EP1427789A1 - Aqueous dispersion of high molecular weight polyester for chip resistant primer - Google Patents

Aqueous dispersion of high molecular weight polyester for chip resistant primer

Info

Publication number
EP1427789A1
EP1427789A1 EP01968756A EP01968756A EP1427789A1 EP 1427789 A1 EP1427789 A1 EP 1427789A1 EP 01968756 A EP01968756 A EP 01968756A EP 01968756 A EP01968756 A EP 01968756A EP 1427789 A1 EP1427789 A1 EP 1427789A1
Authority
EP
European Patent Office
Prior art keywords
polyester
salt
water
polymeric vehicle
molecular weight
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01968756A
Other languages
German (de)
English (en)
French (fr)
Inventor
Gary Eugene Spilman
Michael Charles Knight, Jr.
Lisa Kay Kemp
Joseph Leo Nothnagel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Chemical Co
Original Assignee
Eastman Chemical Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Chemical Co filed Critical Eastman Chemical Co
Publication of EP1427789A1 publication Critical patent/EP1427789A1/en
Withdrawn legal-status Critical Current

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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
    • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
    • 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
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
    • C08G63/16—Dicarboxylic acids and dihydroxy compounds
    • C08G63/20—Polyesters having been prepared in the presence of compounds having one reactive group or more than two reactive groups

