REACTIVE ADDUCTS OF VINYLDIOXO COMPOUNDS

Abstract: New adducts of vinyldioxo compounds comprising a crosslinkable silyl-functional terminal group are disclosed. Such adducts are useful for preparing curable coating compositions.

Description: TITLE REACTIVE ADDUCTS OF VINYLDIOXO COMPOUNDS BACKGROUND OF THE INVENTION This invention relates to reactive adducts of certain vinyldioxo compounds and to curable coating compositions comprising such reactive adducts. Vinyldioxo compounds (also referred to herein as VDO compounds).are well known. All are cyclic acetals, extensively studied and patented by Dceda (U.S. Patents 3,010,918; 3,010,923; 3,197,484), by Brachman(U.S. Patent 3,014,924), and by others and described in detail by Hochberg (JOCCA 48, 11, 1043-1068, 1965). The simplest compounds in this class are made by a reaction of acrolein with a compound having two hydroxyl groups, either on adjacent carbon atoms or on carbon atoms separated by an additional carbon atom. When more than two hydroxyl groups are present in a compound, different pairs of hydroxyl groups can react with the aldehyde to form a cyclic acetal. Typical compounds having at least two hydroxyl groups include, for example, ethylene glycol, glycerin, 1,2,6-hexanetriol, and trimethylolpropane. Depending on the number and type of hydroxyl groups, the resulting VDO can be either a substituted 1,3-dioxolane or a substituted 1,3-dioxane, but frequently it is a mixture of a dioxolane with a dioxane. The reaction of acrolein (1) with trimethylolpropane (2) is shown below in Equation 1. The formation of VDO compounds, like other acetal-forming reactions, is catalyzed by acids. Equation 1 C-- H (1) (2) (3) The reaction product according to formula (3) is a 2-vinyl-l,3- dioxane substituted with an ethyl group in the 4-position and with a hydroxymethyl (methylol) group in the 6-position. Analogous reactions can be used to prepare substituted rings having four to ten carbon ring members, that is, substituted dioxirane, dioxetane, dioxolane, dioxane, dioxepane, dioxocane, dioxonane, and dioxecane. VDO compounds and their various derivatives have been described as useful polymerizable materials, which have the potential of providing both pigmented and clear-coat finishes in automotive and other applications. Those compounds polymerize in the presence of oxygen, such reactions being catalyzed by cobalt compounds. In an aqueous medium and in the presence of acids, the VDO compounds are unstable, so that further reactions are carried out in either a neutral, alkaline, or organic medium. Hochberg (op. cit.) discusses various syntheses and properties of many VDO compounds. In spite of the great industrial potential of VDO compounds, they have not been successfully commercialized in high performance coatings, for whatever reasons. It has recently been found that VDO compounds can be polymerized, with ring opening, in the presence of an acid, as described in the copending application of S.N. 08/186,367 (docket no. FA-0637). For example, one of several reactions that take place involves the above compound of formula (3) in the following equation 2: Equation 2 (4) The hydroxyl group of the polymer, represented by a broken o line arrow in formula (4), can be used for crosslinking by reaction with a difmctional or polyfunctional compound to form a solid coating. This is done starting with a liquid component or with two liquid components, in the absence of a solvent or with a minimum amount of a solvent or diluent. 5 Instead of crosslinking a polymerized VDO compound, it is also practical to form an adduct of VDO compound with a compound having two reactive groups under such conditions that only one group reacts, without crosslinking or with a minimum amount of crosslinking; so that the adduct can be polymerized in the presence of an acid, with ring o opening, and then undergo a second reaction or crosslinking through the second reactive group. SUMMARY OF THE INVENTION According to the present invention, there is now provided a 5 class of adducts of vinyldioxo compounds with difimctional compounds having two reactive functional groups, at least one of those functional groups being a silyl group, most preferably a di- or trialkoxysilyl group where the alkyl groups having from 1 to 4 carbon atoms, those adducts being represented by the following generic formula (5): (5), Where R is a branched, unbranched, or cyclic alkyl of 1 to 12, preferably 1 to 6 carbon atoms, most preferably methyl or ethyl, and Z is a divalent radical between the oxygen on the VDO moiety and the terminal silyl group. Also disclosed are new curable coating compositions comprising such adducts