KR20040062944A - Aqueous dispersion of high molecular weight polyester for chip resistant primer - Google Patents

Abstract

The present invention relates to a polymeric carrier comprising an aqueous dispersion of polyester salts and an aqueous dispersion of such polyester salts. Polymeric carriers are particularly effective in providing a coating binder for cured primer coatings. Primer coating compositions are useful for multilayer paint coating films having at least two paint film layers, including cured primer coating composition films. The use of the primer polymeric carrier of the present invention in combination with one or more additional top coating film overlayers provides a multilayer coating with improved adhesion and chip resistance.

Description

Aqueous Dispersion of High Molecular Weight Polyesters for Chip Resistant Primers {AQUEOUS DISPERSION OF HIGH MOLECULAR WEIGHT POLYESTER FOR CHIP RESISTANT PRIMER}

Automotive coatings and other durable coatings are complex multilayer systems that rely on specific performance criteria at each level for overall success. Much of the responsibility for providing improved chip resistance lies in the primer surface. However, improving chip resistance of automotive coatings or other protective or decorative durable coating types is clearly a system dependent task. In many systems, several key components appear to increase the improvements. Chip resistance testing is due to high stress, impact, and shear force characteristics, which intuitively build a hypothesis based on the ductility or rubbery properties of the primer layer. Any contributor to the primer on increasing fragility may result in chip degradation. This may be related to the degree of crosslinking. Very low and very high levels of crosslinking in such systems lead to poor chip resistance. In the case of low crosslinking, the coating does not possess the strong properties necessary to resist the impact and shear forces exerted on the gravel road. The basis molecular weight is generally too low to provide adequate elasticity with respect to low crosslinking. As a result, it flows down and splits due to the gravel impact. Extremely high crosslink densities provide a number of covalent crosslinks that impair the coating and breakage occurs because the coating is unable to absorb and evenly disperse these concentrated forces applied by cobbled impacts. The material neither flows down nor elastically deforms, but instead soft fractures occur. In addition, crosslinkers often generate VOCs by VOC byproducts that are released from the crosslinking reaction between the crosslinker and the polymer resin. In addition, complex systems using separate crosslinkers tend to react with the crosslinkers themselves. For example, self-condensation of melamine crosslinkers is a potential competitive reaction, which can result in highly concentrated localized regions of highly crosslinked melamine resins. This creates a localized fragility that can result in chip or adhesion failure. Another key contributor to successful chip resistance is the adhesion of the primer to the substrate and subsequent adhesion of another paint coating to the primer (generally internal coat adhesion). A major contributor to this effect is the functional group, which is a primer resin-polar group functional group that includes hydroxyl and carboxyl groups that play a key role in interacting with the substrate and other paint layers.

In order to obtain optimum chip resistance, the coating and primer base resin overlaid on the primers must each balance the properties in the final coating. The easiest way to minimize the mechanical properties of the primer resin is to increase the molecular weight. However, increasing the molecular weight generally increases the viscosity of these resins. High viscosity resins can be cut with organic solvents, but this results in an undesirable increase in volatile organic compounds (VOCs).

Summary of the Invention

The present invention relates to a polymeric carrier comprising an aqueous dispersion of polyester salts and an aqueous dispersion of such polyester salts. Polymeric carriers are particularly effective in providing a coating binder in a cured primer coating (cured primer paint coating film). Primer coating compositions (also known as formulated coating compositions) are useful for multilayer paint coating films having at least two paint film layers, including cured primer coating composition films. The use of the primer polymeric carrier of the present invention in combination with one or more additional top coating film overlays provides a multilayer coating system with improved adhesion and chip resistance.

The primer polymeric carrier of the present invention makes it possible to use less crosslinking agents for crosslinking the polyester salts. Using less crosslinker reduces the release of VOCs upon crosslinking and lowers the crosslinker density in the cured coating binder film in the cured primer coating composition. Together with the relatively high molecular weight of the polyester salts, the reduced crosslink density provides improved chip resistance. While not wishing to be bound by theory, the polyester salts of the present invention are compositionally identical (also have high molecular weight to improve chip resistance and also require less crosslinking agent (which also improves chip resistance). Harder than polyesters with low molecular weight). These low molecular weight polymers are used in highly solid systems and are dispersed in organic solvents or organic / water solvent systems. In addition, the molecular weight of the polyester in the latter highly solid system cannot be increased without increasing the viscosity of the polymer dispersion or solution (in such a system the increase in molecular weight essentially increases the viscosity). Therefore, the polymeric carriers of the present invention are characterized by high molecular weights, relatively low hydroxyl groups or numbers, specific ratios of hydroxyl groups to number average molecular weights, and acid-valued polyesters that form water dispersible salts. Water dispersible polyester salts with specific combinations.

The polyester salts can be crosslinked to form a cured coating binder in the primer paint coating film, which will be part of a multilayer paint coating system having at least two paint film layers, including a cured primer paint coating film layer. When chip resistance is indicated. Cured coating binders of the primers of the invention also provide chip resistance to multilayer paint coating systems. Therefore, the polymeric carrier of the primer coating composition will balance the hydroxyl value of the polyester salt in the aqueous dispersion with the number average molecular weight, thereby providing improved chip resistance and adhesion to the cured primer paint coating film of the primer coating composition. In addition, VOC reduction is provided through the use of an aqueous system with a reduced amount of crosslinker.

