JPH0651862B2 - Coating curing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to vapor penetration curable coatings, and more particularly to the synthesis and use of polymercapto resins therefor.

(Prior Art) A conventional vapor permeation curable coating is a type of coating that is composed of an aromatic hydroxy-functional polymer and a multi-isocyanate crosslinking agent, and the coating is exposed to a vaporized tertiary amine catalyst. To cure. A curing chamber has been developed to economically and safely contain and handle vaporous tertiary amine catalysts. A typical cure chamber is a substantially empty box through which a conveyor carrying a coated substrate passes, in which vaporous tertiary amines, usually carried by an inert gas carrier, are used. Contact the coated substrate. The use of aromatic hydroxy functional polymers is recommended if a stable one-pack system is required. If a two-pack formulation is acceptable, then an aliphatic hydroxy-functional resin can be used. The multi-isocyanate crosslinker in conventional vapor penetration curable coatings contains at least some aromatic isocyanate groups in order to achieve a practical cure rate.

The need for such conventional vapor permeation curable paint was
It was modified by the vapor amine catalyst spraying method disclosed by Blegen in U.S. patent application Ser. No. 06 / 615,135 filed March 30th. Such a vapor catalyst spraying method relies on the action of simultaneous generation of a mist of the coating composition and a carrier gas carrying a catalytic amount of a vaporous tertiary amine catalyst. The atomized material thus generated and the vaporized catalytic amine carrying carrier gas are mixed and guided to the substrate to form a film thereof. The use of a curing chamber is unnecessary as curing proceeds rapidly. Moreover, all-aliphatic isocyanate curing agents can be utilized in such spraying processes. However, the hydroxyl groups of the resin are still needed.

(Problems to be Solved by the Invention) One drawback to the necessity of the aromatic hydroxyl group of the resin is that such aromaticity gives an inherent constraint on the formulation of a high-solids coating material. The same applies to the need for aromaticity in multi-isocyanate crosslinkers. Such non-volatile solids content limits even apply to the vapor amine catalyst spraying method described above.

The present invention solves many of the limitations that have been placed on vapor permeable curable coatings that are cured in the curing chamber.

(Means for Solving the Problems) The coating composition film curing method according to the present invention comprises exposing the coating composition to an atomized product or a vaporized tertiary amine catalyst of a coating film. It consists of The coating composition comprises a polymercapto compound and a multi-isocyanate curing agent. In the case of coatings, the coating composition is cured by exposing the coating composition coating to a vaporized tertiary amine catalyst in a cure chamber. Alternatively, a mist of the coating composition is generated with a vaporized tertiary amine catalyst and mixed with it,
The mixture can then be applied to a substrate and cured.

Another aspect of the present invention includes a coating composition comprising a hydroxy functional compound, a polymercapto compound, and a multi-isocyanate curing agent. The curing agent may be an all-aliphatic isocyanate curing agent, and the polymercapto compound is present in a minor proportion to catalyze or enhance the curing reaction of the polyol resin and the aliphatic isocyanate curing agent. It can be a reactive diluent.

Advantages of the present invention include the ability to produce high solids coating compositions having non-volatile solids contents up to 100%. Another advantage is that an all-aliphatic isocyanate-containing curative can be utilized to still achieve rapid cure in the cure chamber. Another advantage is the unusually high gloss of polymercapto-containing vapor penetration cured coatings when cured in a curing chamber. These and other advantages will be readily apparent to one of ordinary skill in the art based on the disclosure herein.

