KR19990051134A - Improved Curing Catalyst for Epoxy Resin Curing - Google Patents

Abstract

The present invention comprises a nucleophilic adduct (1) of an imidazole and an unsaturated compound and an epoxy resin (2) containing one or more imidazole residues per molecule, and 50 equivalent% of the imidazole residue in the adduct. It relates to a curable formulation characterized by less than being neutralized with an acid. The adduct acts as a curing catalyst in the hot or cold curing process. The formulation is prepared and applied to the coating as a powder paint or laminated as a matrix resin. It is used in solvent or liquid systems.

Description

Improved Curing Catalyst for Epoxy Resin Curing

The present invention relates to the field of catalysts useful in curing catalysts for epoxy resins, in particular powder formulations.

It is well known to apply a powder containing an epoxy resin, a curing catalyst and an optional curing agent to a substrate for coating. Generally, the substrate is heated to add powder in a hot state, or the powder is added to a cold substrate and the substrate is then heated. In either case, the heated powder melts and flows to coat the substrate and then harden. Appropriate methods in this regard are described in Kaufman, U.S. Patent 4,358,571 (November 9, 1982), Column 5, lines 5 to 49; Lee & Neville, Handbook of Epoxy Resins, Pages 20-15 to 20-20 (McGraw-Hill Book Co. 1967); and Tess, "Epoxy Resin Coatings," Epoxy Resins (2nd Ed.), Pages 772 to 778 (Marcel Dekker Inc. 1988). For example, paint is applied to a metal substrate using an electrostatic sprayer or fluidized bed and the substrate is heated to 140-240 ° C.

Many curing catalysts are known for curing both epoxy powder coatings and solvent type coatings. Examples of suitable catalysts include tertiary amines and quaternary ammonium, tertiary phosphines and quaternary phosphoniums. Known potential catalysts contain salts with conjugates of almonium or phosphonium moieties and weak nucleophilic acids such as boric acid or fluoroboric acid. Examples of suitable and potential catalysts include lower alkyl (C ₁ -C ₆ ) -triphenyl-phosphonium halides and Pham et al., US Patent 5,202,407 (January 24, 1992); Bertram et al., US Patent 4,725,652 (March 4, 1987); Bertram et al., EPO Patnet Publication 0 328 020 A3 (August 16, 1989); Muskopf et al., US Patent 5,140,079) (August 18, 1992); Gan et al., US Patent 5,308,895 (May 3, 1994); And Bertram et al., US Patent 4,169,473 (November 8, 1992). Kaufman et al., US Pat. No. 4,358,571 (November 9, 1982) described the reaction of imidazoles or substituted imidazoles with acrylate esters, epoxy resins or isocyanates and then neutralizing the imidazoles with fatty acids or dicarboxylic acids. To teach you how to make an adjunct. These adducts are used as curing catalysts to cure epoxy resins at 132 ° C (270 ° F).

See, Burba et al., U.S. Patent 5,175,219 (December 29, 1992) discloses (1) reacting an imidazole compound with an epoxy resin to make an adduct; (2) It teaches to react hydrogenation of the amine hydrogen atom in an adduct by making an adduct react with acrylic acid or its derivative (s). The resulting adduct reacts with the epoxy resin and cures at 120 ° C.

In recent years, powder coatings have been applied to substrates of new materials that cannot withstand high temperatures such as wood and plastic. In this case, general curing agents and curing catalysts are not suitable because they are cured at too high a temperature. What is needed at this time is a curable epoxy formulation that does not cure with the epoxy resin at ambient temperature, but forms a thermosetting material that is cured at a temperature that does not damage the temperature sensitive substrate by melt flow, solidification and curing with the epoxy resin.

It is also desirable to cure the solvent type epoxy formulation at temperatures below the normal cure temperature in order to protect the substrate and reduce the time and cost of heating the formulation to very high temperatures. What is needed at this time are curing catalysts and curable epoxy formulations which are stable to ambient temperatures and which cure rapidly at temperatures below the general epoxy curing temperature to form excellent cured thermosetting materials.

A first aspect of the invention provides a nucleophilic step of reacting an imidazole with an unsaturated compound containing at least one activating double bond to form a nucleophilic adduct containing one or more imidazole moieties per molecule (1). (2) preparing a formulation containing an adduct and an epoxy resin, wherein less than 50 equivalent% of the imidazole residue in the nucleophilic adduct is neutralized with an acid prior to step (2). It provides a manufacturing method.

A second aspect of the invention provides a nucleophilic adduct (1) of an imidazole and an unsaturated compound containing at least one activated double bond (which contains at least one imidazole moiety per molecule) and an epoxy resin (2) In a proportion of 0.02 to 10 equivalents of nucleophilic adduct per equivalent of epoxy resin, and less than 50 equivalent% of imidazole moiety in the adduct is neutralized with acid.