Definitions

  • the present invention relates to stable aqueous polyester dispersions useful as primers. More particularly, the aqueous polyester dispersions balance relatively high molecular weights and low hydroxyl numbers to provide a primer coating that effectively improves chip resistance of paint coatings overlaying the primer while maintaining adhesion and low levels of volatile organic compounds and low viscosities.
  • Automotive and other durable coatings are complex multilayer systems which rely on certain performance '' criteria at each level for overall success.
  • the bulk of the responsibility for providing improved chip resistance ' lies with the primer surface layer.
  • improving chip resistance properties of automotive coatings or other types of protective or decorative durable coatings is clearly a system-dependent task.
  • a chip- resistance test is by nature high in stress, impact, and shear, which intuitively generates hypotheses based on the softness, or rubber- like characteristics of the primer layer. Any contributions from the primer to increase brittleness eventually may lead to reduced chip performance. This can be related to the degree of cross linking. Very low and very high levels of cross linking in such systems lead to poor chip resistance.
  • the coating does not possess the strength properties necessary to withstand the impact and shear forces applied by the gravel.
  • the base molecular weight is usually too low to provide appropriate elastic properties associated with light cross linking. The result is flow and scission on gravel impact.
  • An extremely high cross link density affords large numbers of covalent cross links which impart brittleness to the coating, and failure is based on the inability of the coating to absorb and evenly distribute these concentrated forces applied at the gravel impact.
  • the material neither flows, nor elastically deforms, but instead suffers brittle fracture.
  • cross linkers often cause VOCs by virtue of VOC by product release from the cross link reaction between the cross linkers and polymeric resin.
  • the coatings overlying the primer and the primer base resin must each deliver a balance of properties to the final coating.
  • the easiest way to maximize mechanical properties of the primer resin is to increase molecular weight. Increases in molecular weight, however, generally increase the viscosity of such resins. While high viscosity resins may be cut with organic solvents, this results in an undesirable increase in volatile organic compounds (VOCs) .
  • VOCs volatile organic compounds
  • the present invention is directed to an aqueous dispersion of a polyester salt and polymeric vehicles which include the aqueous dispersions of a polyester salt.
  • the polymeric vehicle is particularly effective for providing coating binders in cured primer coatings (the cured primer paint coating film) .
  • the primer coating compositions (also known as formulated coating compositions) are useful for multilayer paint coating films which have at least two layers of paint film including the cured primer coating composition film.
  • the use of the primer polymeric vehicles of the present invention in conjunction with one or more additional overlaying top coating film layers provide a multiple layer coating system having improved adhesion and chip resistance.
  • the primer polymeric vehicle of the invention permits the use of less cross linker to cross link the polyester salt.
  • the use of less cross linker results in the release of less VOCs upon cross linking and a lower cross linker density in the cured coating binder film of in the cured primer coating composition.
  • the reduced cross link density with the relative high molecular , weight of the polyester salt provides improved chip resistance.
  • the polyester salt of the present invention has a higher molecular weight which enhances chip resistance and needs less cross linker (which also enhances chip resistance) to cure into a useable film than a polyester which is compositionally the same (and is not a metal or ammonium salt), but has a lower molecular weight.
  • the polymeric vehicle of the present invention includes a water dispersible polyester salt having unique combination of high molecular weight, a relatively low hydroxyl value or number, a unique ratio of hydroxyl value to number average molecular weight and a polyester with an acid value which permits formation of the water dispersible salt .
  • the polyester salt is cross linkable to form a cured coating binder in a primer paint coating film which is chip resistant when it is part of a multilayer paint coating system which has at least two paint film layers including the cured primer paint coating film layer.
  • the cured coating binder of the primer of the invention also renders the multilayer paint coating system chip resistant.
  • the polymeric vehicle of the primer coating composition balances the hydroxyl value and number average molecular weight of the polyester salt in the aqueous dispersion to provide VOC reduction through the use of an aqueous system with reduced amount of cross linker as well as improved chip resistance and adhesion for the cured primer paint coating film of the primer coating composition.
  • the desired hydroxyl number is generally inversely related to .the polyester molecular weight.
  • the polymeric vehicle for the primer coating composition or formulated coating comprises an aqueous dispersion of a polyester salt which is the residue of a polyester having a number average molecular weight of about 1500 Daltons and a hydroxyl value of about 90.