In order to improve the chip resistance of the coating system, the primer of the invention is used inside the system, with the preferred number of hydroxyl groups being generally inversely proportional to the polyester molecular weight. By way of example, polymeric carriers for primer coating compositions or formulated coatings include aqueous dispersions of polyester salts that are residues of polyesters having a number average molecular weight of about 1500 Daltons and a hydroxyl group of about 90. In this aspect, the polyester has a hydroxyl group equivalent of about 600. Such aqueous dispersions are effective to provide polymeric carriers containing less than about 5 wt% organic solvent. In terms of higher molecular weight, the polymeric carrier for the primer coating composition or formulated coating comprises an aqueous dispersion of polyester salts that are residues of a polyester having a number average molecular weight of about 2800 Daltons and a hydroxyl group of about 50. In this aspect, the polyester has a hydroxyl group equivalent of about 1100. Such aqueous dispersions are effective to provide polymeric carriers containing less than about 5 wt% organic solvent.

The chip resistance of a multilayer paint coating system comprising a coating binder of a primer of the present invention is superior to the chip resistance of a multilayer paint coating system comprising a primer having a low molecular weight and having a compositionally identical polyester that is not a salt. . These latter low molecular weight polyesters are generally used in organic solvents or mixed organic / water solvent systems. They have high VOCs content and generally require more crosslinking agents than the polymeric carrier of the present invention for curing.

In an important aspect of the invention, the polymeric carrier for the primer coating composition or formulated coating comprises an aqueous dispersion of polyester salts which are residues of a polyester having a number average molecular weight of at least 1500 Daltons and a hydroxyl group of 90 or less. In one aspect, the polyester has a hydroxyl group equivalent of about 600 to about 1100. Such aqueous dispersions are effective to provide polymeric carriers containing less than about 5 wt% organic solvent. In another important aspect, the polyester salt in the aqueous dispersion has a particle size of less than 400 nm.

In yet another aspect, the polyester salt is a residue of a polyester having an acid value of at least 30, and in an important aspect from about 40 to about 50, a polyester salt having a hydroxyl group from about 90 to about 50 and from about 1500 to Salts having a number average molecular weight of about 2800 Daltons (excluding the cationic portion of the salt wherein the polyester comprises residues of a polyester having a molecular weight of about 1500 to about 2800 Daltons). The polymeric carrier of the present invention has a two pint chip count rating of at least about 5 and at least when the polymeric carrier of the primer is cured to become part of a multilayer paint coating system of at least two layers including a primer coating binder. It is effective to provide a multilayer paint coating system and primer coating binder having a two pint size of about A (measured using Chip Test J400 from the Society of Automotive Engineers). Despite the use of relatively high molecular weight polyesters, the polymeric carriers and aqueous dispersions of the invention, when used with less than about 5 wt% organic solvent, and in important aspects less than about 2 wt% organic solvent, Have a viscosity of less than about 10 poise at a temperature of < RTI ID = 0.0 >

As noted above, polyester salts require less equivalent weight of crosslinking agent than the same low molecular weight polyester (but not salt) having a molecular weight of less than about 1500 Daltons for crosslinking, wherein the polyester is generally about Less than 800 Daltons. Suitable crosslinkers include multifunctional amino resins and bulk isocyanate compounds. The polymeric carrier of the present invention will generally comprise from about 15 to about 25 wt% of the crosslinker, based on the weight of the polymeric carrier. Polymeric carriers using the aforementioned low molecular weight polyesters that are not salts and are used in highly solid systems will generally require from about 35 to about 50 wt% crosslinker.

According to the invention, the ionic functional polyester polymer is synthesized purely and then mixed with a hydrophilic organic solvent. Aqueous polymer dispersions are prepared by forming a polyester having sufficient ionizable functional groups to provide a polyester having an acid value of about 30 to about 50. The polymer has a solubility in hydrophilic solvent of at least about 50 wt%, and the organic hydrophilic solvent has a solubility in water of at least about 5 wt%. As noted above, the polyester prior to the neutralization reaction to form salts has a number average molecular weight of at least about 1500, and in important respects from about 1500 to about 2800 and a number of hydroxyl groups from about 50 to about 90. At least about 30% of the ionizable functional groups of the polyester polymer in the solvent are neutralized by an amount of neutralizing agent effective to form a neutralized polymer salt solution. The neutralized polymer salt solution is then mixed with water to form a blend of water / organic solvent / neutralized polymer. The organic solvent is then separated from the latter blend at about 65 ° C. or lower to form a neutralized polyester salt dispersion in water. Such dispersions have a viscosity of less than about 10 poise at a temperature of about 25 ° C. The neutralizer may be any salt forming base that is compatible with the ionizable functional polymer, such as sodium hydroxide or amine. In a very important aspect, the neutralizer is an amine type selected from the group consisting of ammonia, triethanol amine, dimethyl ethanol amine, and 2-amino-2-methyl-1-propanol. Not all ionizable functional groups on the polymer need to react (or neutralize) with a base.

