MXPA00001312A - Sprayable coating compositions comprising oxazolidines and isocyanates - Google Patents

Abstract

The present invention relates to a coating composition comprising:a) a bicyclic oxazolidine compound;b) a monocyclic oxazolidine compound;and c) an isocyanate functional compound. The invention further relates to a method of coating a substrate with the coating composition and to a substrate coated with the coating composition.

Description

COMPOSITIONS FOR SATISFACTORY REVERSIBILITY COMPRISING OXAZOLIDINES AND ISOCYANATES The present invention relates to a new coating composition based on oxazolidines and isocyanates. It is required that the coatings used to paint automotive vehicles and repair the original paint have good physical properties such as hardness, mechanical resistance, and resistance to water, acids and solvents. The coatings are also required to have good appearance properties, which means that the films must be uniform and have a high gloss and high image distinction (DOI). It is also desirable that all properties be maintained under prolonged outdoor conditions. For environmental reasons, the use of a coating composition that can be easily applied using a spray application with a low volatile organic content (VOC) is required. When using coatings with low organic solvent content, lower levels of solvent are emitted and therefore the atmosphere is contaminated to a lesser degree. One way to achieve a lower solvent content is to use the so-called high solids compositions. Such compositions comprise a relatively high level of non-volatile materials, such as film-forming polymer, pigments and fillers, and a relatively low level of organic solvent. A problem in the formulation of high solids coating compositions is that such compositions have an unacceptably high viscosity due to the high molecular weight of the conventional film-forming polymer. The high viscosity causes problems in spray application with poor paint atomization and low output flow and, consequently, low brightness levels and poor appearance. The use of low molecular weight film-forming polymers, which results in viscosities of suitable applications, has the disadvantage that the resulting coating is soft and easily marked. The increase in hardness of the coating is therefore unacceptable. Another way to reduce the amount of volatile organic compounds in the coating compositions is the use of reactive diluents. Examples of reactive diluents include aldimines and ketimines. In EP-A-0 686 654 such compounds are analyzed. Other reactive diluents, such as oxazolidines, are mentioned but claimed to have limited utility as a reaction element alone with isocyanate due to their generally slow film-binding properties. Aldimines are used as reactive thinners for low VOC paint systems. These diluents are commercially available, and reference is made to the use of such aldimides in US 5,214,086 and EP-AO 686 654. In general, these reactive diluents offer good cure and good hardness development. However, they are known to cause skin irritation and cause adhesion problems when applied to clear low VOC coatings. Bicyclic oxazolidines are also used as reactive diluents for low VOC paint systems. These diluents are commercially available and reference is made to the use of such bicyclic oxazolidines in WO 95/14528. In general, these reactive diluents offer good durability and color stability as well as low toxicity. However, compositions based on bicyclic oxazolidines may exhibit an unacceptably long healing time. The monocyclic oxazolidines are also used as reactive diluents for low VOC paint systems. In EP 0499 188 A1 reference is made to the coating compositions based on monocyclic oxazolidines. The monocyclic oxazolidines and dimers thereof are commercially available. The coating compositions based on monocyclic oxazolidines may exhibit a loss of adhesion with the passage of time. Although it has been described in the use of mono- or bicyclic oxazolidines (see for example US 5), 126, 441), nowhere is the use of both oxazolidines, monocyclics and bicyclics described. WO 92/13907 refers to the use of monocyclic and bicyclic oxazolidines (page 7, lines 20-21), but refers to the use of these compounds as an alternative and does not describe a mixture as the two oxazolidines. Surprisingly, it has been found that the use of mixtures of oxazolidines, bicyclic and monocyclic, in low VOC coatings provides properties that can compete with the imines, without exhibiting loss of adhesion. The present invention relates to a coating composition comprising: a) A bicyclic oxazolidine compound; b) a monocyclic oxazolidine compound; and c) an isocyanate functional compound. The variables listed in the following formulas have been created with the intention of being able to choose them independently, both from one part to the next, and from one component to the next. The bicyclic oxazolydin component (a) has the structure: where z is from 0 to 9; m and p are independently chosen from 1 and 2; R3, R4, R5 and Re may be the same or different and are selected from the group of hydrogen, (cyclo) linear or branched alkyl, and linear or branched aryl, optionally substituted; R3 and R4, and R5 and Re can be joined to form a ring of 5 or 6 carbons with the carbon atom attached to the ring in the formula, ie R3 and R4, and R5 and e collectively represent