(Working) The use of polymercapto-functional monomers, oligomers or polymers in vapor permeation-curable coatings, including their ability to be compounded into a single filling system that has storage stability over hours to days, includes aromatics. Despite possessing the advantageous properties achieved in the use of hydroxy-functional compounds, this coating formulation cures rapidly upon exposure to a vaporized tertiary amine catalyst at room temperature. Moreover, several unique advantages are achieved through the use of such resin or non-resin thiols. One of these advantages is the ability to formulate very high solids coatings up to 100% non-volatile solids.
Such high solids content is due in part to the freedom afforded by the use of thiols to reduce the aromatic content of both the resin and the curing agent. That is, the aromatics adjacent to the mercapto group are unnecessary for storage stability and for the curability of the coating composition. Also, the aromaticity of the curing agent is not necessary to achieve room temperature rapid cure in the presence of the vaporized tertiary amine catalyst. It will be appreciated that the aromaticity in the coating composition is quite desirable when conventional curing chamber curing techniques are employed. Another advantage of being able to formulate coating compositions with reduced fragrance groups is that they may increase the flexibility of the cured coating composition. This is because aromatic groups tend to give steric hindrance to the polymer and increase brittleness, making it difficult to realize a highly flexible system having high extensibility. Of course, the conventionally known vapor permeation curable coating compositions contain at least some aromatic curing agent in order to achieve rapid curing and do not retain the long pot life advantage of the coating composition. Because of this, the resin contained aromatic hydroxy functionality. The use of polymercapto resins in accordance with the scheme of the present invention in the formulation of vapor penetration curable coatings provides greater flexibility.

Monomers, oligomers or polymers containing pendant mercapto or thiol groups are commercially available or can be easily synthesized. For example, polymers such as polyesters, polyacrylates, polyethers, and other free hydroxyl groups and mercapto-terminated acids such as 3-
The mercapto group can be attached to the oligomer or polymer by esterification with mercaptopropionic acid or thiosalicylic acid. Similarly, the epoxy functional resin can be reacted with an acid having a mercapto end group under acidic conditions to enhance the selective reaction of the carboxylic acid group and the epoxy group. In addition, at least two pendant mercapto groups are provided by reaction of pendant primary or secondary amine groups with acids having mercapto end groups or by free isocyanate groups on oligomers or polymers having isocyanate end groups. , A mercapto group can be introduced into an oligomer or a polymer by reacting with an acid ester having a mercapto terminal group. Furthermore, the reaction mechanism for introducing a mercapto group into an oligomer or polymer includes conducting a Michael addition reaction between polymercaptan and polyolefin. Yet another synthetic mechanism involves reaction of an aryl or alkyl halide with NaSH to introduce a pendant mercapto group into the alkyl or aryl compound. It is even possible to react the Grignard reagent with sulfur to introduce a pendant mercapto group into the structure. In fact, disulfides can be reduced (eg, with zinc or other catalysts under acidic conditions) to produce mercapto-functional monomers for use as reactive diluents in vapor penetration cure coatings. The mercapto group is
It can be incorporated into an oligomer or polymer in a number of other ways well known in the art. The mercapto group is pendantly attached to the oligomer or polymer. For purposes of this application, pendant mercapto groups include terminal mercapto groups. Attaching in a pendant form means attaching such a mercapto group to the polymer chain or to the pendant side chain of a polymer or oligomer. The resinous material containing pendant mercapto groups should be at least difunctional in order to crosslink with the curing agent, although higher functionality may also be used. The monofunctional mercapto-containing resinous material can be used as a reactive diluent, as further detailed below.

Various polymercaptans suitable for synthesizing the mercapto-functional resinous material used to form the dye composition of the present invention include, for example, 1,4-butanedithiol, 2,3-dimercaptopropanol, toluol-3. , 4-Dithiol, and alpha, alpha'-dimercapto-p-
Includes xylol. Other suitable active mercapto compounds are thiosalicylic acid, mercaptoacetic acid, mercaptopropionic acid, 2-mercaptoethanol, dodecanedithiol, didodecanedithiol, dithiolphenol, di-para-chlorothiophenol, dimercaptobenzthiazole, 3,4 -Dimercaptotoluene, allyl mercaptan, 1,6-hexanedithiol, 1,2-ethanedithiol, benzylmercaptan, 1-octanethiol, p-thiocresol, 2,3,5,6-tetrafluorothiophenol, cyclohexylmercaptan , Methylthioglycolate, mercaptopyridine, dithioerythritol, 6-ethoxy-2-mercaptobenzthiazole, and the like. Other useful mercaptans can be found in various types of commercially available mercaptans.

