Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
  • C09D5/448—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications characterised by the additives used
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/182—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing using pre-adducts of epoxy compounds with curing agents
  • C08G59/184—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing using pre-adducts of epoxy compounds with curing agents with amines
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
  • C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
  • C09D5/443—Polyepoxides
  • C09D5/4434—Polyepoxides characterised by the nature of the epoxy binder
  • C09D5/4438—Binder based on epoxy/amine adducts, i.e. reaction products of polyepoxides with compounds containing amino groups only
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0058—Biocides

Definitions

• the present invention relates to an improved electrodeposition process. More particularly the present invention relates to an improved electrodeposition bath comprising a mixture of at least one boron-containing compound and chlorhexidine.
• Electrodeposition as a coating method has become increasingly important in the coatings industry. Globally, more than 80 percent of all motor vehicles produced are given a primer coating by cationic electrodeposition.
• electrodeposition offers the advantages of increased paint utilization, improved corrosion protection and relatively low environmental contamination. Electrodeposition typically offers environmental advantages because (1) electrodepositable coating compositions contain very little organic solvent and, (2) downstream processes, such as closed loop rinsing, can minimize loss of coating components to the surrounding environment during coating application.
• the electrodeposition process is well known, and involves immersing an electroconductive substrate (that is, the work-piece) into a bath of an aqueous electrocoating composition.
• an electroconductive substrate that is, the work-piece
• the work-piece serves as the cathode.
• the electrocoated substrate is rinsed with an aqueous rinsing composition.
• Typical rinsing operations have multiple stages which can include closed loop spray and/or dip applications.
• closed loop spray process removes excess electrocoat material from the substrate by spray washing the surface with deionized or reverse osmosis water.
• a dip application removes excess electrocoat material from a substrate by submerging the substrate in a tank of dionized or reverse osmosis water.
• the rinse composition can be re-circulated and re-used.
• the electrodeposition bath is ultrafiltered to remove ionic contaminants and the ultrafiltrate is used in the rinsing operations.
• Recirculating the coating or rinse compositions is both economically and environmentally desirable.
• an aqueous coating or rinse composition can create an environment conducive to the growth of microorganisms such as algae, fungi and bacteria.
• Microorganisms can adversely affect the quality and appearance of an electrodeposited coating.
• the presence of microorganisms in the electrocoating or rinsing composition can cause the formation of precipitates in the tanks, and variation in process parameters, for example, pH, conductivity, film build, throwpower (that is, the rate of film deposition relative to the position of the anode) and stability.
• particulate “dirt” deposition and bio-fouling can occur, thereby detrimentally affecting the appearance of the applied coating and reducing system performance.
• the “ultrafiltrate” used in the rinse stages typically contained solvents, heavy metals, and other organic materials which assisted in the suppression of the aforementioned microorganism growth.
• environmentally undesirable components such as volatile organic compounds (VOC), hazardous air pollutants (HAPs), and heavy metals, such as lead and chrome have been reduced, increased bacterial infestation has occurred.
• a number of compounds for controlling the growth of bacteria in heavy metal-free, low organic solvent content-electrodeposition baths are known.
• silver ion has been utilized, as well as oxidizing agents such as hydrogen peroxide and calcium hypochlorite.
• oxidizing agents such as hydrogen peroxide and calcium hypochlorite.
• silver ion is costly and can contribute to dirt formation the electrodeposition bath.
• Oxidizing agents can oxidize organic components of the electrodepositable composition.
• a microbiocide composition containing a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one can cause a rougher appearance than a coating composition without this microbiocide.
• such microbiocide compositions can contain metal salts, for example, magnesium nitrate and magnesium chloride, which can cause coating defects due to gas generation at the cathode.
• Use of microbiocides may not be convenient, and they can lose their effectiveness over time. Moreover, some microbiocides can require special handling and disposal.
• Halonitroalkanes can negatively affect the appearance of an applied coating and can contribute to corrosion of metallic parts.
• U.S. Pat. No. 4,732,905 discloses a composition used to control microorganism growth in water systems.
• U.S. Pat. No. 6,017,431 discloses the use of sulfamic acid in electrodeposition baths.
