GB2200126A

GB2200126A - Vapor permeation curable coatings comprising polymercaptan resins and multi-isocyanate curing agents

Info

Publication number: GB2200126A
Application number: GB08806411A
Authority: GB
Inventors: Gary Lee Linden
Original assignee: Ashland Oil Inc
Current assignee: Ashland LLC
Priority date: 1985-05-31
Filing date: 1988-03-18
Publication date: 1988-07-27
Also published as: BR8602441A; SE8602437L; ZA864009B; AU562533B2; ATA141386A; JPS61283669A; BE904829A; GB2176197B; IT8620632A0; AU6870487A; NL8601386A; KR900007877B1; FR2582660B1; CA1254454A; MX167983B; SE468437B; IT1208620B; ES8706734A1; JPH0651862B2; FR2582660A1

Description

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VAPOR PERMEATION CURABLE COATINGS COMPRISING POLYMERCAPTAN RESINS AND MULTI-ISOCYANATE CURING AGENTS I0 The present invention relates to vapor permeation curable coatings and more particularlyto the synthesis and utilization of polymercapto resins therefor.

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Vapor permeation curable coatings traditionally are a class of coatings formulated from aromatic hydroxyl-functional polymers and multiisocyanate cross-linking agents wherein an applied film thereof is cured by exposure to a vaporous tertiary amine catalyst. In order to contain and handle the vaporous tertiary amine catalyst economically and safely, curing chambers were developed, Curing chambers typically are substantlally empty boxes through i which a conveyor bearing the coated substrate passes and in which the m' vaporous tertiary a me, normally borne by an inert gas carrier, contacts such coated substrate. The use of aromatic hydroxy-functional polymers is recommended if a stable one-pack system is required. If two-pack formulations are acceptable, then use of aliphatic hydroxyl-functional resins can be made. Multi-isocyanate cross-linking agents in traditional vapor permeation curable coatings contain at least some aromatic isocyanate groups in order for practical cure rates to be achieved.

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Such traditional vapor permeation curable coatings requirements have been altered to a degree by the vaporous amine catalyst spray method disclosed vy Blegen in application U.S.S,N. 06/615,135, filed May 30, 1984. Such vaporous catalyst spray method relies on the concurrent generation of an atomizate of a coating composition and a carrier gas bearing a catalytic amount of a vaporous tertiary amine catalyst. Such generated atomizate and vaporous catalytic amine-bearing carrier gas flow are admixed and directed onto a substrate to form a film thereof. Curing is rapid and use of a curing chamber is not required. Moreover, all aliphatic isocyanate curing agents can be utilized in such spray process. Hydroxyl groups on the resin, however, st111 are required.

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One drawback to the requirement of aromatic hydroxyl groups on the resin is the inherent limitation which such aromaticity provides in formulating high -I- solids coatings. The same is true of the requirement of aromatieity in the multi-isocyanate cross-linking agent. Such non-volatile solids content restriction oven applies to the vaporous amine catalyst spray method described above.

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t The present invention solves many of the limitations which have been placed on chamber cured vapor permeation curable coatings. The method for curing a film of a coating composition in accordance with the present invention comprises exposing said coating composition as an atomizate or as an applied I0 film to a vaporous tertiary-amine catalyst. The coating composition comprises a polymercapto-eompound and a multi-isocyanate curing agent. As an applied film, the coating composition is cured by exposure of an applied film of said coating composition to a vaporous tertiary amine catalyst in a curing chamber.

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Alternatively, an atomizate of said coating composition can be generated and admixed with a vaporous tertiary amine catalyst, which mixture then is applied to a substrate and cured.

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Another embodiment of the present invention involves the coating composition comprising a hydroxyl-functional compound, a polymercapto-compound, and a multi-isocyanate curing agent. The curing agent may be an all aliphtic isocyanate curing agent and the polymercapto--eompound can be a reactive diluent present in small proportions for catalyzing or enhancing the cure of the polyol resin and the aliphatic isocyanate curing agent.

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Advantages of the present invention include the ability to formulate high solids coating compositions containing upwards to 100% non-volatile solids content. Another advantage is the ability to utilize ail aliphatic isocyanate-containing curing agents and still achieve rapid cure in a curing chamber. Another advantage is the unusual high gloss which polymercaptocontaining vapor permeation cured coatings possess when cured in a curing o chamber. These and other advantages will be readily apparent to those skilled 30 in the art based upon the disc!osure contained herein.

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The use of polymercapzo-tunctional monomers, oligomers, or polymers in vapor permeation curable coatings retains the advantageous properties achieved in the use of aromatic hydroxyl-functional compounds including the ability to formulate single package systems which are storage stable for several hours on up to several days, but which formulations rapidly cure at room temperature by exposure to vaporous tertiary amine catalysts. Several unique benefits additionally are achieved by the use of such resinous or non-resinous thiols. One of these benefits is the ability to formulate very high solids coating ranging on up to 100% non-volatile solids. Such higher solids content, in part, is due to the freedom which the use of thiols permits in reducing aromatic content of both the resin and the curing agent. That is, aromaticity adjacent the mercapto groups is not required for storage stability nor for curability of the coating composition. Also, aromatieity is not required of the curing agent in order for room temperature rapid cure to be achieved in the presence of vaporous tertiary amlne catalysts. It will be appreciated that aromaticity was quite desirable in coating compositions when conventional chamber eura techniques were employed. Another benefit in the ability to formulate coating compositions diminished in aromatic groups is the ability to increase the flexibility of the cured coating composition. This is true since it is difficult to arrive at a very flexibIe system with high elongation since aromatic groups tend to impart stearic hindranee to the polymer resulting in increased brittleness. Of course, traditional vapor permeation curable coating compositions contained at least some aromatic curing agent in order for rapid cure to be achieved and contained aromatic hydroxyl functionality on the resin in order to retair benefits of increased pot life of the coating composition. The use of polymercapto resins in accordance with the precepts of the present inventlon provides greater flexibility in formulating vapor permeation curable coatings.

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Monomers, oligomers, and polymers containing pendant mercaptan or thiol groups are commercially available or can be readily synthesized. For example, mercaptan groups can be attached to the oligomer or polymer by esterification of free hydroxyl groups on the polymer, for example, a polyester, a polyacrylate, a polyether, or the like with a mercaptanterminated acid,.:uch as 3-mereapto propionic acid or thiosalicylie acid. Similarly, an epoxy-functional resin can be reacted with a mercaptanterminated acid under acidic conditions for enhancing the preferential reaction of the carboxylic acid group with the epoxy group. Mereaptan groups can be introduced into the oligomer or polymer additionally by reacting pendant primary or secondary amine groups with a mercaptanterminated acid or by reacting the free-isocyanate groups on an isocyanate-terminated oligomer or polymer with a mercaptan-terminated acid ester having at least two pendant mercaptan groups. Further reaction schemes for introducing the mercaptan groups into an oligomer or polymer include conducting a Michael addition reaction of a polymercaptan with a polyolefin. A further synthesis scheme involves the reaction of an aryl or alkyl halide with NaSH for introducing a pendant mercaptan group into the alkyl or aryl 5 compound. It is possible even to react a Grignard reagent with sulfur for introducing a pendant mercaptan group into the structure. In fact, a disulfide can be reduced (e.g. zinc or other catalyst under acid conditions) to produce a mcrcaptan-functional monomer which may be used as a reactive diluent m vapor permeation cure coatings. Mercaptan groups can be introduced into the 10 oligomer or:polymer by numerous other methods which are well known m the art. The mercaptan groups are pendantly attached to the oligomer or polymer.

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For purposes of this application, pendant mercaptan groups include terminal mercaptan groups. By pendanfly attached is meant that such mercaptan groups are attached to the polymer chain or to a pendant side chain of the polymer or i5 oligomer. The resinous material containing pendant mercaptan groups should e at least difunctional for cross-linking with the curing agent, though higher degrees of functionality may be used additionally. Mono--functional rnercaptan-containing resinous materials may be used as a reactive diluent, as further elaborated on below.