A third aspect of the invention relates to a process of curing a formulation, wherein said formulation is heated to a curing temperature and said curing temperature is 130 ° C. or less.

A fourth aspect of the present invention contains a nucleophilic adduct (1) of an imidazole and an unsaturated compound and an epoxy resin (2), wherein the nucleophilic adduct is present in a catalytic amount (a), and the formulation contains a curing agent for an epoxy resin. It further relates to a curable formulation characterized by containing (b).

The present invention also relates to the use of curable compositions for making coatings, laminates or other constituents or moldings, as a catalyst for nucleophilic adducts, and to articles made thereby.

The adduct promotes epoxy-epoxy curing reactions and branching reactions. The formulations of the present invention are cured at temperatures above about 130 ° C. to provide cured paints having fewer bubbles than similar paints using conventional curing catalysts. In addition, the formulations described in the second aspect of the present invention are cured at temperatures below 130 ° C. to form stable powder coating formulations that provide low temperature powder coatings for temperature sensitive applications.

The present invention uses nucleophilic adducts made by reacting imidazole with an unsaturated compound comprising at least one double bond that is activated by an adjacent electron withdrawing group. For this purpose, the "nucleophilic addition reaction" is described in J. March, Advanced Organic Chemistry, 4th Ed. at pages 741 to 743 (1992).

Unsaturated compounds contain one or more activating double bond residues (Q) per molecule. The activating double bond residue (Q) is preferably linked to a common central residue (A). Unsaturated compounds are represented by Formula 1:

A- (Q) _n

In Chemical Formula 1,

(A) is the central residue defined below,

Each Q is an activating double bond residue,

n represents the number of unsaturated residues attached to the central residue.

The activating double bond residue (Q) contains an aliphatic carbon-carbon double bond adjacent to the activating electron withdrawing group. Examples of stable electron withdrawing groups are aldehyde, ketone, ester, amide, nitrile, nitric acid and sulfonic acid residues. Preferred stabilizing double bond residues (Q) are represented by formulas (2) to (c):

In Chemical Formulas 2a to 2c,

Each R ¹ is independently a linking linkage of a hydrogen or aliphatic moiety, an aromatic moiety, or an activating double bond moiety with an adjacent monomer.

More preferably, each R ¹ is hydrogen or alkyl, most preferably hydrogen or methyl. Each R ¹ should be chosen so as not to inhibit the nucleophilic addition reaction due to steric hindrance. R ¹ contains 12 carbon atoms, more preferably 6 carbon atoms, most preferably 4 carbon atoms.

Each activated double bond residue (Q) preferably comprises an ester residue as shown in formula (2), more preferably an ester residue of acrylic acid or methacrylic acid.

The central moiety (A) is a monomer or oligomer or a polymer containing several monomers. The choice of central moiety is not limited so long as it does not inhibit the synthesis or the use of adducts. For example, the central moiety contains one or more selected from the following: alkyl moieties, aryl rings, ether linkages, ester linkages, aliphatic or phenol hydroxyl groups, glycidyl ether and / or ester moieties, acid residues or halogens. And it is preferable that it does not contain the residue which reacts with an epoxy resin and hardens | cures or accelerates hardening reaction, such as an amine residue, a carboxylic acid, an halide or anhydride of an acid, a thiol group, or a hydroxyl group. The number average molecular weight of the central moiety is chosen to provide an adduct having the desired softening point. The number average molecular weight is preferably about 5,000 or less, more preferably about 3,000 or less. It is preferably at least about 200.

Unsaturated compounds preferably have an average of at least 0.5, more preferably at least 1.0 and most preferably at least 1.5 active double bond residues per molecule. The maximum number of activating double bond residues per molecule is not limited but in most cases is preferably about 10 or less, more preferably about 6 or less and most preferably about 4 or less. Examples of suitable unsaturated compounds include polyacrylates and polymethacrylates, unsaturated polyesters and vinyl ester resins. In addition, there are alkyl, aryl and alkali acrylates.

It is preferable that an unsaturated compound is vinyl ester resin. Vinyl ester resins are the reaction products of epoxy resins and unsaturated acids. The epoxy resin is preferably poly (glycidyl ether), more preferably diglycidyl ether of diphenol. It is preferable that unsaturated acid is acrylic acid or methacrylic acid. The reaction takes place in the presence of a catalyst such as 2,4,6-tri (dimethylaminoethyl) -phenol. Suitable resins and methods for making them are described in Messick, U.S. Patent 4,407,991 (October 4, 1983); Wykowski, EPO Publication 0 436 921 A1 (July 17, 1991). Vinyl ester resins contain epoxy moieties that do not react selectively. The equivalent ratio of vinyl ester resin and epoxy moiety is preferably 1: 1 or more, more preferably 3: 1 or more, more preferably 10: 1 or more, and most preferably 20: 1 or more.

