NO875081L - POWDER COATING RESIN WITH HIGH SALES POWER AND LOW GLOSS. - Google Patents

Abstract

Advanced epoxy resin materials provide improvements in processability, filler acceptability and rheology using epoxy resins down reduced viscosity per unit area. unit epoxy equivalent weight. The materials are usable as powder coatings on metal substrates. The products are obtained by polymerizing, in the grains of a polymerization catalyst, a monomer mixture containing at least one vinyl aromatic monomer, for example styrene, an epoxide group-reactive functionality and polymerizable ethylenically unsaturated group-containing compound, for example methacrylic acid, and optionally a hydroxyalkyl ( crude) acrylate or alkyl (meth) acrylic compound, for example hydroxyethyl acrylate. The monomer mixture is polymerized in the grains of a reaction product of a diglycidyl ether of a dihydric phenol, for example bisphenol A. and an epoxide group-reactive functionality and polymerizable ethylenically unsaturated group-containing compound, for example methacrylic acid. The resulting polymerization product is advanced in the presence of an advancement catalyst with a dihydric phenol, for example bisphenol A.

Description

Advanced epoxy resin materials which have been modified by in situ formation of the copolymerization product of a vinyl aromatic monomer and small amounts of a compound containing a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group are made by Hefner, Jr.,

et al in co-pending U.S. Application No. 790,991 filed October 24, 1985. These resins are used to produce thermosetting powder coatings which, when cured (thermo-set), provide low gloss, high impact coatings. Although excellent cured coatings are provided, it results in relatively high viscosity per unit epoxy equivalent weight for the modified advanced epoxy resins to difficult processability, reduced filler acceptability as well as marginal rheology during curing.

The present invention provides a specific method which results in epoxy resins with low gloss and high impact resistance, with significantly reduced viscosity per unit epoxy equivalent weight and resulting improvements in processability, filler acceptability and rheology.

One aspect of the present invention relates to advanced epoxy resin materials comprising the product resulting from (I) polymerizing, in the presence of a catalytic amount of at least one suitable polymerization catalyst

(A) the reaction product of

(1) a mixture comprising

(a) from 80 to 99, preferably from 90 to 95, wt% of at least one diglycidyl ether of a dihydric phenol having an epoxide equivalent weight of from 111 to 350, wherein the epoxy equivalent weight is calculated on the basis that there is no substituent groups attached to the aromatic ring other than hydrogen; and the ether oxygen atoms although the aromatic rings may actually be substituted with groups other than hydrogen; (b) from 1 to 20, preferably from 5 to 10,

% by weight of at least one diglycidyl ether of a mono-, di- or polyether diol; with

(2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to 0.05, preferably from 0.005 to 0.025, equivalent per epoxide equivalent contained in component (A-I); with

(B) a monomer mixture comprising

(1) at least one vinyl aromatic monomer in an amount of from 31 to 60, preferably from 35 to 45, weight % of the combined weight of components (A), (B) and (C);

(2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to 0.05, preferably 0.005 to 0.025, equivalent per epoxy equivalent contained in component (A-I); and

possibly

(3) one or more of hydroxyalkyl acrylate, hydroxyalkyl methacrylate, alkyl acrylate, or alkyl methacrylate in an amount of from zero to 15, preferably from zero to 5,% by weight of the

combined weight of components (B-1) and (B-3); and (II) advancing in the presence of a catalytic amount of at least one suitable advancement catalyst, the product resulting from (I) with

(C) at least one dihydric phenol in an amount of from 0.125 to 0.8, preferably from 0.375 to

0.5, hydroxyl equivalent per epoxide equivalent in component (A-I).

Another aspect of the present invention relates to advanced epoxy resin materials comprising the resulting product

(I) to polymerize, in the presence of a catalytic amount of

at least one suitable polymerization catalyst,

(A) the reaction product of

(1) at least one diglycidyl ether of a dihydric phenol having an epoxide equivalent weight of from 111 to 350, the epoxide equivalent weight being calculated on the basis that there are no substituent groups attached to the aromatic ring other than the hydrogen and ether oxygen atoms, although the aromatic rings may actually be substituted with groups other than hydrogen; (2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to 0.05, preferably from 0.005 to 0.025, equivalent per epoxide equivalent is contained in component

(A-I); with

(B) a monomer mixture comprising

(1) at least one vinyl aromatic monomer in an amount of from 31 to 60, preferably from 35 to 45, weight percent of the total weight of components (A), (B) and (C); (2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to about 0.05,

preferably from 0.005 to 0.025, equivalent per epoxide equivalent contained in component (A-I); and eventually