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Various polymercaptans suitable for synthesizing the mercapto-functional resinous materials for use in forming the coating compositions of the present invention include, for example, 1,4-butane dlhlol,'t ' 2,3-<limercapto propanol, toluene-3,4-dithiol, and alpha,alpha'-dimercapto-p-xylene. Other suitable active mercaptan compounds include thiosalicylic acid, mercapto acetic acid, mercapto propionic acid, 2-mercapto ethanol, dodecane dithiol, didodecane dithiol, dithiol phenol, di-para-chlorothiophenol, dimercapto benzothiazole, 3,4dimercapto toluene, allyl mercaptan, 1,6 hexane dithiol, 1,2-ethane dithiol, benzyl mercaptan, 1-octane thiol, p-thiocresol, 2,3,5,6-tetrafluorothiopbenol, cyclohexyl mercaptan, methylthioglycolate, mercapto pyridines, dithioerythritrol, 6-ethoxy-2-mercaptobenzothiazoI, and the like. Further useful mercaptans can be found in various catalogs of commercially-available mercaptans.

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Virtually any oligomer, polymer, or resinous compound can be modified to contain pendant mercaptan or thiol groups. Representative resinous materials containing mercaptan groups can be derived from, 'for example, epoxy and epoxy-modified diglycidyl ethers of bisphenol A structures, various aliphatic polyethylene or polypropylene glycol (diglycidyl ether) adducts, and glycidyl ethers of phenolic resins. Other useful polymers containing pendant mercaptan groups include polyamide resins, for example, condensation products of dimerized fatty acids coreacted with difunctional amine, such as ethylene diamine, followed by reaction with 3-mercapto propionic acid or the like. A variety of acrylic resins and vinyl resins can be readily envisioned for modification in accordance with the precepts of the present invention additionally....

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In this regard, it should be understood that virtually any conventional hydroxl-containing monomer, oligomer, or polymer previously proposed for use in vapor permeation curable coatings can be suitably modified to contain pendant mercaptan groups for use in formulating coating compositions in accordance with the present invention. For example, esterification (or transesterification) of such polyols with a mercaptanterminated acid is but one technique which can be readily envisioned for use in modifying such prior vapor permeation curable materials for use in formulating the coating compositions of the present invention. While not exhaustive, the following discussion discloses prior vapor permeation curable coating compositions which can be suitably modified. U.S. Pat. No. 3,409,579 discloses a binder composition of a phenol-aldehyde resin (including resole, novolac, and testicle), which preferably is a benzylic ether or a polyether phenol resin. U.S. Pat. No. 3,676,392 discloses a resin compositlon in an organic solvent composed of a polyether phenol or a methylol-terminated phenolic (resole) resin. U.S. Pat. No. 3,429,848 discloses a composition like that in U.S. Pat. No. 3,409,579 with the addition of a silane thereto.

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U.S. Pat. No. 3,789,044 discloses a polyepoxide resin capped with hydroxybenzoic acid. U.S. Pat. lqo. 3,822,226 discloses a curable composition of a phenol reacted with an unsaturated material selected from unsaturated ratty acids, oils, fatty acid esters, butadiene homopolymers, butadiene copolymers, alcohols and acids. U.S. Pat. No. 3, 836,491 discloses a similar hydroxy-functional polymer (e.g. polyester, acrylic, polyether, etc.) capped with hydroxybenzoic acid. British Pat. 1, 369,351 discloses a hydroxy or epoxy compound which has been capped with diphenolic acid. British Pat. 1,351,881 modifies a polyhydroxy, polyepoxy, or polycarboxyl resin with the reaction product of a phenol and an aldehyde.

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U,S. Pat. No. 2,967,117 discloses a polyhydroxy polyester while U.S. Pat. No. 4,267,239 reacts an alkyd resin with para-hydroxybenzoic acid. U.S. Pat. No. 4,298,658 proposes an alkyd resin modified with 2,6-dimethylol-p- cresol.

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--5-- U.S. Pats. Nos. 4,343,839, 4,365,039, and 4,374,167 disclose polyester resin coatings especially adapted for flexible substrates. U.S. Pat. No. 4,374,181 discloses resins especially adapted for applieation to reaction injection molded (RIM) urethane parts. U.S. Pat. No. 4,331,782 discloses a hydroxybenzoic acid-epoxy adduct. U.S. Pat. No. 4,343,924 proposes a stabilized phenol-functional condensation product of a phenol-aldehyde reaction product. U.S. Pat. No. 4,366,193 proposes the use of 1,2-dihydroxybenzene or derivatives thereof in vapor permeation curable coatings. U.S. Pat. No. 4,368,222 discloses the uniqueness of utilizing vapor permeation curable coatings on surface-porous substrates of fibrous'reinforced molding compounds (e.g. SMC). Finally, U.S. Pat. No. 4,396,647 discloses the use of 2,3',4-trihydroxy diphenyl.

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It will be appreciated that the foregoing aromatic-hydroxyl polymers or resins as well as many other resins suitably can be modified to contain mereaptan groups for use in formulating coating compositions in accordance with the precepts of the present invention.

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Finally, the mercapto resinous materials of the present invention can be utilized for formulating coating compositions ideally suited for the vaporous amine catalyst spray method of Blegen, cited above. Such vaporous amine catalyst spray method comprises the concurrent generation of an atomizate of i the coating composition and vaporous tertiary amine, which flows are admixed and applied to a substrate. The increased non-volatile solids content of coating compositions formulated wit]1 mercapto resinous materials even can per;it the spray application of pigmented coatings containing in excess of 80% non-volatile solids. In this regard, the coating compositions may contain reactive or volatile solvent for formulating the coating compositions, for viscosity control for application (e,g. spraying or the like)or for other purposes as is necessary, desirable, or convenient in conventional fashion.

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Multi-isocyanate cross-linking agents cross link with the mercaptan or thlol groups of the resulting adduet-capped polymer under the influence of a vaporous tertiary amine to cure the coating. Aromatic isocyanates may be preferred in order to obtain reasonable pot life and the desired rapid reaction in the presence of the vaporous tertiary amine catalysts at room temperature. For high performance coatings, initial color as well as the discoloration due to sunlight can be minimized by including at least a moderate level of aliphatie isocyanate content in the curing agent. Of course, polymeric isoeyanates are employed in order to reduce toxic vapors of isocyanate monomers. Further, alcohol-modified and other modified isocyanate compositions (e.g.

thiocyanates) find utility in the invention. Multi-isocyanates (i.e.

polyisocyanates) preferably will have from about 2-4 isocyanate groups per molecule for use in the coating composition of the present invention. Suitable multi-isocyanates for use in the present invention include, for example, hexamethylene diisocyanate, 4,4'-toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethyl polyphenyl isocyanate (Polymeric MDI or PAPI), m- and p-phenylene diisocyanates, bitolylene diisocyanate, triphenylmethane triisocyanate, tris-(4-isocyanatophenyl) thiophosphate, cyelohexane diisocyanate (CHDI), bis-<isocyanatomethyl) cyelohexane (H6XDI), dicyclohexylmethane diisocyanate (HI2MDI), trimethylhexane diisocyanate, dimer acid dilsocyanate (DDI), dicyclohexylmethane diisocyanate, and dimethyl derivatives thereof, trimethyl hexamethylene diisocyanate, lysine diisocyanate and its methyl ester, isophorone diisocyanate, methyl cyclohexane diisocyanate, 1,5napthalene diisocyanate, triphenyl methane triisocyanate, xylylene diisocyanate and methyl and hydrogenated derivatives thereof, polymethylene polyphenyl isocyanates, ehlorophenylene-2,4diisocyanate, and the like and mixtures thereof. Aromatic and aliphatic polyisocyanate dimers, trimers, oligomers, polymers (including biuret and isocyanurate derivatives), and isocyanate functional prepolymers often are available as preformed packages and such packages are suitable for use in the present invention also.

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The ratio of mereaptan groups from the mercapto resinous materials to the isocyanate equivalents of the multi-isoeyanate cross-linking agents preferably should be greater than about l:l and can range on up to about 1:2. The preoise intended application of the coating composition often will dictate this ratio or isocyanate index.

