or PVDF copolymer, suitable monomers VdF copolymerization being selected from HFP, CTFE, TFE, TrFE, VF or mixtures thereof. A preferred comonomer is HFP. Up to about 30% by weight of the comonomers can be incorporated into PVDF polymers to form copolymers, with more than 0% to 20% by weight being preferred. The lattices of VDF terpolymers, particularly those of VDF, TFE and HFP can also be incorporated in the latex used as starting materials for the acrylic modified fluoropolymer of the invention.

The invention contemplates the use of emulsion or suspension polymerization in vertical or horizontal batch reactors or in continuous reactors. The acrylic and methacrylic monomers that are polymerized by seeding in the presence of the fluoropolymer latex are acrylic acid, alkyl esters of acrylic acid, methacrylic acid and alkyl esters of methacrylic acid, wherein the alkyl group in the ester portion of the The molecule is from 1 to about 10 carbon atoms, with 1 to about 4 carbons being preferred. Suitable acrylic esters include, without limitation, ethyl acrylate, methyl acrylate, butyl acrylate, propyl acrylate, isobutyl acrylate, amyl acrylate, 2-ethylhexylacrylate, and hexyl acrylate. Suitable methacrylic acid esters include without limitation, ethyl methacrylate, methyl methacrylate, butyl methacrylate, propyl methacrylate, isobutyl methacrylate, amyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, and 2-ethylhexyl methacrylate. Preferred monomers are acrylic acid, methacrylic acid, ethyl acrylate, methyl acrylate, butyl acrylate and methyl methacrylate. The acrylic and methacrylic acid and ester monomers can be used alone or in combination. For the fine toning properties of the final formed coating films, small amounts of other copolymerizable monomers and / or olibers can be copolymerized with the acrylic and / or methacrylic acid and ester monomers. These include, without limitation, conjugated dienes, such as 1,3-butadiene and isoprene, fluoroalkyl acrylates, fluoroacrylalkyl methacrylates, aromatic alkenyl compounds, such as, styrene, α-methylstyrene, styrene halides, and divinyl hydrocarbon compounds. , such as divinyl benzene. Reactive emulsifiers can be used, such as those available under the trademarks Burenna, Eliminol, NK ester. The total amount of acrylic acid, acrylic esters, methacrylic acid, methacrylic acid esters or mixtures thereof should be 80% by weight or greater, preferably 90% or greater of the total monomer mixture. The total monomer mixture for the polymerization or copolymerization in the presence of the fluoropolymer seed particles should be from 10 to 200 parts by weight, preferably from 20 to 100 parts by weight per 100 parts by weight of seed particles. Seed polymerization can be carried out under the same conditions as for conventional emulsion polymerizations. The desired acrylic and / or methacrylic monomers and a polymerization initiator and, optionally, a surfactant, a transfer agent, a pH regulator, and, optionally optionally, a solvent and a chelating agent, are added to the latex Sowing and the reaction is carried out under atmospheric pressure of 0.5 to 6 hours at temperatures of 20 to 90 ° C, preferably 40 to 80 ° C.