(3) one or more of hydroxyalkyl acrylate, hydroxyalkyl methacrylate, alkyl acrylate or alkyl methacrylate in an amount of from zero to 15, preferably from zero to 5, weight percent of the total weight of the components (B-1) and

(B-3); and

(II) advancing, in the presence of a catalytic amount of at least one suitable advancement catalyst, the product resulting from (I) with a mixture comprising

(C) at least one dihydric phenol in an amount of from 0.125 to 0.8, preferably from 0.375 to 0.5, hydroxyl equivalent per epoxide equivalent in component (A-I) and (D) at least one diglycidyl ether of a mono-, di- or polyether diol or at least one phenolically covered

adduct of a diglycidyl ether of a mono-, di- or polyether diol or combination thereof wherein the amount of the diglycidyl ether or the amount of the diglycidyl ether contained in the covered diglycidyl ether is from 1 to 20, preferably from 5 to 10, weight percent of the components (I-A-l) and ( II-D).

A further aspect of the present invention relates to thermosetting (curable) materials produced by combining one or more of the advanced epoxy resin materials with a curing amount of at least one suitable curing agent for the aforementioned advanced epoxy resin materials.

Yet another aspect of the present invention relates to the products and materials that result from curing the aforementioned thermosetable materials.

Suitable diglycidyl ethers of a divalent phenol which may be used herein include, for example, those represented by the formulas: wherein each A is independently a divalent hydrocarbon group having from one to 10 carbon atoms, -O-, -S-,

each X is independently hydrogen,

bromine, chlorine, or a hydrocarbyl or hydrocarbyloxy group having 1-10 carbon atoms; each R is independently hydrogen or a methyl group; m has a value from zero to 5, preferably from zero to 3; and n has a value of zero or 1.

The term hydrocarbyl as used herein means aliphatic, cycloaliphatic, aromatic, aryl substituted aliphatic or aliphatic substituted aromatic groups. Likewise, the term hydrocarbyloxy group means a hydrocarbyl group which has an oxygen bond between it and the point to which it is attached

Suitable diglycidyl ethers of a dihydric phenol which can be used herein include, for example, diglycidyl ethers of resorcinol, hydroquinone, catechol, bisphenol A (4,4'-isopropylidene diphenol), bis(4,4'-dihydroxyphenyl)methane, 2,2'-bis (4-hydroxy-phenyl)pentane, 3,3', 5,5'-tetramethyl-4,4'-dihydroxydiphenyl, 4,4'-dihydroxyphenylsulfone, 4,4'-dihydroxybenzophenone, 3,3', 5,5 '-tetrabromo-4,4'-isopropylidenediphenol, 4,4'-bis(p-hydroxy-phenyl)-diphenyl ether, 4,4'-dihydroxydiphenyl sulphide and mixtures thereof. Most preferred as the diglycidyl ether of a divalent phenol is the diglycidyl ether of bisphenol A.

Suitable diglycidyl ethers of a mono-, di- or polyetherdi which may be used herein include, for example, those represented by the following formula: wherein Z is a hydrocarbyl group containing 1-12 carbon atoms or a

where each R<1> is independently hydrogen or a hydrocarbyl group having 1-6 carbon atoms, and p has a value from 1 to 100, preferably from 1-25; m and R are as defined previously. The term mono-, di- or polyetherdiol is also meant to include aliphatic or cycloaliphatic diols or mixtures of said diols.

Suitable diglycidyl ethers of a mono-, di- or polyetherdiol that can be used herein include, for example, the diglycidyl ethers of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, butylene glycol, polyethylene glycols, polypropylene glycols, polybutylene glycols, 1,12-dihydroxydodecane, 1, 2-dihydroxyundecane, 1,6-hexanediol, 1,3-dihydroxy-2,2-dimethylpropane and mixtures thereof. Most preferred are the diglycidyl ethers of ethylene glycol, propylene glycol, polyethylene glycol and polypropylene glycol.

The diglycidyl ether of a mono-, di- or polyether diol can be converted to a phenol-capped adduct suitable for use herein via reaction with a stoichiometric excess of a divalent phenol such as those represented by formulas VI and VII. An equivalent ratio of 1:2 or more epoxy

groups relative to phenolic hydroxyl groups are used to prepare the phenolic capped adduct. An equivalent ratio of 1:2.5 to 1:5 is most preferred. The phenolic covered adduct is preferably produced by using an advancement catalyst with reaction times and temperatures that are proposed here for advancement reactions.