In fact, any oligomer, polymer or resinous compound can be modified to contain pendant mercapto or thiol groups. Typical resinous substances containing a mercapto group include, for example, epoxy and epoxy-modified diglycidyl ether of bisphenol A structure, various aliphatic polyethylene or polypropylene glycol (diglycidyl ether) adducts, and glycidyl ether of phenolic resin. Can be induced. Other useful polymers containing pendant mercapto groups are polyamide resins, such as dimerized fatty acids,
Includes those condensation products that have been reacted with difunctional amines such as ethylenediamine, followed by reaction with 3-mercaptopropionic acid or analogs thereof. Furthermore, it is easily conceivable to modify various acrylic resins and vinyl resins according to the method of the present invention.

In this regard, any conventionally known hydroxyl group-containing monomer, oligomer, or polymer previously proposed for use in a vapor permeation-curable coating may be appropriately modified to form a pendant for use in formulating the coating composition of the present invention. -A mercapto group can be contained. For example, esterifying (or transesterifying) such a polyol with an acid having a mercapto end group can be used to modify such conventional vapor osmosis curable materials for the formulation of the coating compositions of the present invention. This is the only technique that can be easily conceived. Although not exhaustive, the following discussion discloses conventional vapor osmosis curable coating compositions that can be suitably modified. U.S. Pat. No. 3,409,579 discloses binder compositions of phenol / aldehyde resins (including resoles, novolacs and resistols), which are preferably benzyl ether resins or polyether phenolic resins. U.S. Pat. No. 3,676,392 discloses resin compositions in organic solvents formed with polyetherphenolic resins or methylol terminated phenolic (resole) resins. U.S. Pat.No. 3,429,848 is U.S. Pat.
It discloses silane additions to compositions such as 579.

U.S. Pat. No. 3,789,044 discloses hydroxybenzoic acid capped polyepoxy resins. US Patent No.
No. 3,822,226 discloses curable compositions of phenols reacted with unsaturated substances selected from unsaturated fatty acids, oils, fatty acid esters, butadiene homopolymers, butadiene copolymers, alcohols and acids. U.S. Patent No. 3,
836,491 discloses similar hydroxy-functional polymers capped with hydroxybenzoic acid (eg, polyesters, acrylics, polyethers, etc.). British Patent 1,369,351 discloses diphenolic acid capped hydroxy or epoxy compounds. British Patent 1,351,881 modifies a polyhydroxy, polyepoxy, or polycarboxylic acid resin with the reaction product of a phenol and an aldehyde.

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

U.S. Pat.Nos. 4,343,839, 4,365,039 and
No. 4,374,167 discloses a polyester resin coating that is particularly compatible with flexible substrates. U.S. Pat.No. 4,374,181
In particular, it discloses resins suitable for application in reaction injection molded (RIM) urethane parts. U.S. Pat.No. 4,331,782
No. discloses hydroxybenzoic acid-epoxy adducts. 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 its derivatives in vapor permeable curable coatings. U.S. Pat.No. 4,368,
No. 222 discloses the peculiarity of utilizing a vapor permeable curable coating on a superficially porous substrate of a fiber reinforced molding material (eg sheet molding compound or SMC). Finally, U.S. Pat. No. 4,396,647 describes 2,3 ',
The use of 4-trihydroxydiphenyl is disclosed.

It is recognized that the above aromatic hydroxypolymers or resins, like many other resins, may be suitably modified to contain mercapto groups for use in formulating coating compositions in accordance with the method of the present invention. .

Finally, the mercapto resin-like materials of this invention can be utilized to formulate coating compositions that are ideally suited to the above-referenced Bregen vapor amine catalyst spraying process.
Such vapor amine catalyst substituting methods comprise the simultaneous generation of a coating composition dew and vapor tertiary amine, the streams being mixed and applied to a substrate. Although the non-volatile solids content of coating compositions incorporating mercapto resinous substances is increasing, it may allow the spray painting of pigmented paints which still contain more than 80% non-volatile solids. In this respect, the coating composition may be for coating composition (eg spraying, etc.), or for any other purpose as required, desirable or convenient in the conventional manner. It may contain a reactive or volatile solvent for compounding the substance.