vinyldixo compounds. DETAILED DESCRIPTION OF THE INVENTION New adducts of VDO compounds are disclosed and have been found useful in silane coatings. These adducts can readily be formed using a starting VDO compound made from , for example, a vinyl aldehyde and a tri-hydroxyl compound. One such example is the vinyl-substituted dioxane made from acrolein and trimethylolpropane, as disclosed in the copending application S.N. (docket no. FA-0637), which application is herein incorporated by reference in its entirety. When the VDO compound is made from acrolein and trimethylolpropane, the R substituent in the above formula (5) will be ethyl; when it is made from acrolein and trimethylolethane, R will be methyl, etc.. The divalent radical Z in the above formula (5) is derived from a compound having two reactive groups, at least one of which groups is a silyl groups represented by Si(R2)( 3)(R4), wherein R2, R3, and R4 are independently alkyl, phenyl, alkyl ether, or phenyl ether, preferably at least two of R2, R3, and R4 being a hydrolyzable group, more preferably two of which are alkyl ether, wherein each alkyl is independently selected from the group consisting of branched, unbranched, or cyclical hydrocarbons having 2 to 12, preferably 1-6, and more preferably 1-4 carbon atoms, most preferably methyl or ethyl. A preferred silyl group is Si(R)(OR 5 )(OR6), where R is either CH 3 , CH 3 CH 2 , CH 3 0, or CH3CH2O; and R5 and R are CH3 or CH3CH2. Examples of the compounds which form the Z moiety when reacted with a VDO compound are 3-isocyanatopropyl trimethoxysilane (according to formula 6 below) and silane oligomers (according to formula 7 below). (6) (7) In formula 7 above, n can suitably be 0 to 50 or mixtures thereof, for example octamethoxytrisiloxane when n equals one. A commericially available mixture of such silane compounds s is RDS-1™ (methysilicate 51) supplied by Colcoat Co., Ltd. (Tokyo, Japan). This RDS-1 product is believed to be represented by formula 7 above when n is l to 3. Based on formulas 6 and 7 above, for example, the corresponding adducts from a VDO compound (for example, obtained from trimethylolpropane and acrolein) can be represented by the following respective formulas 8 and 9. (8) (9) Similar compounds can be produced in which Z is the -CONH-(CH2) n -Si(OCH3)3 group in which n is 1 to 10, preferably 2 to 4 or in which Z is the -[Si(OCH3)2] n -Si(OCH3)3 group wherein n is 0 to 10, preferably 1 to 4. In the cases of adducts (8) and (9), each has a trimethoxysilyl end group, which can under proper conditions undergo further reactions. For example, in an acid-catalyzed polymerization of the VDO adduct, which is accompanied by ring opening, as shown above in Equation 2, some alkoxysilyl groups are hydrolyzed and new Si-O-Si bonds can form with another adduct or with a crosslinking agent or functional polymer in a coating composition. For example, silane and/or hydroxyl groups on a polymer may crosslink with the VDO adduct. While the reaction of the starting VDO compound with a difunctional compound having end groups possessing different reactivities, such as compound (6), above, give essentially a single adduct compound quite readily, the reaction with compound (7) will result in a mixture of adduct products, which however, is also useful for coating applications and, if fact, may have the advantage of being less expensive to produce. Ideally, both types of reactions should be conducted under anhydrous conditions because water readily splits the methoxysilyl groups. Under those conditions, the isocyanate group of compound (6) reacts preferentially with the pendant methylol group of the starting VDO compound. Compound (7) will, of course, first react with one molecule of the VDO compound through one of its identical trimethoxysilyl groups. Theoretically, the remaining trmethoxysilyl group of either compound (6) or compound (7) could then further react with a second molecule of the VDO compound. Under anhydrous conditions and at low temperature and low catalyst, this second reaction can be largely avoided, although it usually occurs to a small extent. The VDO adducts describe above are useful as components of a curable coating composition for the purpose of lowering VOC (volatile organic compounds). Such compositions may comprise 10-80% by weight of a liquid organic carrier and 20 to 90% by weight, based on the weight of the composition, of a binder. The VDO compounds are considered to be part of the binder (solids other than pigments in the composition). The binder can suitably comprise from 5 to 50% by weight of binder of the VDO adduct, 80 to 10% by ,weight of binder of a silane functional