MXPA00004639A - Particles and process for corrosion- and creep-resistant coatings - Google Patents

Abstract

This invention concerns particulate polymeric compositions that impart desirable properties to metal substrates coated with such particles, for instance by electrostatic spraying or fluidized bed application. The properties include corrosion and creep resistance which are designed into the composition by careful control of the following composition variables:selection of either an acid-functionalized semicrystalline or acid-functionalized amorphous polymer component, concentration of acid functionality of the polymer component, and degree of cross-linking of the acid functionality. Also disclosed are methods for producing such compositions and coatings;multilayer self-supporting and substrate-supported coatings with exceptional bonding between layers and the method for producing them;hardened coatings and methods for producing them by neutralizing the acid functionality of the polymer component. Coated substrates are also disclosed as are particulate compositions containing anticorrosive pigments.

Description

PARTICLES AND PROCESS FOR RESISTANT COATINGS TO THE CORROSION AND TO THE PLASTIC DEFORMATION FIELD OF THE INVENTION This invention relates to the particles used for coatings that exhibit improved resistance against corrosion, plastic deformation and chipping, and to a process for effecting these improved properties.

BACKGROUND OF THE INVENTION This invention relates to particulate acid functionalized polymer compositions designed to impart improved corrosion resistance to substrates coated therewith by a fluidized bed process. When the polymers are semi-solid, improved strength against plastic deformation is imparted to the coating layer or layers by controlling the degree of the acid functionality and the degree to which the cross-linking of the acid functionality exists. Although it is known to employ polymeric compositions for REF .: 33128 substrates through a fluidized bed process, such compositions and process have had very limited success. The limitations have been caused, to a significant degree, by the deficiencies of the properties in the polymer-containing particulate materials used in the fluidized bed. The particulate, layered and hard film compositions, and the coated substrates described herein and the processes for making and using them, overcome the deficiencies characterizing the materials known to date for use in bed technologies. fluidized U.S. Patent No. 4,739,011 discloses the use of a thermoplastic composition for injection molding, while the present invention relates to a coating that imparts resistance against corrosion. U.S. Patent No. 4,849,264 discloses a single coat system that does not provide adhesion to subsequent decorative layers such as those found in an automotive coating system as described in the present invention.

U.S. Patent No. 5,244,957 discloses the use of calcium sulfonate and a terpolymer composition containing acid groups, but is not directed to a powder / particle coating composition does not disclose the need for a select range of acid content. for operation against corrosion. U.S. Patent No. 5,411,809 describes the use of epoxy / acid / anhydride systems as sizing compositions, but does not disclose the importance of controlling the acid content for corrosion performance. U.S. Patent No. 5,470,893 discloses the use of a powder coating with film-forming and non-film-forming components for specific decorative or operating attributes. However, these powder particles are not the uniformly blended film formers of this invention, with the pigments and / or other additives uniformly distributed. The corrosion resistance in this patent is also not described. U.S. Patent No. 5,596,043 discloses the use of a powder coating as a primer in a multilayer system for improved anti-chip performance. Operation against corrosion as related to the acid composition is not mentioned in this patent. The spherical polymeric particles can be made by the process shown in U.S. Patent No. 3,933,954.

BRIEF DESCRIPTION OF THE INVENTION Process A: This invention relates to a process for controlling the anti-corrosion and adhesion properties to the substrate of a coating prepared from a particulate polymer composition, and applied from a fluidized bed or by electrostatic spraying, comprising: i) selection as the particulate polymer of one that has acid functionality; ii) maintaining the acid functionality of the polymer within the range of about 2 to 16 percent, based on the weight of the polymer; iii) preferably the improvement of the anticorrosion property of the coating by maintaining the acid content in the range of about 2 to 9 percent, based on the weight of the polymer; iv) preferably increasing the adherence to the substrate, of the coating, by maintaining the content of the acid in the range of about 5 to 16 percent, based on the weight of the polymer; and v) making a complete balance of the anticorrosion and adhesion to the substrate by maintaining the acid content in the range of about 5 to 9 percent, based on the weight of the polymer. This invention also relates to the following preferred embodiments of Process A: the process of A employing an acid content in the range of about 4 to 12 percent, based on the weight of the polymer; the process of A that employs steps i, ii and iii; the process of A that employs steps i, ii and i; the process of A wherein the anticorrosive pigment comprises at least one member of the group consisting of BaS0, zinc phospho-oxide complex, and calcium-strontium-zinc fosilicate fos; and the process of A wherein the anti-corrosive pigment is barium sulfate employed at a weight ratio of pigment to binder of 2: 100 to 300: 100.

Composition This invention further relates to a polymeric coating or self-supporting film of at least one layer, comprising acid functionality of between about 2 and 16 weight percent, the acid functionality is neutralized by exposure to a basic or saline solution , to form a surface or interface hardened with salt. This invention further relates to a substantially spherical polymer particle, imparting anticorrosive attributes with which it is used as a coating or film, comprising a copolymer and at least one member selected from the group consisting of pigment, crosslinker, surfactant, stabilizer light the process of A that employs steps i, ii and v; the process of A comprising carrying out step ii by hydrolyzing the anhydride portions in the polymer; the process of A comprising performing step ii by piling excess acid; the process of A comprising performing step ii by cross-linking the excess acid; the process of A comprising performing step ii by neutralizing the excess acid; the process of A for improving the plastic deformation resistance of a particulate, semicrystalline polymer composition, which comprises crosslinking or neutralizing the acid functional group to the extent of at least about 0.5 percent, based on the weight of the polymer; the process of A comprising the improvement of the anticorrosion property of the coating by the addition of at least one anticorrosive pigment; ultraviolet, antioxidant, antiozonant, flow agent, and leveling agent, the particle has an acid level of between about 2 and 16 percent by weight of the polymer. Preferred aspects of the composition of this invention include: a composition imparting resistance against plastic deformation to a coating prepared therefrom, comprising a semicrystalline polymer having its acid functionality crosslinked or neutralized to the degree of at least about 0.5 percent by weight of the polymer; a single layer film of a polymer comprising acid functionality of between 2 to 16 weight percent; a multilayer film comprising at least two layers described above, which are crosslinked at their interface; a multilayer film comprising at least one of the layers bonded with ionomer to another layer of the film; a composition in the form of a coating or a film whose acid functionality has been neutralized by contact with a source of neutralizing ions; and a substrate coated with one of the compositions described.