The multi-isocyanate cross-linking agent, under the action of a vaporized tertiary amine, cross-links with the mercapto or thiol groups of the polymer adduct capped to cure the paint. Aromatic isocyanates are preferred to obtain a reasonable pot life and the desired rapid reaction at room temperature in the presence of vaporized tertiary amine catalysts. For high performance coatings, at least the usual amount of aliphatic isocyanate can be included in the curing agent to minimize initial coloration and discoloration by sunlight. Of course, polymeric isocyanates are used to reduce the toxic vapors of the isocyanate monomers. In addition, alcohol-modified and other modified isocyanate compositions (eg thiocyanate)
Are useful in the present invention. The multi-isocyanates (ie polyisocyanates) used in the coating composition of the present invention preferably have about 2-4 isocyanate groups per molecule. Suitable multis for use in the present invention
Isocyanates include, for example, hexamethylene diisocyanate, 4,4′-toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethyl polyphenyl isocyanate (polymer MDI or PAPI),
m- and p-phenylene diisocyanate, bitolylene diisocyanate, triphenylmethylene triisocyanate, tris- (4-isocyanatophenyl) thiophosphate, cyclohexane diisocyanate (CH
DI), bis- (isocyanatomethyl) cyclohexane (H ₆ XDI), dicyclohexylmethane diisocyanate (H ₁₂ MDI), trimethylhexane diisocyanate, dimer acid diisocyanate (DDI), and their dimethyl derivatives, lysine diisocyanate and its methyl ester, isophorone Diisocyanates, methylcyclohexane diisocyanates, 1,5-naphthalene diisocyanates, triphenylmethane triisocyanates, xylene diisocyanates and their methyl and hydrogenated derivatives, polymethylene polyphenyl isocyanates, chlorophenylene-2,4-diisocyanates, and the like. As well as mixtures thereof. Aromatic and aliphatic polyisocyanates dimers, trimers, oligomers, polymers (including biuret and isocyanurate derivatives), and isocyanate-functional prepolymers are often available as preformed packages. Are also suitable for use in the present invention.

The ratio of mercapto groups from the mercapto resin-like material to the isocyanate equivalents of the multi-isocyanate crosslinker should be greater than about 1: 1 and can range up to about 1: 2. If the coating composition is applied with strict intent, this ratio or the number of isocyanates is often specified.

As mentioned above, a solvent or vehicle may be included as part of the coating composition. Some aromatic solvent may be required, typically it is part of the volatiles impregnated in commercial isocyanate polymers, but volatile organic solvents minimize viscosity. To this end, ketones and esters may be included. 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 that are commercially available for polyisocyanate polymers include, for example, toluene, xylene and the like. The combination of relatively low volatility or non-volatile (high boiling) ester plasticizers retained for most of the cured coating increases the effective non-volatile solids content of the coating composition. It should be noted that you get. Such suitable ester plasticizers include, for example, dibutyl phthalate, di (2-ethylhexyl) phthalate (DOP),
Etc. are included. The proportion of ester plasticizer should not exceed about 5-10% by weight, otherwise mar resistance may be lost.

In addition, the coating composition contains matte pigments and inert extenders, such as, for example, titanium dioxide, zinc oxide, clays such as kaolinite clay, silica, talc, carbon or graphite (eg conductive coatings), etc. be able to. Moreover, the coating composition can contain color pigments, rust-preventive pigments and various agents commonly found in coating compositions. Such additional additives are
For example, surfactants, fluidizers or leveling agents,
Pigment dispersants, etc. are included.

For the performance requirements that this coating composition meets, the coating composition, polymercapto resin and isocyanate crosslinker, can have a minimum pot life of at least 4 hours in the open container, and usually a pot life of 8
It should be noted that it is possible to formulate paints which can exceed the time and extend to over 18 hours. Such a long pot life means that refilling the containers during the shift work hours at the factory is usually unnecessary. Further, the pot life of the coating composition in the closed container may exceed one month depending on the formulation of the coating composition. After storage of the coating composition, the stored composition can be reduced to coating viscosity (if necessary) with a suitable solvent, and such composition has all of the excellent performance characteristics originally possessed. Hold.