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As noted above, a solvent or vehicle may be included as part of the i'i coating compos t on. Volatile organic solvents may include ketones and esters for minimizing viscosity, though some aromatic solvent may be necessary and typically is part of the volatiles contained in commercial isocyanate polymers. Representative volatile organic solvents include, for example, methyl ethyl ketone, acetone, methyl isobutyl ketone, ethylene glycol monoethyl ether acetate (sold under the trademark Cellosolve acetate), and the like. Organic solvents commercially utilized in polyisocyanate polymers include, for example, toluene, xylene, and the like. It should be noted that the effective non-volatile solids content of the coating composition can be increased by incorporation of a relatively low or non- volatile (high boiling) ester plasticizer which is retained for the most part in the cured film. Such suitable ester plasticizers include, for example, dibutyl phthlate, di(2-ethylhexyl) phthlate (DOP), and the like. The porportion of ester plasticizer should not exceed about 5-10% by weight, otherwise loss of mar resistance can occur.

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The coating composition additionally can contain opacifying pigments and inert extenders such as, for example, titanium dioxide, zinc oxide, clays such as kaolinite clays, silica, talc, carbon or graphite (e.g. for conductive coatings), and the like. Additionally, the coating compositions can contain tinctorial pigments, orrosion-inhibiting pigments, and a variety of agents typically found I0 in coating compositions. Such additional additives include, for example, surfactants, flow or leveling agents, pigment dispersants, and the like.

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As to the performance requirements which are met by the coating composition, it should be noted that the coating composition, polymercapto resin and isocyanate cross-linking agent, can have a minimum pot life of at least 4 hours in an open pot and generally the coating can be formulated to have a pot life which exceeds 8 hours and can range up to 18 hours or more. Such long pot life means that refilling the pot at the plant during shLfts generally is not required. Moreover, the pot life of the coating composit,on In a closed container can exceed one month depending upon formulation of the coating composition. After storage of the coating compositioni the stored composition can be cut to application viscosity with suitable solvent (if required)and such composition retains all of the excellent performance characteristlcs which it initially possessed.

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The vaporous amine catalyst will be a tertiary amine include, for example, tertiary amines containing substituents such as alkyl, alkanol, aryl, cycloaliphatic, and mixtures thereof. Additionally, heterocyclic tertiary amines may be suitable for use in the invention also. Representative tertiary amines include, for example, triethyl amine, dimethyl ethyl amine, trimethyl amine, tributyl amine, dirnethyl benzyl amine, dimethyl cyclohexyl amine, dimethyl ethanol amine, diethyl ethanol amine, triethanol amine, pyridine, 4-phenylpropyl pyridine, 2,4,6-óoilidine, quinoline, isoquinoline, N-ethyl morpholine, trietbylene diamine, and the like and mixtures thereof. Additionally, it is conceivable to use amine oxides and quaternary ammonium amines depending upon the practicality of providing such amines in the vaporous phase. A myriad of proprietary tertiary amine catalysts currently are available and should function in the process additionally. "It should be noted that the catalytic activity of the tertiary amine catalysts may be enhanced by the addition of complex salts to the coating composition as reported in the bulletin, "The Activation of IPDI by Various Accelerator Systems", Veba-Chemie AG, Gelsenkirchen-Buer, West Germany, Thus, the addition of ferric, manganic, and aluminum salts to the liquid coating composition may be implemented as an embodiment of the present invention.

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While the proportion of vaporous amine catalyst may range on up to 6.% or more, percentages of less than 1 volume-percent typically will suffice, e. g. between about 0.25 and 1% by volume. It should be cautioned that higher levels of amine catalyst are not recommended where air or sources of molecular oxygen are present as exposive mixtures may result. The tertiary amine catalyst is in vaporous form in a carrier gas which may be inert, such as nitrogen or carbon dioxid, or may be in air, or mixtures thereof. It will be appreciatd that depending upon the carrier gas and the particular tertiary amine catalyst of choice, certain minimum temperatures and pressures of the atomizing gas stream must be maintained in order to ensure that the amine catalyst remains vaporous and does not condense in any lines. Additionally, the proportion of amine and carrier gas may be altered depending upon whether a Conventional curing chamber is utilized or whether the Blegen vaporous amine catalyst spray method is employed. In this regard, the preferred curing chambers for use with the coating compositions of the present invention are disclosed in U.S. Pats. Nos. 4,491,610 and 4,492, 041. It must be recognized, however, that other curing chambers may be utilized, e.g. as disclosed in U.S. Pats. Nos. 3,851,402 and 3,931,684.

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Upon exposure to vaporous tertiary amine catalyst, the merc.ptan groups of the resinous material and isocyanate groups of the curing agent react to form a cured network of earbamothioate groups (carbamothiolic acid ester groups). The reaction is rapid at room temperature enabling handling of cured parts in a short time following catalyst cure, e.g. often as short as I-5 minutes. Such rapid curing retention of the coating compositions of the present invention is a decided benefit. In this regard, it will be appreciated that such rapid cure also takes place whether the curing agent is 'all aliphatic, all aromatic, or a mixture of aliphatic and aromatic isocyanates.

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In this regard, the use of a minor proportion of mono- or poly-functional mercaptan compounds as a reactive diluent (e.g. up to 20 weight percent) can markedly enhance the reaction between a polyol and aliphatic isocyanate groups of a curing agent under vapor permeation cure conditions. Of a l0 positive benefit in using the mercaptan compounds to enhance the polyolisocyanate reaction, is the retention of performance properties which the polyol and curing agent exhibit without the addition of the mercaptan compounds and even improvement of performance properties on occasion. Besides the in situ formation of carbamothioate groups which appear to be catalytic in nature with respect to the polyollpolyisocyanate reaction, preformed carbamothioate groups (preformed reaction product of a mercapto compound and an isocyanate compound) can be incorporated into the coating composition and a similar catalytic effect observed. The use of a preformed compound may not provide the degree of improvement in cure response as is seen when such groups are formed in situ during the cure of the coating composition. Thus, this aspect of the invention comprises the coating composition being cured in the presence of a compound containing one or more of the following moeities.

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H 0 HS HS L_IIc I u I It -N -S-, -N -C-S-, or -N.C.O-.

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The compound from which such moeity is derived in this preformed embodiment of the invention can be represented as follows:

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H 0 HS HS.- I I _ l |I l I RI-N-C-S-R2, RI-N-C-S'R2, or RI-N-C-O-R2 where R1 and R2 each is a monovalent organic radical which desirably is an alkyl or an aryl group.

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As the data will demonstrate, the preformed embodiment of the invention does not appear to function to the sme degree when an aliphatic isocyanate and an aliphatic polyol comprises the coating composition. Some aromaticity, then, should be present for the preformed embodiment of the invention and preferably such aromaticity is derived from the aromatic isocyanate component of the coating composition. In the in situ preferred embodiment of the invention, however, the film properties and reaction occurring with the mercaptan compound appears to provide a Stronger catalytic or promoting effect in the hydroxyl/Lsocyanate reaction so that aromaticity is not as an important factor as in the preformed embodiment.

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-I0- I0 Nevertheless, some aromaticity is preferred in the coating composition for both embodiments of the invention.

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A variety of substrates can be coated with the coating compositions of the present invention. Substrates include metal, such as, for example, iron, steel, aluminum, copper, galvanized steel, zinc, and the like. Additionally, the coating composition can be applied to wood, fiberboard, RIM, SMC, vinly, acrylic, other polymeric or plastic material, paper, and the like. Since the coating compositions can be cured at room temperature, thermal damage to thermally-sensitive substrates is not a limitation on use of the coating compositions of the present invention. Further, with the ability to use the B1egen vaporous amine catalyst spray method, the flexibility in use of the coating Compositions of the present invention is enhanced even further.

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The followinvg examples show how the present invention can be practiced but should not be construed as limltlng. In this application, all percentages and proportions of the coating compositions are by weight and all percentages and proportions of the vaporous tertiary amine catalyst are by volume, unless otherwise expressly indicated. Also, all units are in the metric system anda11 citations referred to herein are expressly incorporated by reference.