Depending on the type of ionizable functional groups present in the polymer, it may be important to neutralize the polymer prior to blending with water so that the water dispersible neutralized ionizable functional groups are generally uniformly distributed throughout the polymer. It is also important that some of the organic solvent and water are removed or separated from the blend at a time, temperature and pressure effective to provide an aqueous dispersion having an average resin particle size of about 400 nm or less. In an important aspect, the polymer salt concentration is at least about 30 wt% and the concentration of the organic solvent is less than 5 wt%, and much less than 2 wt%. In an important aspect, when the neutralizing agent is an amine or ammonia, the average particle size of the resin is maintained by a separation temperature of about 65 ° C. or less and a pressure to enable this separation temperature.

In another aspect, the invention provides 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- Provided is a formulated coating comprising a co-solvent selected from the group consisting of butyl ether, and mixtures thereof, and the aqueous polymer dispersion of the present invention. These formulated coating compositions will generally include rheology modifiers such as fumed silica and bentonite clay.

The present invention relates to stable aqueous polyester dispersions useful as primers. More specifically, the present invention provides a relatively high molecular weight and low hydride to provide a primer coating that effectively improves the chip resistance of a paint coating overlaid on the primer while maintaining adhesion and low content of volatile organic compounds and low viscosity. Aqueous polyester dispersions with a balanced number of hydroxy groups.

Justice

The "hydroxy group number" or "hydroxy group", also referred to as "acetyl number", is a measure of the degree to which a substrate can be acetylated. mg value. For this application, the number of hydroxy groups is based on solid polyester in the system, not on solution.

The "hydroxy group equivalent" is calculated from the hydroxyl group number (OHN) according to ASTM D1957 as follows.

Hydroxy group equivalent = 56,100 / OHN.

The unit of hydroxyl group number is mg KOH per gram of resin solid.

"Polymeric carrier" means all polymer components and resin components in the formulated coating, that is, prior to film formation, and includes, but is not limited to, water dispersible salts of the polymer. The polymeric carrier may comprise a crosslinking agent.

"Coating binder" means the polymer portion of the coating film after evaporating and crosslinking the solvent.

"Formulated coating composition" means a polymeric carrier and solvents, dyes, catalysts and additives that can optionally be added to impart desirable application characteristics to the formulated coating and impart desirable properties such as opacity and color to the film. .

As used herein, the term "aqueous medium" refers to a mixture of water and a hydrophilic organic solvent with a water content of at least 10 wt%. Examples of hydrophilic solvents include alkyl alcohols 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 functional group" means a functional group on a polymer that affects the water dispersibility of the polymer. Examples of ionizable functional groups include -COOH.

"Neutralizing agent" means a composition that can react with ionizable functional groups on a polymer to affect water dispersibility. Examples of neutralizing agents useful in the present invention include amines, ammonia, and metal hydroxides such as NaOH and KOH. In important aspects of the invention, the neutralizing agents are amines and ammonia.

"Residue of a polyester salt" means the reaction product of a neutralizing agent and an ionizable polyester.

"Crosslinker" or "crosslinker" means a multifunctional compound capable of reacting with the hydroxyl group or the phenolic hydroxyl group of the polyol or both. These formulations include compounds with bifunctional or polyfunctional isocyanate groups or polyfunctional amino resins. Isocyanate compounds or amino resins contain isocyanate groups or other crosslinkable functional groups capable of forming covalent bonds with the hydroxyl groups present in the polyester polyols in the polymeric carrier. Since the crosslinker may be a blend, it may be more than one kind of material that forms a blend of materials that form covalent bonds with the hydroxyl groups of the polyester polyol. Amino resins and polyisocyanates are such crosslinkers.

"Isocyanate compound" means a compound that forms a carbamate bond upon reaction with a hydroxyl group. The isocyanate compound may be bulk polyisocyanate, block biuret, block uretdione and block isocyanurate.

Diisocyanates that can be used in the present invention in addition 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'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2 , 4- or 2,6-toluene diisocyanate.

“Polyisocyanate” may mean a compound having two or more isocyanate groups [—N═C═O], which may be biurets and isocyanurates. Polyisocyanates include dimerized or trimerized diisocyanates such as trimerized HDI or IPDI; Triisocyanates such as triphenylmethane-4,4 ', 4 "-triisocyanate, 1,3,5-triisocyanatobenzene, 1,3,5-triisocyanatocyclohexane, 2,4,6-triisocia Nattoluene and ω-isocyanatoethyl-2,6-diisocyanatocaproate and tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2 ', 5,5'-tetraisocyanate .

"Carbamate bond" means -OC (= 0) N (-H)-, which can be a urethane bond.

"Burette" means an isocyanate that reacts with water in a ratio of 3 equivalents of isocyanate to 1 mole of water, for example a burette of HDI represented by the formula:

"Isocyanurate" is a 6-membered ring having a nitrogen atom substituted with an isocyanate group at positions 1, 3 and 5 and a keto group at positions 2, 4 and 6, for example iso of HDI represented by the formula Cyanurate is:

Methylol (alkoxymethyl) amino crosslinkers are suitable for use in the present invention and are well known as commodities and are generally prepared by the reaction of formaldehyde and optional lower alcohols with di (poly) amide (amine) compounds.