DETAILS OF THE INVENTION COMPOSITIONS OF PARTICLES This invention is directed to the particles that can be used as components in coatings and films having good adhesion, resistance against corrosion, plastic deformation and chipping. The particles are comprised of either semicris talin polymers (eg, polyvinyl chloride, polyolefin copolymers, nylons, aramides and the like) or amorphous polymers (eg, polyesters, polycarbonates, acrylics and copolymers thereof, and the like) . As used herein, "polymer" includes very high molecular weight materials often referred to as oligomers. By "semi-crystalline" it is meant that the polymer has a heat of fusion of at least 2 J / g, preferably at least 5 J / g when measured by Differential Scanning Calorimetry (DSC) using ASTM D3417-83. The crystals often contain considerable amounts of amorphous (non-crystallized) polymer.The vitreous transition temperature, Tg, referred to herein is measured by the method described in ASTM D3417-83 and is taken as the intermediate part of the transition. is the highest Tg for the polymer, if the polymer has more than one T. If the Tg is not detectable by DSC, Termomechanical Analysis can be used to determine the Tg, using the same heating rate as was used in DSC. The melting temperature, Tm, of the polymer is taken at the end of the melting, where the peak of the melting endotherm is reattached to the baseline, as measured by ASTM D3417-83. or it is one that does not contain crystallinity when measured by DSC, or whose heat of fusion is less than 2 J / g. The Tg is measured by the same method used by semicris polymers such inos. The polymers employed in the process of this invention may be one or more thermoplastics or one or more thermosetting agents, or a combination of both. If more than one polymer is used, the (first) temperature of the substrate should be in the gradient of adhesion temperature of each of these polymers if each of them is going to be a significant part of the resulting coating. For fluidized beds, the term 'adhesion temperature' (Tt) means the temperature of the substrate high enough to cause the polymer particles to adhere to it.The 'adhesion temperature gradient' comprises a temperature range whose lower limit is the temperature of adhesion and whose upper limit is approximately 75 ° C higher, with the condition that it remains below Tm. A person skilled in the art will appreciate that Tm has relevance with respect to crystalline and semi-crystalline polymers, not amorphous polymers.As a consequence, when an amorphous polymer has been selected as the coating, the important considerations, as long as it is related temperature, are Tt and the adhesion temperature gradient Useful polymers include: thermoplastics such as polyolefins, poly (meth) acrylates [the term (meth) acrylates includes the esters and amides of acrylates and methacrylates, and the acids acrylic and methacrylic], copolymers of olefins and (meth) acrylates, polyamides, polyesters, fluorinated polymers, polyimides, polycarbonates, polyarylates, poly (ether ketones), poly (methylpentene), poly (phenylene sulfide), liquid crystalline polymers, polyacetals , cellulosic polymers such as cellulose acetats-butyrate, chlorinated polymers such as chlorinated polyethylene, ionomers, styrene (s), and thermoplastic elastomers (below the Tm of the hard segments); and thermosetting materials such as di- and polyhydroxyl compounds, monomers, oligomers and polymers including polyacrylates, poly ethacrylates, polyethers, polyesters and polyurethanes, together with urea-formaldehyde, melamine-formaldehyde and block isocyanate; di- and polycarboxylic acid compounds, monomers, oligomers and polymers including polyacrylates, polymethacrylates, polyethers and polyesters together with epoxy, urea-formaldehyde and / or melamine-formaldehyde; and epoxy and phenolic compounds, monomers, oligomers and polymers. Preferred polymers are selected from thermoplastic polyolefin polymers and copolymers, poly (meth) acrylates and polyesters, and thermosetting polymers selected from the group consisting of polyester containing acid / epoxy, hydroxyl acrylate / isocyanate block or melamine- formaldehyde and acrylate containing epoxy / acid. The contemplated polymers, suitable for preparation as spheres by the process just described, include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 3-methylbut-l-ene, and -met ilpent- 1-ene Ethylene is the preferred olefin. The concentration of the α-olefin is at least 50 mol percent in the copolymer and it is preferred that it be more than 80 mol percent. Examples of α, β-ethylenically unsaturated carboxylic acids are acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, maleic acid, fumaric acid, monoesters of said dicarboxylic acids, such as methyl acid maleate, methyl acid fumarate, acid fumarate of ethyl and maleic anhydride. Although maleic anhydride is not a carboxylic acid since it has no hydrogen bonded to the carboxyl groups, it can be considered as an acid for purposes of the present invention, because its chemical reactivity is that of an acid. Similarly, other α, β-monoethylenically unsaturated anhydrides of carboxylic acids can be employed. Preferred unsaturated carboxylic acids are methacrylic and acrylic acids. As indicated, the concentration of the acid monomer in the copolymer is from 0.2 mol percent to 25 mol percent, and preferably from 1 to 10 mol percent. The copolymer base need not necessarily comprise a two-component polymer. More than one olefin can be used to provide the hydrocarbon nature of the copolymer base. The scope of the base copolymers suitable for the use of the present invention is illustrated by: ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, ethylene / itaconic acid copolymers, e ethylene / methyl acid maleate copolymers, and ethylene / maleic acid copolymers, etc. Examples of three component copolymers include: ethylene / acrylic acid / methyl methacrylate copolymers, ethylene / methacrylic acid / ethyl acrylate copolymers, ethylene / itaconic acid / methyl ethacrylate copolymers, ethylene / acid maleate copolymers of methyl / ethyl acrylate, ethylene / methacrylic acid / vinyl acetate copolymers, ethylene / acrylic acid / vinyl alcohol copolymers, ethylene / propylene / acrylic acid copolymers, ethylene / styrene / acrylic acid copolymers, copolymers of ethylene / methacrylic acid / acrylonitrile, ethylene / fumaric acid / methyl vinyl ether copolymers, ethylene / vinyl chloride / acrylic acid copolymers, ethylene / vinylidene chloride / acrylic acid copolymers, ethylene / vinyl fluoride / methacrylic acid copolymers , and ethylene / chlorotrifluoroethylene / methacrylic acid copolymers. In addition to the third monomeric component of the copolymer set forth above, the third additional monomeric components can be an alkyl ester of an α, β-ethylenically unsaturated carboxylic acid of 3 to 8 carbon atoms wherein the alkyl radical has from 4 to 18 carbon atoms . Particularly preferred are the terpolymers obtained from the copolymerization of ethylene, methacrylic acid, and alkyl esters of methacrylic acid or acrylic acid with butanol. The concentration of this optional component is 0.2 to 25 mole percent, based on the weight of the copolymer, preferably 1 to 10 mole percent. Representative examples of the third component include n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate , isopentyl acrylate, isopentyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, stearyl acrylate, stearyl methacrylate, n-butyl ethacrylate and 2-ethylhexyl methacrylate. -ethylhexyl. Also, the third component includes mono- and di-esters of 4 to 8 carbon atoms, dicarboxylic acids such as n-butyl acid maleate, sec-butyl acid maleate, isobutyl acid maleate, acid maleate -butyl, 2-ethylhexyl acid maleate, stearyl acid maleate, n-butyl fumarate acid, sec-butyl acid fumarate, isobutyl acid fumarate, t-butyl acid fumarate, 2-ethylhexyl acid fumarate, fumarate stearyl acid, n-butyl fumarate, sec-butyl fumarate, isobutyl fumarate, t-butyl fumarate, 2-ethylhexyl fumarate, stearyl fumarate, n-butyl maleate, sec-butyl maleate , isobutyl maleate, t-butyl maleate, 2-ethylhexyl maleate, stearyl maleate. Preferred alkyl esters contain alkyl groups of 4 to 8 carbon atoms.