• U.S. Pat. Nos. 3,937,679; 3,959,106; 3,975,346; and 4,001,101 disclose the use of boric acid as a solubilizing agent for ionic group-containing film-forming resins having onium salt groups, such as quaternary ammonium groups and ternary sulfonium groups.
• 4,443,569 discloses cathodically electrodepositable compositions based on a nitrogen base-containing binder containing tertiary amino groups and primary and/or secondary hydroxyl groups, and a metal compound.
• US2003/0033248 discloses an improved electrodeposition bath containing boric acid.
• the invention provides an improved electrodeposition bath for microorganism resistance.
• the improvement comprises the inclusion of both chlorhexidine and an effective amount of a boron-containing compound selected from at least one of boric acid, boric acid equivalents, and mixtures thereof in the electrodeposition bath in an amount sufficient to retard the growth of microorganisms in the electrodeposition bath relative to their growth in the absence of said components.
• the electrodeposition bath comprises an aqueous dispersion of an aqueous carrier and a film forming binder.
• the film forming binder comprises an epoxy-amine adduct and blocked isocyanates.
• Suitable boron-containing compounds include those selected from boric acid, boric acid equivalents, and mixtures thereof.
• boric acid equivalents any of the numerous boron-containing compounds that can hydrolyze in aqueous media to form boric acid.
• boric acid equivalents include boron oxides, for example, B 2 O 3 ; boric acid esters such as those obtained by the reaction of boric acid with an alcohol or phenol, for example, trimethyl borate, triethyl borate, tri-n-propyl borate, tri-n-butyl borate, triphenyl borate, triisopropyl borate, tri-t-amyl borate, tri-2-cyclohexylcyclohexyl borate, triethanolamine borate, triisopropylamine borate, and triisopropanolamine borate.
• amino-containing borates and tertiary amine salts of boric acid may be useful.
• Such boron-containing compounds include, but are not limited to, 2-(beta-dimethylaminoisopropoxy)-4,5-dimethyl-1,3,2-d-ioxaborolane, 2-(beta-diethylaminoethoxy)-4,4,6-trimethyl-1,3,2-dioxaborin-ane, 2-(beta-dimethylaminoethoxy)-4,4,6-trimethyl-1,3,2-dioxaborinane, 2-(betha-diisopropylaminoethoxy-1,3,2-dioxaborinane, 2-(beta-dibutylaminoethoxy)-4-m46hyl-1,3,2-dioxaborinane, 2-(gamma-dimethylaminopropoxy)-1,3,6,9-tetrapxa-2-boracycloundecane, and 2-(beta-dimethylaminoethoxy)-4,4-(
• Boric acid equivalents can also include metal salts of boric acid (i.e., metal borates) provided that such metal borates can readily dissociate in aqueous media to form boric acid.
• metal borates useful in the electrodeposition bath of the present invention include, for example, calcium borate, potassium borates such as potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, and potassium octaborate, sodium borates such as sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium perborate, sodium hexaborate, and sodium octaborate.
• ammonium borates can be useful.
• optional boron-containing compounds can be included, for example, bismuth borate and yttrium borate.
• Suitable boric acid equivalents can also include organic oligomeric and polymeric compounds comprising boron-containing moieties.
• Suitable examples include polymeric borate esters, such as those formed by reacting an active hydrogen-containing polymer, for example, a hydroxyl functional group-containing acrylic polymer or polysiloxane polymer, with boric acid and/or a borate ester to form a polymer having borate ester groups.
• Polymers suitable for this purpose can include any of a variety of active hydrogen-containing polymers such as those selected from at least one of acrylic polymers, polyepoxide polymers, polyester polymers, polyurethane polymers, polyether polymers and silicon-based polymers.
• active hydrogen-containing polymers such as those selected from at least one of acrylic polymers, polyepoxide polymers, polyester polymers, polyurethane polymers, polyether polymers and silicon-based polymers.
• silicon-based polymers is meant a polymer comprising one or more —SiO— units in the backbone.
• Such silicon-based polymers can include hybrid polymers, such as those comprising organic polymeric blocks with one or more —SiO— units in the backbone.