"Amino resin" includes melamine resin and may also be referred to as "melamine-formaldehyde resin" or "alcoholated melamine-formaldehyde resin". Examples of suitable amino-crosslinking resins may include one or a mixture of the following materials:

Melamine resin:

Wherein R is as follows:

R = CH ₃ (Cymel ^® 300, 301, 303);

R = CH ₃ , C ₂ H ₅ (Cymel ^® 1116);

R = CH ₃ , C ₄ H ₉ (Cymel ^® 1130, 1133);

R = C ₄ H ₉ (Cymel ^® 1156); or

R = CH ₃ , H (Cymel ^® 370, 373, 380, 385).

Preferred melamine is hexamethoxymethyl melamine.

Benzoquanamine series resin:

Wherein R = CH ₃ , C ₂ H ₅ (Cymel ^® 1123).

Urea Resin:

Where

R = CH ₃ , H (Beetle ™ 60, Beetle ™ 65); or

R = C ₄ H ₉ (Beetle ™ 80).

Glycoluril Resin:

Where

R = CH ₃ , C ₂ H ₅ (Cymel ^® 1171); or

R = C ₄ H ₉ (Cymel ^® 1170).

"Polyester" refers to the backbone of the polymer It means a polymer having a bond.

As used herein, a “salt” is yielded as the reaction product of an alkali metal base or amine or ammonia with a carboxyl group or other ionizable functional group that is part of a polyester.

By "substantially solvent free" is meant a polymeric carrier or formulated coating composition containing less than about 5 wt% organic solvent.

"Solvent" means an organic solvent.

"Organic solvent" means a liquid, including but not limited to carbon and hydrogen, wherein the boiling point of the liquid ranges from about 1 atmosphere to about 150 degrees Celsius or less.

"Hydrophilic solvent" means a solvent having a solubility in water of at least about 5 wt% at room temperature.

"Volatile Organic Compounds" (VOCs) are the 40 C.F.R. According to 51.000, the US Environmental Protection Agency.

"High solids" or "coating compositions formulated with high solids" are at least about 30 wt% solids, and in an important aspect of the invention, from about 35 to about 70 wt%, according to ASTM test D-2369-92. By formulated aqueous coating composition containing a solid. A "film" is formed by applying a coating composition formulated to a base or substrate, evaporating the solvent, if present, and then crosslinking if necessary.

By "baked formulated coating composition" is meant a formulated coating composition that provides optimum film properties upon heating or hot drying above ambient temperature.

“Dispersion” in the context of polymeric carriers, formulated coating compositions, or components thereof, means that the composition must comprise liquids and particles that can be detected by light scattering.

"Dissolved" with respect to polymeric carriers, formulated coating compositions, or components thereof, means that the dissolved material is not present in the liquid as particulates in which particles larger than a single molecule can be detected by light scattering. do.

"Soluble" means a liquid or solid that can be partially or completely dissolved in a liquid. "Miscible" means liquids that are mutually soluble. "Absorbing water" means a liquid that is miscible with water.

"Acid value" or "acid value" means the mg value of potassium hydroxide required to neutralize or react with ionizable functional groups present in 1 g of a material such as, for example, a resin.

"Substantially free of emulsifier" means that the composition contains up to about 0.5 wt% emulsifier. The aqueous dispersion of the present invention is substantially free of emulsifiers.

As used herein, the term "conversion" refers to a phase change into a dispersible phase of a mobile phase. For example, when sufficient oil is added to the oil-in-water phase, the transition occurs when the oil-in-water phase changes to the water-in-oil phase. In contrast, in a "no conversion" system, the mobile phase does not become a dispersible phase and no corresponding viscosity increase associated with the dispersion occurs. In an important aspect of the present invention, the viscosity of the system is maintained at less than 20 poise during the process and, in a very important aspect, at less than about 10 poise at 25 ° C.

Step 1: Preparation of Polyester

According to the first step of the invention, the polyester polymer is synthesized purely and then blended into a hydrophilic organic solvent which is defined as infinite solubility in water. Polyester polymers useful in the present invention include those that provide a polyester salt, which is the residue of the polyester having a number average molecular weight of about 1500 to about 2800 Daltons. In an important aspect of the invention, the polyester polymer has an acid value of less than about 50, and in a very important aspect, it has an acid value of about 30 to about 50.

Polyester as used herein is the reaction product of polyhydric alcohols and polycarboxylic acids. Examples of suitable polyhydric alcohols include triols and tetraols such as trimethylolpropane, trimethylolethane, tris (hydroxyethyl) isocyanurate, glycerin and pentaerythritol; And neopentyl glycol, dimethylol hydantoin, ethylene glycol, propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexane dimethanol, Esterdiol 204 (Union Carbide ), 1,3-propane diol, 1,6-hexanediol, and dihydric alcohols or diols, which may include dimethylol propionic acid (DMPA). As can be seen from DMPA, the polyhydric alcohol can have a -COOH group.