Most preferred ones contain 4 carbon atoms. Representative examples of the most preferred esters are n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl acrylate, t-butyl methacrylate. Preferred base copolymers are those obtained by the direct copolymerization of ethylene with a comonomer of monocarboxylic acid and can be neutralized or not neutralized. It is preferred that substantially spherical particles be employed in the described process, said particles comprising the base copolymers and the various additives found that lend desirable properties to the finishing coatings. A preferred semicrystalline polymer system is that of poly (ethylene-co-methacrylic acid) commercially available from Nucrel® of DuPont Co. , Wilmington, DE. U.S. Patent No. 4,351,931 describes the process for making such copolymers.

ANTICORROSIVITY The amorphous and semicrystalline particles of this invention are made anticorrosive in nature by controlling the level of acid present in the particle, as well as the melt index. By "melt index" is meant the flow rate of the polymer mass through a specific capillary under controlled conditions of temperature and pressure (See FW Billmeyer, Jr., Textbook of Polymer Science, Interscience Publishers, NY, 1962 , page 175.) The melt index was determined by the materials used herein by ASTM D-1238, using a load of 2160 g to 190 ° C, whose values are reported in grams per 10 minutes. "acid" is understood as the weight percentage of the acid-containing monomer by the total weight of the polymer. By "acid functionality" is meant that there exists, as part of the polymer, a chemical group that will impart an acidic nature to the polymer, and the amount of functionality is expressed in terms of the weight percentage of the total polymer. it is understood that there exists, as part of the polymer, a chemical group that can be J9 converted to an acid functional group by conventional means (eg, hydrolysis, etc.). The acid level of the polymer can be adjusted to the desired level by one or more of the following methods: the hydrolysis of an anhydride, if present; the encasquetamiento of the acid in excess; the crosslinking of the acid in excess; and the addition of more acidic functionality. When adjusting the acid level by crosslinking, the resistance to plastic deformation can also be affected as will be discussed subsequently. The acid groups can be neutralized using various bases or ionic salts, including zinc acetate, aluminum acetylacetonate, lithium acetate, sodium hydroxide and sodium acetate. However, it should be noted that there are other metal ions not formed in complex, which are suitable in the formation of the ionic copolymers of the present invention. These include mono-, di- and trivalent metal ions in Groups I, II, III, IV-A and VIII of the Periodic Table of the Elements (see page 392, Handbook of Chemistry and Physics, Chemical Rubber Publishing Co., 37? Ed.). The monovalent metal ions not formed in complex, of the metals in the established groups, are also suitable for the formation of ionic copolymers of. the present invention with copolymers of olefins and ethylenically unsaturated dicarboxylic acids. The suitable monovalent metal ions are Na +, K +, Li +, Cs +, Ag +, Hg + and Cu *. The suitable divalent metal ions are Be2 +, Mg2 +, Ca2 +, Sr2 +, Ba2 +, Cu2 +, Cd2 +, Hg2 +, Sn2 +, Pb2 +, Fe2 +, Co2 +, Ni¿ + and Zn2 +. Suitable trivalent metal ions are A1J +, Sc3 +, Fe3 +, and Y3 +. Preferably, ionic salts of Zn2 + and A1J + are used. As used in the following examples, ZnAc or ZNAC represents zinc acetate, and AlAcAc or ALACAC represents aluminum acetylacetonate. The corrosion resistance of a coating is generally tested by exposure to a corrosive environment. Corrosive environments of natural origin include, but are not limited to, ocean breezes, road salt, and acid rain. Test environments include humidity cabinets, salt spray and salt spray cabinets, and the like.