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EXAMPLES .DTD:

EXAMPLE I .DTD:

The nature of VPC cure response of mercaptan groups was evaluated and compared to aliphatic hydroxyl groups on molecules which are structurally identical but for their containing -SH or aliphatic -OH groups. Viscosity and survey performance tests were conducted on the following compositions.

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TABLE I !nredient 1 Ethylene Glycol 18.6 1,2-Ethanedithiol -- Butanediol -- 1,4-Butanedithiol -- Hexanediol -- 1,6-Hexanedithiol -- CurlngAgent(1J 69.3 MII Solvent (2) 20.0 om 18.4 m 46.2 Coating (gm.) 3 4 5 8 27 0 -12.2....

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.. 35.4 -- .... 15.0 69.3 23.1 69.3 23.1 20.0 0 0 Wt-% Solids -- 92.9 -93.5 -- 94.0 (i) Desmodur N-3390 is an aliphatic isocyanate of hexamethylene diisocyanate (NCO content 20%, 90% solids in butyl acetate, equivalent weight of 21U, Mobay Chemical Corporation, Pittsburgh, Pa.) (2) MIBK is methyl isobutyl ketone.

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Each of the coating compositions were exposed to 0.9 vol-% triethylamine catalyst (TEA) in a curing chamber and evaluated with the following results.

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12- m Table 2A .DTD:

Coat ing Viscos i ty (cps) Initial 4hr 24hr 48hr 72hr Cure Time (see)Sward(1) MI(2) Hardness Rub R,r(3) (41: l-r -- Separated 600(5) 18,16 60 14,14 14,20 I00+ 100+ 14,14 18 17 125. is Semi-GeI 60U(5) 6,8 6,8 15 lOU+ 60 6,8 6,6 9 8 Settled Gelled 60U(5) 6 30 30 40 65 95 60 (1) (2) (3) (4) (s) (6) (7) ---(G)...... (7)--- 294 4,4 6 6 Plate glass is defined as 100 for Sward Hardness; two readings per panel were taken.

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Methyl ethyl ketone (MEK) wetted rag rubbed over one area of cured film with moderate thumb pressure until glass substrate is visible.

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RT" Sample allowed to stand for 3 days at room temperature prior to testing.

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HT: Samples held at 160 C for 5 minutes after vaporous amine catalyst exposure, then allowed to stand for 3 days at room temperatureprior to testing.

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Coating not cured after 600 sec; cure time.

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Reading could not be taken because the film bunched.

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Reading not possible because film puddled.

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3 10 4 6 Coating H20 RT I-IX" Pass Pass Pass. Pass Pass.Pass Pass Pass Pass Pass Pass Pass TABLE 2B .DTD:

SOLVENt RESISTAN (1) 5% Naa{ Izr Hr Fail Pass Pass Pass 10% P 894 Xy I en e RT HI" RT HY Fail Pass Pass Pass Pass Pass Pass Pass Fail Fail Fail Fail Fail Fail Pass Fail Fail Pass Pass Pass Fail Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass (i) The indicated solvent in a pool on the coating is placed under a watch glass for 24 hours at ambient indoor temperature and then.the solvent resistance of the coating judged. "'" " The above-tabulated results demonstrate the excellent ombinatmn of stability (as determined by the viscosity data) and rapid cure response. In fact, alJphatic hydroxyl groups cured only after two days, whereas the mercaptan groups were ewed within a minute or so.

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EXAMPLE 2 .DTD:

A variety of isoeyanate curing agents were evaluated with glycol dimer captopropionate (GDP) in the following coating compositions.

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Ingredient 1 24.4 Curing Agent(1) 46.2 MIBK 5.0 Cellosolve(2) -Acetate I0 Wt-% Solids (i) (2) TABLE 3 .DTD:

Coating (g) 18.3 60.3 m 13.0 -- 87.3 58,4 56.9 Coating l-Curing agent 3 4 5 6 7 8 9 12.2 12.8 12.2 61.0 18.3 21.0 24.4 49.8 46.2 11.1 67.3 57.8 46,2 41.6 12.0 5.0.... 5.0 3,0 5.0 hexamethylene diisocyanate (NCO content 20%, 90% solids in Cellosolve acetate, equivalent weight of 210, Mobay Chemical Corporation) Coating 2-Curing agent was Mondur HC, an approximately tetrafuactional reaction product of hexamethylene diisocyanate and toluene diisccyanate (11.5% NCO content, equivalent weight of 365, 60% solids in Ccl]osolve aeetate/xylene, Mobay Chemical Corporation) Coating 3-Curing agent was trimethylolpropane-m-.v,:.', '- metramethylxylene diisocyanate adduct Coating 4-Curing agent was Takenate D-12U-N trimethylolpropane adduct of hydrogenated xylene diisocyanate (NCO content 11.0%, 75% solids in ethyl acetate, Takeda Chemical Industries) Coating 5-Curing agent was methane diisocyanate Coating 6-Curing agent was meta-q,<','-tetramethyl xylene diisocyanate (American Cyanamid Company) Coating 7-Curing agent was Desmodur Z-4370 isocyanurate of isophorone diisocyanate (NCO content ca. 12%, equivalent weight 350, 70% solids in ethylene glycol acetate/xylene (1:1), Mobay Chemical Corporation) Coating 8-Curing agent was Desmodur N-3390 of Example I Coating 9-Curing agent was Desmodur KL5-2550 aliphatic poIyisocyanate (1, 6-hexamethylene diisocyanate, Mobay Chemical Corporation) Cellosolve acetate is ethylene glycol monoethyl ether acetate (Union Carbide Corporation) ml 1 2 3 4 5 15 6 '7 8 9 Each.of the coatings was cured by exposure to 0.9 vol.-% triethylamine catalyst (except Coating 2 which was exposed to 0.5 vol.-% TEA) in a curing chamber and subjected to the survey performance tests described in Example i.

Coating., Initial 4hr 140 150 135 150 Viscosity (cps) 24hr 215 325 Like Water D 545 GeIled Gelled Table 4.A .DTD:

48hr 72hr 310 270 315 560 Tso 125 155 Sward(1) MI(2) Cure Time Hardness Rub (sac) RT(3) Kr(4) M" Hr 8,10 52,40 9"5 90 38,46 64,68 100+ 100+ 8,8 12,16 63 73 10,12 14,14 IOU+ 100+ 240 34,38 72,68 2 2 38,32 76,66 9 3 60,60 52,48 IOU 100+ 2,4 6,6 28 85 6,8 4,4 35 18 Coating 1 2 3 3O 4 5 6 7 8 35 9 Pass Pass Pass PassòPass Pass iPass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass TABLE 4B .DTD:

SOLVEtn" RES IST RT HI" 10% H2SO4 Pass Pass Fail Fail Fail Pass Pass Fail Fail Pass Pass Pass Fall Fail Fail Fail Pass Pass Fail Fail Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass.Pass Pass Fail Fail Fail Fail Xylene RT HT Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass I0 Again, the excellent stability (pot life) of coatings formulated with mercaptan reactants in combination with good cure response is demonstrated. Also, these coatings possessed n very high solids content which contributes to their uniqueness. Of further note is the ability to utilize all-alipahtic multi-isocyanate curing agents in formulating VPC coatings.

.DTD:

EXAMPLE .DTD:

In this series of tests, trimethylolpropane tris (3-mercaptopropionate), hereinafter TMP-3MP, served as the mercaptan-functional compound which was evaluated with a variety of curing agents as in Example 2.

.DTD:

TABLE 5 .DTD:

Ingredient 1 2ZP-3MP 20.7 Curing Agent 44.4 MIBK -- CellosolveAcetate 8.0 Coating (gin.) 2 3 4 5 6 20.7 27.6 20.7 0.2 20.7 60.3 46.2 20.8 33.6 11.1 .. 2.0....

.DTD:

13.0 i0.0......

.DTD:

Wt-% Sol ids 69.5 60.5 82.6 94.3 10u 10u Coating 1-Curing agent was Mondur CB-60 aromatic polyisocyanate (NCO equivalent of I0.0 to 1.0, Mobay Chemical Corporation).