Vapor amine catalysts are tertiary amines, including tertiary amines containing substituents such as, for example, alkyls, alkanols, aryls, alicyclics and mixtures thereof.
Moreover, heterocyclic tertiary amines are also suitable for use in the present invention. Representative tertiary amines are, for example, triethylamine, dimethylethylamine, trimethylamine, tributylamine, dimethylbenzylamine, dimethylcyclohexylamine, dimethylethanolamine, diethylethanolamine, triethanolamine, pyridine, 4-phenylpropylpyridine, 2,4 , 6
-Colidine, quinoline, isoquinoline, N-ethylmorpholine, triethylenediamine, and the like and mixtures thereof. In addition, amine oxides and quaternary ammonium amines are conceivable due to their practical potential to produce such amines in the vapor phase. A myriad of registered tertiary amine catalysts are currently available and they also work in the process of the invention. The catalytic activity of tertiary amine catalysts is shown in "The Activation of IPPD Eye by Warrior Accelerator Systems" by Faberhemie AG, Gelsenkirchen-Buer, West Germany. "The
Activation of IPDI by Various Accelerator System
s ”, Veba-Chemie AG, Gelsenkirchen-Buer, West Germ
It should be noted that complex salts can be enhanced by the addition of complex salts to the coating composition, as reported in the "any" paper. Thus, in the liquid coating composition, ferric iron,
Adding manganese and aluminum salts may be performed as an aspect of the invention.

The proportion of vaporized amine catalyst may range up to 6% or more,
Generally a percentage less than or equal to 1% by volume, eg about 0.25
1% by volume is sufficient. It should be warned that high concentrations of amine catalysts are not recommended as they will create an explosive mixture in the presence of air or a source of molecular oxygen. The tertiary amine catalyst is vaporized in an inert carrier gas such as nitrogen or carbon dioxide, or in air or a mixed gas thereof. To ensure that the amine catalyst remains vapor-like and does not condense on any path, the minimum temperature and pressure of the blowing gas stream is selected by the selected carrier gas and the specified tertiary amine catalyst. It is recognized that and must be maintained. Further, the ratio of amine to carrier gas may be varied depending on whether a conventional curing chamber is utilized or the Breen vapor amine catalyst spraying method is employed.
In this regard, suitable curing chambers for using the coating compositions of the present invention are U.S. Pat. Nos. 4,491,610 and 4,492,
No. 041. However, it should be recognized that other curing chambers may be utilized, such as those disclosed in U.S. Pat. Nos. 3,851,420 and 3,931,684.

Upon exposure to a vaporized tertiary amine catalyst, the mercapto groups of the resin-like material and the isocyanate groups of the curing agent react to form a cured network of carbamothioate groups (carbamothiolate ester groups). The reaction proceeds rapidly at room temperature, making it possible to handle parts which have been cured in a short time after the catalyst has been cured, for example in the shortest time of 1 to 5 minutes in most cases. It is a decisive advantage that the coating composition of the present invention possesses such rapid curing ability. In this respect, it is recognized that such rapid cure occurs whether the curing agent is all fatty acid isocyanates, all aromatic isocyanates or mixtures of aliphatic and aromatic isocyanates.

In this regard, the use of small proportions of monofunctional or polyfunctional mercapto compounds as reactive diluents (eg, up to 20 weight percent) allows polyols and aliphatic isocyanate groups of the curing agent to be reacted under vapor deposition permeation cure conditions. The reaction during can be significantly accelerated. A clear benefit of using a mercapto compound to accelerate the polyol-isocyanate reaction is that the polyol and curing agent retain the performance characteristics they exhibit without the addition of the mercapto compound, sometimes improving performance characteristics. You can even see it. In addition to forming carbamothioate groups that are believed to actually catalyze the polyal / polyisocyanate reaction in situ (eg, "in situ formation"), preformed carbamothioates (mercapto compounds and isocyanates) Preformed reaction products with compounds) can be incorporated into the coating composition and similar catalytic effects are observed. The use of preformed compounds may not provide the degree of improvement in cure response as seen when forming such groups in situ during curing of coating compositions. Thus, this aspect of the invention includes coating compositions that cure in the presence of a compound containing one or more of the following moieties:

The compounds that induce such moieties in this preformed embodiment of the invention can be represented as follows:

As illustrated by the data, the preformed embodiment of the invention does not appear to work to the same extent when aliphatic isocyanates and aliphatic polyols are included in the coating composition. Therefore, some aromaticity should be present for the preformed embodiment of the present invention, and it is preferred to derive such aromaticity from the aromatic isocyanate component of the coating composition. However, in the preferred in-situ formation of the present invention, the coating properties and reactions that occur with the mercapto compound are believed to provide a stronger catalytic or accelerating effect in the hydroxyl / isocyanate reaction, so aromaticity is It is not as important a factor as in the preformed embodiment. Nevertheless, for both aspects of the invention, some aromaticity in the coating composition is preferred.