The emulsion polymerization using the fluoropolymer as seed can be carried out according to standard methods: Batch polymerization, wherein the monomers, the initiator and the other ingredients, if required, are added to the aqueous fluoropolymer dispersion from the start; Semi-continuous polymerization, wherein a part of all of one of the ingredients is continuously fed as a batch during the reaction; Continuous polymerization, wherein all the ingredients and the aqueous fluoropolymer dispersion are simultaneously fed into a reactor. The ingredients can be added to the pure reactor, solubilized in a suitable solvent (organic or aqueous) or as a dispersion in a suitable solvent. The use of all types of polymerization reactors (stirred tank, tubular, in cycles) is contemplated by the invention. A stirred tank reactor operating in semi-continuous mode it is preferred due to its convenience and flexibility. The process used to manufacture the products of the invention involves at least two stages. At least one step is required for the polymerization of the fluoropolymer emulsion and at least one is required for the polymerization of the sown emulsion of the acrylic monomers. These steps can be carried out in the same reactor or different reactors. Each stage can contain its specific monomers, surfactants, initiator, chain transfer agent, pH regulator, solvent and / or chelating agents. It is preferred that the same reactor be used for the various steps. The final latex may be composed of dispersed particles, homogeneous in size and composition or dispersed particles having several populations of size and / or composition. Latex having a homogeneous composition distribution of the dispersed particles is preferred. A broad particle size distribution or a multi-modal particle size distribution that allows efficient packing of the particles may be preferred for a homogeneous particle distribution. The final latex particle may be composed of one, two or more phases of various geometries such as homogeneous particle, core cover, incomplete core cover, reverse core cover, half moon, strawberry, interpenetrating lattice, etc. All these geometries and morphologies are well known in the art. The preferred morphology is the homogeneous particle. The active agent ten that can be used includes anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants. They can be used separately or in combinations of two or more, as long as obviously incompatible types can be combined. They can be mixed with the seed latex or with the monomer mixture, or in a suitable combination with other polymerization ingredients. The anionic surfactant agent includes higher alcohol sulfate esters (e.g., sodium salts or alkyl sulfonic acids, sodium salts of sulfonic acids of benzene, sodium salts of succinic acids, sodium salts of sulfonic acids of dialkyl esters of succinic acid; sodium salts of disulfonic acids of alkyl diphenylether). Suitable cationic surfactants are an alkyl pyridinium chloride or alkylammonium chloride. The nonionic surfactant includes polyoxyethylene alkyl phenyl esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl phenyl esters, glycol esters, sorbitan alkyl esters and derivatives thereof. A suitable amphoteric surfactant is lauryl betaine. Reactive emulsifiers, which are capable of copolymerizing with the aforementioned monomers, (e.g., sodium styrene sulfate, sodium alkyl sulfate, sodium alkyl aryl sulfate) can also be used. The amount of surfactant usually used is 0.05 to 5 parts by weight per 100 parts by weight of the total fluoropolymer particles. Any kind of initiator which produces radicals suitable for the polymerization of free radicals in aqueous media, for temperatures of 20 to 100 ° C, can be used, such as the polymerization initiator. They can be used alone or in combination with a reducing agent (e.g., sodium acid bisulfite, sodium L-ascorbate, sodium thiosulfate, sodium acid sulfite). For example, persulfates, hydrogen peroxide, can be used as water-soluble initiators and eumenohydroperoxide, diisopropyl peroxydicarbonate, benzoyl peroxide, 2,2'-azobis methylbutanonitrile, 2,2'-azobisisobutyronitrile, 1, 1 'azobi sci clohexnao-1-carbon itri lo, isopropylbenzenehydroxy peroxide can be used as oil-soluble initiators. Preferred initiators are 2,2'-azobis methyl butanonitrile and 1,1'-azobiscyclohexane-1-carbonitrile. The oil-soluble initiator can be dissolved in a small amount of solvent if desired. The amount of initiator used is 0.1 to 2 parts by weight per 100 parts by weight of the aggregate monomer mixture. There are no limitations on the type of chain transfer agents that can be used, as long as they do not excessively decelerate the reaction. Chain transfer agents that can be used include, for example, mercaptans (e.g., dodecyl mercaptan, octyl mercaptan), halogenated hydrocarbon (e.g., carbon tetrachloride, chloroform), xanthogen (e.g., dimethylxanthogen disulfide). The amount of chain transfer agent used is usually 0 to 5 parts by weight per 100 parts by weight of the aggregate monomer mixture. A small amount of solvents can be added during the reaction in order to help the seed particle to sponge. The amount of solvent added should be at such scales so that manipulation, environmental safety, production safety, fire hazard prevention are not damaged. The amount of pH adjusting agents (eg, sodium carbonate, carbonate) of potassium, sodium acid carbonate) and chelating agents (e.g., ethylene diamine tetraacetic acid, glycine, alanine) used is 0 to 2 parts by weight and 0 to 0.1 per 100 parts by weight of the mixture of monomers added, respectively. Additional amounts of surfactants or pH adjusting agents can be added to the final latex. This usually helps to improve storage stability. The isolation of the fluoropolymer resin modified by latex polymer latex acrylics can be achieved when desired by the normal methods well known in the art such as latex drying, coagulation by high shear mixing, centrifugation and / or alteration of the ionic balance and / or freezing followed by filtration and optional washing and the like. If it is desired to combine the pigment with the latex prior to the isolation of the modified acrylic fluoropolymer from the latex, it can be mixed by standard methods known to be suitable for this purpose, such as suspending the pigment particles in water and adding the suspension to the latex. with careful agitation to induce complete, uniform mixing. The pigment can also be dry mixed with the modified acrylic fluoropolymer after the last isolation of the latex. The same pigments useful in other coatings based on PVDF can be successfully used in the practice of the present invention. The pigments include, for example, those pigments identified in the U.S. Patent. No. 3,340,222. The pigment can be organic or inorganic. According to one embodiment, the pigment may comprise titanium dioxide or titanium dioxide in combination with one or more inorganic pigments wherein the titanium dioxide comprises the main part of the combination. Inorganic pigments that can be used alone or in combination with titanium dioxide include, for example, silica, iron oxides of various colors, cadmium, lead titanate and various silicates, for example, talc, diatomaceous earth, asbestos, mica, clay and basic lead silicate. The pigments that can be used in combination with titanium dioxide include, for example, zinc oxide, zinc sulphide, zirconium oxide, white lead, carbon black, lead chromate, metal pigments in films or without films, orange molybdate, calcium carbonate and barium sulfate. The preferred pigment category is the ceramic-type metal oxide pigment that is calcined. Chromium oxides and some iron oxides of the calcined type can also be used satisfactorily. For applications where a white coating is desired, a non-yellowish type of rutile that is not sprayed with titanium dioxide is recommended. Lithophones and the like are unsuitable as they suffer from lack of resistance to spraying and / or inadequate concealment. Anastase TiO2 is similarly not recommended.