  • the polyester has a hydroxyl equivalent weight of about 600. This aqueous dispersion is effective for providing the polymeric vehicle with less than about 5 weight percent organic solvent.
  • the polymeric vehicle for the primer coating composition or formulated coating comprises an aqueous dispersion of a polyester salt which is the residue of a polyester having a number average molecular weight of about 2800 Daltons and a hydroxyl value of about 50.
  • the polyester has a hydroxyl equivalent weight of about 1100. This aqueous dispersion is effective for providing the polymeric vehicle with less than about 5 weight percent organic solvent.
  • the chip resistance of the multilayer paint coating system which includes the coating binder of the primer of the invention is superior to the chip resistance of a multilayer paint coating system which includes a primer which has compositionally the same polyester which has a lower molecular weight and is not a salt. It is these latter lower molecular weight polyesters which are generally used with organic solvent or mixed organic/water solvent ⁇ systems . They are high in VOCs and generally require more cross linker to cure ' than the polymeric vehicle of the present invention.
  • the polymeric vehicle for the primer coating composition or formulated coating comprises an aqueous dispersion of a polyester salt which is the residue of a polyester having a number average molecular weight of at least 1500 Daltons and a hydroxyl value of not more than 90.
  • the polyester has a hydroxyl equivalent weight of about 600 to about 1100.
  • This aqueous dispersion is effective for providing the polymeric vehicle with less than about 5 weight percent organic solvent.
  • the salt of the polyester in the aqueous dispersion has a particle size of less than 400 nm.
  • the polyester salt is the residue of a polyester having an acid value of at least 30, and in an important aspect, from about 40 to about 50, the polyester salt having a hydroxyl value of from about 90 to about 50 and the salt having a number average molecular weight of from about 1500 to about 2800 Daltons (not including the cationic portion of the salt, that is the salt includes the residue of a polyester where the polyester has a molecular weight of from about 1500 to about 2800 Daltons) .
  • the polymeric vehicle of the invention is effective for providing a multilayer paint coating system and primer coacing binder with a two pint chip number rating of at least about 5 and a two pint chip size of at least about A (using the Society of Automotive Engineers Chip Test No.
  • the polymeric vehicle of the primer when the polymeric vehicle of the primer is cured and a part of a multilayer paint coating system of at least two layers inclusive of the primer coating binder.
  • the polymeric vehicle and the aqueous dispersion of the present invention have a viscosity of less than about 10 poise at a temperature of about 25 °C. using less than about 5 weight percent organic solvent, and in an important aspect, less than about 2 weight percent organic solvent.
  • the polyester salt requires less equivalent amounts of cross linker for cross linking than the same lower weight polyester (which is not a salt) having molecular weights of less than about 1500 Daltons, which polyester is generally less than about 800 Daltons.
  • Suitable cross linkers include multifunctional amino resins and blocked isocyanate compounds.
  • the polymeric vehicles of the invention generally will include from about 15 to about 25 weight percent crosslinker, based on the weight of the polymeric vehicle.
  • Polymeric vehicles which use the low molecular weight polyesters previously described are polyesters which are not salts and which are used in high solids systems will generally require from about 35 to about 50 weight percent crosslinker.
  • an ionic functional polyester polymer is synthesized neat and subsequently mixed with hydrophilic organic solvent.
  • the aqueous polymer dispersion is made by forming a polyester having sufficient ionizable groups to provide the polyester with an acid value of from about 30 to about 50.
  • the polymer has a solubility in the hydrophilic solvent of at least about 50 weight percent, and the organic hydrophilic solvent has a solubility in water of at least about 5 weight percent.
  • the polyester prior to neutralization reactions to form a salt has a number average molecular weight of at least about 1500, and in an important aspect, about 1500 to about 2800 and a hydroxyl number of from about 50 to about 90. At least about 30 percent of the ionizable groups of the polyester polymer in the solvent are neutralized with an amount of neutralizer effective to form a solution of neutralized polymer salt.
  • the neutralizer may be any salt- forming base compatible with the ionizable functional polymer such as sodium hydroxide or an amine.
  • the neutralizer is an amine type which is selected from the group consisting of ammonia, triethanol amine, dimethyl ethanol amine, and 2 -amino-2 -methyl-1-propanol . Not all of the ionizable groups on the polymers need to be reacted with the base (or neutralized) .
  • the polymer is neutralized before it is blended with water so that water dispersible neutralized ionizable groups are generally evenly distributed throughout the polymer. It is also important that the organic solvent and some water are removed or stripped from the blend at a duration, temperature and pressure effective for providing an aqueous dispersion having a resin mean particle size of not greater than about 400 nm.