tetramethylene group or a pentamethylene group; and R7 is an aliphatic, aromatic, arylaliphatic or cycloaliphatic mono- or multivalent moiety, which optionally may contain oxygen, nitrogen, sulfur and silica; and R can be H when z = 0. Preferably, z is from 0 to 3. Preferably m and p are 1. Preferably R3, R4, R5 and R6 are selected from the group of hydrogen, phenyl, benzyl and a linear or branched C? -12 alkyl group. Most preferably R3, R4, R5 and Re are selected from the group of hydrogen and isopropyl. Most preferably, z is 0 and R7 is an alkyl group comprising from 1 to 10 carbon atoms, most preferably methyl, ethyl or propyl. Especially it is preferred that the component (a) comprises 1-aza-3,7-dioxo-2,8-diisopropyl-5-ethyl bicyclo (3,3,0) octane, which is commercially available under the trade name " ZOLDINE® "RD-20 from Angus Chemical Company (Buffalo Grave, IL) and has the structure: ig ^^^^^ g¡ ^^^^^^^ _ || _ ^^^^^^^^^^^^ > * * ^^^^^^^^ Component (a) of bicyclic oxazolidine may comprise a mixture of bicyclic oxazolidines. The component (b) of the monocyclic oxazolidine of the present invention has the general structure: where z is from 0 to 9; n is 2 or 3; R i and R 2 may be the same or different and are selected from the group of hydrogen, linear or branched (cyclo) alkyl, and linear or branched aryl, optionally substituted; Ri and R2 can be joined to form a ring of 5 or 6 carbon atoms with the carbon atom attached to the ring in the formula, ie Ri and R2 collectively represent a tetramethylene or pentamethylene group; and R7 is an aliphatic, aromatic, arylaliphatic or cycloaliphatic mono- or multivalent moiety, which optionally may contain oxygen, nitrogen, sulfur and silica and R7 may be H when z = 0. Preferably z is from 0 to 3. Preferably n is 2. Preferably Ri and R2 are selected from the group of hydrogen, phenyl, benzyl and a linear or branched C? .- t2 alkyl group. Most preferably, Ri and R2 are chosen from the group of hydrogen and isopropyl. Preferably, R7 is multivalent and most preferably R7 is an aliphatic, arylaliphatic or cycloaliphatic moiety comprising from 2 to 15 carbon atoms and, optionally, ester, carbonate and urethane groups. The monocyclic oxazolidines wherein R comprises ester groups can be based on acrylate polymers as described in GB-B-992,721. Most preferably, z is 1 and R7 is a divalent moiety comprising either a carbonate group or at least two urethane groups. The compounds having a group R7 comprising carbonate groups are described in EP-A-0 499 188. R can be for example - When R7 comprises at least two urethane groups, R may be chosen from the group of the following multivalent portions: - L & teS » Most preferably, z is 1, n is 2, R-i is hydrogen, R 2 is isopropyl and R 7 is: This embodiment is commercially available under the tradename "INCOZOL ™" LV (from Industrial Copolymers Ltd., Preston, Lancashire, UK). Component (b) of the monocyclic oxazolidine may comprise a mixture of monocyclic oxazolidines. The weight ratio of bicyclic oxazolidine to monocyclic oxazolidine is preferably in the range of 5: 1 to 1: 2. Most preferably, there is a ratio of 3: 1 to 1: 1 of bicyclic to monocyclic oxazolidine. A 2: 1 ratio is especially preferred. __t________i______ _5_s5fias Component (c) comprises a functional compound socianato and can be aromatic, aliphatic, cycloaliphatic and / or araliphatic. Component (c) can be an isocyanurate, uretdione, Biuret reagent, allophanate, an adduct, NCO prepolymers, or mixtures thereof. Examples of isocyanates suitable for use in the functional compound isocyanate, or co or starting materials for preparing an isocyanate functional compound comprising an isocyanurate structure, Biuret reagent or uretdione include organic polyisocyanates represented by the formula R (NCO) where k is 2 or greater and R represents an organic group obtained by the removal of the isocyanate groups of an organic polyisocyanate having aromatic or (cyclo) aliphatically bound isocyanate groups. The diisocyanates represented by the above formula are preferred where k is 2 and R represents a divalent aliphatic hydrocarbon group having from 2 to 18 carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms, a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms or a hydrocarbon group divalent aromatic having 6 to 15 carbon atoms. Examples of Organic diisocyanates which are particularly suitable include ethylene diisocyanate, 1,3-propylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1-6-diisocyanate. hexamethylene, pentane-2-methyl-1,5-diisocyanate, butane-2-ethyl-1, 4- diisocyanate, diisocyanate of 1.12-do ^ phthathylene. cyclohexane-1, 3- and -1,4-diisocyanate, cyclopentane-1-isocyanate-2-isocyanatomethyl, IPDI, bis- (4-isocyanatocyclohexyl) -methane, 2,4'-dicyclohexylmethane diisocyanate, 1, 3 and 1, 4-bis (isocyanatomethyl) -cyclohexane, bis- (4-isocyanato-3-methyl-cyclohexyl) -5 methane, cyclohexane-1-methyl-2,4-diisocyanate, cyclohexane-1-isocyanato-1-methyl -4 (3) -isocyanomethyl, xylene diisocyanate, benzene-1-methyl-2,4-diisocyanate, a, a, a ', a'-tetramethyl-1, 3- and di-isocyanate-1,4-xylene diisocyanate, 2,4- diisocyanate and 2,6-hexahydrotoluylene diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2,6-toluylene diisocyanate, 2,4- and 4,4'-diisocyanate 10 diphenylmethane, naphthalene-1, 5-diisocyanate and mixtures thereof. Aliphatic polyisocyanates containing 3 