The carboxylic acids used in the present invention include aromatic carboxylic acids such as isophthalic acid, terephthalic acid, phthalic acid, phthalic anhydride, dimethyl terephthalic acid, naphthalene dicarboxylate, tetrachlorophthalic acid, terephthalic acid bisglycol esters and benzophenone dicarboxylic acid; And alicyclic carboxylic acids, aliphatic carboxylic acids, and polyacids such as trimellitic anhydride (TMA). As can be seen from the TMA example, the double acid can have additional -COOH groups.

In another important aspect of the invention, purely synthesized polyester polymers 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; And ether esters such as methyl cellosolve acetate and ethyl cellosolve acetate; Dioxane; Dimethylformamide; Diacetone alcohol; Methyl ethyl ketone; It is blended with a solvent selected from the group consisting of acetone and tetrahydrofurfuryl alcohol. The polymers of the present invention have a solubility in hydrophilic solvent of at least about 50 wt%, more preferably at least about 80 wt%, based on the total weight of the composition at the treatment temperature.

The first step provides a resin in a hydrophilic solvent that can be stored, which can be further processed in the second step. In an important aspect, the resin provided in the first step can be stored stably for at least about 6 months.

Second Step: Polyester Dispersion

Neutralization of resin

Polyester salts are formed in situ in organic solvents by mixing the polyester salt / organic solvent blend with water. According to the present invention, a neutralizing agent is added to an organic solvent solution containing polyester in an amount effective to neutralize the polyester to provide sufficient salt to allow the polyester to be dispersed in water. Neutralizers useful in the present invention include, but are not limited to, ammonia, triethanol amine, dimethyl ethanol amine, 2-amino-2-methyl-1-propanol, NaOH, and KOH.

The amount of neutralizer added depends on the acid value and molecular weight. In one aspect, when about 30 to about 100% of the carboxyl groups are neutralized, a solid and low content of VOC of the dispersion of the present invention is obtained. In another aspect, when the neutralizing agent is mixed with the polyester polymer in an amount effective to provide at least about 70 parts of the polymer salt in less than about 30 parts of solvent, and then mixed with water, the neutralized polymer results in a weight loss of the dispersion. It will provide a dispersion comprising up to about 70 wt% of water on a basis.

In a very important aspect of the invention where the ionizable functional group is a carboxyl group, the polyester requires about 70 to about 100% neutralization to stabilize the dispersion. In another important aspect of the invention, there is provided an average particle size of about 400 nm or less, with typical average particle sizes as measured by scattering of laser light ranging from about 40 to about 200 nm.

The polyester polymer may be preneutralized by preparing the polymer with metal salts, amine salts or ammonia salts of ionizable functional groups such as -COOH. Polymers made from these "pre-neutralized" monomers, as determined by titration, will have an acid value of at least about 30 if the ionizable functional groups that form part of the polymer have not been neutralized beforehand. In this aspect of the invention, the monomer has a multifunctional group, such as a bifunctional group, to form a polymer further having a salt form of the ionizable functional group.

One example of such a monomer is the following formula,

Wherein A and B are -OH and / or -COOH capable of forming a polyester in a condensation reaction, and C is -COOX, wherein X is an alkali metal such as sodium or potassium.

Water addition

In the next step of the second step, water at a temperature of about 25 to about 65 ° C. is added to the neutralized resin solution. The lower the temperature, the smaller the average particle size.

In an important aspect of the present invention, the initial ratio of solvent to water (solvent / water) relative to the polyester polymer is from about 0.15 to about 0.45. The initial ratio of solvent to water is important to ensure that no conversion occurs during subsequent solvent separation. The amount of water to be added may be more than required to obtain the desired solid state of the final dispersion. Some of the water is usually lost during solvent distillation. The system needs sufficient solvent to start dissolving the salt before adding water.

In an alternative aspect of the present invention, the polymer in the hydrophilic solvent may be added to the water in which the neutralizing agent is added.

Removal of solvent

In the next step of the process, the organic solvent and water are removed or separated from the neutralized resin / water / solvent mixture, if necessary. Atmospheric pressure at reduced pressure is applied to the mixture to help remove solvent and water. In an important aspect, the vacuum may range from about 22 to about 29 inches of the mercury gauge. If the reaction temperature is low, a higher vacuum must be used to remove the solvent. Low reaction temperatures reduce foaming because higher vacuum coupled with the surface tension of the bubbles helps to break the bubbles. In another aspect of the invention, the solvent / water is separated by the heat provided using a heat exchanger. Using a heat exchanger can shorten the distillation time, reduce the distillation temperature, and further minimize the breakdown of salts.

In a very important aspect of the invention, at least about 30 wt% to about 45 wt% of solid state can be reached for the polyester.

In another aspect of the invention, the removed solvent can be purified and reused. Simple flash or multistage distillation is sufficient to purify any contaminated solvent.

In an alternative aspect, the present invention allows an aqueous dispersion to be prepared from a polymer using one reaction vessel. The aqueous dispersions of the present invention do not require an emulsifier and, after distilling off the solvent, contain less than about 2 wt% of organic solvent based on the weight of the composition. In an important aspect, the aqueous dispersion contains about 0.2 to about 2 wt% organic solvent.

