JPH0341113B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to vapor permeation curable coatings, and more particularly to the synthesis and use of polymercapto resins therefor. BACKGROUND OF THE INVENTION Conventional vapor osmotic curable paints are a class of paints formulated from aromatic hydroxy-functional polymers and multi-isocyanate crosslinkers, in which the coating is exposed to a vaporous tertiary amine catalyst. and harden. Curing chambers have been developed to economically and safely contain and handle vaporous tertiary amine catalysts. A typical curing chamber is a substantially empty box through which a conveyor carrying the coated substrates passes, through which a vaporous tertiary amine is transported, usually by an inert gas carrier, to Contact with painted substrates. If a stable one-pack system is required, the use of aromatic hydroxy-functional polymers is recommended. If two-pack formulations are acceptable, then aliphatic hydroxy functional resins can be used.
Multi-isocyanate crosslinkers in conventional vapor permeation curable coatings contain at least some aromatic isocyanate groups to achieve practical cure rates. The need for such conventional vapor-penetration curable paints is
U.S. Patent Application No. 06/06 filed May 30, 1984
This was significantly changed by the vaporous amine catalyst spraying process disclosed by Blegen in No. 615,135. Such vaporous catalyst spraying methods rely on the simultaneous generation of a mist of the coating composition and a carrier gas carrying a catalytic amount of vaporous tertiary amine catalyst. The mist thus generated and the vaporous catalyst amine carrier gas are mixed and directed onto the substrate to form a film thereon. Curing proceeds so rapidly that the use of a curing chamber is not necessary. Additionally, all aliphatic isocyanate hardeners can be utilized in such spraying methods. However, hydroxyl groups on the resin are still required. One drawback to the need for aromatic hydroxyl groups in resins is that such aromaticity imposes inherent constraints on the formulation of high solids coatings. The same applies to the need for aromaticity in multi-isocyanate crosslinkers. Such non-volatile solids content limitations apply even to the vaporous amine catalyst spraying process described above. The present invention overcomes many of the limitations that have been imposed on vapor permeation curable coatings cured in a curing chamber. (Means for solving the problems) The coating composition film curing method according to the present invention includes the following steps:
The method comprises exposing the coating composition to a vaporous tertiary amine catalyst, either as a mist or as a coating.
The coating composition consists of a polymercapto compound and a multi-layer paint composition.
and an isocyanate curing agent. In the case of coatings, the coating composition is cured by exposing the coating of the coating composition to a vaporous tertiary amine catalyst in a curing chamber. Alternatively, a mist of the coating composition can be generated and mixed with a vaporous tertiary amine catalyst, and the mixture can then be applied to a substrate and cured. Other embodiments of the invention include coating compositions 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 small proportion to catalyze or enhance the curing reaction between the polyol resin and the aliphatic isocyanate curing agent. Can be a reactive diluent. Advantages of the present invention include the ability to produce high solids coating compositions with non-volatile solids contents as high as 100%. Another advantage is that a fully aliphatic isocyanate-containing curing agent can be utilized and still achieve rapid curing in the curing chamber. Another advantage is the unusually high gloss that polymercapto-containing vapor permeation cured coatings possess when cured in a curing chamber.
These and other advantages will be readily apparent to those skilled in the art based on the disclosure herein. Effect: The use of polymercapto-functional monomers, oligomers or polymers in vapor-permeation curable coatings can contain aromatic compounds, including that they can be formulated into single-fill systems with storage stability ranging from hours to days. While retaining the advantageous properties achieved in the use of hydroxy-functional compounds, this coating formulation cures rapidly upon exposure to a vaporous tertiary amine catalyst at room temperature. Moreover, several unique advantages are:
This is accomplished through the use of such resinous or non-resinous thiols. One of these advantages is the ability to formulate very high solids coatings, up to 100% non-volatile solids. These high solids contents are due in part to the latitude afforded by the use of thiols to reduce the aromatic content of both the resin and the curing agent. That is, the aromatic group adjacent to the mercapto group is unnecessary for storage stability and for the curability of the coating composition. Aromaticity of the curing agent is also not necessary to achieve rapid room temperature curing in the presence of a vaporous tertiary amine catalyst. It would be appreciated that if conventional curing indoor curing techniques were employed, the aromatic nature of the coating composition would be desirable. Another advantage of being able to formulate reduced aromatic coating compositions is that the flexibility of the cured coating composition can be increased. This is because aromatic groups tend to sterically hinder the polymer and increase its brittleness, making it difficult to achieve highly flexible systems with high extensibility. Of course, previously known vapor penetration curable coating compositions contain at least some aromatic curing agent in order to achieve rapid curing and also retain the benefits of a long pot life of the coating composition. Therefore, the resin contained aromatic hydroxy functionality. The use of polymercapto resins according to the method of the present invention in the formulation of vapor permeation curable coatings results in:
Gives greater flexibility. Monomers, oligomers and polymers containing pendant mercapto or thiol groups are commercially available or can be easily synthesized. For example, mercapto groups may be attached to oligomers or polymers by esterification of free hydroxyl groups of the polymer, such as polyesters, polyacrylates, polyethers, etc., with acids having mercapto end groups, such as 3-mercaptopropionic acid or thiosalicylic acid. be able to. Similarly, epoxy-functional resins can be reacted with acids having mercapto end groups under acidic conditions to promote selective reaction of carboxylic acid groups with epoxy groups. Moreover,
by reaction of a pendant primary or secondary amine group with an acid having a mercapto end group; or
Free isocyanate groups on oligomers or polymers having isocyanate end groups are
Mercapto groups can be introduced into oligomers or polymers by reacting with acid esters having mercapto end groups, which have several pendant mercapto groups. Furthermore, the reaction mechanism for introducing mercapto groups into oligomers or polymers is
It involves conducting a Michael addition reaction between a polymercaptan and a polyolefin.
Yet another synthetic mechanism involves combining an aryl or alkyl halide to introduce a pendant mercapto group into an alkyl or aryl compound.
Including reaction with NaSH. It is even possible to react the Grignard reagent with sulfur to introduce pendant mercapto groups 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 cured coatings. Mercapto groups can be introduced into oligomers or polymers in a number of other ways well known in the art. The mercapto groups are attached pendantly to the oligomer or polymer. For purposes of this application, pendant mercapto groups include terminal mercapto groups. When attached in a pendant shape,
It is meant to attach such a mercapto group to a polymeric chain or to a pendant side chain of a polymer or oligomer. Resinous materials containing pendant mercapto groups should be at least difunctional for crosslinking with curing agents, although higher functionalities may be used. Monofunctional mercapto-containing resinous materials can be used as reactive diluents, as discussed in further detail below. Various polymercaptans suitable for synthesizing the mercapto-functional resinous materials used to form the dye compositions of the present invention include, for example, 1,4-butanedithiol, 2,3-dimercaptopropanol, toluol-3 , 4-dithiol, and furfur, alpha'-dimercapto-p-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, allylmercaptan, 1,6-hexanedithiol, 1,2-ethanedithiol, benzylmercaptan, 1-octanethiol, p-thiocresol, 2,3,