or more isocyanate groups, such as 4-isocyanatomethyl-1, 8-octane diisocyanate and aromatic polyisocyanate containing 3 or more isocyanate groups, such as 4,4 ', 4"-triphenylmethane triisocyanate, benzene, can also be used. 1, 3,5-triisocyanate, polyphenyl polyisocyanates Polymethylene obtained by phosgenation of aniline / formaldehyde condensates, the adduct of TMP and m-tetramethylxylylene diisocyanate, and mixtures thereof. Preferred diisocyanates are 1,6-hexamethylene diisocyanate and IPDI. Examples of suitable polyisocyanates for use in the isocyanate functional compound or as starting materials for preparing the The functional compound which comprises an allophanate structure includes the organic polyisocyanates mentioned above reacted with a mono- or polyalcohol. The appropriate mono- or polyalcohols that can be used for ? 7 A "A _. The preparation of polyisocyanates containing allophanate groups includes aliphatic, cycloaliphatic, araliphatic or aromatic mono- or polyalcohols. The mono- or polyalcohols may be linear, branched or cyclic, contain at least one carbon atom and have a molecular weight of up to 2500. The mono- or polyalcohols may optionally contain other heteroatoms in the form of, for example, ether groups, ester groups, etc. However, mono- or polyalcohols preferably do not contain heteroatoms other than hydroxyl groups. The molar ratio of mono- or polyalcohols to polyisocyanate is about 0.01 to 0.5, preferably about 0.04 to 0.2. The mono- or polyalcohols which are preferred are mono- or polyalcohols of hydrocarbon and mono- or polyalcohols containing ether groups. The hydrocarbon mono- or polyalcohols preferably contain from 1 to 36, most preferably from 1 to 20 and most preferably from 1 to 8 carbon atoms. Examples of suitable monoalcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, n-pentanol, 2-hydroxybentane, 3-hydroxybentane, isomeric methylbutyl alcohols, isomeric dimethylpropyl alcohols, alcohol neopentyl, n-hexanol, n-heptanol, n-octanol, n-nonanol, 2-ethyl hexanol, trimethyl hexanol, decanol, dodecanol, tetradecanol, hexadecanol, octadecanol, 2,6,8-trimethylnonanol, 2-t-butyl- cyclohexanol, 4-cyclohexyl-1-butanol, cyclohexanol, benzyl alcohol, phenol, cresols, xylene, trimethylphenols, 2,4,6-trimethyl benzyl alcohol, primary chain branched alcohols, and mixtures thereof (which are available from Henkel (Minneapolis, MN) under the tradename "STANDAMUL®") and mixtures of linear primary alcohols (which are available from Shell (Houston, TX). ) under the trademark "NEODOL®"). Preferred ether-containing monoalcohols include ethoxymethanol, methoxyethanol, ethoxyethanol, isomeric methoxy or ethoxypropanols, propoxymethanols and isomeric ethanols, isomeric methoxybutanols, isomeric butoxymethanols, furfuric alcohol and other monoalcohols having a molecular weight of up to 2500 and are based on in ethylene oxide, propylene oxide and / or butylene oxide. It is also possible, in accordance with the present invention, to use mixtures of the monoalcohols described above. Examples of suitable polyalcohols having two or more hydroxyl groups include ethanediol, 1,3-propanediol, 1,2-propanediol, 2-methyl-1,1,3-propanediol, 1,4-butanediol, 1,3-butanediol, , 6-hexanediol, neopentyl glycol, glycerol, pentaerythritol, trimethylol propane, ditrimethylol propane, 1,4-cyclohexane dimethanol, the monoester of neopentyl glycol and hydroxypivalic acid, 2,2,4-trimethyl pentanediol and dimethylol propionic acid, and mixtures of the same. Other polyalcohols that are preferred for Suitable polyurethanes production include polyester and polyether diols having a number average molecular weight of less than 1000, for example the prepared form of polyester diol of 1 mole of italic anhydride and 2 moles of neopentyl glycol. It is also possible in accordance with the present invention use mixtures of the polyalcohols and mixtures of a polyalcohol and the monoalcohols described above. Preferably, the isocyanate functional compound comprising an allophanate structure is prepared from 5-1,6-hexamethylene diisocyanate and / or IPDI which reacted with an alcohol, preferably butanol. Polyisocyanate adducts include the TMP adduct and m-tetramethylxylylene diisocyanate. NCO prepolymers are prepared from polyisocyanates Monomers described above, preferably monomeric diisocyanates, and organic compounds containing at least two isocyanate reactive groups, preferably at least two hydroxyl groups. These organic compounds include compounds with high molecular weight having a number average molecular weight of 400 to about 6,000, preferably from 800 to about 3,000 and optionally low molecular weight compounds with molecular weights below 400. The products obtained by exclusively reacting the polyisocyanates with low molecular weight compounds are adducts of polyisocyanates containing urethane groups and not they are considered prepolymers NCO. Examples of high molecular weight compounds are polyester polyols, polyether polyols, polyhydroxy polycarbonates, polyhydroxy polyacetals, polyhydroxy polyacrylates, polyhydroxy polyester amides and polyhydroxy polythioethers. Preferred are polyester polyols, polyols of polyether and polyhydroxy polycarbonates. Further details on low molecular weight compounds and starting materials, and methods for preparing high molecular weight polyhydroxy compounds are described in document E.U.A. 4,701, 