Unsaturated compounds react with imidazoles to form nucleophilic adducts. Imidazole is not limited as long as the following conditions are met:

(1) imidazole reacts with an unsaturated compound by a nucleophilic reaction to form an adduct;

(2) The adduct promotes the curing reaction of the epoxy resin by reaction with epoxy-epoxy curing or curing agent.

The imidazole is preferably of formula 3:

In Chemical Formula 3,

Each R ² is independently a hydrogen atom, an aliphatic residue or an aromatic residue,

Each R ³ is an aliphatic amino group such as a hydrogen atom or a 3-aminopropyl group.

R ² is preferably hydrogen or alkyl. Each of R ² and R ³ preferably has about 12 carbon atoms, more preferably about 6 carbon atoms and most preferably about 4 carbon atoms. Two R ² residues adjacent to a carbon atom may be optionally linked to each other to form a ring structure. Most preferably R ³ is hydrogen. Suitable imidazoles include imidazole, 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole and N- (3-aminopropyl) imidazole.

The ratio of imidazole and unsaturated compounds should be such that the concentration of unreacted free imidazole in the adduct can be minimized. The reaction mixture contains a stoichiometric excess of imidazole, but preferably contains up to about 1 mole of imidazole compound per equivalent of activating double bond residue, and most preferably up to about 0.95 mole of imidazole compound. do. The minimum concentration of imidazole in the reaction mixture is controlled by the constant concentration of imidazole in the finished adduct. The reaction mixture preferably contains at least about 0.5 moles of imidazole compound per equivalent of activating double bond residue, and more preferably at least about 0.75 moles of imidazole compound.

The reaction temperature is preferably about 50 ° C. or higher, more preferably about 100 ° C. or higher, most preferably about 120 ° C. or higher. About 160 degrees C or less is preferable, and it is more preferable that it is about 150 degrees C or less.

The reaction is preferably carried out in the presence of a polymer reaction inhibitor such as hydroquinone or hydroquinone monomethyl ether to prevent the unsaturated resin from colliding. Some solutions are especially sensitive to gel formation and may require attention. Imideazoles with steric hindrances, such as 2-ethyl-4-methylimidazole, react slowly and require additional stabilizers such as hydroquinone to give sufficient time for the reaction.

The resulting adduct preferably contains the β-imidazole residues of formula 4a, more preferably of formula 4b:

In Chemical Formulas 4a and 4b,

Z is an electron withdrawing group as defined above,

R ¹ and R ² are as defined above,

Each amidazole is linked to a central moiety as previously described.

The preferred number of β-imidazole residues in the adduct depends on the intended use of the adduct but is equal to the number of activating double bond residues in the unsaturated ester compound.

It is preferred that the adduct has Formula 1, wherein at least some Q is a β-imidazole residue and the remaining Q is an activating double bond residue. The equivalent ratio of β-imidazole residues and activating double bond residues is preferably at least 1: 1, more preferably at least 2: 1, most preferably at least 3: 1. All activating double bond residues are converted to β-imidazole residues, but usually the equivalent ratio does not exceed 20: 1 to minimize free imidazole in the adduct. Adducts optionally include reaction products in which imidazole has reacted with an epoxy moiety or other reactor in an unsaturated compound.

The softening point of the adduct should be high enough that the adduct becomes solid at normal storage temperatures and low enough that the adduct softens and solidifies with the powdery epoxy resin at a constant reaction temperature. The Mettler softening point of the adduct measured by the test in the examples is preferably about 50 ° C. or more, more preferably about 60 ° C. or more, most preferably about 80 ° C. or more. Preferably it is 130 degrees C or less, More preferably, it is 100 degrees C or less.

The average molecular weight of the adduct is preferably about 400 or more, more preferably 500 or more, preferably about 1,500 or less, and more preferably about 1,100 or less. The weight average molecular weight of the adduct is preferably about 400 or more, more preferably 500 or more, preferably about 2,500 or less, and more preferably about 1,200 or less.

The melt viscosity of the adduct (measured at 150 ° C. using an ICI Cone and Plate Viscometer in the form of a C cone) is preferably at least about 90 mPa · s, more preferably at least about 140 mPa · s, preferably about 2,000 mPa · s or less, More preferably, it is about 1,500 mPa * s or less.

Ideally, the adduct contains no unbound imidazole that does not react with the unsaturated compound (0% by weight). Up to about 50% by weight of the imidazole is unbound imidazole, more preferably up to about 30% by weight and most preferably up to about 20% by weight is unbound amidazole. The minimum percentage of unbound amidazole is limited by conditions such as steric hindrance but is usually at least 1% by weight.