Includes 5,6-tetrafluorothiophenol, cyclohexylmercaptan, methylthioglycolate, mercaptopyridine, dithioerythritol, 6-ethoxy-2-mercaptobenzthiazole, and the like. Other useful mercaptans can be found in the various types of commercially available mercaptans. In fact, any oligomeric, polymeric or resinous compound can be modified to contain pendant mercapto or thiol groups. Typical resinous substances containing mercapto groups include, for example, epoxy and epoxy-modified diglycidyl ethers with a bisphenol A structure, various aliphatic polyethylene or polypropylene glycol (diglycidyl ether) adults, and glycidyl ethers of phenolic resins. can be derived from. Other useful polymers containing pendant mercapto groups are polyamide resins, such as the condensation product of a dimerized fatty acid reacted with a difunctional amine such as ethylenediamine, followed by 3-mercaptopropylenic acid or the like. Includes those reacted with. Furthermore, it is readily possible to modify various acrylic resins and vinyl resins according to the method of the present invention. In this regard, virtually any of the previously known hydroxyl-containing monomers, oligomers, or polymers previously proposed for use in vapor-permeation curable coatings may be suitably modified to be pendant for use in formulating the coating compositions of the present invention. - Can contain a mercapto group. For example, esterification (or transesterification) of such polyols with acids having mercapto end groups can be used to modify such conventional vapor permeable materials for formulation of 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 curable coating compositions that may be modified accordingly. US Patent No.
No. 3,409,579 discloses binder compositions of phenol/aldehyde resins (including resols, novolaks and resitors), which are preferably benzyl ether resins or polyetherphenolic resins. U.S. Pat. No. 3,676,392 discloses resin compositions in organic solvents formed of polyetherphenolic resins or methylol-terminated phenolic (resol) resins. US Patent No.
No. 3,429,848 discloses the addition of silane to compositions such as U.S. Pat. No. 3,409,579. US Pat. No. 3,789,044 discloses hydroxybenzoic acid capped polyepoxy resins. U.S. Patent No. 3,822,226 discloses unsaturated fatty acids,
Curable compositions of phenols reacted with unsaturated substances selected from oils, fatty acid esters, butadiene homopolymers, butadiene copolymers, alcohols and acids are disclosed. U.S. Patent No. 3,836,491
Similar hydroxy-functional polymers (eg, polyesters, acrylics, polyethers, etc.) capped with hydroxybenzoic acid are disclosed. GB 1369351 discloses hydroxy or epoxy compounds capped with diphenolic acid. GB 1351881 modifies polyhydroxy, polyepoxy or polycarboxylic acid resins with reaction products of phenols and aldehydes. US Pat. No. 2,967,117 discloses polyhydroxy polyesters, while US Pat. No. 4,267,239 reacts an alkyd resin with para-hydroxybenzoic acid. U.S. Patent No. 4,298,658 is 2,6-
An alkyd resin modified with dimethylol-p-cresol is proposed. US Pat. Nos. 4,343,839, 4,365,039 and 4,374,167 disclose polyester resin coatings that are particularly compatible with flexible substrates. US Patent No.
No. 4,374,181 discloses resins particularly suited for application in reaction injection molded (RIM) urethane parts. US Pat. No. 4,331,782 discloses hydroxybenzoic acid-epoxy adducts. US Pat. No. 4,343,924 proposes stabilized phenol-functional condensation products of phenol-aldehyde reaction products. US Pat. No. 4,366,193 proposes the use of 1,2-dihydroxybenzene or its derivatives in vapor permeation curable coatings.
U.S. Pat.
Discloses the uniqueness of utilizing vapor permeation curable paints on superficially porous substrates (SMC). Finally, US Pat. No. 4,396,647 discloses the use of 2,3',4-trihydroxydiphenyl. The aromatic hydroxy polymers or resins described above, as well as many other resins, can be suitably modified to contain mercapto groups for use in formulating coating compositions according to the method of the present invention. Is recognized. Finally, the mercapto resin-like materials of the present invention can be utilized to formulate coating compositions that are ideally suited to the Bregen vaporous amine catalyst spraying process cited above. Such vaporous amine catalyzed spraying processes involve cogenerating a mist of a coating composition and a vaporous tertiary amine and mixing the streams for application to a substrate. Although the non-volatile solids content of coating compositions formulated with mercapto resinous materials is increased, it may still be possible to spray coat pigmented coatings containing greater than 80% non-volatile solids. In this respect, the coating composition may be used for viscosity adjustment for application (e.g. spraying etc.) or for any other purpose as may be conventionally necessary, desirable or expedient. It may also contain reactive or volatile solvents for compounding. The multi-isocyanate crosslinker cures the coating by crosslinking