Aqueous dispersions of the invention include not only salt polymers but also water dispersible amine salts of the polymer, but in the context of the invention where the ionizable functional groups are carboxyl groups, the aqueous dispersions of the invention are polymers that are converted to neutralized polymers or salts It has 30% or more free carboxyl group in the inside. The lower the acid value of the polymer, the higher the percentage of carboxyl groups on the polymer to be neutralized. When the ionizable functional group is -COOH, about 100% of the carboxyl groups on the polymer must be neutralized with salts to maintain the dispersion at less than about 15 acid values. In an important aspect of the invention, about 100% of the carboxyl groups on the polymer are neutralized with salts, and the VOCs of the dispersions of the invention are less than about 1 pound (120 g / l) per gallon of dispersion, and in a very important aspect, The VOC is about 0.2 pounds per gallon of dispersion. Aqueous dispersions of the present invention having a VOC of about 0.2 pounds per gallon are stable for at least about one freeze-thaw cycle and up to about four freeze-thaw cycles. Freeze-thaw cycles can be expanded using small amounts of solvents or glycols, as is commonly used in latex systems.

Formulated Coating Composition

The polymeric carrier is incorporated into the formulated coating composition to provide a formulated coating composition or cured composition that is hot dried immediately upon heating. High temperature drying with ambient crosslinking is carried out above the crosslinking agent to provide a coating binder. A polymeric carrier comprising an aqueous dispersion of the present invention provides a formulated coating composition having less than 1 pound per gallon of VOC formulated coating composition, comprising a water dispersible polymer having the aforementioned molecular weight and salts thereof, Emulsifiers, surfactants and flocculants are not necessary as well as substantially absent.

These aqueous dispersions of high molecular weight polymers have improved chip resistance, adhesion as good as low molecular weight high VOC systems, improved lay dowm performance of wet films, improved film formation properties of films per pass, and quick drying times. Coating binders having improved film performance including, but not limited to, improved corrosion resistant films, improved corrosion resistant films, harder films, more wear resistant films, and improved moisture resistant films per pass, and It provides a hot dried formulated coating composition. The polymeric carrier of the present invention also provides a coating binder for an improved external "ultraviolet resistant" durable film, which is derived from an aqueous, low VOC formulated coating composition. The films provided in the present invention are an improvement over the films of low molecular weight thermoplastic polymers or low molecular weight thermosetting polymers requiring crosslinking, aqueous thermoplastic emulsions or water reducing systems.

The following examples illustrate the methods for carrying out the invention and are intended to be within the scope of the invention as defined in the appended claims and should not be construed as limiting thereof.

Example 1: Polyester Dispersion

A. Synthesis of Polyester Polymer:

1.218.9 g of neopentyl glycol (NPG), 77.2 g of trimethylol propane (TMP), and 1,6-hexanediol (HDO) in a round bottom flask equipped with packed column, partial condenser, receiver, and nitrogen blanket ) 248.4 g.

2. The flask was heated until glycol melted, and 322.8 g of adipic acid (AA) and 322.8 g of isophthalic acid (IPtA) were added with mixing.

3. The temperature was gradually raised to 220 ° C. and water generated in esterification was removed.

4. When the acid value was 6.8, the temperature was reduced to 170 ° C.

5. 80 g of trimellitic anhydride (TMA) was added to the flask and the temperature was maintained at 170 ° C.

6. Water generated in the esterification was removed until the acid value reached 46.3.

7. The temperature was reduced to 90 ° C. and the polymer was cut using methyl ethyl ketone (MEK).

The properties of the polyester solution are as follows:

Solid% (NVM) 70

Acid value (Mg KOH / g) 45

Molecular weight (Mn) 2350

Number of hydroxy groups (Mg KOH / g) 65.

B. Preparation of Polyester Dispersion:

1. A round bottom flask equipped with the entire condenser and receiver was charged with 635 g of polyester solution and 26.4 g of AMP-95 in MEK.

2. The flask was heated to 40 ° C. while mixing.

3. At 40 ° C., 666 g of deionized water was added over approximately 30 minutes.

4. Vacuum the flask and slowly increase to a maximum of 26 inches of mercury.

5. The vacuum was maintained until the desired percent solids of the dispersion was reached.

6. After removing the desired amount of distillate, the vacuum was released and the resulting product was analyzed.

The properties of the polyester dispersions are as follows:

Solid% (NVM) 41.0

Viscosity (cps) 45

pH (unit) 6.0

Particle Size (nm) <80

Weight / gallon (lbs) 8.9.

Example 2: Polyester Dispersion

A. Synthesis of Polyester Polymer:

1.In a round bottom flask equipped with packed column, partial condenser, receiver, and nitrogen blanket, 1170.0 g of neopentyl glycol (NPG), 412.5 g of trimethylol propane (TMP), and butyl-ethyl-propanediol (BEPD) 1687.5 g).

2. The flask was heated until glycol melted, and 1725.0 g of adipic acid (AA) and 1725.0 g of isophthalic acid (IPtA) were added while mixing.

3. The temperature was gradually raised to 220 ° C. and water generated in esterification was removed.

4. When the acid value was 3.1, the temperature was reduced to 170 ° C.

5. 427.5 g of trimellitic anhydride (TMA) was added to the flask and the temperature was maintained at 170 ° C.