480. These NCO prepolymers are prepared in a known manner by reacting the aforementioned starting materials at an NCO / OH equivalent ratio of about 1.05: 1 to 10: 1, preferably about 1.1: 1 to 3: 1. This reaction can be carried out in a suitable solvent which optionally can be removed by distillation after the reaction together with any unreacted volatile starting polyisocyanates still present. The preferred aromatic isocyanates are "DESMODUR®" (toluene diisocyanate socianurate (TDI)), "DESMODUR®" VL (methyl-4,4'-diphenyl diisocyanate prepolymer) and "DESMODUR®" L75 (adduct of TDI / trimetiolpropane (TMP) (all available from Bayer, Pittsburgh, PA) Preferred aliphatic or cycloaliphatic isocyanates are "DESMODUR®" N3400 (hexamethylene diisocyanate uretdione (HDI)), "DESMODUR® N3300" (socianurate) of HDI) and "VESTANAT®" T1890 (isophorone diisocyanate socianurate (IPDI)) (available from Hüls, Chicago, IL) Preferably, component (c) is an aliphatic or cycloaliphatic isocyanate, most preferably, the component ( c) is a mixture of isocyanate functional compounds, preferably at least one uretdione and at least one socianurate. Most preferably, the mixture comprises "DESMODUR®" N3440, "DESMODUR®" N 3300 and "VESTANAT®" T1890. The isocyanate functional compound comprising a uretdione structure is preferably present in an amount of at least 5% by weight, preferably at least 10% by weight, based on the solids content of the polyisocyanate component (c). Preferably, the coating composition of the present invention further comprises a component (d). Component (d) comprises a resin comprising a functional group selected from hydroxyl and amine. The hydroxyl functional resin may be a functional acrylic resin, polyester resin, polyether resin, polyurethane resin, or other constituent materials known in the art, and may be a mixture thereof. Some commercial examples of acrylic hydroxyls are "JONCRYL®" 500 (S.C. Johnson &; Son, Inc., Racine, Wl) and AU608 (Rohm and Haas, Philadelphia, PA). Preferably, the hydroxyl functional resin is a mixture of a polyester resin and a polyurethane polyol. Alternatively, component (d) comprises an amine functional resin. Suitable compounds can be aliphatic, aromatic, cycloaliphatic and / or araliphatic, can contain a saturated, unsaturated, O, S or N groups, and include ethylene diamine, ethylene glycol diamine, propylene glycol diamine, and cycloaliphatic diamines. Preferably, the amine functional resin is an ester of aspartic acid. Suitable resins are available from Bayer under the tradenames "DESMOPHEN®" XP 7052 (spherically hindered amines - adduct of 2 moles of diethyl maleate with the 'R amine "LAROMIN®" C 260 (BASF, Germany) and "DESMOPHEN®" XP 7053 (adduct of 2 moles of diethyl maleate with the PACM 20 amine). Preferably, component (d) is a hydroxyl functional resin. Preferably, the percentages by weight of components (a) to (d) in the total solids of the vehicle are: (a) 2-40%, (b) 3-20%, (c) 30-70% and (d) ) 5-30%; most preferably (a) 8-30%, (b) 4-15%, (c) 35-65% and (d) 7-28%; and especially preferred, (a) 15-25%, (b) 5-13%, (c) 40-60% and (d) 10-25%. The coating composition of the present invention may also comprise hydroxyl (e) or other functional reactive diluents, which may decrease viscosity, decrease VOC and promote reactivity. The coating composition of the present invention may also comprise additional components such as solvents, catalysts, stabilizers, fillers, rheology control agents, flow additives, leveling additives, dispersing agents and other components known to those skilled in the art. Suitable solvents include methyl amyl ketone, butyl acetate, amyl acetate, ethoxyethyl propionate and xylene. Suitable catalysts include aromatic or aliphatic carboxylic acids, arylsulfonic acids and organometal compounds. Useful acids are formic acid, acetic acid, mono-, di-, and trichloroacetic acid, oxalic acid, maleic acid, malonic acid, zu-fumaric acid, heptanoic acid, peygonic acid, isononanoic acid, benzoic acid, 4-hydroxybenzoic acid, mono-, di-, and trichlorobenzoic acid, and salicylic acid and the anhydrides thereof. The acids that are preferred are acetic acid, heptanoic acid and benzoic acid. Useful organometal compounds include zinc alkanoate, such as zinc octoate, dibutyltin dilaurate, dibutyltin (bis) mercaptide, dibutyltin diacetate, and dibutyltin sulfide. An organotin catalyst such as dibutyltin dilaurate is preferred. Most preferably, mixtures of organotin and organozinc catalysts are used. Mixtures of the aforementioned catalysts can also be used. Optionally, the coating composition of the present invention may contain pigments. Useful pigments are of various types common in the art including, but not limited to, titanium dioxide, graphite, carbon black, zinc oxide, calcium sulfide, chromium oxide, zinc sulfide, zinc chromate, strontium chromate, barium chromate, lead chromate, lead cyanamide, lead silicochromate, yellow nickel titanium, yellow chrome-titanium, red iron oxide, yellow iron oxide, black iron oxide, red naphthol and coffee, anthraquinones, violet dioxazinc, yellow isoindoline, yellow and orange arilide, navy blue, blue, phthalocyanine complexes, amaranth, quinacridones, halogenated pioindigo pigments, extender pigments such as magnesium silicate, aluminum silicate, calcium silicate, calcium carbonate, fumed silica, barium sulfate and zinc phosphate.