Suitable compounds containing both a group reactive with an epoxy group and a polymerizable ethylenically unsaturated group include compounds wherein said group reactive with an epoxy group is a compound containing a carboxylic acid, hydroxyl or amido group. Suitable compounds containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group include, for example, the acrylic acids, for example acrylic acid and methacrylic acid; the monoesters of α,[3-unsaturated dicarboxylic acids, for example monomethyl maleate and monobutyl fumarate; the alkenylphenols, for example p-isopropenylphenol, propenylphenol and m-vinylphenol; the hydroxyalkyl acrylates, for example 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and the acrylamides, for example methacrylamide and acrylamide, any combination thereof and the like. Most preferred as the compound containing a group reactive with an epoxy group and a polymerizable ethylenically unsaturated group is methacrylic acid.

The prereaction (step A) between the diglycidyl ether of a dihydric phenol or the diglycidyl ether of a dihydric phenol combined with the diglycidyl ether of a diol and a compound containing both a group reactive with an epoxide group and a polymerizable unsaturated group is carried out at a temperature of from 75 to 200°C, preferably from 140 to 160°C, for from 15 minutes to 150 minutes, preferably from 30 minutes to 60 minutes. The times and temperatures of the prereaction step vary as a function of the type of compounds containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group used.

A catalyst can optionally be used to facilitate the reaction between the group which is reactive with an epoxide group and the epoxide group. In general, a catalyst is not required and is furthermore not desired when said group which is reactive with an epoxide group is -COOH. However, it can be useful to use a catalyst when said group which is reactive with an epoxide group is, for example -OH. Typical of such catalysts which are applicable for this purpose are the advance-

Suitable vinyl aromatic monomers which can be used as component (B-1) in the copolymerization reaction step with the prereaction product of a diglycidyl ether of a dihydric phenol or diglycidyl ethers of a dihydric phenol combined with the diglycidyl ether of a diol and a compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group, includes those represented by the following formula

where R and X are as previously defined.

Representative of the vinyl aromatic monomers that can be used here are styrene, chlorostyrenes, methylstyrenes, t-butylstyrenes, cc-methylstyrene, methoxystyrenes and mixtures thereof. Most preferred as the vinyl aromatic monomer is styrene.

Suitable hydroxyalkyl acrylates or methacrylates, alkyl acrylates or methacrylates or mixtures thereof which can be used as component (B-3) in the copolymerization reaction step with the prereaction product of a diglycidyl ether of a dihydric phenol or the diglycidyl ether of a dihydric phenol combined with the diglycidyl ether of a diol and a compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group can be selected according to structure and amount to effect the final properties of a cured material such as a powder coating. Small amounts (0.25-2 percent by weight based on the total weight of monomer mixture used) of a hydroxyalkyl acrylate or methacrylate are used to increase adhesion of the powder coating to metal substrates. Larger amounts (2.1-15 percent by weight based on the total weight of monomer mixture used) of a powder-coated alkyl acrylate or methacrylate, especially those having eight carbon atoms or more, are used in small amounts (1-5 percent by weight based on the total weight of monomer mixture used) to reduce the gloss of the powder coating. Larger amounts (5.1-15 percent by weight based on the total weight of monomer mixture used) of certain alkyl acrylates or methacrylates can be used to also give modified texture to the powder coating. Combinations of the aforementioned acrylates and methacrylates can also be used. Specific hydroxyalkyl acrylates or methacrylates, alkyl acrylates or methacrylates which may optionally be used herein include those represented by the following formula

where R is as previously defined and Q is a monovalent hydrocarbyl group having from 1 to 25 carbon atoms or a hydroxyalkyl group having from 2 to 25 carbon atoms and may be branched, cyclic or polycyclic. Representative of the hydroxyalkyl acrylates or methacrylates, the alkyl acrylates or methacrylates or mixtures thereof which may possibly be used here are 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, cyclohexyl acrylate, lauryl methacrylate, stearyl acrylate, mixtures thereof and the like.

Suitable free radical-forming catalysts that can be used

in the copolymerization reaction step with the prereaction product of a diglycidyl ether of a dihydric phenol or the diglycidyl ether of a dihydric phenol combined with the diglycidyl ether of a diol and a compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group include the azo and diazo compounds as well such as the organic peroxides and hydroperoxides. Suitable free radical generating catalysts include, for example, 2,2'-azobisisobutyronitrile, 2,2'azobis(2,4-dimethyl-4-methoxyvaleronitrile), 1-t-butylazo-1-cyanocyclohexane, t-butyl perbenzoate, t-butyl- peroctoate, t-butyl hydroperoxide, di-t-butyl peroxide, dicyl peroxide, cumene hydroperoxide and mixtures thereof. A quantity of

from 1.0 to 5.0, preferably from 2.0 to 3.0, weight percent, based on the total weight of monomer mixture used, of at least one free radical-forming catalyst is used.