RESISTANCE AGAINST PLASTIC DEFORMATION It has been found that anticorrosive coatings made from semi-cracked particles are resistant to plastic deformation or shrinkage when crosslinked. By resistant to plastic deformation or shrinkage it is meant that the coating that is applied substantially retains its initial dimension, and maintains good adhesion to any substrate, coating or other layer to which it is applied or with which it is in contact. - The resistance against plastic deformation can be induced by the intra-coating, naturally, and affected by cross-linking through acid and / or other functional group within a monolayer. In general, the initial acid level in the polymer particle is between 2.5 and 24 percent, preferably between 5 and 15 percent and more preferably between 6 and 12 percent. At least 0.5 weight percent of this acid functionality is used by crosslinking, so that the final acid levels after the crosslinking occurs, fall within the levels necessary for resistance against plastic deformation and against corrosion. Coatings with a crosslinking character can be used as any part of a coating system, but a preferred use is as a primer for direct coating to metal and for resistance against corrosion. The preferred application of the coatings described herein is by fluidized bed or electrostatic spray, but it should be understood that applications by other methods are possible and the process of this invention encompasses the application by any method even when the "fluidized bed" methods. and 'electrostatic spray' are the only methods discussed by name (for simplicity and brevity purposes). Another way to achieve the plastic deformation resistant coatings with these particles is to design the semicrystalline polymers so that, when used as part of a multilayer coating, they are crosslinked at the coating interfaces, allowing intercoat adhesion. . The acid groups present react as epoxides, isocyanates, hydroxyls and the like, and the reactive portions may be within the same coating layer, or in layers that share an interface, or both. Because the inter-coating adhesion is relatively strong, the formation of sandwiches of self-supporting film can also be achieved in ways that will be obvious to a person skilled in the art. The ionomeric bond at the interface (s) of the coating layer can also be achieved by neutralizing the surface of the coating layer as described above, preferably using ionic Zn2 + or Al3 + salts. Another way to improve the resistance against plastic deformation is to neutralize these semicrystalline coatings by immersing the coated article in a saline solution. Various ionic solutions can be used, but solutions of Al'3 * or Zn + are preferred. A gradient of ionomeric species is formed from the outer surface downwards of the substrate, with the largest amount of ionomeric species on the outer surface. The proportion of gradient and quantity depends on the ionic solution used. In general, between about 1 and 40 percent of the original acid level is neutralized, and preferably between about 5 and 20 percent. This produces a "salt hardened" coating, wherein the top layer of the semi-crystalline single layer or multi-layer coating is the reaction product of the present acid functionality.The coatings do not necessarily need to be crosslinked, since this hardening "will occur on reticulated and non-crosslinked coatings. One of the most significant results of this subsequent immersion and neutralization is the significant increase in gravel-electric readings that are indicative of coating resistance. Talking in general, the coatings formed by the teaching of this invention show an increase in gravelometric rate by at least one level versus the rate or proportion of a non-neutralized coating or coating of the prior art, 10 being the highest possible rating.

SUPPORTED COATINGS Particles are generally applied to substrates either by electrostatic spray or JZ5 fluidized bed coating. While both are known to those of skill in the art, fluidized bed application is preferred, and the procedure for doing so is as follows. The substrate can be any object that is substantially chemically stable at the operating temperatures of the coating process. It is preferred that the object is also dimensionally stable at the operating temperatures and / or operating times to avoid any dimensional changes such as those caused by melting or deformation. The substrate may be coated with one or more other coating layers prior to coating by this process. For example, a corrosion resistant and / or sizing layer and / or a metal layer such as zinc may be employed. (galvanized). The preferred substrates are metals and plastics. Preferred metals are iron, steel, galvanized steel, electrogalvanized steel (one and two sides), phosphate treated steel, electrogalvanized steel which is treated with phosphate, aluminum, and phosphate treated aluminum. Preferred plastics are composite and compact fibrous structures, and fluoropolymers such as Kapton® and Tediar®. Optionally, the fluidized bed can be vibrated to assist fluidization of the particles. The temperature of the substrate as it enters the fluidized bed of the polymer particles is within the adhesion gradient when a thin coating is desired. Generally speaking, the temperature of the substrate will decrease toward the temperature of the fluidized bed, when the substrate is in the fluidized bed. The temperature of the fluidization gas in the fluidized bed is below the adhesion temperature to prevent agglomeration of the polymer particles before their contact with the hot substrate. The coating is applied in a fluidized bed of polymeric particles which are fluidized by the passage of a gas through the particles to form a reasonably uniform fluid mass. It is preferred that the polymer particles in the fluidized bed are not electrostatically charged to a degree that will cause their adhesion to the substrate when the substrate is below the adhesion temperature. A coherent and substantially continuous coating will usually have a thickness of at least about 5 microns. Preferred coatings of this invention are those described herein as "thin." Such coatings are from about 5 to 150 micrometers thick, preferably not more than about 75 micrometers, and more preferably not greater than 60 micrometers. 150 to 300 microns using the process of this invention are certainly possible but are less preferred.Preferably, about eighty percent by weight of the coating particles are in a size range of about 10 microns to 80 microns, more preferably about 20 microns. micrometers to 60 microns It is more preferred that at least 90 weight percent of the polymer particles are in these size ranges Substantially none of the particles will be greater than 200 to 250 microns The particle size of the polymer is measured by the general technique of submitted by Heuer, et al., Part. Charact. , Vol. 2, pages 7 to 13 (1985). The measurement is performed using a Vario / La Helos analyzer available from Sympactec, Inc., 3490 U.S. Route i; Princeton, NJ 08540, E.U.A., using the volumetric percentage measurement. After removal from the fluidized bed, the coated substrate can be heated above the gradient of adhesion temperature of the polymer, at the coating level and effect the cure if it is a thermosetting polymer. This is carried out in a typical heating apparatus such as a convection or infrared oven. If the polymer is thermosetting, it is preferred that the substantial cure does not take place before the leveling takes place. The time required for leveling will depend on the particle size, the distribution, the thickness, the temperature used and the viscosity of the polymer. Higher temperatures and lower polymer viscosities favor faster leveling. An advantage of this coating process is the ability to obtain relatively thin uniform coatings without the need for electrostatic forces or other forces that help to adhere the polymer to the substrate. The more uniform coverage of irregular and 'hidden' surfaces is usually achieved by this method than by electrostatic methods.This more uniform coverage is attributed to the control of particle size and particle size distribution as described herein, as well as the lack of inhibitory Faraday path effect, in an electrically charged system.The coatings produced by the present process are useful for imparting resistance against corrosion, resistance against chemicals, and other properties such as will easily occur for a The person skilled in the art may act as a preparer for a subsequent coating layer and / or to provide pleasing aesthetic properties such as color, smoothness, and the like To provide such advantages, it may be useful to include with or within polymer particles other materials used in recu polymeric coatings such as fillers, reinforcers, pigments, dyes, antioxidants, corrosion inhibitors, leveling agents, antiozonants, UV filters, stabilizers, and the like. In many cases, the coating attributes depend on the good adhesion of the polymeric coating to the substrate.