polymer, and an effective amount of a curing catalyst. The composition may suitably comprising a crosslinking agent, for example a melamine resin, a further VDO compound (without the Z moiety), a hydroxy functional polyol acrylic polymer, and/or a non-aqueous dispersed polymer or NAD. Other crosslinking agents are epoxy, isocyanate, and carbodiimide compounds or resins. For these and other conventional components of a coating composition, further description is to be found in U.S. patent number 5,244,696 to Hazan et al., hereby incorporated by reference in its entirety. As indicated therein, the silane-fiicntional polymer may be an alkoxysilane functional acrylic polymer having a weight average molecular weight of 500 to 30,000 comprising from about 30 to 95% by weight, based on the weight of the polymer, of polymerized ethylenically unsaturated monomers which do not contain an alkoxysilane functionality and about 5 to 70% by weight of ethylenically unsaturated monomers which contain an alkoxysilane functionality. The silane-functional polymer may also have hydroxy-functional groups by copoylmerizing monomers of hydroxy-functional esters of methacrylic or acrylic acid. This invention is now illustrated by the following representative example. All parts and percentages are by weight unless otherwise indicated. Example 1 This example illustrates the preparation of a VDO adduct from 3-isocyanatopropyltrimethoxysilane. The 3-isocyanatopropyltrimethoxy silane(from OSI Specialties, Inc. of Tarytown, New York), 1498.62 g, 7.3 moles, was added slowly, with good mixing, under anhydrous conditions, to a flask containing 1498.38 g, 8.7 moles; of compound (3) and 3g of DBTDL (dibutyl tin dilaurate). No solvent or diluent was used. The flask contents were heated over a period of 3 hours and 7 minutes from 21.5°C to 101.7°C. Infrared spectra of the flask contents were taken at intervals to follow the progress of the reaction. The reaction was considered complete when the isocyanate peak was no longer detectable. The reaction product was a 100% solids material, useful as a reactive component of a silane resin-based coating system. .Example 2 This example illustrates a coating composition comprising a VDO-6/isocyanate adduct according to the present invention. The isocyanate was 3-isocyanatopropyltrimethoxysilane. VDO-6 is another name for 2-vinyl-5-ethyl-5-hydorxymethyl-l,3-dioxane. The other components were analogous to corresponding components in U.S. Patent No.5,244,696, particularly in examples 1 to 4, hereby incorporated by reference. A coating composition was prepared by blending together the following components: Component Wt. % Solids Parts by Weight Acrylic silane resin 79.50 50.314 NAD (non-aqueous 65.50 30.534 dispersed resin) VDO-6/isocyante 100.00 18.10 adduct Cymel™1161 100.00 7.800 melamine resin Microgel rheology 70.00 7.429 control agent Silica rheology control 34.20 8.772 dispersion Resiflo™ polybutyl 50.00 0.400 acrylate flow agent UV screeners (blend) 32.50 4.00 TMOA (trimethyl 0.00 3.00 orthoacetate water scavenger) DDBSA* 44.99 2.778 Tetrabutyl 25.00 0.800 phosphonium chloride Dibutyl tin dilaurate 100.00 0.250 *Dodecyl benzene sulfonic acid, unblocked or blocked with AMP (aminomethylpropyl). The final composition had a weight solids content of 68.97, a measured VOC of 2.85 lbs/gal and a calulated VOC of 2.62 lbs/gal, indicating very low loss of the VDO-6 adduct. The final viscosity was 95 cps (ICI). Example 3 This example illustrates a coating composition comprising a VDO-6/RDS-1 adduct in a 1/1 weight ratio. RDS-1 is a methoxy silane compound commercially available from Colcoat Co., Inc. (Tokyo, Japan). VDO-6 is another name for 2-vinyl-5-ethyl-5-hydorxymethyl-l,3-dioxane. The other components were analogous to corresponding components in Example 2 above. A coating composition was prepared by blending together the following components: Component Wt. % Solids Parts by Weight Acrylic silane resin 79.50 45.031 NAD (non-aqueous 65.50 30.534 dispersed resin) VDO-6/RDS1 adduct 100.00 18.100 RDS-1 silane 100.00 18.100 oligomer Melamine resin 100.00 7.800 Microgel rheology 70.00 7.429 control agent Silica rheology control 34.20 8.772 dispersion Resiflow™ polybutyl 50.00 0.400 acrylate flow agent UV screeners (blend) 70.00 5.00 DDBSA* 44.99 2.223 Tetrabutyl 25.00 0.800 phosphonium chloride Dibutyl tin dilaurate 100.00 0.200 *Dodecyl benzene sulfonic acid, unblocked or blocked with AMP (aminomethylpropyl). The final composition had a weight solids content of 76.17, a calculated VOC of 2.07 lbs/gal anda final vicosity was 95 cps (ICI). The composition exhibited good application properties and