The pigment component, when present, is advantageously present in the composition in the amount of from about 0.1 to about 50 parts by weight per 100 parts of resin component. While for most applications the preferred scale is from about 5 to about 20 parts by weight of the pigment per 100 parts of the resin component. The transparent metallic pigmented coatings have very low amounts by weight of the pigment. The powder coating composition is prepared by mixing the modified acrylic fluoropolymer and the pigment together with any optional additives such as low molecular weight acrylic flow control agents, such as those mentioned in the US Patent. . No. 4,770, 939. As stated above, mixing can take place by suspending the pigment in water and adding the suspension to the latex of the acrylic modified fluoropolymer with careful agitation. The mixed solids can then be recovered from the latex by the aforementioned normal techniques to do so. The particle size in many cases can be controlled by the recovery techniques of the latex solids and the drying technique used. These techniques are common in the field and were not described in detail here.

The dry solids thus recovered, if not within the scales of the desired particle size, can be milled if necessary at room temperature and classified by sieving. Particle sizes of less than 200 microns are preferred and very fine particles, less than 10 microns, can be avoided as they tend to interfere with transport of the powder in the application equipment and contribute to excessive amounts of atmospheric dust. An alternative method for forming the powder coating formulation is to coat the latex acrylic modified fluoropolymer as a dry powder by the conventional recovery methods described above and combine the dry pigment powder with them. Classification of the desired particle size scales, less than 200 microns, can be achieved, if necessary, by grinding and sieving the modified fluoropolymer powder with acrylic and the pigment separated before mixing or together after mixing. Any other optional additives such as flow control agents and the like, can be incorporated at any stage, for example, into the latex prior to recovery of the solids thereof, to dry latex, to pigment or to dry latex, to the pigment mixture before or after grinding and optional classification. As stated above, the acrylic modified fluoropolymer contemplates the inclusion of terpolymers of vinylidene fluoride among the vinylidene fluoride copolymers contemplated as starting materials of the seed polymer.