In the prior art, imidazole moieties are neutralized with organic acids before they form part of the epoxy formulation. In the present invention, at least a substantial residue of the imidazole moiety should not be hydrogenated (neutralized). Preferably, at least about 50 mole percent of the imidazole moieties are not hydrogenated, more preferably at least about 75 mole percent, even more preferably at least about 90 mole percent, most preferably at least about 95 mole percent It is not hydrogenated. As much as possible, 100% should not be hydrogenated. Unhydrogenated imidazole residues must be present in the free state.

The formulation of the present invention also contains an epoxy resin. The epoxy resin is preferably a glycidyl ether or ester compound, more preferably a glycidyl ether compound, most preferably a diglycidyl ether of diphenol, such as diphenol A and F of diphenol. The epoxy resin is preferably in a solid state at about 25 ° C.

The epoxy equivalent (EEW) is preferably at least about 100, more preferably at least about 200 and most preferably at least about 500. The maximum EEW is not limited but is preferably about 2,500 or less, more preferably about 2,000 or less, most preferably about 1,500 or less. The Mettler softening point of the epoxy is preferably about 50 ° C. or higher, more preferably about 60 ° C. or higher, most preferably about 65 ° C. or higher. The Metter softening point of the epoxy is preferably less than about 130 ° C, more preferably less than about 100 ° C.

Suitable epoxy resins include epoxy powder coating resins, epoxy novolak resins, high and medium molecular weight solution epoxy resins, MDI-modified epoxy resins, glycidyl (meth) acrylic acid polymers or copolymers, liquid epoxy resins and mixtures thereof There is this. Epoxy resins useful in the present invention are diphenol A and diphenol F, tetrabromodiphenol A. Other methods can be understood by those skilled in the art (Lee & Neville, Handbook of Epoxy Resins, Pages 2-1 to 3-24 (McGraw-Hill Book Co. 1967)). As in many literatures. Epoxy resins are also epoxy functional oxazolidone containing the power generation products of liquid epoxy resins and copolymers described in tetrabromodiphenol A or US Pat. No. 5,112,932.

The appropriate ratio of adducts to epoxy resins depends on the content and use of the formulation.

When the adduct promotes curing without separating the curing agent and the crosslinking agent, the equivalent ratio is preferably about 0.02 equivalents or more, more preferably about 0.05 equivalents, most preferably about 0.2 equivalents to 1 equivalent of the epoxy resin. More than equivalent The maximum concentration is preferably about 10 equivalents or less of the adduct relative to 1 equivalent of epoxy resin, more preferably about 5 equivalents or less, even more preferably about 2 equivalents or less, and most preferably about 1 equivalent or less. The weight ratio of the epoxy resin and the adduct is preferably 1:10 or more, more preferably 1: 1 or more, most preferably 2: 1 or more. The weight ratio of the epoxy resin and the adduct is preferably 10: 1 or less, more preferably 5: 1 or less, and most preferably 3: 1 or less.

When the formulation contains a curing agent and is cured at elevated temperatures, it is desirable that a very small amount of adduct occur. The equivalent ratio is preferably at least about 5 milliliters (meq) of adducts relative to 1 equivalent of the epoxy resin, more preferably at least about 20 milliequivalents, most preferably at least about 80 milliequivalents. The maximum concentration is preferably about 200 milliliters or less of the adduct with respect to 1 equivalent of epoxy resin, more preferably about 150 milliliters or less, even more preferably about 100 milliliters or less, and most preferably about 50 milliliters or less. to be. The weight ratio of the epoxy resin and the adduct is preferably 1: 100 or more, more preferably 3: 100 or more, most preferably 5: 100 or more. The weight ratio of the epoxy resin and the adduct is preferably 15: 100 or less, more preferably 10: 100 or less, most preferably 5: 100 or less.

Curing agents used in such formulations will depend upon the intended use of the formulation, but will be understood by those of ordinary skill in the art. Several curing agents are described in Lee & Neville, supra, Page 20-11; Tess, supra, Pages 776-778. Suitable curing agents include dicyandiamides and other amines and polyhydric anhydrides such as amides, polyhydrogenated phenols, and styrene malic anhydride copolymers. Although the appropriate ratio of a hardening | curing agent and an epoxy resin changes with the kind of hardening | curing agent, and the purpose of use of resin, normally an equivalent ratio becomes like this. Preferably it is 0.1: 1-10: 1, More preferably, it is 0.2: 1-2: 1.

Formulations containing sufficient adducts to promote epoxy-epoxy curing reactions further comprise a curing agent. The equivalent ratio of adducts to the curing agent is preferably 25:75 or more, more preferably 50:50 or more, even more preferably 75:25 or more, most preferably 90:10 or more.