  • the polymer salt concentration is at least about 30 weight percent, the organic solvent concentration of less than 5 weight percent, and even less than 2 weight percent.
  • the neutralizer is an amine or ammonia
  • the mean particle size of the resin is maintained with a stripping temperature of not more than about 65°C at a pressure which permits such a stripping temperature.
  • the invention provides formulated coatings that include aqueous polymer dispersions of the invention with co- solvents selected from the group consisting of butoxy ethanol, diethylene glycol monobutyl ' ether, secondary butyl alcohol, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, propylene glycol n-propyl ether, propylene glycol t-butyl ether, and mixtures thereof.
  • co- solvents selected from the group consisting of butoxy ethanol, diethylene glycol monobutyl ' ether, secondary butyl alcohol, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, propylene glycol n-propyl ether, propylene glycol t-butyl ether, and mixtures thereof.
  • These formulated coating compositions generally will include rheology modifiers such as fumed silica and bentonite clays.
  • “Hydroxyl number” or “hydroxyl value” which is also called “acetyl value” is a number which indicates the extent to which a substance may be acetylated; it is the number of milligrams of potassium hydroxide required for neutralization of the acetic acid liberated on saponifying 1 g of acetylated sample.
  • hydroxyl number is based on solid polyester in the system and not on solution.
  • the hydroxyl number units are mg KOH/gram of resin solids.
  • Polymeric vehicle means all polymeric and resinous components in the formulated coating, i.el, before film formation, including but not limited to the water dispersible salt of a polymer.
  • the polymeric vehicle may include a cross linking agent.
  • Coating binder means the polymeric part of the film of the coating after solvent has evaporated and after crosslinking.
  • Formated coating composition means the polymeric vehicle and solvents, pigments, catalysts and additives which may optionally be added to impart desirable application characteristics to the formulated coating and desirable properties such as opacity and color to the film.
  • aqueous medium as used herein means water and a mixture of water and hydrophilic organic solvent in which the content of water is at least 10% by weight.
  • hydrophilic solvents include alkylalcohols such as isopropanol, methanol , ethanol, n-propanol, n-butanol, secondary butanol, tert-butanol and isobutanol, ether alcohols such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, methyl carbitol and ethyl carbitol, ether esters such as methyl cellosolve acetate and ethyl cellosolve acetate, dioxane, dimethylformamide, diacetone alcohol, methyl ethyl ketone, acetone, and tetrahydrofurfuryl alcohol.
  • Ionizable group refers to functional groups on the polymer that
  • Neutralizer refers to compositions which can react with ionizable groups on the polymer to affect water dispersibility.
  • Examples of neutralizers useful in the present invention include amines, ammonia, and metal hydroxides including NaOH and OH. In an important aspect of the invention, the neutralizers are amines and ammonia .
  • Residue of a polyester salt refers to the reaction product of an ionizable polyester with a neutralizer.
  • Cross linker or “cross linking agent” means a polyfunctional compound capable of reaction with a hydroxyl of a polyol or a phenol hydroxyl or both. These agents include a compound having di- or polyfunctional isocyanate groups or a polyfunctional amino resin.
  • the isocyanate compound or amino resin contains isocyanate or other cross linking functional groups that are capable of forming covalent bonds with hydroxyl groups that are present on the polyester polyol in the polymeric vehicle.
  • the cross linking agent may be a blend; hence, there may be more than one substance which forms a blend of substances which form covalent bonds with the hydroxyl groups of the polyester polyol . Amino reins and polyisocyanates are such cross linking agents.
  • Isocyanate compound means a compound which when reacted with an hydroxyl results in a carbamate linkage.
  • the isocyanate compound may be a blocked polyisocyanate, a blocked biuret, a blocked uretdione and a blocked isocyanurate .
  • Diisocyanates which may be used in the invention additional to HDI include isophorone diisocyanate (IPDI) , tetramethylxylene diisocyanate (TMXDI) , and other aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1, 2 -propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4- trimethylhexamethylene diisocyanate; cycloalkylene diisocyanates such as 1, 3-cyclopentane-diisocyanate, 1,4- cyclohexane-diisocyanate and 1, 3-cyclohexane- diisocyanate; and aromatic diisocyanates such as m- phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-
  • the polyisocyanates may be dimerized or trimerized diisocyanates such as trimerized HDI ' or IPDI and triisocyanates such as triphenylmethane-4, 4 ', 4"- triisocyanate, 1, 3, 5- triisocyanatobenzene, 1,3,5- triisocyanatocyclohexane, 2, 4, 6-triisocyanatotoluene and ⁇ -isocyanatoethyl-2, 6-diisocyanatocaproate; and tetraisocyanates, such as 4,4 ' -diphenyldimethylmethane- 2 , 2 ' , 5 , 5 ' - tetraisocyanate.
  • Bouret means an isocyanate reacted with water in a ratio of three equivalents of isocyanate to one mole of water, such as the biuret of HDI shown below:
  • isocyanurate is a six-membered ring having nitrogens at the 1, 3 and 5 positions and keto groups at the 2, 4 and 6 positions, the nitrogens being substituted with an isocyanate group, such as shown below in the isocyanurate of HDI.