the mercapto or thiol groups of the polymer capped with the product adduct under the action of the vaporous tertiary amine. Aromatic isocyanates are preferred to obtain a reasonable pot life and the desired rapid reaction at room temperature in the presence of a vaporous tertiary amine catalyst. For high performance coatings, initial coloring and discoloration due to sunlight can be minimized by including at least a conventional amount of aliphatic isocyanate in the curing agent. Of course, polymeric isocyanates are used to reduce the toxic vapors of isocyanate monomers. Additionally, alcohol-modified and other modified isocyanate compositions (eg, thiocyanates) are useful in the present invention. Multi-layer paint used in the coating composition of the present invention
Isocyanates (i.e. polyisocyanates)
preferably has about 2 to 4 isocyanate groups per molecule. Suitable multi-isocyanates for use in the present invention are, for example, hexamethylene diisocyanate, 4,4'-toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylpolyphenyl isocyanate (polymeric MDI or PAPI ), m- and p-phenylene diisocyanate groups, bitolylene diisocyanate, triphenylmethylene triisocyanate, tris-(4-isocyanate phenyl) thiophosphate, cyclohexane diisocyanate (CHDI), bis-(isocyanate methyl) cyclohexane (H ₆ XDI), dicyclohexylmethane diisocyanate ( _H12 MDI),
Trimethylhexane diisocyanate, dimic acid diisocyanate (DDI) and their dimethyl derivatives, lysine diisocyanate and its methyl ester, isophorone diisocyanate,
Methylcyclohexane diisocyanate, 1,5
- naphthalene diisocyanate, triphenylmethane triisocyanate, xylene diisocyanate and their methyl and hydrogenated derivatives,
Includes polymethylene polyphenyl isocyanate, chlorphenylene-2,4-diisocyanate, and analogs thereof and mixtures thereof. Aromatic and aliphatic polyisocyanate 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 isocyanate equivalents of the multi-isocyanate crosslinker should be greater than about 1:1 and can range up to about 1:2.
If the paint composition is applied with strict intent,
Often this ratio or isocyanate number is specified. As mentioned above, a solvent or vehicle may be included as part of the coating composition. Some aromatic solvent may be necessary, typically it is part of the volatiles contained in commercially available isocyanate polymers, but volatile organic solvents are used to minimize viscosity. may include ketones and esters. Typical volatile organic solvents include, for example,
Includes 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 for polyisocyanate polymers include, for example, toluene, xylene and the like.
The effective non-volatile solids content of the coating composition is increased by the incorporation of relatively volatile or non-volatile (high boiling point) ester plasticizers that are retained for most of the cured coating. It should be noted that this is possible. Such suitable ester plasticizers include, for example, dibutyl phthalate, di(2-ethylhexyl) phthalate (DDP), and the like. The proportion of ester plasticizer should not exceed about 5-10% by weight, otherwise surface mar resistance may be lost. In addition, the coating compositions contain matting pigments and inert fillers, such as, for example, titanium dioxide, zinc oxide, clays such as kaolinite clay, silica, talc, carbon or graphite (for example conductive coatings), etc. can do.
Additionally, the coating composition can contain coloring pigments, anticorrosion pigments, and various agents commonly found in coating compositions. Such additional additives include, for example, surfactants, flow agents or leveling agents, pigment dispersants, and the like. For performance requirements met by this coating composition:
The coating composition, i.e., the polymercapto resin and isocyanate crosslinker, is capable of having a minimum pot life of at least 4 hours in an open container, and typically has a pot life of greater than 8 hours up to 18 hours or more. It should be noted that this is something that can be obtained. Such a long pot life means that there is usually no need to refill containers during shifts in the factory. Furthermore, the pot life of a coating composition in a closed container can exceed one month depending on the formulation of the coating composition. After storage of the coating composition, the stored composition can be reduced to a coating viscosity with a suitable solvent (if necessary) and such composition retains all the good performance properties it originally possessed. hold. Vaporous amine catalysts are tertiary amines, including, for example, tertiary amines having substituents such as alkyls, alkanols, aryls, alicyclics, and mixtures thereof. Moreover, heterocyclic tertiary amines are also suitable for use in the present invention. Representative tertiary amines include, for example, triethylamine,