Preferably, the coating composition comprises less than 500 g / l of volatile organic solvent based on the total composition, most preferably less than 480 g / l, most preferably less than 420 g / l. The solids content of the resin is preferably greater than 50%, most preferably greater than 52%, very much preferably greater than 58%. The coating compositions of the present invention are useful as clear coatings, base coatings, top coatings and sizing. The coating composition of the present invention can be used in the preparation of coated substrates. These substrates include glass, ceramic, paper, wood, plastic and metal. The coating composition is especially useful in the finishing industry, particularly in body shops, for automotive repair. The coating composition is also applicable in the automotive industry for the finishing of large transport vehicles, like trains and trucks, and can also be used in airplanes. The substrate may be a material without coating or may have sizing. The substrate may also be coated with paint products applied at the time of manufacture or together before application of the compositions of the present invention. The coating composition can be applied using conventional spray equipment or high volume low pressure spray equipment resulting in a high quality finish.

VI 9 Among other application modes are: roller coating, brushing, spraying, flow coating, immersion, electrostatic spraying or electrophoresis, the spray being the application mode that is preferred. Some exemplary metallic substrates include steel, aluminum, copper, zinc, magnesium and alloys thereof. The curing temperatures are preferably between 0 and 80 ° C, and most preferably between 20 and 60 ° C. The following examples illustrate the preparation of compositions according to the present invention. The examples are illustrative of the invention and contain a better mode. Comparative examples are included to illustrate the benefits of the present invention over other systems.

EXAMPLES EXAMPLE 1 A clear coating was prepared according to the present invention as indicated below. The percentages given are by weight of each component mixture. The components are listed in order of addition. The components were added while stirring and mixed in an air mixer for a minimum of 20 minutes after completion of the addition.

Component A Quantity (%) - Type PE 42.97 Binder (see below) (80.5% solids) PUPO 13.55 Binder (see below) (60.8% solids) Byk 358 0.23 Flow agent and leveling agent (Byk Chemicals, Wallingford, CT). Byk 333 0.28 Flow agent and leveler (Byk Chemicals) Fascat 4202 0.10 Tin catalyst (Elf Atochem, Philadelphia, PA) Nuxtra Zinc 0.65 Zinc catalyst (Hüls) Butyl acetate 13.81 Solvent (Eastman Chemical, Kingsport, TN) EXXATE 600 5.35 Solvent (mixture of esters) (Exxon, Houston, TX) Methyl isobutyl ketone 6.42 Solvent (Eastman Chemical) Butyl acetate solvent 2.14 Solvent Aliphatic dibasic ester 1.66 Solvent (DuPont, Wilimington, DE) Methylarmyl ketone 12.87 Solvent (Eastman Chemical) Preparation of polyester resin (PE): In a 10-liter round bottom reaction vessel equipped with a stirrer, packed column, condenser, heating mantle, thermometer and nitrogen inlet, were charged: 2608 g of hexahydrophthalic anhydride, 2981 g of trimethylolpropane, 2015 g of isononanoic acid, 195 g of italic anhydride and, .. ^ ______ £ -3 ggggl 9.2 g of an aqueous solution comprising 85% phosphoric acid. The reaction mixture was heated under a nitrogen flow of 10 liters / hour. The temperature of the mixture was gradually raised to 240 ° C. The reaction water was distilled at such a rate that the temperature at the top of the packed column did not exceed 103 ° C. After the reaction ran at 240 ° C for one hour, the flow of nitrogen was increased to 50 liters / hour and the reaction continued at 240 ° C until an acid value of 9.3 was reached. The reaction mixture was subsequently cooled to 130 ° C and diluted with 1 817 g of butylacetate. A polyester polyol solution was obtained with a solids content of 80.5%, a viscosity of 7.5 Pa.s measured at 20 ° C, an acid value of 9.3 and a hydroxyl value of 145, both based on solids. The polyester polyol showed a Tv of -2 ° C. The polyester polyol had a MW of 1 900 and a MWO of 4,500 (as measured by gel permeation chromatography using polystyrene as a standard).

Preparation of polyurethane polyol (PUPO): In a 2-liter round-bottom reaction vessel equipped with a stirrer, packed column, condenser, heating mantle, thermometer and nitrogen inlet were charged: 426 g of 2-butyl-2 -ethyl-1, 3-propanediol, 440 g of butyl acetate, 0. 11 g of dibutyltin dilaurate. The mixture was heated under a nitrogen atmosphere at 55 ° C. Subsequently 934 g of a 70% solution in butyl acetate of the Isocyanurate trimer from IPDI (available as "VESTANAT®" T 1890 E from Hüls) for a period of approximately 60 minutes. During this addition, the temperature was not allowed to exceed 70 ° C. After the addition was complete, the mixture was further reacted at 70 ° C until the NCO content, calculated on solid ingredients, fell below 0.1% by weight. After cooling, a clear polyurethane polyol solution with a viscosity (at 20 ° C) of 2.8 Pa.s, a solids content of 60.8% (determined at 150 ° C for 60 minutes) and a hydroxyl value of approximately 136 calculated on solids. Using polystyrene as standard, gel permeation chromatography (GPC) He indicated a PM number of 1, 300 and PMpeSo of 1, 800. The polyurethane polyol showed a Tv of 81 ° C.