The formulation optionally contains a solvent, with powder coating formulations being preferred. The solvent should be an organic solvent. As a suitable organic solvent, a well-known thing can be purchased and used. Suitable solvents include xylene, glycol ethers, ketones, toluene, alcohols and dimethylformamide. The solid concentration in the solvent depends on the viscosity, the price and the need to recover the solvent from the eluate, but is preferably 20 to 80% by weight, more preferably 40 to 60% by weight.

The formulations optionally contain other additives useful for the purpose of use. For example, paint formulations optionally contain stabilizers, surfactants, fluid modifiers, fillers, pigments, and mattes. The stack and components that make up the formulation optionally contain stabilizers, fillers, fluid modifiers, and short fibers. The concentration of the additives excluding the pigments, fillers and short fibers in the formulation is preferably about 5% by weight or less, more preferably about 3% by weight or less. The concentration of short fibers, fillers and pigments is preferably about 80% by weight or less, more preferably about 50% by weight or less.

Formulations that are cured by an epoxy-epoxy homopolymerization reaction are preferably cured at a temperature of at least about 80 ° C., more preferably at a temperature of at least about 90 ° C., most preferably at a temperature of at least about 100 ° C. It is preferably cured at a temperature of 130 ° C or lower, more preferably 120 ° C or lower, and most preferably about 110 ° C or lower. However, it can be used at temperatures above 200 ° C.

Formulations containing small amounts of adducts and special curing agents are preferably cured at temperatures of at least about 120 ° C., more preferably at least about 130 ° C. and most preferably at least about 150 ° C. The maximum curing temperature depends on the intended use, but is preferably about 250 ° C. or less, more preferably about 220 ° C. or less.

The formulations of the present invention are used in general epoxy applications such as paints, laminations and molding. For example:

(a) Solution Paint Formulations:

(1) apply | coated to a board | substrate by well-known means, such as spraying, combing, rolling, dipping, electroprecipitation,

(2) It is hardened by heating to a suitable hardening temperature.

(b) powder coating formulation:

(1) heat the substrate to the appropriate curing temperature of the formulation,

(2) The formulation is applied by known means such as an electrospray or fluidized bed.

Also,

(1) the powder is applied to a cold substrate by an electrical coating method,

(2) The powder and the substrate are applied by heating to the temperature at which the powder flows and hardens.

(c) Preparation of Laminates:

(1) the formulation is incorporated into a fibrous substrate and then heated to form a prepreg,

(2) Compress two or more layers of prepreg at a suitable temperature to cure the formulation.

(d) Preparation of moldings:

(1) optionally injecting the formulation into a mold having a fibrous substrate,

(2) The formulation is heated to cure.

Automotive parts such as leaf springs can be made into the formulations of the present invention.

The catalyst of the present invention may be used in electrical laminates in the form of powder paints or solvents, as described in US Pat. No. 5,112,932.

Working Example

The following examples are for illustrative purposes only and should not limit the specification or claims of the present invention.

Preparation of adducts.

The specific reactants and the properties of the adducts for making the adducts of the present invention are shown in Table I. The adducts are prepared by the following general method:

(1) Optionally, an epoxy resin is made. DER ^* 330 (trade name of Dow Chemical) The liquid epoxy resin is reacted with diphenyl A at a temperature of about 140 ° C. in a nitrogen atmosphere in the presence of a phosphonium catalyst. The amount of each reactant and the EEW of the resulting advanced resin are shown in Table 1 (in Table 1, unless otherwise noted, the amount of reactant is in weight parts (pbw)).

(2) A vinyl ester resin is made. A sample of the resin advanced in step (1) or the sample of the DER ^* 330 liquid epoxy resin is heated to 80 to 100 ° C. to form bubbles by a constant air flow in the resin. About 500 ppm hydroquinone is added as inhibitor and acrylic acid or methacrylic acid is added. Add 750 ppm ANCAMINE K54 catalyst and raise the temperature to about 120 ° C. If the residual epoxy concentration is 7 or 8%, add 750 ppm ANCAMINE K54 catalyst. Once the remaining epoxy reaches the concentrations in Table 1, the reaction is stopped and the temperature is lowered. After reducing the air flow, the vinyl ester resin is purged with nitrogen. The amount of reactants and the amount of residual epoxy in the vinyl ester resin are shown in Table 1.

(3) The imidazole adduct of vinyl ester resin is formed. The imidazole of Table 1 is added at about 15 minute intervals by dividing into several residues. The temperature is slowly increased to 140 ° C. over 15 minutes and the mixture is allowed to react at 140 ° C. for 60 minutes. The product is recovered and cooled. Residual imidazole in the adduct is determined by HPLC.