Dimethylethylamine, trimethylamine, tributylamine, dimethylbenzylamine, dimethylcyclohexylamine, dimethylethanolamine, diethylethanolamine, triethanolamine, pyridine, 4-phenylpropylpyridine, 2,4,6-collidine, quinoline, isoquinoline, N - Ethylmorpholine, triethylenediamine, and their analogs and mixtures thereof. Additionally, the use of amine oxides or quaternary ammonium amines is conceivable, depending on the practical possibility of forming such amines in the vapor phase. A myriad of registered tertiary amine catalysts are currently available and will also function in the process of the present invention. The catalytic activity of tertiary amine catalysts is
“The Activation of I.P.D.I.
of IPDI by Various Accelerator Systems”，
Veba-Chemie AG, Gelsenkircher-Buer,
It should be noted that this can be enhanced by adding complex salts to the coating composition, as reported in the paper West Germany). Thus, the addition of ferric, manganese and aluminum salts to liquid coating compositions may be implemented as an aspect of the present invention. The proportion of vaporous amine catalyst may range above 6%, but generally a percentage of less than 1% by volume is sufficient, for example from about 0.25 to 1% by volume. It should be cautioned that high concentrations of amine catalysts are not recommended in the presence of air or molecular oxygen sources as explosive mixtures will form. The tertiary amine catalyst is in vapor form in an inert carrier gas such as nitrogen or carbon dioxide, or in air, or a mixture thereof. With the selected carrier gas and the specified tertiary amine catalyst, to ensure that the amine catalyst remains in vapor form and does not condense in any path.
It is recognized that certain minimum temperatures and pressures of the blown gas stream must be maintained. Additionally, the ratio of amine to carrier gas may be varied depending on whether a conventional curing chamber is utilized or Bregen's vaporous amine catalyst spraying process is employed. In this regard, suitable curing chambers for use with the coating compositions of the present invention are disclosed in US Pat. No. 4,491,610 and US Pat. No. 4,492,041. However, for example, U.S. Pat.
It should be recognized that other curing chambers such as those disclosed in US Pat. No. 3,931,684 may be utilized. Upon exposure to a vaporous tertiary amine catalyst, the mercapto groups of the resin-like material and the isocyanate groups of the curing agent react to form a hardened network of carbamothioate groups. The reaction proceeds rapidly at room temperature, allowing the cured part to be handled within a short period of time, often on the order of 1 to 5 minutes, after the catalyst has cured. It is a decisive advantage that the coating composition of the present invention possesses such rapid curing ability. In this regard, it is recognized that such rapid curing occurs whether the curing agents are all aliphatic isocyanates, all aromatic isocyanates, or mixtures of aliphatic and aromatic isocyanates. In this regard, the use of a small proportion of a mono- or polyfunctional mercapto compound as a reactive diluent (e.g. up to 20 weight percent) will allow the aliphatic isocyanate groups of the polyol and curing agent to bind together under vapor permeation curing conditions. can significantly accelerate the reaction between The obvious benefit of using mercapto compounds to promote polyol-isocyanate reactions is that the performance properties exhibited by the polyol and curing agent without the addition of mercapto compounds are retained, and in some cases improved performance properties. You can even see it. In addition to forming the carbamothioate group that actually catalyzes the polyol/polyisocyanate reaction in situ (hereinafter referred to as "in-situ formation"), preformed carbamothioate groups (mercapto and isocyanate compounds) (preformed reaction products with) can be incorporated into coating compositions and similar catalytic effects are observed. The use of preformed compounds may not provide the degree of improvement in curing response that would be seen if such groups were formed in situ during curing of the coating composition. Thus, this aspect of the invention includes coating compositions that cure in the presence of compounds containing one or more of the following moieties:

【formula】

[expression] or

[Formula] The compound deriving such a moiety in this preformed embodiment of the invention can be represented as follows.

【formula】

[Formula] Also teeth

[Formula] [In the above formula, R ₁ and R ₂ each represent a monovalent organic group, preferably an alkyl group or an aryl group. ] As illustrated by the data, the preforming embodiment of the present invention does not appear to work to the same extent when aliphatic isocyanates and aliphatic polyols are included in the coating composition. Some aromaticity should therefore be present for the preformed embodiments of the present invention, and it is preferred that such aromaticity be derived from the aromatic isocyanate component of the coating composition. However, in the in-situ preferred embodiment of the present invention, the aromaticity is This is not as critical a factor as in the case of preformed embodiments. 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. Substrates include, for example, metals such as iron, steel, aluminum, copper, galvanized steel, zinc, and the like. Furthermore, this coating composition can be applied to wood, organic fiberboard, RIM, SMC, vinyl, acrylic,
It can be applied to other polymeric or plastic materials, paper, etc. Because the coating composition can be cured at room temperature, the coating composition of the present invention is not subject to any limitations in use due to thermal damage to heat-sensitive substrates. Additionally, the flexibility in the use of the coating compositions of the present invention is further increased since Bregen's vaporous amine catalyst spraying process can be used. (Examples) The following examples illustrate embodiments of the present invention and should not be interpreted as limiting. In this reaction example, all percentages and proportions of coating composition are by weight and all percentages and proportions of vaporous tertiary amine catalyst are by volume, unless otherwise indicated.
In addition, all units are in the metric system, and
All citations referred to herein are incorporated herein by specific reference to the source. Example 1 The vapor permeation curing (VPC) curing response of mercapto groups was evaluated and compared with aliphatic hydroxyl groups on molecules that are structurally identical except for containing -SH or -OH groups. Viscosity and general performance tests were conducted on the following compositions.

[Table] Each coating composition was evaluated by exposing it to 0.9% by volume triethylamine catalyst (TEA) in a curing chamber and the following results were obtained.

【table】

【table】

[Table] After being placed at ambient temperature, the solvent resistance of the coating was determined.
The results listed in the table above demonstrate an 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 two days. Example 2 Various isocyanate curing agents were evaluated with glycol dimercaptopropionate (GDP) in the following coating compositions.

[Table] Paint 2 - Curing agent is Mondur
HC, i.e., schematically, the tetrafunctional reaction product of hexamethylene diisocyanate and toluene diisocyanate (NCO content 11.5%, equivalent weight
365, Cellosolve Acetate/60% solids in xylene, manufactured by Mobay Chemical Corporation). Paint 3 - Hardening agent is trimethylolpropane -
It was m-α, α, α', α'-tetramethylxylene diisocyanate adduct. Paint 4-Hardening agent is Takenate
D-120-N, a trimethylolpropane adduct of hydrogenated xylene diisocyanate (11.0% NCO content, 75% solids in ethyl acetate, manufactured by Takeda Pharmaceutical Company). Coating 5 - The curing agent was methane diisocyanate. Paint 6 - The curing agent is meta-α,α,α′,α′-tetramethylxylene diisocyanate [American Cyanamid Company (American
It was manufactured by Cyanamid Company. Paint 7 - The curing agent is Desmodyur Z-4370, an isocyanate of isophorone diisocyanate (NCO content approximately 12%, equivalent weight 350, solids content 70% in ethylene glycol acetate/xylene (1:1), Mobay Chemical Corp. Made by Chillon). Coating 8 - The hardener was Desmodur N-3390 from Example 1. Paint 9-Hardening agent is Desmodyur KL5-
2550, i.e. aliphatic polyisocyanate (1,
6-Hexamethylene diisocyanate, Mobay
Chemical Corporation). Note (2): Cellosolve acetate is ethylene glycol monoethyl ether acetate [Union
Union Carbide
Corporation)]. Each coating was exposed to a 0.9% by volume triethylamine catalyst in a curing chamber (with the exception of paint 2, which had a 0.5% triethylamine catalyst).
% TEA by volume) and subjected to general performance testing as described in Example 1.

【table】

【table】

[Table] Once again, the combination of excellent stability (pot life) and good curing response of paints formulated with mercapto reactants was illustrated. Also, these paints had extremely high solids content which contributed to their special properties. More importantly, all-aliphatic multi-isocyanate hardeners can be utilized in the formulation of VPC coatings. Example 3 In this series of tests, trimethylolpropane tris(3-mercaptopropionate),
(hereinafter referred to as TMP-3MP) acted as a mercapto-functional compound and was evaluated with various curing agents as in Example 2.

Table: Each paint was cured in a curing chamber with 0.5% by volume triethylamine catalyst for paints 1 and 2, and 0.9% by volume for all other paints, and subjected to the general performance tests described above. It was attached to.