6. Water generated in the esterification was removed until the acid value reached 41.2.

7. The temperature was reduced to 90 ° C. and the polymer was cut using isopropyl alcohol (IPA).

The properties of the polyester solution are as follows:

Solid% (NVM) 69.4

Acid value (Mg KOH / g) 41.1

Molecular weight (Mn) 2050

Number of hydroxy groups (Mg KOH / g) 65

B. Preparation of Polyester Dispersion:

1. A round bottom flask equipped with the entire condenser and receiver was charged with 1352 g of polyester solution in IPA and 26.4 g of N, N-dimethylethanolamine (DMEA).

2. The flask was heated to 40 ° C. while mixing.

3. At 40 ° C., 1476 g of deionized water was added over approximately 30 minutes.

4. Vacuum the flask and slowly increase to a maximum of 26 inches of mercury.

5. The vacuum was maintained until the desired percent solids of the dispersion was reached.

6. After removing the desired amount of distillate, the vacuum was released and the resulting product was analyzed.

The properties of the polyester dispersions are as follows:

Solid% (NVM) 42.6

Viscosity (cps) 45

pH (unit) 7.0

Particle Size (nm) <80

Weight / gallon (lbs) 8.9.

Example 3: Paint Formulations Containing Polyester Dispersion

Manufacture of paints:

The dispersed polyester of Example 1 was formulated with a primer as follows:

1. A 228 g aliquot of the resin dispersion prepared as described in Example 1 was placed in a 1 L stainless steel mixer.

2. Then 9 g of propylene glycol monobutyl ether and 36 g of deionized water were added to the resin dispersion.

3. A vertical disperser was inserted.

4. While stirring, 195 g of TiO ₂ (R-960, Dupont) and 5 g of Raven 16 were added.

5. Approximately 300 g of glass beads were added to the mixer, and the mixture was dispersed at high speed for 30 minutes to disperse the dye up to 7 Hegman.

6. The mill was lowered to the mixing rate and the following let down ingredients were added with gentle stirring:

143 g polyester dispersion

40 g of Cymel 301

7.2 g Nacure 3525

0.5 g of Surfynol 104BC.

7. After incorporation of the components, the mixture was filtered through a 25 micron filtration funnel to remove the glass beads. The pH was then adjusted to 8.2-8.5 with AMP-95 and then reduced to 34-36 seconds # 4 Ford cup with deionized water.

The theoretical VOC of the resulting paint was less than 2.0 pounds per gallon and 51 wt% of nonvolatile material.

The properties of the paint are as follows:

Formulated paints were tested by spraying on high edge protection electrodeposition coated galvanized steel panels. The film thickness of the primer was 1.0 mil on drying. The paint sprayed steel plate was flashed at room temperature for 5 minutes and then flashed for 10 minutes in a 180 ° F. oven. The steel plate sprayed with paint was hot dried at 330 ° F. for 25 minutes. The top 3 inches of the steel sheet was stripped off and then top coated with a commercially available automotive waterborne base coat / transparent coat system and hot dried at 275 ° F. for 20 minutes. Thereafter, the adhesion of the primer to the electrodeposition coating region of the steel sheet alone and the adhesion of the primer to the top coat region of the steel sheet were confirmed using 3 mm crosshatch, respectively. Excellent adhesion was seen in these two areas of the steel sheet. The lower half of the steel sheet was chipped in a Q-panel gravelometer using 2 pints of gravel at -20 ° C. Excellent chip resistance was seen.

* Adhesive Grade:

Primer alone 0

Top coat 1

(0 here means no breakage, 1 means less than 5% breakage)

Gravelometer rating: GM8

Example 4: Paint Formulations Containing Polyester Dispersion

Manufacture of paints:

The dispersed polyester of Example 2 was formulated with a primer as follows:

1. A 201 g aliquot of the resin dispersion prepared as described in Example 2 was placed in a 1 L stainless steel mixer.

2. Then 15 g of butoxy ethanol and 26 g of deionized water were added to the resin dispersion.

3. A vertical disperser was inserted.

4. While stirring, 151 g of TiO ₂ (R-960, DuPont) and 3 g of Raven 16 were added.

5. Approximately 300 g of glass beads were added to the mixer, and the mixture was dispersed at high speed for 30 minutes to disperse the dye up to 7 Hegman.

6. The mill was lowered to the mixing rate and the following extract ingredients were added slowly with stirring:

106 g polyester dispersion

56 g of BL-3175

5.4 g of Cymel 303

6.8 g of Nacure 5528

2.2 g of DC-14.

7. After incorporation of the components, the mixture was filtered through a 25 micron filtration funnel to remove the glass beads. The pH was then adjusted to 8.2-8.5 using DMEA and then reduced to 30-32 seconds # 4 Ford cup using deionized water.

The theoretical VOC of the resulting paint was less than 2.0 pounds per gallon and the nonvolatile material was 53 wt%.

The properties of the paint are as follows:

Formulated paints were tested by spraying onto cold rolled steel plates with electrodeposition coating. The film thickness of the primer was 1.0 mil on drying. The paint sprayed steel plate was flashed at room temperature for 5 minutes and then flashed for 10 minutes in a 180 ° F. oven. The steel plate sprayed with paint was then hot dried at 330 ° F. for 25 minutes. The steel plate was top coated with a commercially available automotive waterborne base coat / transparent coat system and hot dried at 250 ° F. for 30 minutes.