Inclusion of vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene terpolymer of the U.A. Patent is contemplated. 5,346,727, in amounts of up to about 5.0 percent by weight of the seed polymer latex, as well as the inclusion of the terpolymers of European Patent Application No. 0659846A2. The terpolymers can be mixed in the starting latex for the formation of seed polymers or the seed polymers can be formed from them separately and the desired proportion mixed in the formulation either in the latex or in the stage in dry powder. The copolymers and terpolymers affect the melting point of the acrylic modified fluoropolymer and therefore the AMFs formed from seed polymers having a melt viscosity, as measured by ASTM D3835, at 232 ° C and 100 s "1" are preferred. scale from 2 to 3 Cpoises, although superior fume flow viscosity materials are also suitable where higher coalescing temperatures for the coating are permissible.The powder coating can be added to the substrate by any application method. conventional known which will provide a niform lining.The normal techniques are fluidized bed, thermal spraying or, preferably, electrostatic coating. The powder coating can be applied to the substrate with or without an initiator coating. After application, the coating is subjected to a temperature above the melting temperature of the coating formulation.; preferably between about 232 ° C and 260 ° C although with a higher proportion of thermopolymer included in the seed polymer, it is possible to fuse the coatings at temperatures as low as 160 ° C. Due to the higher baking temperatures, the coatings are mainly useful as coatings on metal substrates and thermally similar substrates, such as aluminum, steel, glass and ceramics. Applications of such coated substrates are primarily decorative where long-term UV resistance, exterior durability, abrasion resistance and / or impact resistance are required. Normal examples are exterior metal construction parts (window frames, door frames, ceilings, wall panels and similar) and automotive components. The use as functional coatings (for example, for resistance to corrosion and / or wear) is also contemplated. Somebody skilled in the art will understand that if it is desired to apply a non-pigmented powder coating derived from acrylic-modified fluoropolymers to a substrate, one may also practice the manner described above for practicing the invention with pigment with the pigment omitted. The following examples also illustrate the best mode contemplated by the inventor for the practice of his invention and are intended to be indicative and not restrictive of them.

In the following examples, all proportions and percentages are by weight. Example 1: AMF based on PVDF homopolymer co-coagulated with titanium dioxide Pigment Dispersion 50. Og DuPont ti-Pure R-960 (TiO2) 50. Og Distilled Water 0.7g from Rohm and Haas Tamol 983 (polymeric acrylic dispersant ). Mixture A Latex 100.0 AMF latex: 38% solids, PVDF (15 Kpoise) (70 parts) / MMA / EA = (21 parts / 9 parts) 11.4 Dispersion A Pigment. Procedure: The pigment dispersion A was milled for 1 hour with 100 g of 4 mm glass grinding media before use. The Latex Mixture A was prepared and slowly stirred for 5 minutes to homogenize followed by coagulation of shear with a high speed dispersion spatula at 3600 rpm for 5 minutes. The coagulated sample was dried at 35-40 ° C for 24 hours.