(Effects of the Invention) Various substrates can be coated with the coating composition of the present invention. The substrate is, for example, iron, steel, aluminum,
Includes metals such as copper, galvanized steel, zinc, and the like. Furthermore, this coating composition is used for wood, organic fiberboard, RIM, SMC.
, Vinyl, acrylic, other polymeric or plastic materials, paper, etc. Since the coating composition can be cured at room temperature, the coating composition of the present invention is not subject to any use restrictions due to thermal damage to heat sensitive substrates. Also, since the Bregen vapor amine catalyst spraying method can be used, the flexibility of use of the coating composition of the present invention is further enhanced.

Examples The following examples are illustrative of embodiments of the invention and should not be construed as limiting. In this reaction example,
Unless otherwise indicated, all percentages and ratios of coating compositions are by weight and all percentages and ratios of vaporized tertiary amine catalysts are by volume. Also, all units are in the metric system, and all citations referenced herein are specifically incorporated by reference into the book.

Example 1 The curing responsiveness of mercapto group vapor permeation curing (VPC) was evaluated and compared with an aliphatic hydroxyl group on the same structurally identical molecule except that it contains -SH group or -OH group. Viscosity and general performance tests were performed on the following compositions.

Each coating composition was exposed to 0.9% by volume triethylamine catalyst (TEA) in a curing chamber for evaluation and the following results were obtained.

The results set forth in the table above illustrate the excellent combination of stability (as measured by viscosity data) and rapid cure response. In fact, the mercapto groups cured within a minute or so, although the aliphatic hydroxyl groups only cured after 2 days.

Example 2 Various isocyanate curing agents were evaluated in the following coating compositions with glycol dimercaptopropionate (GDP).

Again, this demonstrated the combination of excellent stability (pot life) and good cure response of coatings incorporating mercapto reactants. Also, these paints had a very high solids content, which contributed to their particularity. More importantly, the ability to utilize all-aliphatic multi-isocyanate hardeners in VPC paint formulations.

Example 3 In this series of tests, trimethylolpropane tris (3-mercaptopropionate), (hereinafter TMP-3M
P) was allowed to act as a mercapto-functional compound and evaluated with various curing agents as in Example 2.

0.5% by volume for paints 1 and 2 and 0.9% by volume for all other paints in the curing chamber
It was cured by exposure to the above triethylamine catalyst and subjected to the general performance test described above.

The results in the table above again reaffirm the unique combination of properties exhibited by the paints of the present invention: stability, good cure response, and availability of aliphatic isocyanate hardeners. Although the trifunctional mercaptans were used in this example as compared to the difunctional mercaptans used in Example 2, the performance of these paints matches that of the paints tested in Example 2. Tend. Regarding this point, each paint 2 of Examples 2 and 3, paint 3 of Example 3 and paint 1 of Example 2, paint 4 of Example 3 and Example 2
The paint 9 of Example 3, the paint 5 of Example 3 and the paint 6 of Example 2, and the paint 6 of Example 3 and the paint 5 of Example 2 are compared with each other. The most noticeable performance improvement in the paint of Example 3 is in MEK rub against Paints 4, 5 and 6.

Example 4 The evaluated mercapto-functional compounds were dimercaptodiethyl ether (DMDE), pentaerythritol tetra (3-mercaptopropionate) (PT-3MP), and dipentaerythritol hexa (3-mercaptopropionate) ( DPM-3MP).

Coatings 1, 4 and 5 were cured by exposure to 0.9% by volume triethylamine catalyst in the cure chamber, while coatings 2 and 3 were cured by exposure to 0.5% by volume of the same catalyst. The following general performance test results were recorded.