.DTD:

Coating 2-Curing agent was Mondur HC of Example 2.

.DTD:

Coating 3-Curing agent was KL5-2444 of Example 2.

.DTD:

Coating 4-Curing agent was KL5-2550 of Example 2.

.DTD:

Coating 5-Curing agent was meta-tetramethyl xylene diisocyanate of Example 2.

.DTD:

Coating 6-Curing agent was methane diisocyanate of Example 2.

.DTD:

Each of the coatings was cured by exposure to triethyl amine catalyst, 0. 5 vol.-% for Coatings I and 2 and 0.9 vol.-% for all other coatings, in a curing chamber and subjected to the survey performance tests described above.

.DTD:

Table 6A .DTD:

Coating. Viscosity (cps) Cure Time Initial 4hr 24hr 48hr 72hr (see).

.DTD:

1 150 140 2 135 145 3 Gelled -4 II0 5800 5 60 55 6 Like Water 295 m Gelled 60 -- 260 60 570 1186 60 -- 60 .. 60 60 .. 240 Sward(1) MI(2) Hardness Rub RTIs) r(4) RT Hr 56,60 80,84 I00+ i00+ 62,60 62,64 10U+ 100+ 14,18 48,52 10U+ IUU+ 18,20 24,34 10U+ 100+ 34,38 64,58 37 18 38,40 58,58 22 20 TABLE 6B .DTD:

Coating H20 RT Hr 1 Pass Pass 2 Pass Pass 3 Pass Pass 4 Pass Pass Pass Pass SOLVENT RES ISTANCZ 5% Naa{ 10% H2SO4 Xylene RT Hr RT Hr Fir Fail Pass Pass Pass Pass Pass Fail Fail Fail Fail Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Fail Pass Pass Pass Pass Pass The above-tabulated results once again establish the unique combination of properties exhibited by the inventive coatings: stability, good cure response, and the ability to utilize aliphatie isocyanate curing agents. The performance of these coatings tends to match the performance of the coatings tested in Example 2, even though a tri-funetional mercaptan was used in this example compared to a di-funetional mereaptan in Example 2. In this regard, compare Coatings 2 of Examples 2 and 3, Coating 3 of Example 3 and Coating 1 of Example 2, Coating 4 of Example 3 and Coating 9 of Example 2, Coating 5 of Example 3 and Coating 6 of Example 2, and Coating 6 of Example 3 and Coating 5 of Example 2. The most noticeable performance improvement m the coatings of Example 3 are in MEK Rubs for Coatings 4, 5, and 6.

.DTD:

EXAMPLE 4 .DTD:

The mercaptan-functional compounds evaluated were ether (DMDE), pcntaerythrito] tetra(3-mercaptopropionate) dipentaerythritol hexa(3mercaptopropionate) (DPH-3MP).

.DTD:

TABLE 7 dimercaptodiethyl PT-3MP), and.

Ingredient I0 I]VDE PT-3MP DPH-3MP Curing Agent MIBK CelIosolve Acetate i 7.2 mm 23.1 10.0 m 2 10.8 m m 60.3 7.0 Coat ing (gin) 3 mm 18.8 m 60.3 15.0 D 25.2 m 46.2 10.0 Wt.-% Solids 69.4 60.2 58.4 82.1 lOU Coatings 1 and 4-Curing agent was KI.;-5-2444 of Example 2. Coatings 2 and 3-Curing agent was Mondur HC of Example 2. Coating 5-Curing agent was methane diisocyanate of Example 2.

.DTD:

Coatings I, 4, and 5 were cured by exposure to 0.9 vol.-% triethylamiune catalyst in a curing chamber while Coatings 2 and 3 were cured by exposure to 0,5 voi.-% of the same catalyst. The following survey performance test results were recorded.

.DTD:

Table 8A .DTD:

Coating. Viscosity (cps) Initial 4hr 24hr 48hr 72hr Cure Time (sec) 1 Gelled........

.DTD:

2 110 220 1212.5 3200 8300 Sward(1) MI(2) Hardness Rub RT(3) HY(4) RT Hr r 3 130 155 620 2975 4 130 Gelled in 5 minutes 12,14 54,48 62,64 95 I00 66,68 iO0+ IOU+ Seni-Cl 60 48,44 70,60 lOU+ 10U+ 60 34,30 72,66 IOU+ 100+ 5,.ow' i'kY'v, cosC llcd), y...... 300 12,12 lO,lO so 5o TAHhE 8B Coating H20 5% NaOH 10%}SO4 Xylene RT HT RT Hr RT Hr RT Hr 1 Pass Pass Pass Pass Fail Fail Pass Pass 2 Pass Pass Fail Fail Pass Pass Pass Pass 3 Pass Pass Fail Fail Pass Pass Pass Pass 4 Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Fail Pas Pass Pass Pass Pass Again, the uniqueness of the inventive coatings is demonstrated. The use of aliphatie or mixed aliphatie/aromatic curing agents for Coatings 1 and 2 or Coatings 3. and 4 does not appear to alter performance significantly. The same can be said of the results of Coating 1 (Example 2), Coating 3 (Example 3), and Coating 4 (Example 4) which used the same curing agent but a difunctional mercaptan (Example 2), a trifunctional mercaptan (Example 3), and a tetrafunetional mercaptan (Example 4).

.DTD:

20- EXAMPLE 5 ' .DTD:

The following mercaptan functional compounds were evaluated: polyethylene glycol di(3-mercaptopropionate) (MW of about 776, PEG 776-M), polyethylene glycol di(3-mercaptopropionate) (MW of about 326, PEG 326-M), Rucoflex S-I028-210 (a difunctional polyester, OH no. of about 21u, Ruco Chemical Co., Hicksville, N.Y.) capped with 3-mercaptopropionic acid (R- 3MP), polypropylene glycol (Dow P1200, MW of about 1200, Dow Chemical Company, Midland, Michigan) capped with 3-mercaptopropionic acid (PG-3MP), Tone M-10t] homopolymer (polycaprolactone monoacrylate homopolymer, MW of about 344, Union Carbide Corporation, Danbury, Connecticut) capped with 3-mercaptopropionic acid (TIOU-3MP), and Tone 200 (difunctiona/ polycaprolactone, OH no. of 215, Union Carbide Corporation, Danbury, Connecticut) capped with 3-mercaptopropionie acid (T200-3MP).

.DTD:

TABLE 9 .DTD:

I ngr ed i en t PI3 776-M PB3 326-M R-3MP PC-3MP T100- 3MP T209-3MP Curing Agent MIIK Coat ing (gin.) 3 4 5 6 72.8 ".....

.DTD:

-- 56.5....

.DTD:

.. 41.4 -- ..... 34.9 46.2 23.1 23.1 23.1 20.0 5.0 10.0 5.0 Wt.-% Solids 96.3 88.5 81.3 88.9 82.4 87.3 Desmodur N-3390 curing agent of Example i.

Each of the coatings was cured by exposure to 0.9 vol-% triethylamine catalyst in a curing chamber except for Coating 1 which air dried in one minute. The following survey performance test results were recorded.

.DTD:

Coating., Viscosity (cps) Initial 4hr 24hr I Exothermed and Gelled 2 90 90 135.

.DTD:

3 135 140 240 4 150 Semi.Celled 48hr mm mm 145 175 190 6 120 120 235 328 Table 10A .DTD:

H20 Kr HI' Sward(1) MI(2) Cure Time}rdness Rub 72hr (sec) ET(3) HI'(4) RT PlY -- 8,6 8,8 2 3 -- 60 6,4 4,4 40 32 Coating -- 60 2,4 2,4 30 16 "2,4 2,2 5 5 210 60 2,0 0,0 6 7 530 60 4,4 4,4 i6 21 TABLE 10B .DTD:

SOLVENT RES ISTAN NaOH 10 H2S94 Xylene RT HI' RT HI' RT HI' 1 Fail Fail 2 Pass Pass 3 Pass Pass 4 Pass Pass Pass Pass 6 Pass Passs Fail Fail Fail Fail Pass Fail Fail Fail Fail Fail Pass Pass Fail Fail Pass Pass Pass Pass Fail Fail Fail Fail Fail Fail Fail Fail Fail Fail Pass Pass Pass Fail Fail Fail Pass Pass With respect to Coatings 1 and 2, the lower molecular weight polyether (Coating 2) had a longer pot" life, superior MEK resistance, and superior solvent resistance than the higher molecular weight polyether (Coating I). With respect to Coatings 3 and 4, the Rucoflex-based system (Coating 3)yielded better pot life, solvent resistance, and MEK rub resistance compared to the polypropylene glycol-based system (Coating 4). The performance of both polycaprolactonebased systems (Coatings 3 and 4) were about equivalent.