  • Methylol (alkoxymethyl) amino crosslinking agents are suitable for use in the present invention and are well known commercial products, and are generally made by the reaction of di (poly) amide (amine) compounds with formaldehyde and, optionally, a lower alcohol.
  • “Aminio resins” includes melamine resins amd may also be referred to as “melamine- formaldehyde resins” or “alcoholated melamine-formaldehyde resin.”
  • suitable amino- crosslinking resins include one or a mixture of the following materials:
  • R CH,, C.H. (Cymel ® 1130, 1133);
  • R CH., H (Cymel ® 370, 373, 380, 385).
  • the preferred melamine is hexamethoxymethyl melamine.
  • R CH 3 , H (BeetleTM 60, BeetleTM 65); or
  • the reaction product of an alkali metal base or amine or ammonia with a carboxyl group or other ionizable group which is part of a polyester produces a "salt".
  • “Substantially solventless” means a polymeric vehicle or formulated coating composition having not more than about five weight percent organic solvent.
  • “Solvent” means an organic solvent.
  • Organic solvent means a liquid which includes but is not limited to carbon and hydrogen which liquid has a boiling point in the range of not more than about 150 °C at about one atmosphere pressure.
  • Hydrophilic solvent means . a solvent that has a solubility in water of at least about 5 weight percent at room temperature .
  • VOCs Volatile organic compounds
  • a “high solids” or “high solids formulated coating composition” means an aqueous formulated coating composition containing more than about 30 weight percent solids, and in an important aspect of the present invention about 35 weight percent to about 70 weight percent solids as per ASTM test D-2369-92.
  • "Film” is formed by application of the formulated coating composition to a base or substrate, evaporation of solvent, if present, and cross- linking if necessary.
  • “Baked formulated coating composition” means a formulated coating composition that provides optimum film properties upon heating or baking above ambient temperature .
  • Dispossion in respect to a polymeric vehicle, formulated coating composition, or components thereof means that the composition must include a liquid and particles detectable by light scattering.
  • Dissolved in respect to a polymeric vehicle, formulated coating composition or components thereof means that the material which is dissolved does not exist in a liquid in particulate form where particles larger than single molecules are detectable by light scattering.
  • Soluble means a liquid or solid that can be partially or fully dissolved in a liquid.
  • miscible means liquids with mutual solubility.
  • Immbibe water means a liquid is miscible with water.
  • Acid number or “acid value” means the number of milligrams of potassium hydroxide required for neutralization of or reaction with ionizable groups present in 1 g of material, such as resin.
  • Substantially free of emulsifier means a composition with not more than about 0.5 weight percent emulsifiers.
  • Aqueous dispersions of the present invention are substantially free of emulsifier.
  • the term "inversion” refers to a phase change where a mobile phase becomes a disperse ⁇ phase.
  • an inversion takes place where sufficient oil is added to an oil in water phase such that phases invert to change from a oil in water phase to ' a water in oil phase.
  • the mobile phase does not become the disperse phase and the corresponding increase in viscosity associated with dispersions does not occur.
  • the viscosity of the system during processing remains less than about 20 poise, and in a very important aspect, less than about 10 poise at 25°C.
  • a polyester polymer is synthesized neat and subsequently blended into an organic hydrophilic solvent which has limited to infinite solubility in water.
  • Polyester polymers useful in the present invention include those that provide a polyester salt where, the polyester salt is the residue of a polyester having a number average molecular weight of from about 1,500 to about 2,800 Daltons.
  • the polyester polymers have an acid value of less than about 50, and in a very important aspect, about 30 to about 50.
  • polyesters used herein are reaction products of polyhydric alcohols and polycarboxylic acids.
  • suitable polyhydric alcohols include triols and tetraols such as trimethylolpropane, trimethylolethane, tris (hydroxyethyl) isocyanurate, glycerine, and pentaerythritol , and dihydric alcohols or diols that may include neopentyl glycol, dimethylol hydantoin, ethylene glycol, propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, 1 , 4-cyclohexane dimethanol, Esterdiol 204 (trademark of Union Carbide), 1,3 -propane diol, 1, 6-hexanediol, and dimethylol propionic acid (DMPA) .
  • polyhydric alcohols may have -COOH groups.
  • Carboxylic acids utilized in the invention may be aromatic carboxylic acids such as isophthalic acid, terephthalic acid, phthalic acid, phthalic anhydride, dimethyl terephthalic acid, naphthalene decarboxylate, tetrachlorophthalic acid, terephthalic acid bisglycol ester, and benzophenone dicarboxylic acid; and cycloaliphatic, aliphatic carboxylic acids, and polyacids such as trimellitic anhydride (TMA) . As can be seen from the reference to TMA, diacids may have additional -COOH groups.
  • TMA trimellitic anhydride