(4) METTLER softening point is measured by the following method according to Method RPM-108C of The Dow Chemical Company as a modified form of ASTM D 3104. In PRM-108C, the softening point represents the temperature at which the epoxy resin suspended in a cylindrical cup with a 6.35 mm diameter hole at the bottom flows 19 mm apart when heated at linear speed in air.

The sample is ground to a size of 5 mm or less. A sample cup with a 6.35 mm hole in the bottom is placed in an aluminum foil of a hot plate at 150 ° C. (for low molecular weight samples) or 200 ° C. (for high molecular weight samples). The granulated sample in the cup is added until it is filled with bubble-free molten resin. After the cup and foil are removed from the plate and cooled down, the foil is stripped off and excess resin is removed from the outer residues of the cup.

The cup is placed in a Model FP5 / 53 softening point measuring instrument from Mettler Instrument Co. The apparatus includes a furnace and light beams that are interrupted when the sample overflows the cup. The temperature of the furnace is set to 20 ° C. which is less than or equal to the expected melting point of the sample, and the sample is left for 30 seconds or more. The temperature is increased by 2 ° C. per minute until the droplets formed below the hole burst the light beam.

(5) Melt viscosity is measured using an ICI Cone and Plate viscometer with a C cone at about 150 ° C. Average molecular weight is measured using gas phase chromatography. The properties of the reactants and adducts are shown in Table 1.

In Table 1, "Im" represents imidazole, "2-MI" is 2-methylimidazole, "2-PhI" is 2-phenylimidazole, "2E4MI" is 2-ethyl-4-methyl Imidazole.

Adjunct One 2 3 4 5 6 Liquid epoxy resin (pbw) 559 539 48.94 55.10 46.5 48.46 Bisphenol A (pbw) - 57.8 - - - 5.2 Epoxy equivalent weight 180 240 180 180 180 240 Methacrylic acid (pbw) - 209.7 22.82 21.17 - - Acrylic acid (pbw) 120 - - - 18.27 15.78 Epoxy Residual Rate (%) 0.6 1.0 1.0 3.6 <1 1.5 Imidazole selection 2-MI 2-MI 2E4MI 2-MI 2-Phr 2-Phr Imidazole amount (pbw) 231 193.4 28.23 23.73 35.27 30.56 Imidazole Retention Rate (%) 1.2 5.7 16.3 5.9 6.1 6.2 Softening point (℃) 78 71.9 65.8 76.9 82.1 89.4 Melt Viscosity (mPas, 150 ° C) 370 190 110 360 270 600 M _n - 726 704 658 612 516 M _w - 908 777 742 878 1070 M _z - 1177 878 846 1101 1857 Multivariance - 1.25 1.10 1.13 1.43 2.07

Adjunct 7 8 9 10 11 12 Liquid epoxy resin (pbw) 54.97 52.77 55.21 55.00 56.89 539.1 Bisphenol A (pbw) - - 11.25 - 11.59 - Epoxy equivalent weight 180 180 320 180 320 180 Methacrylic acid (pbw) 25.63 24.61 17.59 - - 235.8 Acrylic acid (pbw) - - - 21.57 15.10 - Epoxy Residual Rate (%) 1.0 1.0 1.17 0.95 0.85 1.46 Imidazole selection Im 2-MI 2-MI 2-MI 2-MI 2-MI Imidazole amount (pbw) 19.4 22.62 15.95 23.43 16.42 225.1 Imidazole Retention Rate (%) 4.6 4.7 6.1 1.2 0.6 4.1 Softening point (℃) 62.8 69.3 84.2 77.9 92.6 72 Melt Viscosity (mPas, 150 ° C) 160 140 680 370 1520 1400 ^* M _n 576 529 1060 790 1139 - M _w 639 579 1716 972 1920 - M _z 699 625 2675 1284 3088 - Multivariance 1.11 1.09 1.62 1.23 1.69 -

^* Measured at 120 ° C.

Example 1 -Lamination

Adduct 12 is dissolved in methylethyl ketone at 65% solids concentration. A mixture of 10 g of adduct solution and 125 g of DER ^* 691 A80 epoxy resin solution was immersed in a square weave E glass 7628 (woven E glass 7628 supplied from Inter Glass) of 15 cm x 15 cm. The soaked sheet is heated in an warm air circulation oven at 80 ° C. for 4 minutes to evaporate the solvent. The resulting prepreg contains 60 to 65% resin.

Five pieces of prepreg were sandwiched between two copper foil plates and pressed at 110 ° C. for 20 minutes at a pressure of 0.2 bar (24 MPa). The glass transition temperature of the resulting laminate is 69 ° C.

The same experiment is repeated with 12 g of adduct solution. The glass transition temperature of the resulting laminate is about 99 ° C.

Both appearance of the laminate was excellent.