.DTD:

EXAMPLE 6 .DTD:

Several additional mereaptan-funetional resins were synthesized from the ingredients set forth below, !nredient Adipic Acid tO Neopentyl Glycol Iso-Phthal ie Acid Cardura E(I) Tr imethylol Propane Acryl ie Acid Isobutyl Acrylate],3-Butylene Glycol Propylene Glycol N-3390(2) reapt p pi ni 2-Mereaptoethanol Thiosal ieylic Acid 34 2 1 1 1 2 mm Nm Excess TABLE 11 Res in (moles) m D 3.2 Excess m alm 1.0 2.08 Excess 43 2 1.64 m m n 1.0 Excess O-- Cardura E is a glyeidyl ester fo Versatic 911 acid which is reported to be a mixture of aliphatJe mostly tertiary acids with 9-11 carbon atoms (Cardura and Versatie being trademarks of Shell Chemical Company, New York, New York), Desmodur N-3390 of Example 1.

.DTD:

Coatings were compounded from the above-tabulated resins as follows:

.DTD:

I ngr ed i ant Res in 34 Res in 37 Res in 52 Res in 43 Resin DN Cur ing Agent MIt]K Cel losolve Acetate N-Methyl Pyrrol idone 234 41.9 mm me t 40.2 17.0 TABLE 12 m COating 237 252 105.5 -- -- 48.8 23.1 23.1 -- 21.0 243 2EN 48.8 -- -- 44.9 23.1 23.1 10.0 -- n m -- 27.0 WL.-% Solids 59.6 49.9 74.3 66.4 53.7 Coatin 234-Curing agent was Mondur HC of Example 2.

.DTD:

Coatings 237, 252, 243, and 2DN-Curing agent was Desmodur N-3390 of Example I.

35 Coating 234 was cured by exposure of 0.5 voi.-96 triethylene catalyst while all other coatings were exposed to 0.9 vol.-% of catalyst. The following survey performace test results were recorded.

.DTD:

Coating Viscosity (cps) Initial 4hr 24hr 48hr Table 13A .DTD:

234 145 237 60 243 130 2EN 135 760 340 Gelled in 5 minutes 285 890 Gelled 8050 Gelled -- 245 72hr 400 llt 330 Cure Time (sac) 6O 6O 180 S rd(1) Hardness Rub RT Kr(4) RT Hr 76,68 74,74 65 10U 43,46 62,54 10 17 4,2 4,2 8 0 28,30 44,36 42 37 18,22 34,32 II 19 TABLE.1 3B .DTD:

Coat ing w 234 237 252 243 2I H20 -RI'}]r Pass Pass Fai 1 Pass Pass Pass Pass Pass Pass Pass SCLVENT RESIST (I) 5% NaCl-I RT I-It Fail Fail Fail Fail Fail Fail Fail Fail Fail Pass r 10% H2SO4 Xylene IT HT RT} Pass Pass Pass Pass Pass Pass Fail Fail Fail Fail Pass Pass Pass Pass Pass Pass Fail Fail Pass Pass Coating 234 clearly provided the best performance as the above-tabulated results reveal. Coating 237 lacked pot life and possessed only fair solvent resistance, yet provided fairly good Sward Hardness. Coating 252 was a bit soft, but may be improved by the addition of aromatic structure to the resin backbone. Coating 243 which contained aromatic mereaptan groups performed admirably but for its short pot life. Finally, coating 2DN possessed good properties but for some sensitivity to MEK rub resistance.

.DTD:

EXAMPLE 7 .DTD:

In this example, GDP of Example 2 was used as a reactive diluent along with aromatic hydroxyl-functional resins in order to ascertain whether cure speed with aliphatic isocyanates could be improved. The following polyol resins were evaluated.

.DTD:

Polyol 274:

.DTD:

Polyester Polyoh Acrylic Polyol- Tone M-100 homopolymer of Example 5 capped with p-hydroxy benzoic acid.

.DTD:

Aromatic hydroxyl-terminated polyester of Example 1 of U.S. Pat. No. 4, 374,167.

.DTD:

Butyl acrylate (4 moles), butyl methacrylate (4 moles), styrene (I mole), 2-ethyl hexylacrylate (2 moles), gycidyl methacrylate (2 moles), diphenolic acid (2 moles, second stage reaction).

.DTD:

Coatings were formulated from these polyol resins, Desmodur N-3390 uring agent of Example 1, and varying amounts of GDP. Curing conditions (0.9 vol.-% TEA catalyst) as described above were again utilized with the following results being recorded.

.DTD:

O% GDP Test RT I-IT Cure (sec) 300 300 Sward Hardness 4,4 6,4 MRUbs Solvents: 15 H20 5% NaOH 10% H2SO4 Xylene 9 5 PolyoI 274 5%(IX 10%GDP 20%GDP RT HI' RT HI" RT HI 240 240 180 180 180 180 4,4 6,6 4,4 4,6 2,2 2,2 I0 13 13 13 7 9 Pass Pass Pass Pass Fail Fail Fail Fail Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Fail Fail Pass Pass Pass Pass Pass Pass Fail Fail Pass Pass Pass Pass TABLE I5 .DTD:

Solvents: 30 IO 5% NaCH I0%K2OSO4 Xylene 0% G 2:5 Tea t RT HY Cure (see) 240 240 Sward Hardness 56,60 54,52 l Rubs 29 16 Polyester Polyol 5% GDP 10% (I3P RT: HI" RT HI' 180' 180 180 180 66,58 54,58 56,58 54,54 48 22 49 27 Pas s Pass Pass Pass Pass Pass Pass:Fail Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Fail Pass Fail Pass Pass Pass 20% CP RT HI 12U 12U 62,62 58,52 39 28 Pass Pass Pass Pass Pass Pass Pass Pass 0%GOP Test RT} Cure (see) 180 180 SwardHardness 44,48 86,82 39 30 IVIRubs Solvents:

.DTD:

IO Pass Pass 5% NaOH Pass Pass I0%H20SO4 Pass Pass Xylene Pass Pass TABLE 16 Acrylic Polyol 5%GDP 10%GZP 20%COP KI" HI" RT} ITl" HI" 180 180 120 120 56,52 92,84 48,52 86,82 36,32 74,66 44 32 35 37 31 45 Pass Pass Pass Pass Pass Pass Fail Fail Fail Pass Fail Pass Fail Pass Fail Fail Fail Pass Pass Pass Pass Pass Pass Pass The above-tabulated results demonstrate that cure speed of aliphatic isocyanate/po]yol coatings can be increased by the addition of a mercaptan compound while: maintaining, if not improving, performance.

.DTD:

EXAMPLE 8 .DTD:

Duplicate pigmented formulations were compounded for long-term QUV evaluation as follows:

.DTD:

i0 I ngred ient GDP TiO2(Z) Curing t ent12) MIBK I-430 Sur factant(3 TABLE 17 ls in (g) 78E 79B 36.6 36.6 38.5 38.5 69.3 69.3 20.0 20.0 8 drops 8 drops Viscosity 55 cps 55 cps Solids (wt.-%) 83.6 83.6 (i) RCL-6 titanium dioxide pigment (SCM Corporation, (2) (3) Baltimore, Md), pre-formed pigment grind (Hegman 7) with GDP (122.0 g GDP and 128.4 g ] CL-6) Desmodur N-3390 of Example I n TC-430 surfactant is a no-lomc fluorocarbon used at 25% in MEK (Minnesota Mining and Manufacturing Company} The coatings were applied to RIM substrates by the Blegen vaporous catalyst spray method described above (0.25 vol.-% dimethyiethanol amine catalyst). Both coatings displayed excellent cure response and good gloss. The following optical measurements (Hunter Color Difference readings) were recorded.