  • the polyester polymers that are synthesized neat are blended with a solvent selected from the group consisting of alkylalcohols such as isopropanol , methanol , ethanol , n-propanol , n-butanol , secondary butanol , tert -butanol and isobutanol , ether alcohols such as methyl cellosolve , ethyl cellosolve , propyl cellosolve , butyl cellosolve , methyl carbitol and ethyl carbitol , ether esters such as methyl cellosolve acetate and ethyl cellosolve acetate , dioxane , dimethylformamide , diacetone alcohol , methyl ethyl ketone, acetone , and tetrahydrofurfuryl alcohol .
  • the polymers of the invention have a solubility at processing temperatures
  • Stage one provides a resin in a hydrophilic solvent which can be stored, and which can be further processed in stage two.
  • the resin provided in stage one has a storage stability of at least about 6 months .
  • the polyester salt is formed in situ in the organic solvent with water being mixed with the polyester salt/organic solvent combination.
  • neutralizer is added to an organic solvent solution containing the polyester in an amount effective for neutralizing the polyester to provide sufficient salt to render the polyester dispersible in water.
  • Neutralizer useful in the present invention include but are not limited to ammonia, triethanol amine, dimethyl ethanol amine, 2-amino-2-methyl-l-propanol, NaOH and KOH.
  • the amount of neutralizer added is dependent on acid value and molecular weight. In one aspect, from about 30 to about 100 percent of the carboxyl groups are neutralized to obtain the solids level and low VOC level of the dispersions of the invention.
  • neutralizer is mixed with the polyester polymer in an amount effective to provide at least about 70 parts polymer salt in less than about 30 parts solvent wherein with subsequent mixing with water, the neutralized polymer will provide a dispersion which comprises not more than about 70 weight percent water, based on the weight of the dispersion.
  • the polyester requires about 70% to about 100% neutralization to stabilize the dispersion.
  • the process provides a mean particle size of not more than about 400 nm, with a typical mean particle size in the range of about 40 nm to about 200 nm as measured by laser light scattering.
  • the polyester polymer can be preneutralized by making the polymer with metal, amine or ammonia salts of the ionizable groups such as -COOH.
  • the polymer made from these "preneutralized" monomers would have an acid value, as measured by titration, of at least about 30 if the ionizable groups which form part of the polymer were not already neutralized.
  • monomers have a polyfunctionality such as. a difunctionality which permits them to form polymers that also have the salt form of the ionizable groups.
  • a polyfunctionality such as. a difunctionality which permits them to form polymers that also have the salt form of the ionizable groups.
  • An example of such a monomer is
  • a and B are -OH and/or -COOH which can form a polyester in a condensation reaction and C is -COOX, where X is an alkali metal such as sodium or potassium.
  • the initial ratio of solvent to water is from about 0.15 to about 0.45 for polyester polymer.
  • the initial ratio of solvent to water is important to ensure that inversion does not take place during subsequent stripping of solvent.
  • the amount of water to be added may be greater than that required to obtain the desired solids of the final dispersion. Some water loss typically occurs during solvent distillation. The system requires sufficient .solvent at the beginning to solubilize the salt prior to water addition.
  • polymer in hydrophilic solvent is added to water that already contains a neutralizer.
  • the organic solvent and water if required are removed or stripped from the neutralized resin/water/solvent mixture.
  • a reduced atmospheric pressure may be applied to the mixture to aid in the removal of solvent and water.
  • vacuum may range from about 22 inches to about 29 inches of mercury gauge. With lower temperatures, a higher vacuum must be used to remove solvent. Lower reaction temperatures result in less foaming, as the higher vacuum coupled with the surface tension of the bubbles helps to break the bubbles.
  • solvent/water is stripped with heat being supplied through the use of a heat exchanger. Use of a heat exchanger may reduce distillation times and temperatures and further minimize destruction of the salt.
  • solids levels of at least about 30 weight percent to about 45 weight percent can be attained for polyesters.
  • solvent that is removed can be purified and reused.
  • a simple flash or multiple stage distillation is sufficient to clean the solvent of any contamination.
  • the invention permits manufacture of the water dispersion from the polymer using one reaction vessel.
  • the water dispersion of the invention does not require emulsifying agents and does not have more than about 2 weight percent, based on the weight of the composition, of organic solvent after the distillation of the solvent.
  • the aqueous dispersion contains from about 0.2 to about 2 weight percent organic solvent.
  • the water dispersion of the invention includes the water dispersible amine salt of the polymer as well as the unsalified polymer, but in the aspect' of the invention where the ionizable group is a carboxyl, the aqueous dispersion of the invention does not have less than 30 percent of the free carboxyl groups of the polymer neutralized or converted into a salt. As the acid number of the polymer goes down, the higher the percent of the carboxyl groups on the polymer must be neutralized. Where the ionizable groups are -COOH, to maintain the dispersion below an acid value of about 15, about 100% of the carboxyl groups on the polymer should be neutralized to the salt.