The dried sample was crushed and the material passed through a 90 micron sieve was collected for use. The 90 micron powder was electrostatically sprayed onto aluminum substrates with negative polarity at 60-70 KV, and the powder was melted at 232 ° C for 10 minutes. The coating obtained had an average roughness of 17.1 microns and a brightness of degree 60 less than 10. The formation of continuous film was observed in the areas of the thick film construction. Example 2: AMF based on PVDF / HFP copolymer co-coagulated with titanium dioxide Mix B of latex 100. Og latex AMF: 47% solids, PVDF (63 parts) / HFP (7 parts) (24 Kpoise) (70 parts) / MMA / EA = (21 parts / 9 parts). 7.0g of Dispersion A of Pigment Procedure The preparation and application were as described in Example 1. The coating obtained had a very rough surface with low gloss (> 10). Example 3: AMF based on PVDF homopolymer co-coagulated with titanium dioxide Dispersion B of Pigment 70. Og DuPont ti-Pure R-960 30. Og of Distilled Water 1.4g of Rohm and Haas Tamol 731A (polymeric acrylic dispersant). Latex C blend 100. AMG Latex Og: 43% solids, PVDF (2 Kpoise) (75 parts) / MMA / EA = (23 parts / 2 parts) 4.6g Pigment Dispersion B. Procedure The pigment dispersion B was milled for 1 hour with 100 g of 4 mm glass grinding media before use. The latex mixture C was prepared and slowly stirred 5 minutes. The coagulated sample was dried at 50 ° C for 24 hours. The dried sample was crushed and the material passed through a 125 micron sieve was collected for use. The 125 micron powder was electrostatically sprayed onto aluminum substrates with negative polarity at 60-70 KV, and the powder was melted at 232 ° C for 12 minutes. The coating obtained had a continuous film formation over the entire panel with an average roughness of 2.9 microns and a grade 60 glass of 14. Example 4: AMF based on PVDF homopolymer dry blended with titanium dioxide and flow additive. Powder The AMF latex was coagulated at 4000 rpm for 5 minutes with a high speed disperser and dried for 24 hours at 50 ° C. The powder was used to prepare the following mixture as well as in the same mixture without ethyl carbonate. 20. Og of AMF powder: PVDF (2 Kpoise) (75 parts) / MMA / MMA = (23 parts / 2 parts) 1.4g DuPont TiPure R-960 0.2g of Ethylene Carbonate Each dry powder mixture was placed in a mini mill during seconds to achieve a homogeneously mixed powder followed by sieving at 300 microns. Powders of 300 microns were electrostatically sprayed on aluminum substrates with negative polarity at 60-70 KV and were fused at 232 ° C for 20 minutes. Both powders produced continuous opaque white coatings, but the coating with ethylene carbonate was more uniform ( average roughness = 8 6 microns) than the coating without ethylene carbonate (average roughness = 9 7 microns) Example 5 AM F based on PVDF homopolymer sprayed dry AM latex F 50% solids, PVDF (8 Kpoise) (70 parts) / MMA / EA / MAA = (19 5 parts / 9 5 parts / 1 0 parts) The latex AM F was spray-dried in a Buchi laboratory spray dryer The powder obtained from the cycle collector was used without sieving for electrostatic powder spraying The powder was electrostatically sprayed on aluminum substrates with negative polarity at 60-70KV and melted at 232 ° C for 10 m inutes. The films produced had continuous film formation over most of the panel with a average roughness of 4 3 microns Example 6 AMF based on PVDF / HFP homopolymer spray-dried AMF latex 50% solids, PVDF (63 7 parts) -HFP (6 3 parts) (24 Kpoise) (70 parts) / M MA / EA / MAA = (19 5 parts / 9 5 parts / 1 0 parts) The latex AM F is dried by spray in a 76 2 cm spray dryer Bowen The powder obtained from the cycle collector was used without sifting for electrostatic powder spraying. The powder was electrostatically sprayed on aluminum substrates with negative polarity at 60-70 KV and was fused to 232 ° C for 10 minutes. The coatings produced were continuous at thicknesses of approximately 100 microns and the coatings had a uniform texture across the entire surface with an average roughness of 9.6 microns. Example 7: AMF based on co-dispersed PVDF homopolymer with titanium dioxide. Dispersion C of Pigment 150. Og DuPont TiPure R-960 50. Og of Distilled Water. 3.0g from Rohm and Haas Tamol 983 Mix Latex D 200g Latex AMF: 50% solids, PVDF (8 Kpoise) (70 parts) MMA / EA / MAA = (19.5 parts / 9.5 parts / 1.0 parts) 10g Pigment Dispersion C The latex and pigmented dispersion were mixed and rolled slowly overnight to ensure uniform mixing. The mixture is spray-dried in a Buchi laboratory spray dryer. The cycle collector material was screened at 120 microns and electrostatically applied to aluminum substrates with negative polarity at 60-70KV. The applied powder was melted at 232 ° C for 10 minutes. The obtained coating was continuous and opaque with a grade 60 gloss of 38. The coating surface was uniform with an average roughness of 1.4 microns. Example 8: AMF-based mixed PVDF homopolymer dried with carbon black Powder Mixture 1000g of AMF Powder: PVDF (8 Kpoise) (70 parts) / MMA / EA / MAA = (19.5 parts / 9.5 parts / 1 .0 parts) 3g of carbon black Cabot Sterling R. The AMF latex was spray-dried in a Bowen 76.2 cm spray dryer and the powder obtained from the cycle collector was sieved at 125 microns before use. The AMF powder and the carbon black were mixed in a Henschel high intensity mixer for a total time of 2 minutes at 2200 rpm. The resulting powder mixture was electrostatically applied to steel substrates with positive polarity of approximately 30 KV and baked at 232 ° C for 10 minutes. The powder was also applied to aluminum substrates with negative polarity at 60-70KV and baked at 232 ° C for 5 minutes. The coating prepared by both methods showed good film build and average roughness of 6.2 m and brightness values of grade 60 of 21 -22. In all of the above examples, all relative amounts of monomers provided are in percent by weight. The 60 ° brightness was determined in accordance with ASTM D523-89 a Normal Test Method for Specular Brightness. These test measurements of the mirror reflectance (mirror) of a reference compared to a normal black brightness. The 60 ° angle was used for specimens of medium brightness and also for the testing of specimens re ported in the application.