.DTD:

Weathering (hours) Initial 2OO 300 5O0 L 94.7 94.2 93.9 94.2 TABLE 18 Resin 78E a b -0.7 -0.5 -0.4 -0.8 Resin 79B L a b +1.2 94.4 -0.8 +0.5 +2.0 93.7 -0.6 +1.3 +2.3 93. -0.5 +1.3 +2.3 93.3 -0.8 +1.5 Thus, the anti-yellowing behavior of these coatings is demonstrated.

.DTD:

EXAMPLE 9 .DTD:

Coating 9 of Example 2 and Coating 234 of Example 6 were tested and found to possess elongations of 166% and 4.5%, respectively (at failure of coating on the substrate). The same coatings, however, possessed average tensile strengths of i15.5 kg/cm2 (1643 psi) and 151.2 kg/cm2 (2151 psi), respectively.

.DTD:

EXAMPLE I0 .DTD:

A preformed carbamothioate co-catalyst, 4423-195, was made from trimethyl01propane tri(3-mereaptopropionate) (TMP-3MP, 142.9 g), phenyl isocyanate (i 19 g), methyl isobutyl ketone solvent (112 g), and Amberlyst A-21 catalyst beads (acidic ion exchange resin, 5 g) by holding this mixture for 8 hours following by removal of the catalyst beads by filtration. No appreciable residual mercaptan or isocyanate were detected.

.DTD:

Coating compositions were formulated without the co-catalyst and with 5% by weight of the co-catalyst. Each sample was applied by the Blegen catalyst spray method described above using 0.6 vol-% dimethylethanol amine catalyst. The coatings formulations were made at an isocyanate index (NCO:OH molar ratio) of l:l and cut to application viscosity of 60 cps with MIBK solvent. Cure response data are set forth below.

.DTD:

TABLE 19 .DTD:

Formulation No. (wt. Parts) Ingredient 4423-196-I 4423-197-2 4423-197-3 4423-197-4 Polyester Polyol 50,3 50.3 -- -- DESMODUR HL 40.2 -- 40.2 -DESMOPHEN 800 -- -- 19.5 19.5 DESMODUR N3390 -- 21.6 -- 2i.6 MIBK 25.0 20.0 21.0 20.0 Polyester Polyol of Example 7 DESMODUR HL is DBSMODUR HC (Example 2) but with butyl acetate solvent DBSMOPHBN 800 polyester polyol, 100% n.y. solids, OH no 290, Mobay Chemical Co.

DESMODUR N3390 See Example I.

Formulation No.

4423-196-1: 4423-197-2 4423-197-3 4423-197-4 TABLE 20 .DTD:

Tack Free Time (mln0 wt-% Control Co-Catalyst Immediate 3 Immediate loo 6 This data unquestionably demonstrates the efficacy of the co-catalyst in promoting the hydroxyl/isoeyanate reaction.

.DTD:

EXAMPLE 11 .DTD:

Preformed mercapto/isocyanate or mercapto/thioeyanate compounds were evaluated for their effect in promoting the hydroxyl/isocyanate curing reaction. The following reactants were used to make the preformed compounds evaluated in this example, Compound No.

4541-85-1 4541-85-2 41-85 -3 41-85-4 TABLE 21 Mercapto Reactant Methyl 3-meroaptopropionate Methyl 3-mereaptopropionate Methyl 3mereaptopropionate Methyl 3-mereaptopropionate } Isocyanate Reactant Phenyl thiocyanate Butyl isocyanate Butyl thiocyanate Phenyl isocyanate The foregoing compounds were dissolved in methyl isobutyl ketone (MIBK) solvent at 10% solids. These compounds (co-catalysts) were tested at i% and 5% by weight levels,:

.DTD:

The various coating compositions tested were applied by the Blegen vaporous amine spray method of U.S. Pat. No. 4,517,222 using vaporous dimethylethanol amine (DMEOLA) at 0.7 vol,%. Duplicate samples were i cured at ambient indoor room temperature or were subjected to a 5 minute bake at about 121.1 C (250 F). The data reported to the left of the slash are for the ambient temperature samples while the data to the right ofl the slash are for the post-cure baked samples. Data lacking a slash are for the ambient temperature samples only. The coating composition formulation and the results recorded are set forth below.

.DTD:

-3 l- Test Data Co-Catalyst Pot Life (eps) Init. 4 Hr 24 Hr 48 Hr 72 Hr Formulation (g) VIC 5033 Mondur IIC MIBK 4541-86-I None.

*.DTD:

360 gel 4541-86-2 4591-85-I Co-Catalyst.....

.DTD:

II0 225 gel 50.3 50.3 36.5 36.5 27.0 22 5.4 454 I-86-3 4591-85-I 220 gel TABLE 22 Formulation No.

4541-86-5 4541-86-6 4541-85-2 4541-85-2 I05 130 225 I95 gel gel 50.33 50.3 50.3 36.5 36.5 36.5 0 22 0 27 5.4 27 454 I-86-8 454 I-85 -3 gel gel gel 454 I-86 -9 454 I-85 -3 gel gel gel gel 50.3 50.3 36.5 36.5 22 0 5.4 27 4541-86-11 4541-86-12 4541-85-4 4541-85-4 350 235 gel gel 50.3 50.3 36.5 36.5 22 0 5.4 27 Tack Free 5/yes 1/yes (rain) MEK Rubs I Hr 15/45 22/55 24 Hr 40/78 40/74 72 Hr 147/157 155/171 1/yes 3/yes 3/yes 2/yes 4/yes 4/yes 20/46 37156 38/60 65/143 32155 36/58 53/73 70/II I 74/96 147/327 140/231 135/2 I0 156/180 173/200 175/200 137/348 265/+500 +500/+500 VIC 5033 is a phenolic acrylic polyol, equivalent wt 504, 69.9% n.y. solids, oH no. III, Ashland Chemical Company, VIC is a registered trademark MONDUR HCsee Example 2 MIBK is methyl isobutyl ketone MEK Rubs is methyl ethyl ketone double rubs.

.DTD:

! k.D ! Test Data Co'Catalyst Pot Life (cps) Init, 39 4 Hr 425 24 Hr gel 48 Hr gel 72 Hr gel Formulation (g) K-flux 148 23.9 Mondur HC 36.5 MIBK 24 Co-Catalyst 4541-88-I None 454 I-88-2 454 I-85 -I TABLE 23 .DTD:

Formulation No.

4541-88-3 4541-88-5 4541-88-6 4541-88-8 4541-85-I 4542-85-2 4541-85-2 4541-85-3 4541-88-9 45 4 I-85 -3 4541-88-II 4541-88-12 4541-85-4 4541-85-4 30 30 30 30 30 30 475 500 450 435 460 450 450 475 gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel gel Tack Free (rain) MEK Rubs 23.9 23.9 23.9 23.9 23.9 23.9 23.9 23.9 36.5 36.5 36.5 36.5 36.5 36.5 36.5 36.5 19 19 19 0 19 0 19 0 5 24 5 24 5 24 lO/yes lO/yes 8/yes lO/yes lO/yes 8/yes 8/yes 6/yes 6/yes 14/39 21/69 26/38 19/57 35/67 32/42 37t43 39/48 40/45 35/67 1351145 206/225 200/197 230/21Z 202/217 I Hr 8/15 15/35 24 Hr 40/36 40/45 72 Hr 2061217 1951210 KFLEX 148 is a flexible polyester polyol, 100% n.y. solids, OH No. 235, King Industries.