【table】

[Table] The results in the above table show that the properties exhibited by the paint of the present invention, namely, stability, good curing response,
aliphatic isocyanate curing agents may be utilized;
This unique combination has been confirmed once again. The performance of these coatings is commensurate with that of the coatings tested in Example 2, although trifunctional mercaptans were used in this example as opposed to difunctional mercaptans 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 paint 9 of Example 2, paint 5 of Example 3 The paint 6 of Example 2, the paint 6 of Example 3, and the paint 5 of Example 2 are compared. Example 3
The most significant performance improvement in the paints was in MEK friction for paints 4, 5 and 6. Example 4 The mercapto-functional compounds evaluated were dimercapto diethyl ether (DMDE), pentaerythritol tetra(3-mercaptopropionate) (PT-3MP), and dipentaerythritol hexa(3-mercaptopropionate)
(DPH-3MP).

【table】

[Table] Paints 1, 4 and 5 are 0.9% by volume in the curing chamber.
Coatings 2 and 3 were cured by exposure to 0.5% by volume of the same catalyst, 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.

【table】

Table: Once again, the uniqueness of the coating according to the invention is illustrated. The use of aliphatic or mixed aliphatic/aromatic hardeners for paints 1 and 2 or paints 3 and 4 does not appear to appreciably alter performance. Paint 1 (Example 2), Paint 3 using the same curing agent but with a difunctional mercaptan (Example 2), a trifunctional mercaptan (Example 3), and a tetrafunctional mercaptan (Example 4). The same can be said of 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 approximately 776, referred to as PEG776-M);
Polyethylene glycol di(3-mercaptopropionate) (molecular weight approximately 326, referred to as PEG326-M); Rucoflex S-1028-
210 [Difunctional polyester, OH number approx. 210, New York, Hitz virus, Ruco Chemical
Manufactured by Ruco Chemical Co.
Capped mercaptopropionic acid (R
-3MP); polypropylene glycol [Dow P1200, molecular weight approximately 1200, Michigan;
3-mercaptopropionic acid capped (PG-
Tone M-100 homopolymer (polycaprolactone monoacrylate homopolymer, molecular weight approximately 344, manufactured by Union Carbide Corporation, Danbury, Conn.) with 3-mercaptopropionic acid capped (T100-);
3MP); and Tone 200 (difunctional polycaprolactone, OH
Number 215, manufactured by Union Carbide Corporation, Danbury, CT (referred to as T200-3MP).

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

【table】

【table】

[Table] Regarding paints 1 and 2, the lower molecular weight polyether (paint 2) has a longer pot life, better MEK friction resistance, and better MEK friction resistance than the higher molecular weight polyether (paint 1). It had solvent resistance. Regarding paints 3 and 4, the Lucoflex based system (paint 3) showed better pot life, solvent resistance and MEK friction resistance compared to the polypropylene glycol based system (paint 4). . 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.

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

【table】

Table: Paint 234 cured when exposed to 0.5% by volume triethylamine catalyst, while all other paints
Exposure to 0.9% catalyst by volume. The following general performance test results were recorded.

【table】

[Table] As the results in the table above show, paint 234 clearly had the best performance. Paint 237 lacked pot life and had only considerable solvent resistance, but
Sword hardness was also quite good. Paint 252 is
Although it was somewhat flexible, this could be improved by adding an aromatic structure to the resin skeleton. Paint 243, which contains aromatic mercapto groups, would have performed admirably if not for its short pot life. Finally, paint 2DN had good properties, except for being slightly sensitive to NEK abrasion resistance. Example 7 In this example, the GDP of Example 2 was used as a reactive diluent with an aromatic hydroxy-functional resin to see if aliphatic isocyanates could improve cure speed. 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 U.S. Pat. No. 4,374,167. Acrylic polyols: 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) ). Various amounts of these polyol resins and Desmodyur N-3390 curing agent from Example 1 were used.
The paint was mixed with GDP. Cure conditions as described above (0.9% TEA catalyst by volume) were again utilized with the following results.