Such adhesion can often be improved by commonly known methods such as the use of a primer, the cleaning of the surface of the substrate, the chemical treatment of the surface of the substrate and / or the modification of the chemical constitution of the coating to be applied. In this latter category, for example, when coated directly on metal, adhesion can often be improved by the inclusion of polar groups in the coating polymer, such as carboxyl or hydroxyl groups. One or more surfaces of the substrate can be coated, as desired, by controlling the immersion conditions. The coatings applied by the process of this invention are useful in many applications, such as the coating of coil material, automotive, truck and vehicle bodies, instruments, ceramic parts, plastic parts, and the like. For example, for automotive bodies, coatings can be applied directly on the metal surface or can be first applied with a primer. The coated body is thus protected from corrosion and physical damage. One or more coating layers of the typical finishing coatings such as the so-called base coat (usually colored), and then a clear coating can be applied. Care must be taken to ensure adequate adhesion between the various coatings, and between the polymeric coating and the metal body. The applications for coating by the present process can be relatively thin and uniform for good protection against corrosion, while at the same time do not add much weight to the vehicle, nor do they use too much relatively expensive polymer. In addition, the coating will be smooth and uniform when measured, for example, by a profilometer. This process gives coatings substantially free of empty spaces. In general, the temperature of the substrate (and any polymer coated thereon) will decrease toward the temperature of the fluidized bed, when the substrate is in the fluidized bed. Preferred operating conditions include substrate temperatures of about 20 ° C or more above the Tt, not significantly exceeding about 40 ° C or more above the Tt (but below Tm). The temperature of the substrate as it enters the fluidized bed (at a temperature above the adhesion temperature) together with the selection of appropriate size of the coating particles largely governs the thickness of the coating regardless of time, after a time minimum critical immersion in the fluidized bed. It has been found that thin coatings can be obtained substantially independently of time (after a minimum residence time) using the process of this invention. This is achieved by preheating the substrate within the gradient of the adhesion temperature, preferably close to the adhesion temperature, Tt, and controlling the particle sizes as described. When these variables are controlled within the teaching of this invention, the increase in residence in the fluidized bed has little or no effect on the thickness of the coating. The benefits of this invention are more important when intriguing objects or very large objects such as vehicle bodies are found. Without the benefits of this invention, immersion of intricate objects for relatively long periods of time to achieve some coverage of all surfaces would produce overly coarse coatings, and immersion of large objects to achieve desirable thin coatings would produce non-uniform coating thicknesses. The process for the production of spherical particles comprises the cutting in a closed section of a cutting device under positive pressure, of water, ammonia and copolymer of α-olefins of the formula R-CH = CH 2, wherein R is a hydrogen radical or an alkyl radical having from 1 to 8 carbon atoms, and α, β-ethylenically carboxylic acids unsaturated having 3 to 8 carbon atoms. The copolymer is a direct copolymer of the α-olefins and the unsaturated carboxylic acid in which the carboxylic acid groups are randomly distributed over all molecules and in which the α-olefin content of the copolymer is at least 50 mole percent, based on the α-olefin-acid copolymer. The unsaturated carboxylic acid content of the copolymer is from 0.2 to 25 mole percent, based on the α-olefin acid copolymer, and any other monomeric component optionally copolymerized in said copolymer is monoethylenically unsaturated.

A temperature that is above the melting point, but below the thermal degradation point of the polymer is used to form a homogeneous suspension, wherein the polymer particles have an average particle size less than 100 microns in diameter, containing the suspension at least 0.6 weight percent ammonia and up to 50 weight percent said polymer; after completion of the cut, the suspension is maintained with agitation at a temperature above the melting point of the polymer for at least 0.5 minutes until essentially all the polymer particles become spherical; While stirring is continued by cooling the suspension to a temperature below about 80 ° C over a period of at least 0.3 minutes, the pressure is maintained sufficient to maintain the water in the liquid state; simultaneous with or subsequent to the heating of the suspension the pressure of the cooled suspension is reduced to atmospheric pressure; and the polymer particles are separated. Partially spherical particles have an average diameter of 10 to 100 micrometers and are characterized in that the surface of the particles may be rough and / or covered with hemispherical protuberances of approximately 0.1 micrometer in diameter, or with "depressions".

COATINGS / FILMS NOT SUPPORTED The particulate compositions of this invention can be used to make single layer and multi-layer films of self-support. Typically, the particles can be coated on a dimensionally stable substrate to which a release agent has been applied and heated and cured to the desired layer thickness. The layer is then removed from the substrate and used as such or contacted with one or more other layers prepared in the same manner or by any method known in the art for producing films. The functionality of the film layers that can be produced from the particulate compositions of this invention will lend desirable properties to the films intended for use in food packaging and for other end uses in which the polymeric component with group functional acid of a first layer, can be crosslinked in a second contact layer to improve the adhesion capacity, and gas impermeability, and the like. Alternatively, the acid functionality can be used in any other way that will be obvious to a person of ordinary skill in the art based on the description shown herein. For example, the improved properties can be achieved for the end use by neutralizing the acidic portions on or below the surface of the layer; or, acidic groups can be linked via ionomeric bonding mechanisms, and the like. The neutralizing agent or the ionic link component can be applied by immersing the acid-functionalized layer within it, or they can be incorporated on the surface of a complementary layer which is then put in contact with the first layer to complete the reaction and form the adventitious union. Other potential uses for single layer and sandwich films, made according to the description of this invention, include food and article packaging, high strength / low elongation films, and the like.