Thereafter, the adhesion of the top coat region of the steel sheet was confirmed using a 3 mm cross hatch. Excellent adhesion appeared on the steel sheet. The lower half of the steel plate was chipped in an Erichsen chip tester using a 1.0 kg steel shot at room temperature. Excellent chip resistance was seen.

* Adhesive Grade:

Topcoat 0 (where 0 means not broken)

* Erichsen rating: 7 (where 10 is the best and 0 is the lowest)

Example 5: Adhesion Grading Results

The procedure was carried out according to SAE J400.

Example 6: Chip Grading Results

The procedure was performed according to ASTM D3359.

In the practice of the present invention, various changes and modifications may be made by those skilled in the art after reading the detailed description of the present invention. In conclusion, such changes and modifications are included within the scope of the following claims.

Claims (16)

A polymeric carrier comprising an aqueous dispersion of a polyester salt, wherein the polyester salt is a residue of a polyester having an acid value of at least 30, a number average molecular weight of at least 1500, and no more than 90 hydroxyl groups, and the aqueous dispersion is about 5 wt% A polymeric carrier comprising an aqueous dispersion of a polyester salt, effective to provide a polymeric carrier containing less than organic solvents. The aqueous dispersion of polyester salt according to claim 1, wherein the polyester salt is a residue of a polyester having an acid value of about 40-50, a hydroxyl group of about 90-50, and a number average molecular weight of about 1500-2800. A polymeric carrier comprising. The polymeric carrier of claim 2, wherein the polyester salt in the aqueous dispersion has an aqueous dispersion of polyester salt having a particle size of less than 400 nm. The 2 pint chip number rating and at least about A of claim 3, wherein the polymeric carrier is at least about 5 and a two pint chip number rating when the primer coating composition film is part of a multilayer coating having at least two layers including a primer film. A polymeric carrier comprising an aqueous dispersion of a polyester salt, effective to provide a cured primer coating composition film that is effective to provide a multilayer paint coating having a pint chip size. The polymeric carrier of claim 2, wherein the polyester comprises an aqueous dispersion of a polyester salt comprising a —COOH group that may be neutralized to form a water dispersible salt. The polymeric carrier of claim 1, wherein the polyester comprises an aqueous dispersion of polyester salt comprising a —COOH group that may be neutralized to form a water dispersible salt. 4. The polymeric carrier of claim 3, wherein the polymeric carrier further comprises a crosslinker selected from the group consisting of amino resins, isocyanate compounds, and mixtures thereof. Preparing a polyester having a -COOH group sufficient to provide a polyester having an acid value of about 30 to about 50, a number average molecular weight of about 1500 to about 2800, and a hydroxyl group number of about 50 to about 90; Mixing the polyester with the organic hydrophilic solvent, the polyester polymer having a solubility in at least about 50 wt% of the hydrophilic solvent, the organic hydrophilic solvent having a solubility in water of at least about 5 wt%; Neutralizing at least about 30% of the ionizable functional groups of the polyester in an amount of neutralizing agent effective to prepare a solution of neutralized polymer salts; Preparing a blend of water / organic solvent / neutralized polyester by mixing water with a solution of neutralized polyester salt; And Preparing an aqueous neutralized polyester salt dispersion by separating an organic solvent from a blend of water / organic solvent / neutralized polyester blend at about 65 ° C. or less, at a temperature of about 25 ° C. An aqueous polymer dispersion having a viscosity of less than 10 poise. The aqueous polymer dispersion of claim 8 wherein the neutralizing agent is selected from the group consisting of ammonia, triethanol amine, 2-amino-2-methyl-1-propanol, and dimethyl ethanol amine. The aqueous polymer dispersion of claim 8 wherein water is added to a solution of neutralized polyester in an amount effective to provide an initial ratio of organic solvent to water of about 0.15 to about 0.45. The aqueous polymer dispersion of claim 10 wherein the organic solvent is removed without conversion. The aqueous polymer dispersion of claim 8 wherein the process is effective to provide a polyester salt in an aqueous dispersion having an average particle size of about 400 nm or less. Polyester salts are residues of polyesters having a number average molecular weight in the range of about 1500 to about 2800, a hydroxyl value of about 90 to about 50, and an acid value of about 40 to about 50, the polyester being neutralized to form a water dispersible polyester. An aqueous dispersion of a polyester salt which is a polyester having a -COOH group capable of forming a salt. 14. The aqueous dispersion of polyester salt of claim 13, wherein the polyester has a number average molecular weight of about 1500 and a hydroxyl group of about 90. 14. The aqueous dispersion of polyester salt of claim 13, wherein the polyester has a number average molecular weight of about 2800 and a hydroxyl group of about 50. 2 pint chip number grade and at least about 5, provided by applying to a substrate a polymeric carrier comprising an aqueous dispersion of a polyester salt that is a residue of a polyester having a number average molecular weight of at least 1500 and a hydroxyl group of 90 or less Multi-layer paint coating with a 2-pin chip size of about A.