Example 9: AM F based on homopolymer of co-dispersed PVDF with commercial titanium dioxide slurry% by Weight Component 95.1% Latex AMF: 35.8% solids, PVDF (13 Kpoise) (80 parts) / MMA / EA = (14 parts / 6 parts) 4.9% DuPont Ti-Pure R-746: 76.7% solids (titanium dioxide slurry in water) The components were mixed under slow stirring while feeding directly in a Bowen BLSA spray dryer.

The coated material was a fine white powder with passage of 96% through a sieve of 125 microns. The sieved powder at 125 microns was electrostatically sprayed on chrome-plated aluminum substrates with negative polarity at 60-70KV and melted at 232 ° C for 10 minutes to produce homogeneous opaque white coatings with general physical properties as shown below compared to a coating powder of commercial PVD F that is produced by melt extrusion, cryogenic grinding and sieving.

Claims (10)

1. REVIVAL DICATIONS 1. An improved blend of polyvinylidene fluoride based on polymer, acrylic polymer and pigment useful for powder coatings wherein the improvement comprises the polyvinylidene fluoride polymer and the acrylic polymer being combined as an acrylic modified fluoropolymer.
2. 2. An improved mixture as defined in claim 1, wherein the pigment is combined with the acrylic modified fluoropolymer using the acrylic modified fluoropolymer was suspended as a latex.
3. 3. An improved mixture as defined in claim 1, wherein the fluoropolymer modified with acrylic and the pigment are combined as dry powders.
4. 4. A process for the preparation of an improved mixture as defined in claim 1, comprising: a) dipping the pigment in an acrylic modified fluoropolymer latex to create a first mixture; b) recovering the solids of the first mixture to obtain a mixture as defined in claim 1 as a powder; and, optionally, if necessary, c) obtaining the improved mixture of claim 1 in the desired particle size by a process of selecting the size of selected particles from grinding, screening or a combination of the same. A process for the preparation of the improved mixture of claim 1, comprising a) recovering the solids of an acrylic modified fluoropolymer latex, b) if necessary, converting the solids recovered in step a, to the particle size desired by a selected process of grinding, sieving or a combination thereof, c) combining the solids in the desired particle size in step a, or optional step b, with pigment particles to obtain the improved blend of claim 1 A process for the preparation of the improved mixture of claim 1, which comprises combining the dry resin coated with an acrylic modified fluoropolymer latex, the resin having the desired particle size with the pigment particles having the desired particle size An article for manufacture comprising a substrate coated with at least one surface thereof with a derived coating of the improved mixture as defined in claim 1 A process for the preparation of an article for manufacturing as defined in claim 7, comprising applying at least one surface of a substrate on which a coating is desired, a layer of the powder coating composition comprising a mixture of fluoropolymer modified with acrylic and pigment and coalescing the layer in a coating fixed by application of heat. 9. A article for manufacture comprising a substrate having at least one surface thereof in a coating derived from a fluoropolymer modified with non-pigmented acrylic. 10. A process for manufacturing an article of manufacture as defined in claim 9, which comprises applying a powder coating composition of non-pigmented acrylic modified fluoropolymer to the surface of a substrate on which a coating is desired and the layer is made to coalesce in the fixed coating by application of heat. R ESU MEN An improved blend for powder coating comprising an acrylic-modified fluoropolymer and a pigment, processes for their preparation and use and coated articles produced therefrom is described. The use of fluoropolymers modified by non-pigmented acrylics to form powder coating and objects thus coated is also described.