.DTD:

40/45 35/89 40/45 37/112 197/190 175/202 i i ! ! Test Data Co-Catalyst Pot Life (cps) Init, 4 Hr 24 Hr 48 Hr 72 Hr Formulation (g) VIC 5033 Des N3390 MIBK Co-Catalyst 4541-89-I None 70 u 40.1 21.6 4541-89-2 4541-85-I 40.1 21.6 4541-89-3 4541-85-I II0 40.1 21.6 TABLE 24 .DTD:

Formulation No. 4541-89-5 4541-89-6 4541-89-8 4541-85-2 4541-85-2 4541-85-3 gel gel gel, 40.1 21.6 40.1 21.6 0 24 40,1 21.6 19 5 4541-89-9 4541-85-3 40.1 21.6 4541-89-I1 4541-89-12 4541-85-4 4541-85-4 II0 115 40.1 40.1 21.6 21'6 19 0 24 Tack Free (rain) MEK Rubs 90/yes 901yes 90/yes 90/yes 90/yes 901yes 901yes I Hr 111 112 /15 /17 24 Hr 47/55 52/51 55155 44/52 72 HR 1201189 111/202 I171197 110/189 /13 49/57 I09/195 118 50/55 1101185 /20 55/60 120/205 901yes 90/yes 50/55 1351185 117 50/58 102/185 DESMODUR N3390'see Example l These results demonstrate that the preformed thiourethane co-catalyst is effective in improving the cure of the polyol/polyisocyanate coating composition. The 4541-85-4 do-catalyst appeared to be the most effective of the compounds evaluated, though all of the compounds were effective in promoting the cure.

.DTD:

.CLME:

Claims

-CLAIMS .CLME:

I. Method for curing a film of a coating composition which comprises exposing said coating composition as an atomizate which then is applied to a substrate or as an applied film on a substrate to a vaporous tertiary amine catalyst, said coating composition comprising a polymercapto compound and a multi-isocyanate curing agent.

.CLME:

I0
2. The method of claim I dispersed in a fugitive organic solvent.

.CLME:

wherein said coating composition is 3. The method of claim 1 wherein said polymercapto compound is a monomer, oligomer, or polymer.

.CLME:

4. The method of claim 1 wherein the molar ratio of mercapto g.oups to isocyanatew groups in said coating composition is between about I:: and 1:2.........."....

.CLME:

5. The method of claim 1 wherein said coating composition also contains a particulate filler' 6. The method of claim 1 wherein said polymercapto compound is selected from or the mercapto groups thereon are derived from 1,4-butane dithiol, 2,3-dimercapto propanol, toluene-3,4-dithiol, alpha,alpha'-dimercaptop- xylene thiosalicylic acid, mercapto acetic acid, 2-mercapto ethanol, monododecane dithiol, didodecane dithiol, dithiol phenol, di- parachlorothiophenol, dimercapto benzothiazole, 3,4-dimercapto toluene, allyl mercaptan, 1,6 hexane dithiol, benzyl mercaptan, l-octane thiol, p- thiocresol, 2,3,5,6-tetrafluorothiophenol, cyclohexyl mercaptan, methylthioglycolate, mercapto pyridines, dithioerythritrol, 6-ethoxy-2mercaptobenzothiazol, and mixtures thereoL 7. The method of claim 1 wherein the coating composition is cured by exposure of an applied film thereof to a vaporous tertiary amine catalyst.

.CLME:

8. The method of claim I wherein an atomizate of said coating compositionn concurrently generated with a vaporous tertiary amine catalyst are admixed, said mixture applied to a substrate, and said coating composition cured... - 9. The method of cliam I wherein said curing agent is selected from an aliphatie multi-isoeyanate curing agent, an aromatic multi-isocyanate curing agent, and mixtures thereof.

.CLME:

I0 I0. A coating composition rapidly curable at room temperature in the presence of vaporous tertiary amine catalyst comprising a polymereapto compound and a multi-isoeyanate curing agent.

.CLME:

II. The composition of claim I0 wherein said coating eompodtion additionally comprises a fugitive organic solvent.

.CLME:

12. The composition of claim 10 wherein said polymercapto compound is selected from a monomer, oligomer, or polymer.

.CLME:

13. The coating composition of claim I0 wherein said polymercapto compound is selected from or is derived from an ingredient selected from 1,4butane dithiol, 2,3-dimereapto propanol, toluene-S,4-dithiol, alpha, alpha'dimercapto-p-xylene thiosalieylie acid, mercapto acetic acid, 2mereapto ethanol, monododecane dithiol, didodecane dithiol, dithiol phenol, di-paraehlorothiophenol, dimereapto benzothiazole, 3,4-dimercapto toluene, allyl mercaptan, 1,6 hexane dithiol, benzyl mereaptan, l-octane thiol, p-thioeresol, 2,3,5,6-tetrafluorothiophenol, eyclohexyl mercaptan, methylthioglycolate, mercapto pyridines, dithioerythritrol, 6-ethoxy-2mereapt0benzothiazol, and mixtures thereof.

.CLME:

14. The coating composition of claim I0 wherein said multi-isocyanate curing agent is selected from an aliphatic multi-isocyanate curing agent, an aromatic multi-isoeyanate curing agent, and mixtures thereof.

.CLME:

15. In a method for euring the film of a coating composition which comprises exposing said coating composition as an atomizate which then is applied to a substrate or as an applied film on a substrate to a vaporous tertiary amine catalyst, said coating composition comprising a polyol and a multi-isocyanate curing agent, the improvement which comprises said coating I0 composition being cured in the presence of a thio-urethane compound formed by the reaction of a mercaptan compound and an isocyanate compound.

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16. The method of claim 15 wherein said coating composition additionally comprises a mercapto compound which forms said thio-urethane compound in situ during the curing of said coating composition.

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17. The method of claim 15 wherein said thio-urethane compound is preformed and added to said coating composition.

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18. The method of claim 15 wherein said thio-urethane compound is represented by the following structure:

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H 0 HS HS I II. | II I II RI-N -C -S-R2, RI-N -C,S-K2, or RI-N -C-O-R2 where R1 and R2 each is a monovalent organic radical which desirably is an alkyl or an aryl group.

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19. The method of claim 16 wherein said mercapto compound is a monomercapto compound, apolymercapto compound, or mixtures thereof.

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20. The method of claim 15 wherein said multi-isocyanate curing agent is an aromatic multi-isocyanate, an aliphatic multi-isocyanate, and mixtures thereof; and said polyol is selected from an aromatic polyol, or mixtures of an aliphatic polyol and an aromatic polyol.

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2l. A method of curing a film of a coating composition according to Ciaim] and substantially as described in any of the examples herein.

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CLAIMS:

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i.

Amendments to the claims have been filed as follows In a method for curing the film of a coating composition which comprises exposing said coating composition as an atomizate which then is applied to a substrate or as an applied film on a substrate to a vaporous tertiary amine catalyst, said coating composition comprising a polyol and a multi'isocyanate curing agent, the improvement which com- prises said coating composition being cured in the presence of a thio-urethane compound formed by the reaction of a mercaptan compound and an isocyanate compound.

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IO 2. The method of claim 1 wherein said coating composition additionally comprises a mercapto compound which forms said thio-urethane compound in situ during the curing of said coating composition.

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3. The method of claim 1 wherein said thio-urethane compound is pre-formed and added to said coating composition.

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4. The method of claim 1 wherein said thio-urethane compound is represented by the following structure:

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HO HS HS I |I | II I II R1-N-C.S-R2, R1-N-C-S-R2, or R1-N-C-O-R2 where R1 and R2 each is a monovalent organic radical which desirably is an alkyl or an aryl group.

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5. The method of claim 2 wherein said mercapto compound is a monomercapto compound, a polymercapto compound, or mixtures thereof.

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6. The method of claim 1 wherein said multi-isocyanate curing agent is an aromatic multi-isocyanate, an aliphatic multi- isocyanate, and mixtures thereof; and said polyol is selected from an aromatic polyol, or mixtures of an aliphatic polyol and an aromatic polyol.

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Pubhshed 1968 a: The Patent Office, Sae House, 66'71 l=hgh Plolborn, London WCIR 4TP. FurUher copies may be obu.ued from The Paent ce.

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Sa/es Branch. St Mary Cravo 0roington. Kent BK5 3RD. Printed by Mu]m]ex teehrsues lUl St Mary Cray, Kent. Con. 1-/87.

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