appearance. .Example 4 This example illustrates a coating composition comprising a VDO-6/RDS-1 adduct in a 2/1 weight ratio. RDS-1 is a methoxy silane compound commercially available from Colcoat Co., Inc. (Tokyo, Japan). VDO-6 is another name for 2-vinyl-5-ethyl-5-hydorxymethyl-l,3-dioxane. The other components were analogous to corresponding components in Example 2 above. A coating composition was prepared by blending together the following components: Component Wt. % Solids Parts by Weight Acrylic silane resin 79.50 50.314 NAD (non-aqueous 65.50 30.534 dispersed resin) VDO-6/RDS1 adduct 100.00 18.100 Melamine resin 100.00 7.800 Microgel rheology 70.00 7.429 control agent Silica rheology control 34.20 8.772 dispersion Resiflow™ polybutyl 50.00 0.400 acrylate flow agent UV screeners (blend) 32.50 12.308 DDBSA* 44.99 2.223 Tetrabutyl 25.00 0.800 phosphonium chloride Dibutyl tin dilaurate 100.00 0.250 Methanol 0.00 2.778 *Dodecyl benzene sulfonic acid, unblocked or blocked with AMP (aminomethylpropy 1) . The final composition had a weight solids content of 68.97, a calculated VOC of 2.63 lbs/gal and a final vicosity was 95 cps (ICI). This VDO- 6/silicate 2/1 adduct is less volatile than the 1/1 addduct of the previous example. The best mode presently contemplated for carrying out the invention is represented by the disclosure and claims herein, it being understood that selection of the best mode will depend on a variety of factors. Those skilled in the art will no doubt be able to compose numerous variations on the themes disclosed, such as changing the amounts of ingredients insignificantly from those shown, adding innocuous or supplementary substances, or substituting equivalent components for those shown. Such variations are considered to be within the inventive concept, as defined in the following claims.

Claims: CLAIMS 1. A compound which is an adduct of a vinyldioxo compound with a difunctional compound having two reactive functional groups, at least one of those functional groups being a silyl group, the adduct being represented by the following generic formula: wherein R is a branched, unbranched, or cyclic alkyl having 1 to 12 carbon atoms and Z is a divalent radical teraiinated by a silyl group. 2. The compound of claim 1 wherein R is methyl or ethyl. 3. The compound of claim 1 wherein the silyl group is Si(R2)( 3)(R4), wherein R2, R3, and R4 are independently alkyl, phenyl, alkyl ether, or phenyl ether, at least two of R2, R3, and R4 being a hydrolyzable group 4. The compound of claim 3 wherein two of R2, R3, and R4 are alkyl ether, wherein each alkyl is independently selected from the group consisting of branched, unbranched, or cyclical hydrocarbons having 1 to 12 carbon atoms. 5. The compound of claim 1 wherein Z is the -CONH-(CE-2) n -Si(OCH3)3 group wherein n is 1 to 10, or -[Si(OCH3)2]n-Si(OCH 3 )3 wherein n is 0 to 10. 6. A curable coating composition comprising 10 to 80% by weight of a liquid organic carrier and 20 to 90% by weight, based on the weight of the composition, of a binder wherein the binder comprises: a) from 5 to 50% by weight of binder of an adduct of a vinyldioxo compound with a difimctional compound having two reactive functional groups, at least one of those functional groups being a silyl group, the adduct being represented by the following generic formula: wherein R is a branched, unbranched, or cyclic alkyl having 1 to 12 carbon atoms and Z is a divalent radical terminated by a silyl group; and b) 80 to 10% by weight of binder a silane functional polymer; c) and an effective amount of a curing catalyst. 7. The composition of claim 6 wherein the silyl group is Si(R2)(R3)( 4), wherein R2, R3, and R4 are independently alkyl, phenyl, alkyl ether, or phenyl ether, at least two of R2, R3, and R4 being a hydrolyzable group. 8. The composition of claim 6 wherein Z is the -NH-(CH2) n -Si(OCH3)3 group wherein n is 1 to 10, or -[Si(OCH3)2]n-Si(OCH3)3 wherein n is 0 to 10. 9. The composition of claim 6 wherein the silane-functional polymer is an alkoxysilane functional acrylic polymer having a weight average molecular weight of 500 to 30,000 comprising about 30 to 95% by weight, based on the the weight of the polymer, of polymerized ethylenically unsaturated monomers which do not contain an alkoxysilane functionality and about 5 to 70% by weight of ethylenically unsaturated monomers which contain an alkoxysilane functionality.

Inventors: GREGOROVICH BASIL V, HAZAN ISIDOR, OMURA HISANORI, GREGOROVICH, BASIL, V., HAZAN, ISIDOR, OMURA, HISANORI
Applicants: DU PONT, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1995
Main classification: C07F7
IPC codes: C07F7, C09D4, C09D137, C09D143