Here too, the specificity of the coating composition according to the invention is demonstrated. The use of aliphatic or mixed aliphatic / aromatic hardeners for Paints 1 and 2 or Paints 3 and 4 is not seen to change performance significantly. A coating (Example 2), a coating 3 (using the same curing agent, but using difunctional mercaptan (Example 2), trifunctional mercaptan (Example 3), and tetrafunctional mercaptan (Example 4)). The same applies to the results of Example 3) and paint 4 (Example 4).

Example 5 The following mercapto functional compounds were evaluated.

Polyethylene glycol di (3-mercaptopropionate) (molecular weight about 776, called PEG776-M); polyethylene glycol di (3-mercaptopropionate) (molecular weight about 326, called PEG326-M); Rucof
lex) S-1028-210 (difunctional polyester, OH number about 210
Manufactured by Ruco Chemical Co., Hickswil, NY) capped with 3-mercaptopropionic acid (referred to as R-3MP);
Polypropylene glycol (Dow P1200, molecular weight about 1200, Dow Chemical, Midland, Michigan)
Company (Dow Chemical Company)] capped with 3-mercaptopropionic acid (referred to as PG-3MP); Tone M-100 homopolymer (polycaprolactone monoacrylate homopolymer, molecular weight approximately 344, Union, Dumberry, Connecticut)・ Carbide Corporation capped with 3-mercaptopropionic acid (referred to as T100-3MP); and Tone 200 (difunctional polycaprolactone, OH number 215, Danbury, Connecticut, Union Carbide Corporation) (T200 -3MP).

Each paint was cured in a curing room except that paint 1 was air dried for 1 minute.
Cured by exposure to 0.9% by volume triethylamine catalyst. The following general performance test results were recorded.

Regarding paints 1 and 2, the method of lower molecular weight polyether (paint 2) has a longer pot life, better MEK friction resistance, and better solvent resistance than the higher molecular weight polyether (paint 1). And had. Regarding paints 3 and 4, the Rucoflex-based system (paint 3) has a better pot life than the polypropylene glycol-based system (paint 4).
It showed solvent resistance and MEK friction resistance. The performance of both polycaprolactone-based systems (Paints 5 and 6) was approximately equivalent.

Example 6 Several additional mercapto-functional resins were synthesized from the following ingredients.

The paint was formulated from the resins in the above table as follows.

Paint 234 was cured by exposure to 0.5 wt% triethylamine catalyst, while all other paints were exposed to 0.9 vol% catalyst. The following general performance test results were recorded.

As the results in the table above show, Paint 234 had clearly the best performance. Paint 237 had a short pot life and only had a good solvent resistance, but the Ford hardness was also good. Paint 252 was somewhat flexible, but could be improved by adding aromatic structures to the resin backbone. Paint 243 containing aromatic mercapto groups was a commendable performance without its short pot life. Finally, the paint 2DN had good properties except that it was slightly sensitive to MEK rub resistance.

Example 7 In this example, the GD of Example 2 was investigated to determine if the aliphatic isocyanate could improve the cure rate.
P was used as a reactive diluent with an aromatic hydroxy functional resin. The following polyol resins were evaluated.

Polyol 274: Tone M-100 homopolymer of Example 5 capped with p-hydroxybenzoic acid.

Polyester Polyol: Aromatic hydroxy terminated polyester of Example 1 of US Pat. No. 4,374,167.

Acrylic polyol: butyl acrylate (4 mol), butyl methacrylate (4 mol), styrene (1 mol), 2-ethylhexyl acrylate (2 mol), glycidyl methacrylate (2 mol), diphenolic acid (2 mol, second reaction) Stage).

These polyol resins and the death module of Example 1
A paint was formulated from N-3390 hardener and various amounts of GDP. The following results were obtained using the above curing conditions (0.9% by volume TEA catalyst) again.

The results in the above table illustrate that the addition of mercapto compounds can increase the cure rate of aliphatic isocyanate / polyol paints while maintaining, if not improving, performance.

Example 8 Two sets of colored paints were subjected to long-term QUV (standard weather resistance test by UV, heat, humidity, and exposure by a weather resistance tester manufactured by Q-Panel).
For evaluation, it was prepared by blending as follows.