Component B Quantity (%) Type DESMODUR N3390 53.73 HDI isocyanurate (Bayer) (90% solids in butyl acetate) VESTANAT T1890E 34.51 Isocyanate from IPDI (Hüls) (70% solids in butyl acetate) DESMODUR N3400 10.89 Uretdione HDI (Bayer) Component C Quantity (%) Type ZOLDINE RD20 LC 66.00 Bicyclic oxazolidine (Angus Chemical) INCOZOI LV 34.00 Oxazolidine monocyclic (Industrial Copolymers) Component A, B and C were mixed by weight as indicated below: 40.00 grams A 91. 00 grams B 41. 81 grams C.

To this mixture was added 15.20 grams of butyl acetate to give the viscosity flow rate 4 DIN less than 20 seconds. (The viscosity was measured at DIN flow rate number 4 in accordance with DIN 53221-1987). The VOC of the composition was (285 g / l). (The VOC was measured in accordance with ASMT 3960-92).

COMPARATIVE EXAMPLE (1A) For comparison, a clear coating was made using the same components as in Example 1, with the exception that instead of using the oxazolidine C mixture of Example 1, the aldimine "VESTAMIN®" A-139 (available from Hüls). The VOC of the composition it was (276 g / l).

Experimental procedure Two E-coated cold-rolled steel panels were prepared as follows: The steel panels were degreased with M600 Degreaser (commercially available from Ako Nobel Coatings Inc., Norcross GA) and scoured with a red Scotch fiber. Brite. Subsequently the panels were degreased again with M600. "AUTOBASE" (commercially available from Akzo Nobel Coatings) was reduced with 790 Reducer Slow (commercially available from Akzo Nobel Coatings) at a mixing ratio of 100: 80 (by volume). The following AUTOBASE color formula was used: Percentage by weight (before the addition of the reductant) Organic pigment 777 10 Organic pigment 666 10 Organic pigment 333C 40 Organic pigment 956 40 After reduction with the 790 reducer, three coatings were applied, plus one drop coating of the base coat, using a SATA NR95 HVLP spray gun (with tip adjustment of 1.3) at an air pressure of 0.703 kg / cm2 of the gun at 21.1 ° C and 16% relative humidity. A resting time of 5 to 10 minutes was allowed between each coating application and 30 minutes before the application of the clear coating. The compositions of Example 1 and Comparative Example 1A were applied in two coatings by spraying with HVJU? (SATA NR95 with tip adjustment from 1.5 to 0.703kg / cm2) at 21.1 ° C and a relative humidity of 16%. The first coatings were allowed to stand for 10 minutes before the application of the second coating. All light coatings were applied to a dry film construction of approximately 76.2 microns. All clear coatings were baked for 1 hour at 60 ° C. Afterwards, the healing speed was tested. Hardness and adhesion were tested after one day of storage at 21.1 ° C and 16% relative humidity. The results are shown in table I: TABLE I fifteen [1] Healing determined manually by pressing with a finger on the fresh film of clear coating. 20 [2] Persoz hardness in accordance with ISO 1522-1973 using steel instead of a glass plate. [3] Cross-cut adhesion test with tape; "10" indicating that there is no adhesion failure, "0" indicating a complete adhesion failure. a¡_iga_33 «8fea_¡_r-.

As can be seen from the above data, the composition of Example 1, which modalizes the present invention, showed good adhesion, an acceptable hardness and an acceptable healing time. In comparison, the composition containing the aldimine in place of the oxazolidines (comparative example 1A) showed a good cure and a good level of hardness, but shows poor adhesion.