ADJUVANTS FOR THE ION ANTICORROS Another facet of this invention is the improvement of the anticorrosive properties by the addition of pigments to the coating system. Using the compositions as described above, pigments such as Nalzin®, preferably Halox® and more preferably barium silicate greatly increase the corrosion resistance of the coatings as shown in the following Examples. Again, the crosslinking can take place within and between the applied coatings, but is not necessary for the increased resistance against corrosion. The coatings can be applied to any type of substrate, although in general metals are used and preferred. In certain cases, the ratio of pigment to binder (P / B) is critical. The preferred P / B 's for BaS04 are 2: 100 to 30: 100, and for Nalzin ® and Halox ® they are 0.5: 100 to 10: 100.

PROCEDURES The vibration of the or of the substrates when it was used, was applied at 1000 to 2000 Hz with a force of approximately 90 Newtons. The vibrator was mounted on the part that is submerged. The vibrator is a Vibco VS100®. The spherical particles described therein are 'substantially spherical', that is, they have a smooth radius of curvature and have almost no sharp edges such as the characteristic particles that are made by cryogenic grinding.A person skilled in the art will appreciate that the substrates coated by the process of this invention can be previously treated, or subsequently treated with various heating techniques including gas, electric, microwaves, dielectric, infrared and the like.

TAPE ADHESION TEST The adhesion of the applied coatings was tested via a tape adhesion test based on the method described in ASTM D3359-95a. Briefly, cross-hatched grids are cut into the coating, a piece of tape is firmly applied to the cross-hatched area, and the tape is rapidly removed in a movement perpendicular to the paint film. The adhesion of the coating is qualified, and is relative to the amount of the coating that is removed by the tape. The classifications are 0, < 5 percent, 5-15 percent, 15-35 percent, 35-65 percent and 65 percent. The lower the color, the better the adhesion score.

RESISTANCE TO DESPORT ILLUSTRATION OF COATING The resistance to chipping of the applied coatings was evaluated using a gravelometer (Gravel.). The panels were taken from the freezer at -20 ° C, placed in a gravelometer (Q Panel, Model QGR, Cleveland, OH), and gravel was fed at a speed of 1 pint of stones in 20 seconds. In general, these panels had been exposed to 96 hours of humidity as described below. The panels were rated from 0 to 10, after comparison to commonly used pictorial standards. In general, the higher the number, the lower the number of chips in the coating. The 'point of failure' is also annotated, and is described in the following table.

Notation Failure Level Type of Failure 'S / P Adhesive Adhesive Substrate S / T Adhesive Top Coating Substrate P Cohesive Coater P / T Adhesive Top Coating Adhesive T Cohesive Top Coating P / P Adhesive Adhesive Adhesive S Cohesive Substrate * 'Adhesive' means the Interlayer Failure 'Cohesive' means intralayer failure.

CORROSION The corrosion performance of the materials was tested using the cyclic salt fog test method. Cold rolled steel panels (CRS) treated with zinc phosphate (Code: APR 12936, ACT Laboratories, Hillsdale, MI) were coated by fluidized bed application, at a thickness of 25 μm ± 2.5 μm. After tracing, the panels were exposed to the following set of conditions for the time specified by a Q-Fog Cyclic Corrosion Tester, Model No. CCT600, Q-Panel Lab Products, Cleveland, OH. The measurement of corrosion reported, represents the measurement in millimeters of the distance that the coating is grated from the panel.

Step 1: Steps' 2-3 of the subcycle and repetition 4 times . Step 2: Fog salt ina 25 ° C for 15 minutes. Step 3 Drying at 25 ° C for 75 minutes. Step 4 Drying at 25 ° C for 120 minutes. Step 5 100 percent relative humidity (RH) at 49 ° C per hours. Step 6: Drying at 60 ° C for 7 hours. Step 7: Drying at 25 ° C for 1 hour.

PROOF OF HUMIDITY The effect of humidity (100 percent relative humidity with condensation on the test specimen at all times) was tested using the apparatus described in ASTM B1117. The examples included herein were tested in a Harshaw Moisture Cabinet, Model 24, Cleveland, OH. The prepared panels were placed in the chamber for 96 hours at 100 percent relative humidity and at 38 ° C. The degradation of the finish was evaluated in terms of adhesion and corrosion of the tape.

PLASTIC DEFORMATION TEST The amount of plastic deformation of the coating was measured from the edge of the panel to the edge of the coating, and is reported as the "shrinkage" in mm.

DEFINITIONS Unless otherwise specified, all chemicals, materials and reagents were used as received from Sigma-Aldrich Chemical Co. , Mil aukee, Wl.

MATERIAL NUMBER CHEMICAL Nucrel® Poly (ethylene-methacrylic acid) (DuPont Wilmington, DE) Bisphenol A 4,4'- (1-methylidene) -bis-1,1'-oxypropyloxirane epoxide (Ciba Geigy, Ha thorne, NY) Epoxies: De Ciba-Geigy Co. , Plastics Division, Hawthorne, NY Araldite® GT7013 Phenol, 4, 4U- (1-methyl ethylidene) Bis-, polymer with (chloromethyl) oxirane (BPADG) Araldite "GT7097 Phenol, 4- (1,1-dimethylethyl) -polymer with (chloromethyl) oxirane and 4,4U- (1-methylethylidene) Bis (phenol) Araldite® GT6703 Phenol, 4- (1,1-dimethylethyl) -polymer with (chloromethyl) oxirane and 4,4U- (1-methylethylidene) Bis (phenol) TGIC 1, 3, 5-triglycidyl isocyanurate Pigments: BaS04 Sulphate from Sachtleben Chemie Gmbh c / o Bario The Ore + Chemical Co., New York, NY Ti02 Pigment from DuPont, Co., Wilmington, DE Titanium dioxide Rheox oxide complex, Inc., Hightstown, NJ Zinc - phosphorus (Nalzin®2) phosphosilicate from Halox Pigments, Hammond, IN calcio-strontium-zinc (Halox®) Catalysts from Sigma-Aldrich Chemical Co., Milwaukee, Wl: TBPB Tetrabutyl Phosphonium Bromide Materials and Processing of Superior Coatings: Unless otherwise specified, when the Examples are marked as "coated," this means that the substrate that is coated with a film prepared from the particles of this invention is also coated with a surface primer (PS) , base coat (BC) and clear coat (CC) This is generally shown as a coating with PS / BC / CC.