The paint was sprayed onto the above-mentioned Bregen vapor catalyst (0.25% by volume).
Dimethyl ethanolamine catalyst) of RIM substrate. Both coatings showed excellent cure response and good gloss. The following optical measurements (Hanta Colorimeter readings) were recorded.

Thus, the yellowing resistance behavior of these coatings was demonstrated.

Example 9 Coating 9 of Example 2 and coating 234 of Example 6 were tested and found to have elongations (when the coating on the substrate broke) of 166% and 4.5%, respectively. However, the average tensile strength of the same coating is 115.5 kg / cm ² and 151.2 kg / cm ² respectively.
It was cm ² .

Example 10 Trimethylolpropane tri (3-mercaptopropionate) (TMP-3MP, 142.9 g), phenyl isocyanate (119 g), methyl isobutyl ketone solvent (112
g), and Amberlyst A-21 catalyst beads (acidic ion exchange resin, 5 g) from this mixture.
The catalyst beads were removed by holding for a time followed by filtration to make the preformed carbamothioate cocatalyst, 4423-195.
No appreciable residual mercaptan or isocyanate was detected.

A coating composition without cocatalyst and with 5% by weight of cocatalyst was added, respectively. Each sample was applied by the Bregen catalyst spraying method described above using 0.6% by volume of dimethylethanolamine catalyst. The paint was formulated with an Isocyanate Index (NCO: OH molar ratio) of 1: 1 and diluted with MIBK solvent to an applied viscosity of 60 cps. The curing response data is shown below.

This data undoubtedly demonstrates the effect of cocatalysts in promoting the hydroxyl / isocyanate reaction.

Example 11 For preformed mercapto / isocyanate or mercapto / thiocyanate compounds, hydroxyl /
The effect of promoting the isocyanate curing reaction was evaluated. The following reagents were used to make the preformed compounds evaluated in this example.

The above compound in methyl isobutyl ketone (MIBK) solvent
Dissolved at 10% solids. 1 of these compounds (cocatalysts)
Tested at concentrations of 5% and 5% by weight.

The various coating compositions tested were applied by the Bregen vapor amine spray method of U.S. Pat. No. 4,517,222 using 0.7% by volume of vaporized dimethyl ethanolamine (DMEOLA). Two sets of samples were cured at room temperature in an indoor environment, and about 12
Baking at 1.1 ° C for 5 minutes. The data to the left of the shaded lines are for ambient temperature samples, while the data to the right of the shaded lines are for post-cure baked samples. Data without hatching are for ambient temperature samples only. The coating composition formulation and the results obtained are shown below.

These results demonstrate that the preformed thiourethane cocatalyst is effective in improving cure of polyol / polyisocyanate coating compositions. Although all compounds were effective in promoting cure, cocatalyst 4541-85-4 appeared to be the most effective of the compounds evaluated.

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Claims (6)

[Claims] 1. A method comprising exposing a coating composition to a vaporized tertiary amine catalyst either as a dew to be applied to a substrate or as a coating applied on a substrate, said coating composition comprising: Wherein the coating composition is cured in the presence of a thiourethane compound formed by the reaction of a mercapto compound and an isocyanate compound, wherein the coating composition comprises a polyol and a multi-isocyanate curing agent. A method for curing coating films. 2. The improved coating composition of claim 1 wherein said coating composition further comprises a mercapto compound which forms said thiourethane compound in situ during the curing of said coating composition. Membrane curing method. 3. The improved method for curing a coating film according to claim 1, wherein the thiourethane compound is preformed and added to the coating composition. 4. The thiourethane compound has the following formula: An improved method for curing a coating film according to claim 1 represented by the following formula. 5. The improved coating film curing method according to claim 1, wherein the mercapto compound is selected from a monomercapto compound, a polymercapto compound and a mixture thereof. 6. The multi-isocyanate curing agent is an aromatic multi-isocyanate, an aliphatic multi-isocyanate or a mixture thereof, and the polyol is an aromatic polyol and a mixture of an aliphatic polyol and an aromatic polyol. Selected Claims No. 1
An improved method for curing a coating film according to the item.