Examples 2 to 16 -powder coating

Epoxy Resin A is made as follows: First, 6,830 g of DER ^* 330 liquid epoxy resin and 3170 g of ER grade diphenyl A are stirred with 500 ppm of phosphonium catalyst at 100 ° C. in a nitrogen atmosphere, and then the mixture is brought to 140 ° C. Heat. Thereafter, the reaction was carried out at 140 ° C. for about 2 hours until the viscosity of the resin became about 5,000 mPa · s at 120 ° C. The methyl ester of p-toluenesulfonic acid is added to quench the catalyst, stir for 30 minutes, then cool and solidify. The objective EEW of the resin is about 1,000.

Immediately after the methyl ester of p-toluenesulfonic acid was added, Epoxy Resin B was prepared in the same manner, except that 6.6% by weight of DEN ^* 438 (trade name of Dow Chemical Company) epoxy novolac resin was added to the reaction mixture.

Two 70 g samples of DEH ^* 85 (Dow Chemical Company's tradename) phenol curing agent are melted at 140 ° C. in a nitrogen atmosphere. 30 g of adduct 1 is mixed with a first sample (curing agent A), and 30 g of adduct 2 is mixed with a second sample (curing agent B). The mixture is stirred for 15 minutes and then cooled to room temperature.

The epoxy resins, hardeners and additives shown in Table 2 are mixed at 420 rpm for 2 minutes in an experimental mixer. The mixture is melt extruded at 65 ° C. at 300 rpm in a double screw extruder and the extrudate is cooled, cut and ground to a powder. The powder is applied to the steel panel using an electric sprayer and the panel is cured for 20 minutes at 110 ° C., 120 ° C., 130 ° C. in an oven. Inspect the paint as follows:

Flow-visually inspect and compare to hot powder-coated samples. The result is 0 = poor and 4 = excellent.

Flexibility—Erichsen indentation test.

Impact Resistance—Test the ASTM D 2794-84 by adding 4 lb (1.8 kg) to an area 1/2 inch (1.25 cm) in diameter. Test measurements are expressed in in-lb (N-m) forces that can be applied without damage.

Check the glossiness—DIN 55 990 at 20 degrees of reflection.

All tests are repeated for age-cured powder at 35 ° C. for 6 days. The results are shown in Table 2.

Example 2 3 4 5 6 7 8 9 10 Epoxy Resin A (pvw) 532.8 532.8 532.8 532.8 532.8 532.8 - - - Epoxy Resin B (pbw) - - - - - - 461.3 461.3 461.3 Curing Agent A (pbw) 59.2 59.2 59.2 59.2 59.2 59.2 - - - Curing Agent B (pbw) - - - - - - 80 80 80 MODAFLOW MFIII (pbw) 8.0 8.0 8.0 8.0 8.0 8.0 8.1 8.1 8.1 Titanium dioxide (pvw) 400 400 400 400 400 400 405.4 405.4 405.4 Aging Hardening (Day) 0 0 0 6 6 6 0 0 0 Application temperature (℃) 110 120 130 110 120 130 110 120 130 Flow rate 2 2.5 3 1.5 2.5 3 3 3.5 4 Erichsen indentation (mm) - 8.3 8.9 - 8.0 8.3 - 8 7 Impact Resistance lbs (N-m) - 160 (18.1) 160 (18.1) - 160 (18.1) 160 (18.1) - 140 (15.8) 160 (18.1) Glossiness (%) - 101 100 - 96 98 - 92 93

Example 11 12 13 14 15 16 Epoxy Resin A (pvw) - - - - - - Epoxy Resin B (pbw) 461.3 461.3 461.3 461.3 461.3 461.3 Curing Agent A (pbw) - - - - - - Curing Agent B (pbw) 80 80 80 80 80 80 MODAFLOW MFIII (pbw) 8.1 8.1 8.1 8.1 8.1 8.1 Titanium dioxide (pvw) 405.4 405.4 405.4 405.4 405.4 405.4 Aging Hardening (Day) 7 7 7 14 14 14 Application temperature (℃) 110 120 130 110 120 130 Flow rate 2 3 3 One 2 3 Erichsen indentation (mm) - - - - 6.3 7.4 Impact Resistance lbs (N-m) - - - - 160 (18.1) 160 (18.1) Glossiness (%) - 92 93 - 90 93

Example 17

A dimethanolamine modified phenol curing agent is prepared as follows: (1) 32.8 parts by weight of liquid epoxy and 62.7 parts by weight of diphenol A are mixed at 100 ° C. in a nitrogen atmosphere, and (2) 4.5 parts of diethanolamine melted at 50 ° C. (3) When the heat of release reached 180 ° C, it was cooled to 150 ° C and left for 30 minutes.