EXAMPLE 2 A sizing was made in accordance with the present invention and was prepared from the following: (the percentages given are by weight of the total coating composition mixture). 4.0% DESMOPHEN 670-80 polyester resin (Bayer) 4.0% JONCRYL SCX 910 acrylic resin (SC Johnson) 12.8% ZOLDINE RD-20 4.2% INCOZOL LV 14% DESMODUR IL, an aromatic polyisocyanate based on TDI (51% solids) in butylacetate) (Bayer) 15.8% MONDUR MRS, an aromatic polyisocyanate based on 4,4 diphenylmethane diisocyanate (Bayer) 3% DESMODUR 3400, HDDI uretdione (Bayer) Other components (42.3%) 20.8% pigments, including anti-corrosive pigments , fillers, TiO2 and carbon black. 4.7% flow agent, polyacrylate type 16.8% solvents, including esters and ketones. The sizing was prepared as indicated below. In a clean and dry tank was charged and mixed: 776.7115 g DISPERBYK-110 (dispersant) (Byk) 268.0569 g butyl acetate During mixing was added the following: 650.6976 g DESMOPHEN 670A-80 650.6976 g JONCRYL SCX 910 Subsequently added mixing as follows: 53.4307 g COSMIC BLACK D-2 (carbon black) (Ebonex, Melvindale, Ml) 379.9125 g BLANC FIXE MICRO (pigment filler) (Sachtleben Chemie, Duisburg, Germany) 975.1328 g TALC 399 LO MICRON MAGNESIUM SILICATE (pigment filler) (Barretts Minerals, Bethlehem, PA) 703.8150 g WOLLASTOCOAT 10ES (filler pigment) (Nyco, Willsboro, NY) 703.8755 g TI-PURE R-902 28 (TiO2) (DuPont, Wilmington, DE) 626.4065 g HALOX CW 491 (anti-corrosive pigment) (Halox Corp., Hammond, IN) Mixing was continued for five minutes, then ground with DYNOMILL at 20-25 microns, as verified by a quality control ground check. Subsequently the following was added while mixing: 600.0000 g butyl acetate A quality control check of 0.946 liters was performed to verify the percentage of non-volatiles (acceptable is 81.8 ± 2.0). The Stomer viscosity (95-100 Krebs units) and the density (1686 ± 60 g / l) were also verified. It is important that the tank remains closed during this quality control check. The lot can be filled in the next 24 hours. The batch was filtered through a bag of 100 microns.

Activator In a clean and dry tank was charged: 200.7000 g ZOLDINE RD-20 66.6700 g INCOZOL LV This was mixed at low speed for 5 minutes. Subsequently, the following was added and mixed for 30 minutes: 1.4400 g DESMOPHEN 670A-80 0.3600 g MULTIFLOW (flow agent and leveling agent) (Monsanto, St. Louis, MO) 37.5000 g Methylamine ketone 37.5000 g ethylamyl ketone 88.8900 g butyl acetate to a quality control check a sample of 0.946 liters to test the density (889 ± 60 g / l) and viscosity in a # 4 cup at 25 ° C (12.0 ± 2.0). It is important that the tank remains closed during quality control verification.

Hardener Under conditions to minimize moisture content, in a clean and dry tank closed with nitrogen blanket, it was dosed and mixed at low speed for 10 minutes: 2,057 kg DESMODUR IL 2,333 kg MONDUR MRS 0.439 kg DESMODUR 3400 Water content verified in a 102 ml sample. The water content must be less than 1500 ppm. Subsequently added: 0.082 kg n-Butyl acetate 0.0395 kg DOWANOL PMA (Dow, Midland, Ml) 0.0296 kg butylcelosolv acetate 0.0131 kg Aromatic 100 (Exxon) The water content was checked again. The solvent mixture was mixed at low speed for 30 minutes. A sample of 0. 946 liters was subjected to a quality control check to obtain density (1156.35 + 60), percentage of non-volatiles (75.1 + 2.0) and viscosity with a cup of number 4 at 25 ° C (60.0 + 3.0). It is important that the tank remains closed during quality control verification. The batch must be filled within 24 hours and filtered through a bag of 10 microns. The VOC of the composition was 335 g / l.

COMPARATIVE EXAMPLES For comparison purposes, 3 additional sizes were made using the same components as in Example 2, except that instead of using the oxazolidine mixture of Example 2, the following was used: Comparative Example 2A was carried out with a di-monocyclic oxazolidine ("INCOZOL ™" LV) as the sole component of oxazolidine. Comparative example 2B was carried out with a bicyclic oxazolidine ("ZOLDINE® RD 20) as the single component of oxazolidine." Comparative example 2C was carried out with an aldimine ("VESTAMIN® A 139 available from Hüls) instead of the oxazolidine component. The VOC of these compositions was 335 g / l. The composition of Examples 2 and Comparative Examples 2A, 2B, and 2C were applied using a SATA 95 HVLP spray gun and the cure was carried out in ambient air and baked for 1-60 minutes at 60 ° C. They were tested to obtain drying times (no dust and no stickiness) and "cross-bonding." Example 2 is the same as Example 2 except that the dust-free and tack-free times were measured under a relative humidity of 25% compared to a relative humidity of 70% of example 2. Comparative examples 2A, 2B and 2C were subjected to a relative humidity of 21% The results are shown below in table 2.

TABLE 2 10 fifteen The pot life is the time between the initial mixing of all the components and the point where the viscosity has increased twice the initial viscosity value. Example 2 (mixture of oxazolidines) showed a useful life in the improved vessel over 2C (aldimine), and to a lesser extent over 2A (monocyclic alone) and 2B (bicyclic alone). The tack-free time of Example 2 is greatly improved over Example 2A (monocyclic) and the ? f l ^^^^^^ l * 4_j «__» ____ i ___ tt-A- example 2B (bicyclic), and the syn-pdvo time was greatly improved over 2B (bicyclic). The viscosity is lower in example 2, compared to example 2C (aldimine). The adhesion was equivalent.

EXAMPLE 3 A clear coating according to the present invention (3C) and 4 comparative examples (3A, 3B, 3D and 3E) were prepared as in example 1 using the following ingredients.