These coatings are conventionally applied with dry film thicknesses (DFT) as shown below. PS - pigmented polyester melamine, sprayed, cured for 30 minutes at 150 ° C (302 ° F); ~ 25 μm DFT BC - pigmented polyester melamine, sprayed and turned on 3 minutes before the application of CC; ~ 25 μm DFT CC - acrylosilane, sprayed, turned on for 15 minutes, cured for 35 minutes at 129 ° C (265TF); ~ 50 μm DFT EXAMPLES Examples 1 to 12 Particle Composition Corrosion performance was tested using the cyclic salt fog test method. Cold rolled steel panels (CRS) treated with zinc phosphate (Code: APR 12936, ACT Laboratories, Hillsdale, MI) were coated by fluidized bed application, up to a thickness of 25 μm ± 2.5 μm. The polymers used (Nucrel®) had a melt index (MI) of 1000, and they were polyethylene copolymers with either methacrylic acid (MAA) or acrylic acid (AA) The acid level established in the following table is the percentage weight of the acid to the ethylene polymer The acid level was adjusted in the reactor where the copolymers were made under high pressure gas phase polymerization.Unless otherwise specified, the metal panels were preheated before the application of the particles in a fluidized bed The panel is then post-heated for a specified length of time These parameters are shown in the following Tables.

TABLE 1 Acid Level, Example No Type of Acid Percent Corrosion, mm. 1 AA 3 50 2 AA 4.5 30 '3 AA 6 4 4 AA 8 10 5 AA 10 10 6 AA 16 20 7 MAA 3 45 MAA 4.8 14 9 MAA 7 10 MAA 10 11 11 MAA 12 24 12 MAA 18 20 Examples 13 to 17 TABLE 2 Acid Level versus Melt Index (MI) of Nucrel® and Corrosion Acid used Percent Corrosion Index, Example No. with Nucrel® Acid Fusion mm 13 MAA 8 10 6.5 14 MAA 15 60 14 15 MAA 10 500 7 16 MAA 10 850 8 17 AA 10 2000 8 Example 18 Particle Coating Study; Coated with BC / CC; Epoxy = TGIC, Catalyst = TBPB, Nucrel® with MAA. CRS panels were treated as described above and coated with particles (epoxy = TGIC, catalyst = TBPB) where the Nucrel® used was a MAA copolymer. The panels were preheated to 100 ° C, coated in the fluidized bed, then post-heated at 150 ° C for 6 minutes. These were coated with BC / CC. The coated panels were subsequently tested via a gravelometer, receiving a rating of '8.' The results of the moisture adhesion test were '0' •, and after 1000 hours of salt spray, they showed a corrosion of 2 mm.

Example 19 Nucrel® + Bisphenol A + TBPB; It is tequiometry at 1: 1, 0.5 percent Catalyst, Preheating = 100 ° C, Postheating = 120-180 ° C, Post-heating Time 5-30 minutes.

The CRS panels were treated as described above, and then coated with Nucrel® containing bisphenol A epoxy (1: 1 stoichiometry) with 0.5 TBPB catalyst. The preheating temperature was 100 ° C, the post-heating temperature was 180 ° C for 30 minutes. The coating thickness was 43.2 micrometers (1.7 mils). Half of the panels were coated with PS / BC / CC. The gravelometer results were 9 for both the coated and the uncoated, the moisture adhesion rating of 0 for both, no salt spray corrosion after 1000 hours for both, and no shrinkage noted for the PS coated panels. / BC / CC.

Examples 20 to 22 Nucrel® with various epoxies and with TBPB catalyst: Corrosion and Viscosity. CRS panels were prepared as previously described, and the epoxies used and the test results are shown in the following Table. The viscosity was measured by pressing a film of the mixture by inhibiting the viscosity in a plate viscometer parallel to 150 ° C at 10 radians / second for approximately 30 minutes.

TABLE 3 Corrosion Viscosity, mm Paséales Ef. No Epoxy Nd Coated * 5 minutes 15 minutes 30 minutes coated 20 GT7097 5.2 5.4 138 302 3382 21 GT6703 5.2 4.9 577 2025 2591.9 22 GT7013 2.4 2.5 382 1654.2 Coated with PS / BC / CC Example 23 Measurement of viscosity / crosslinking / plastic deformation In this Example, a Brabender mixer was first charged with Nucrel® with 10% MAA, then epoxide (TGIC, 5.7 g), followed by catalyst (TBPB, 0.5%). The time was counted from the time of the introduction of the catalyst. The RPM was adjusted to 50 and the temperature to 160 ° C. The product was obtained as a mixture that was cooled in liquid nitrogen. The torsion was measured at 200 units, and is an indicator of the viscosity, which is in turn an indicator of the degree of crosslinking as well as the plastic deformation / shrinkage.

Examples 24 to 25 The primer (Nucrel®) treated with metallic salt to form ionomer and the subsequent test via the gravelometer, moisture and salt spray. Panels were prepared in a fluidized bed as described above. The coated panels were immersed in a 1% solution of either ZnAc or AlAcAc. The test results of the gravelometer, the adhesion of moisture and salt spray (1000 hours) are shown below. 1000 hours of Dew Ei. No. Gravel Treatment Provider. Saline Humidity, mm 24 Nucrel 1% ZnAc 9 (P / T) 5 to 15 5 25 Nucrel 1% Alacac 9 (P / T) 5 to 15 8 Examples 26 to 29 Corrosion, adhesion and gravelometric tests of Nucrel® RX76 after neutralization by immersion in ionic bath. The data is reported in Table 4 for various immersion times in minutes.

TABLE 4 Neutralization Obtained through Immersion in Ionic Baths Corrosion Time Example No. Immersion, min. Adhesive mm Gravel. 261 0 0 16 7 271 60 0 5 9 282 5 9 6 9 293 0 0 100 7 1 - . 1-10 weight percent ZnAc in water 2-10 weight percent AlAcAc in Butanol 3-10 weight percent NaOH in water Examples 30 to 32 Nucrel® with various pigments at various P / B's: studies of corrosion, plastic deformation and viscosity. The "?" Method is the humidity test, and the "B" method is the cyclic salt fog test. "Coated" means that the panels are also coated with PS / BC / CC. "Uncoated" means only the fluidized bed applied coating that has been applied to the metal substrate.