• boric acid is used in the electrodeposition bath of the present invention.
• Boric acid or boric acid equivalents of the present invention are present in the electrocoat bath at a level ranging from greater than 0.3% to less than 2.0% of the total weight of the bath.
• boric acid or boric acid equivalents of the present invention are present in the electrocoat bath at a level ranging from 0.4% to 1.7% of the total weight of the bath.
• boric acid or boric acid equivalents of the present invention are present in the electrocoat bath at a level ranging from 0.5% to 1.6% of the total weight of the bath.
• Chlorhexidine is a known antiseptic compound. It is also known as 1,6-bis [5-(p-chlorophenyl)biguanidino]hexane and has the structural formula as shown in Figure I.
• Chlorhexidine is present in the electrocoat bath at a level of from greater than 0.01% to 0.2% of the total weight of the bath.
• chlorhexidine is present in the electrocoat bath at a level ranging from 0.02% to 0.18% of the total weight of the bath.
• chlorhexidine is present in the electrocoat bath at a level ranging from 0.03% to 0.16% of the total weight of the bath.
• chlorhexidine When chlorhexidine is present at its lowest level, 0.01% of the total weight of the bath, it is desired to keep the level of boric acid at greater than 0.5% of the total weight of the bath, more preferably at a level of greater than or equal to 1.0% of the total weight of the bath.
• the present invention is an electrodepositable composition suitable for use as an electrodeposition bath comprising film-forming resins having ionic salt groups wherein the electrodeposition bath includes boric acid and chlorhexidine.
• film-forming resins are epoxy-based resins having amine salt groups and/or sulfonium salt groups.
• the electrodepositable composition has a pH of 7 or less. At a pH of greater than 7, such cationic compositions tend to adsorb carbon dioxide from the surrounding atmosphere and, consequently, can drift below pH 7 over time. Therefore, compositions having a pH of 7 or less are more stable and process conditions are easier to control.
• the term “principal emulsion” as used herein means an electrocoating composition comprising an aqueous emulsion of a binder of an epoxy amine adduct blended with a crosslinking agent which has been neutralized with an acid to form a water-soluble product.
• the binder of the electrocoating composition typically is a blend of an epoxy amine adduct and a blocked polyisocyanate crosslinking agent. While the microbiocides are potentially usable with a variety of different cathodic electrocoat resins, the epoxy amine adduct resins are particularly preferred. These resins are generally disclosed in U.S. Pat. No. 4,419,467 which is incorporated by reference.
• Preferred crosslinkers for the epoxy amine adduct resins are also well known in the prior art. These are aliphatic, cycloaliphatic and aromatic isocyanates such as hexamethylene diisocyanate, cyclohexamethylene diisocyanate, toluene diisocyanate, methylene diphenyl diisocyanate and the like. These isocyanates are pre-reacted with a blocking agent such as oximes, alcohols, or caprolactams which block the isocyanate functionality, i.e., the crosslinking functionality. Upon heating the blocking agents separate, thereby providing a reactive isocyanate group and crosslinking occurs. Isocyanate crosslinkers and blocking agents are well known in the prior art and also are disclosed in the aforementioned U.S. Pat. No. 4,419,467.
• the cathodic binder of the epoxy amine adduct and the blocked isocyanate are the principal resinous ingredients in the electrocoating composition and are usually present in amounts of about 30 to 50% by weight of solids of the composition.
• the solids are generally reduced with an aqueous medium.
• the electrocoating composition usually contains pigment which is incorporated into the composition in the form of a pigment paste.
• the pigment paste is prepared by grinding or dispersing a pigment into a grinding vehicle and optional ingredients such as wetting agents, surfactants, and defoamers. Any of the pigment grinding vehicles that are well known in the art can be used or the novel additive described above can be used. After grinding, the particle size of the pigment should be as small as practical; generally, the particle size is about 6-8 using a Hegman grinding gauge.
• Pigments which can be used in this invention include titanium dioxide, basic lead silicate, strontium chromate, carbon black, iron oxide, clay and the like. Pigments with high surface areas and oil absorbencies should be used judiciously because these can have an undesirable affect on coalescence and flow of the electrodeposited coating.