CLEAR FORMULATION FORMULATION OF HARDENER ACTIVATOR FORMULAS EXAMPLE 3C AND COMPARATIVE EXAMPLES Conditions: 38% relative humidity, 26.6 ° C Example 3C was prepared according to the present invention using a mixture of bicyclic and monocyclic oxazolidines. Comparative example 3A was prepared using only bicyclic oxazolidine. Comparative example 3B was prepared using only monocyclic oxazolidine. The 3D comparison example was prepared using aldimine instead of oxazolidine. Comparative Example 3E is used to show a conventional composition (using "AUTOCLEAR®" and "AUTOCRYL®" components available from Akzo Nobel Coatings Inc.) with acceptable properties having a higher VOC content than the compositions of the present invention.

RESULTS The results of the test are shown in the following tables comparing the pot life, drying characteristics, physical properties (adhesion and hardness of Persoz), brightness and DOI (image distinction).

VID UTIL EPH & CONTAINER The results show that the composition according to the present invention, 3C, shows an improved shelf life compared to 3D (the composition using aldimine instead of oxazolidine). Life useful in the 3D container is short, but may still be acceptable for small applications such as repairs of brands and panels. However, it is unacceptable for a complete spray.

DRYING-BAKING CHARACTERISTICS AT 60 ° C 15 NA = not acceptable The drying characteristics of the di- / mono-cyclic 3C oxazolidine mixture were better over the bicyclic oxazolidine alone (3A) at 60 ° C. In fact, 3A was still wet after the normal 35-minute bake period at 60 ° C. This was not acceptable.

L « * The 3A panels had to be baked during > 120 minutes to be cured until dry and able to be handled. The panels gave an unacceptable result because the hardness was not acceptable after a normal healing time of 35 minutes. The adhesion and hardness of Persoz of the baked panels was tested. The composition of the present invention comprises bicyclic and monocyclic oxazolidine (3C) shows an adhesion and hardness better than 3B (monocyclic oxazolidine alone) and 3D (aldimine), and also a hardness better than 3A (bicyclic oxazolidine alone) under baking conditions normal (see the previous note).

The brightness of is measured in accordance with ISO 2813: 1994 (angle of 20 °) and is expressed in GU. The DOI is determined by projecting an image -7? $ ,. , standard (original) on a cover p € »The sharpness of the reflected image and the original image will be matched. If the reflected image is (almost) as sharp as the original image, the DOI of the coating is high. If the reflected image is much less sharp than the original image, the DOI of the coating is low. The data of brightness and DOI (distinction of image) indicate that the appearance of all the panels is acceptable. There are no appreciable differences after days 6 and 10. One skilled in the art will appreciate that the present invention can be practiced in other ways than those described, which are presented for purposes of illustration and not limitation, the present invention is limited only by the claims below.

Claims (10)

1. - A coating composition comprising: a) a bicyclic oxazolidine compound of the structure: where z is from 0 to 9; m and p are independently chosen from 1 and 2; R3, R4, R5 and R6 may be the same or different and are selected from the group of hydrogen, linear or branched (cyclo) alkyl, and linear or branched aryl, optionally substituted; R3 and R4, R5 and R6 can be joined to form a ring of 5 or 6 carbons, with the carbon atom attached to the ring in the formula, ie R3 and R4, R5 and Re collectively represent a tetramethylene or pentamethylene group; and R7 is an aliphatic, aromatic, arylaliphatic or cycloaliphatic mono- or multivalent moiety that optionally may contain oxygen, nitrogen, sulfur, and silica; and R7 can be H when z = 0; b) a monocyclic oxazolidine compound of the structure: where z is from 0 to 9; n is 2 or 3; Ri and R2 may be the same or different and are selected from the group of hydrogen, (cyclo) linear or branched alkyl, and linear or branched aryl, optionally substituted; Ri and R2 can be joined to form a ring of 5 or 6 carbons with the carbon atom attached to the ring in the formula, ie Ri and R2 collectively represent a tetramethylene or pentamethylene group; and R7 is an aliphatic, aromatic, arylaliphatic, mono- or multivalent cycloaliphatic moiety that optionally may contain oxygen, nitrogen, sulfur and silica; and R can be H when z = 0; and c) a functional isocyanate compound.

2. The composition according to claim 1, further characterized in that component (a) has the formula:

3. - The composition according to any of the preceding claims further characterized in that in component (b) z = 1.

4. The composition according to claim 3 further characterized in that in component (b) z = 1, n = 2, Ri is hydrogen, R2 is isopropyl, and R7 has the structure:

5. - The composition according to any of the preceding claims, further characterized in that the component (c) is chosen from an aromatic isocyanate functional compound and an aliphatic.

6. The composition according to any of the preceding claims further characterized in that it comprises (d) a resin comprising a functional group selected from hydroxyl and amine.

7. The composition according to claim 6, further characterized in that the component (d) comprises a functional hydroxyl resin.

8. The composition according to any of the preceding claims further characterized in that it comprises (e) a reactive hydroxy functional reactant.

9. A method for coating a substrate comprising the coating of the substrate with the coating composition according to any of the preceding claims.

10. - A substrate coated with the composition according to any of the preceding claims. - * < -_