  • the dispersions of the invention do not have more than about 1 pound per gallon of dispersion (120 g/1) VOCs, and in a very important aspect the dispersion has about 0.2 pounds per gallon of dispersion VOCs.
  • the water dispersion of the invention with about 0.2 pounds per gallon VOC is stable through at least about 1 freeze- thaw cycle, and up to about 4 freeze-thaw cycles. Freeze-thaw cycles can be " increased with small amounts of solvents or glycols as is typically used for latex systems.
  • the polymeric vehicle is incorporated into a formulated coating composition which upon heating provides a baked formulated coating composition or cured composition. Baking is above ambient temperatures with a cross linker to provide a coating binder.
  • the polymeric vehicle which includes the water dispersion of the invention provides a formulated coating composition having VOCs of less than 1 pound per gallon of formulated coating composition, includes water dispersible polymers and salts thereof having the above indicated molecular weights and not only eliminates a need for, but is substantially free of emulsifiers, surfactants and coalescents .
  • Water dispersion of such high molecular weight polymers provide a coating binder and baked formulated coating compositions with improved film performance characteristics which include, but are not limited to improved chip resistance, adhesion which is just as good as lower molecular weight higher VOC systems, improved lay down performance of the wet film, enhanced film build of the film per pass, faster dry times, improved corrosion resistant films per pass, improved corrosion resistant films, harder films, more abrasion resistant films, and improved humidity resistant films.
  • the polymeric vehicle of the invention also provides coating binders for improved exterior "ultraviolet resistant" durable films which are derived from an aqueous low VOC formulated coating composition. Films provided from the invention are improved over that of aqueous thermoplastic emulsions or water reducible systems of low molecular weight thermoplastic or those thermosetting polymers requiring cross linking.
  • NPG neopentyl glycol
  • TMP trimethylol propane
  • HDO l, 6-hexanediol
  • trimellitic anhydride (TMA) was added to the flask and the temperature was maintained at 170 degrees centigrade.
  • the temperature was reduced to 90 degrees centigrade and the polymer was cut with methyl ethyl ketone (MEK) .
  • MEK methyl ethyl ketone
  • Vacuum was applied to the flask and slowly increased to a maximum of . 26 inches of mercury.
  • NVM Percent Solids
  • Viscosity 45 pH (units) 6.0 particle size (nm) ⁇ 80 weight/gal (lbs) 8.9
  • NPG nenopentyl glycol
  • TMP trimethyol propane
  • BEPD butyl -ethyl -propanediol
  • trimellitic anhydride (TMA) was added to the flask and the temperature was maintained at 170 degrees Celsius.
  • the temperature was reduced to 90 degrees centigrade and the polymer was cut with isopropyl alcohol (IPA) .
  • IPA isopropyl alcohol
  • Vacuum was applied to the flask and slowly increased to a maximum of 26 inches of mercury. 5. Vacuum was continued until the desired percent solids of the dispersion was reached.
  • the dispersed polyester from Example 1 was formulated into a primer as follows:
  • the resulting paint had a calculated VOC of less than 2.0 pounds per gallon and 51% weight non-volatile.
  • the formulated paint was tested by spraying onto high edge protection electrodeposition coated galvanized steel panels.
  • Film thickness of the primer was 1.0 mil dry.
  • the painted panel was flashed at room temperature for 5 minutes, and then flashed an additional 10 minutes in 180 degrees F oven.
  • the painted panel was baked 25 minutes at 330 degrees F.
  • the top three inches of the panel was masked off and the panel was then top coated with a commercially available automotive waterborne base coat/clear coat system and baked 20 minutes at 275 degrees F.
  • Adhesion was then checked with a 3 mm Crosshatch of both the primer to electrocoat only area and the top coated area of the panel. Excellent adhesion was noted in both areas of the panel.
  • the bottom half of the panel was the chipped in a Q- Panel Gravelometer machine with 2 pints of gravel at -20 degrees C. Excellent chip resistance was noted.
  • the dispersed polyester from Example 2 was formulated into a primer as follows:
  • the mixture was filtered through a 25 micron filter cone to, remove the glass beads.
  • the pH is then adjusted to 8.2 to 8.5 with DMEA, and then reduced to 30-32 seconds #4 Ford cup with deionized water.
  • the resulting paint had a calculated VOC of less than 2.0 pounds per gallon, and 53% weight non-volatile.
  • the formulated paint was tested by spraying onto electrodeposition coated cold rolled steel panels. Film thickness of the primer was 1.0 mil dry. The painted panel was flashed at room temperature for 5 minutes, and then flashed an additional 10 minutes in a 180 degrees F oven. The painted panel was then baked 25 minutes at 330 degrees F. The panel was the top coated with a commercially available automotive waterborne basecoat/ clearcoat system and baked 30 minutes at 250 degrees F.
  • Adhesion was then checked with a 3 mm Crosshatch of the top coated area of the panel. Excellent adhesion was. noted on the panel. The bottom half of the panel was then chipped in a Erichsen Chip tester machine with 1.0 kg. of steel shot at room temperature. Excellent chip resistance was noted.
  • NPG/HDO 73 1 2 0/1 0/0 3/1 1/1 0/1 0/1 0/1 0/1 0/1
  • Chip number ratings: 5 25-49 chips per standard area