• the pigment to binder weight ratio is also important and should be preferably less than 0.5:1, more preferably less than 0.4:1, and usually about 0.2:1 to 0.4:1. Higher pigment to binder weight ratios have been found to adversely affect coalescence and flow.
• the coating compositions of the invention can contain optional ingredients such as wetting agents, surfactants, defoamers and the like.
• surfactants and wetting agents include alkyl imidazolines such as those available from Ciba-Geigy Industrial Chemicals, Tarrytown, N.Y., as “Amine C”, acetylenic alcohols available from Air Products and Chemicals, Allentown, Pa., as “Surfynol® 104”.
• These optional ingredients when present, constitute from about 0.1 to 20 percent by weight of binder solids of the composition.
• plasticizers can be used to promote flow.
• useful plasticizers are high boiling water immiscible materials such as ethylene or propylene oxide adducts of nonyl phenols or bisphenol A.
• Plasticizers are usually used at levels of about 0.1 to 15 percent by weight resin solids.
• the electrocoating composition of this invention is an aqueous dispersion.
• the term “dispersion” as used within the context of this invention is believed to be a two-phase translucent or opaque aqueous resinous binder system in which the binder is in the dispersed phase and water the continuous phase.
• the average particle size diameter of the binder phase is about 0.1 to 10 microns, preferably, less than 5 microns.
• the concentration of the binder in the aqueous medium in general is not critical, but ordinarily the major portion of the aqueous dispersion is water.
• the aqueous dispersion usually contains from about 3 to 50 percent preferably 5 to 40 percent by weight binder solids.
• Aqueous binder concentrates which are to be further diluted with water when added to an electrocoating bath generally have a range of binder solids of 10 to 30 percent weight.
• Electrocoat samples were prepared by adding 1 milliliter (ml) of the challenge inoculum to 49 ml of electrocoat sample dispersion. This bacterial inoculation produced a bacterial count ranging from 1.0 ⁇ 10 5 to 1.7 ⁇ 10 6 CFU/ml. These challenged samples were incubated at room temperature with stirring and sterile air agitation (air at ⁇ 0.1 Liters/minute) for 30 days. Samples were tested for the presence of bacteria by a standard plat count method after 1 hour, 24 hours, 1 week, 2 weeks, 3 weeks, and 30 days after inoculation. Tryptic Soy Agar (TSA) was used for enumeration of bacteria from the electrocoat samples using standard spread plate technique.
• TSA Tryptic Soy Agar
• Table 1 shows the Bacterial Count data for the microbiocides tested and the control data.
• N.D. (1.5%) F Chlorhexidine 1.30 ⁇ 10 6 1.10 ⁇ 10 3 3.45 ⁇ 10 2 N.D. 2.25 ⁇ 10 7 8.00 ⁇ 10 5 2.50 ⁇ 10 5 (0.1%) G Boric Acid 1.70 ⁇ 10 6 1.70 ⁇ 10 6 1.65 ⁇ 10 6 4.50 ⁇ 10 4 1.26 ⁇ 10 3 N.D. N.D. (1.0%) + Chlorhexidine (0.01%) H Boric Acid 1.70 ⁇ 10 6 1.25 ⁇ 10 6 9.05 ⁇ 10 4 6.85 ⁇ 10 2 N.D. N.D. N.D.
• Example E containing 1.5% boric acid showed an increase in the microbe count before eventually controlling the population after 3 weeks.
• electrocoat compositions containing 0.5% or greater of boric acid and greater than 0.01% chlorhexidine showed decreasing microbe populations.

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• 2008
  • 2008-06-12 JP JP2010512213A patent/JP2010529281A/ja active Pending
  • 2008-06-12 US US12/157,762 patent/US20080308423A1/en not_active Abandoned
  • 2008-06-13 CA CA002683718A patent/CA2683718A1/fr not_active Abandoned
  • 2008-06-13 EP EP08768484A patent/EP2155829A1/fr not_active Withdrawn
  • 2008-06-13 MX MX2009013466A patent/MX2009013466A/es unknown
  • 2008-06-13 WO PCT/US2008/007462 patent/WO2008156711A1/fr active Application Filing

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