Pigmentation Capoüión of 1000 hours "A" "B" - "B" Shrinkage Viscosity Example No Pi e PJ Coated Not Coated Coated mm Passes . 30 Halox® 5 0.375 3.5 0.825 2.5 29.8 31 BaSO, 10 0.425 2.3 1.05 3 34 32 CaCOj 10 100 100 100 56.4 Examples 33 to 35 The data shows the results of the systems that are neutralized and which contain anti-corrosive pigment. 'SS' indicates proof of 'saline dew'.

TABLE 5 Coated with PS / BC / CC Not Coated Description Nucrel® Thickness Example of the Micron Sample (thousandths Gxavel, Humidity 1000 hr SS 1000 hr SS Njk of polishing) 33 2 percent Nalzin® 35.56 8 0 3 1 2, ZnAc, 5 min (1.4) 34 2 percent Nalzin® 40.64 9 15 to 35 68 24 2, AlAcAc, 5 min (1.6) 35 2 percent Halox®, 38.1 8 0 2 4 ZnAc, 5 min (1.5) It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (19)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A process for controlling the anti-corrosion and adhesion properties to the substrate of a coating prepared from a particulate polymer composition, the process is characterized in that it comprises: i) the selection for the composition of a particulate polymer having acid functionality greater than one desired range of about 2 to 16 percent, based on the weight of the polymer; ii) the application of said coating from a fluidized bed or by electrostatic spraying on a substrate; and iii) adjusting the content of the acid functionality of the polymer in the coating within the desired range for the control of the anticorrosion properties and adhesion to the substrate of the coatings.

2. The process according to claim 1 or 9, characterized in that it comprises adjusting the content within the range of about 4 to 12 percent, based on the weight of the polymer.

3. The process according to claim 1 or 9, characterized in that it comprises adjusting the content within the range of about 2 to 9 percent based on the weight of the polymer to improve the anticorrosion property of the coating.

4. The process according to claim 1 or 9, characterized in that it comprises adjusting the content within the range of about 5 to 16 percent based on the weight of the polymer to improve the adhesion to the coating substrate.

5. The process according to claim 1 or 9, characterized in that it comprises adjusting the content within the range of about 5 to 9 percent based on the weight of the polymer to effect a complete balance of the anticorrosion and adhesion to the substrate of the coating.

6. The process according to claim 1 or 9, characterized in that it further comprises the addition of at least one anticorrosive pigment to the composition, to improve the anticorrosion property of the coating.

7. The process according to claim 6, characterized in that the anti-corrosion pigment is selected from the group consisting of BaSO4, zinc oxide-forum complex, calcium-strontium-zinc phosphosilicate, and a combination thereof.

8. The process according to claim 7, characterized in that the anti-corrosive pigment is BaS04 used at a pigment-to-binder ratio of 2: 100 to 30: 100.

9. A process for controlling the anti-corrosion and adhesion properties to the substrate of a coating prepared from a particulate polymer composition, the process is characterized in that it comprises: the selection, for the composition, of a particulate polymer containing an acid functionality in a desired range of about 2 to 16 percent based on the weight of the polymer, for the control of the anti-corrosion and adhesion properties to the coating substrate; and the application of the coating on a substrate from a fluidized bed or by electrostatic spraying.

10. The process according to claim 1 or 9, characterized in that the acid functionality on the particulate polymer is in the form of an anhydride portion.

11. The process according to claim 10, characterized in that it comprises the hydrolysis of the anhydride portion of the particulate polymer.

12. The process according to claim 1, characterized in that the step for adjusting the content of the acid functionality of the particulate polymer within the desired range comprises the encapsulation of the excess acid functionality.

13. The process according to claim 1, characterized in that the step of adjusting the content of the acid functionality of the particulate polymer within the desired range comprises the cross-linking of the excess acid functionality.

14. The process according to claim 1, characterized in that the step of adjusting the content of the acid functionality of the particulate polymer within the desired range comprises the neutralization of the excess acid functionality.

15. The process according to claim 1 6 9, characterized in that the particulate polymer is a semicrystalline particulate polymer ino.

16. The process according to claim 15, further characterized by comprising the crosslinking or neutralization of at least about 0.5 percent based on the weight of the polymer of the acid functionality to improve the plastic deformation resistance of said composition.

17. The process according to claim 1, characterized in that the excess acid functionality varies between 2.5 to 24 percent based on the weight of the polymer.

18. A process for controlling the anti-corrosion and adhesion properties to the substrate of a self-supporting film, prepared from a particulate polymeric composition, the process is characterized in that it comprises: i) the selection, for the composition, of a particulate polymer having an acid functionality greater than a desired range of about 2 to 16 percent based on the weight of the polymer; ii) the application of a layer of the composition from a fluidized bed, or by electrostatic spraying on a dimensionally stable substrate; iii) heating and curing the layer to form a film; iv) the removal of the film from said substrate; v) adjusting the content of the acid functionality of the polymer in the film, within the desired range to control the anti-corrosion and adhesion properties of the film substrate.

19. The process according to claim 18, characterized in that the substrate is coated with a release agent. PARTICLES AND PROCESS FOR RESISTANT CORROSION AND PLASTIC DEFORMATION COATINGS SUMMARY OF THE INVENTION This invention relates to particulate polymeric compositions that impart desirable properties to metal substrates coated with such particles, for example by electrostatic spray or fluid bed application. The properties include the resistance to corrosion and plastic deformation, which are designed in the composition by careful control of the following variables of the composition: the selection of either an amorphous semicrystalline polymer component functionalized with acid or amorphous functionalized with acid , the concentration of the acid functionality of the polymer component, and the degree of crosslinking of the acid functionality. Methods for producing such compositions and coatings are also described; the coatings of multiple layers of self-support and supported by the substrate, with exceptional bond between the layers and the method to produce them; hardened coatings and methods for producing them by neutralizing the acid functionality of the polymer component. Coated substrates are also described as particulate compositions containing anticorrosive pigments.