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Paints Or Removers (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
EP01968756A 2001-09-10 2001-09-10 Aqueous dispersion of high molecular weight polyester for chip resistant primer Withdrawn EP1427789A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2001/028284 WO2003022946A1 (en) 2001-09-10 2001-09-10 Aqueous dispersion of high molecular weight polyester for chip resistant primer

Publications (1)

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EP1427789A1 true EP1427789A1 (en) 2004-06-16

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EP01968756A Withdrawn EP1427789A1 (en) 2001-09-10 2001-09-10 Aqueous dispersion of high molecular weight polyester for chip resistant primer

Country Status (5)

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EP (1) EP1427789A1 (enrdf_load_stackoverflow)
JP (1) JP2005527645A (enrdf_load_stackoverflow)
KR (1) KR20040062944A (enrdf_load_stackoverflow)
CN (1) CN1285684C (enrdf_load_stackoverflow)
WO (1) WO2003022946A1 (enrdf_load_stackoverflow)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7666951B2 (en) * 2005-02-24 2010-02-23 Ppg Industries Ohio, Inc. Coating compositions that include a polyester polyol, related coated substrates, multi-layer coating and methods
US10160872B2 (en) * 2014-08-22 2018-12-25 Basf Coatings Gmbh Aqueous dispersion of a polyester and a polyamide of low acid number and coating composition comprising same for applying a basecoat
FR3037589B1 (fr) * 2015-06-17 2020-02-28 Arkema France Resine polyester hydroxylee et/ou carboxylee a haut extrait sec et haut pouvoir couvrant pour revetement de feuille metallique
JP6579292B1 (ja) * 2017-12-08 2019-09-25 東洋紡株式会社 ポリエステル樹脂、ポリエステル樹脂水分散体、及びポリエステル樹脂水分散体の製造方法

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Publication number Priority date Publication date Assignee Title
DE4036378A1 (de) * 1990-11-15 1992-05-21 Basf Lacke & Farben Verfahren zum beschichten von metallischen gegenstaenden im bandlackierverfahren

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Title
See references of WO03022946A1 *

Also Published As

Publication number Publication date
WO2003022946A1 (en) 2003-03-20
CN1285684C (zh) 2006-11-22
JP2005527645A (ja) 2005-09-15
KR20040062944A (ko) 2004-07-09
CN1549849A (zh) 2004-11-24

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