【table】

【table】

【table】

TABLE The results in the table above demonstrate that the addition of mercapto compounds can increase the cure rate of aliphatic isocyanate/polyol coatings while maintaining, if not improving, performance. Example 8 Two sets of colored paints were formulated and prepared as follows for long-term QUV- (standard weathering test using ultraviolet light, heat, humidity, and exposure using a weathering tester manufactured by Q-Panel Co., Ltd.).

【table】

[Table] Paint was applied using the Bregen vapor catalyst spraying method described above (0.25% by volume dimethylethanolamine catalyst).
was applied to the RIM substrate. Both coatings showed excellent cure response and good gloss. The following optical measurements (Hanta colorimeter readings) were recorded.

Table: The anti-yellowing behavior of these coatings was thus demonstrated. Example 9 Testing of paint 9 of Example 2 and paint 234 of Example 6 (at the time of failure of the coating film on the substrate)
The elongation rates were 166% and 4.5%, respectively. However, the average tensile strength of the same coating is
They were 115.5Kg/cm ² and 151.2Kg/cm ² . Example 10 Trimethylolpropane tri(3-mercaptopropionate) (TMP-3MP, 142.9 g), phenyl isocyanate (119 g), methyl isobutyl ketone solvent (112 g), and Amber-lyst A-21 A preformed carbamothioate cocatalyst, 4423-195, was made from the catalyst beads (acidic ion exchange resin, 5 g) by holding the mixture for 8 hours followed by removal of the catalyst beads by filtration. No appreciable residual mercaptans or isocyanates were detected. Coating compositions without a cocatalyst and with 5% by weight of a cocatalyst were formulated. Each sample was applied using the Bregen catalyst spray method described above using 0.6% by volume dimethylethanolamine catalyst. The paint is based on isocyanate index (NCO:OH).
Molar ratio) 1:1 and apply viscosity with MIBK solvent
Diluted to 60 cps. Cure response data is shown below.

【table】

TABLE This data undoubtedly illustrates the effectiveness of the cocatalyst in promoting the hydroxyl/isocyanate reaction. Example 11 For preformed mercapto/isocyanate or mercapto/thiocyanate compounds:
The effect of accelerating the hydroxyl/isocyanate curing reaction was evaluated. The following reagents were used to make the preformed compounds evaluated in this example.

[Table] The above compounds were dissolved in methyl isobutyl ketone (MIBK) solvent at 10% solid content. 1% and 5% by weight of these compounds (cocatalysts)
tested at a concentration of The various coating compositions tested were
It was applied by the Bregen vapor amine spray method of No. 4517222 using 0.7% by volume of vapor dimethylethanolamine (DMEOLA). Two sets of samples were cured at room temperature in an indoor environment, or at approx.
Baked at 121.1°C for 5 minutes. The data to the left of the diagonal line is for the ambient temperature sample;
Data to the right of the diagonal line is for post-cured baked samples. Data without hatching is for ambient temperature samples only. The formulation of the coating composition and the results obtained are shown below.

【table】

【table】

【table】

【table】

【table】

TABLE These results demonstrate that preformed thiourethane cocatalysts are effective in improving cure of polyol/polyisocyanate coating compositions. All compounds were effective in accelerating curing, but among the compounds evaluated, cocatalyst 4541-85-4
seemed to be the most effective.

Claims (1)

Chlorthiophenol, dimercaptobenzothiazole, 3,4-dimercaptotoluene, allylmercaptan, 1,6-hexanedithiol, benzylmercaptan, 1-octanethiol, p
-thiocresol, 2,3,5,6-tetrafluorothiophenol, cyclohexylmercaptan, methylthioglycolate, mercaptopyridine, dithioerythritol, 6-ethoxy-2-
Claim 1 which is selected from the group consisting of mercaptobenzothiazole and mixtures thereof, and contains a mercapto group derived from a compound selected from the above group. paint. 7 The multi-isocyanate curing agent may be an aliphatic multi-isocyanate curing agent or an aromatic multi-isocyanate curing agent.
A paint according to claim 1 selected from isocyanate curing agents and mixtures thereof.