90 parts by weight of the adduct made in Example 1 was mixed with 10 parts by weight of a phenol novolak resin having a hydroxyl group having an equivalent of about 104 at 140 ° C. for 15 minutes in a nitrogen atmosphere. The METTLER softening point of the resulting curing agent composition is about 83 ° C. and the melt viscosity is 3,840 mPa · s at 120 ° C.

A powder coating formulation is prepared according to the method of claim 2. The composition diethanolamine modified phenolic curing agent 10.9 parts by weight of additional curing agent composition containing water 3.5 parts by weight of DER ^* 672U and the epoxy resin 24.9 parts by weight, DER ^* 642U epoxy resin, 30.7 parts by weight of 5 titanium dioxide By weight, 22 parts by weight of BaSO ₄ , 2 parts by weight of mica, and 1 part by weight of MODAFLOW MFIII fluid variant. The formulation is added to a 6 mm steel panel preheated to 245 ° C. using an electric sprayer. The paint is cured at 245 ° C. for 2.5 minutes. The powder is also applied to a glass plate manually preheated to 235 ° C. and cured for 2 minutes. The plate is observed under a microscope, but no bubbles are visible.

Example 18

The adduct 8 was melt mixed with the phenol novolac resin having about 104 equivalents of hydroxyl groups for 30 minutes at 140 ° C. by the method of Example 17. The weight ratio of adduct to novolak resin is 90:10. After mixing, the softening point of the mixture was 86.7 ° C., and the melt viscosity was 440 mPa · s at 150 ° C. and 3360 mPa · s at 120 ° C.

636.8 parts by weight of DER ^* 661E epoxy resin;

44.2 parts by weight of the mixture;

KRONOS 2310 [selling Kronos Co.] 300 parts by weight of titanium dioxide and

Powder formulations containing 8.0 parts by weight of WODAFLOW MEII (Monsanto Co.) fluid variant are prepared according to the methods of Examples 2-16.

The formulation is applied to the steel panel as described in Examples 2-16 and cured at 120 ° C. and 110 ° C. for 20 minutes. Furthermore, it hardens for 30 minutes, 45 minutes, 60 minutes, and 75 minutes at 100 degreeC. The paint is inspected as in Examples 2-16. The results are shown in Table 3. All panels survived without apparent damage in 200 acetone loves.

Minutes Temperature (℃) Thickness (㎛) 20 ° glossiness 60 ° Glossiness Erichsen insertion (mm) Impact Resistance lbs (N-m) 20 110 566 100 103 3.8 110 (11) 20 120 56 99 103 4.6 90 (10) 30 100 59 97 102 5.6 30 (3) 45 100 53 100 101 4.6 50 (6) 60 100 59 99 101 6.0 50 (6) 75 100 67 99 101 4.1 40 (5)

The curable formulations of the present invention are effective for curing epoxy resins.

Claims (10)

Reacting an imidazole with an unsaturated compound having at least one activated double bond to form a nucleophilic adduct containing one or more imidazole moieties per molecule (1) and a formulation containing a nucleophilic adduct and an epoxy resin A process for preparing a curable formulation comprising the step (2), wherein less than 50 equivalent% of the imidazole moiety in the nucleophilic adduct is neutralized with an acid before step (2). The method of claim 1, wherein up to 25% of the imidazole residues in the adduct are neutralized with an acid. The method of claim 2, wherein up to 10% of the imidazole residues in the adduct are neutralized with an acid. The method of claim 3, wherein up to 5% of the imidazole residues in the adduct are neutralized with an acid. The process of claim 4 wherein the imidazole is unsubstituted imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole or N- (3-aminopropyl) imidazole. Which is one of the methods. Nucleophilic adduct (1) of an imidazole and an unsaturated compound and epoxy resin (2) containing 1 or more imidazole residues per molecule are contained in the ratio of 0.05-10 equivalent nucleophilic adduct per equivalent of epoxy resin A curable formulation, wherein less than 50 equivalent percent of the imidazole moiety in the adduct is neutralized with an acid. A method of curing the formulation by heating the formulation of claim 6 to a curing temperature, wherein the curing temperature is less than 130 ° C. 8. The method of claim 7, wherein the curable formulation is a powder coating formulation. A curable formulation comprising an epoxy resin (a), a curing agent for epoxy resin (b) (a ratio of 0.05 to 10 equivalents of curing agent per equivalent of epoxy resin), and a catalyst amount of catalyst (c) for reacting the epoxy resin with the curing agent. Is a nucleophilic adduct of imidazole with an unsaturated compound (less than 50 equivalent percent of the imidazole moiety in the adduct is neutralized with an acid). The curable formulation according to claim 9, wherein the concentration of the adduct per equivalent of epoxy resin is 4 to 200 milliequivalents (meq).