The copolymerization reaction between the prereaction product

(A) of a diglycidyl ether of a dihydric phenol or the diglycidyl ether of a dihydric phenol combined with the diglycidyl ether of

a diol and a compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group with a monomer mixture consisting of (B-1) a vinyl aromatic monomer, (B-2) a compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group, and optionally, (B-3) a hydroxyalkyl acrylate or methacrylate, an alkyl acrylate or methacrylate, or a mixture thereof, can be completed using a series of reaction sequences. In general, the monomer feed (B) containing a free radical forming polymerization catalyst is added to the prereaction product (A) over a period of 45 minutes to 150 minutes, preferably from 75 minutes to 120 minutes, while the reaction temperature is maintained at from 125 to 175°C, preferably from 140 to 160°C. A post-reaction of from 30 minutes to 150 minutes, preferably from 45 minutes to 90 minutes, is completed after the completion of the monomer feed addition.

It is necessary to maintain an inert atmosphere throughout the copolymerization reaction. This is achieved by placing a blanket over the reaction mixture of nitrogen, argon or occasionally other inert gas. Adequate stirring is required for thorough mixing and dispersion of the reactants.

In an equally preferred method according to the present invention, the free radical-forming catalyst can be removed as a component of the monomer feed and added to the reaction mixture separately. If this is done, it is generally desirable to maintain simultaneous addition of the free radical-forming catalyst and the remaining monomer mixture (B-1), B-2 and, optionally, B-3). The rate of this simultaneous addition should be adjusted so that excess unpolymerized monomer mixture does not accumulate.

As a further embodiment of the present invention, a portion of free radical forming catalyst may be added to the reaction mixture at the end of the monomer mixture addition, most preferably 15 minutes to 120 minutes after the completion of the monomer mixture addition. This is done if unpolymerized monomer mixture is present and allows completion of the copolymerization reaction.

When a diglycidyl ether of a dihydric phenol combined with the diglycidyl ether of a diol is used to prepare the pre-reaction product (A), the diglycidyl ether of a diol (A-l-b) may be added to the reaction mixture at any time, but is preferably added simultaneously with the diglycidyl ether of a dihydric phenol .

The advancement reaction between the aforementioned copolymerization product of the prereaction product (step A) of the diglycidyl ether of a divalent phenol combined with the diglycidyl ether of a diol and a compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group and the monomer mixture (step B) with a divalent phenol is carried out in the presence of an advancement catalyst. Suitable divalent phenols include, for example, those represented by the following formulas.

where X, A and n are as previously defined. Representatives of the bisphenols are resorcinol, hydroquinone, catechol, bisphenol A

(4,4'-isopropylidenediphenol), bis(4,4'-dihydroxyphenyl)methane, 2,2'bis(4-hydroxyphenyl)pentane, 3,3',5,5'-tetramethyl-4,4'-dihydroxydiphenyl , 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxybenzophenone 3,3',5,5'-tetrabromo-4,4'-isopropylidenediphenol, 4,4'-bis(p-hydroxyphenyl)diphenyl ether, 4,4' -dihydroxy-diphenyl sulphide and mixtures thereof. The most preferred bisphenol is bisphenol A.

Suitable advancement catalysts that can be used in the process of the present invention include virtually any catalyst that will catalyze the reaction between a vicinal epoxy group and a phenolic hydroxyl group. Such catalysts include, for example, those disclosed in U.S. Patent Nos. 3,306,872, 3,341,580, 3,379,684, 3,477,990, 3,547,881, 3,637,590; 3,843,605, 3,948,855, 3,956,237, 4,048,141, 4,093,650, 4,131,633. 4,132,706, 4,171,420, 4,177,216.

Particularly suitable catalysts are the quaternary phosphonium and ammonium compounds such as, for example, ethyltriphenylphosphonium chloride, ethyltriphenylphosphonium bromide, ethyltriphenylphosphonium iodide, ethyltriphenylphosphonium acetate, ethyltriphenylphosphonium acetate.acetic acid complex, ethyltriphenylphosphonium phosphate, tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, tetrabutylphosphonium iodide, tetrabutylphosphonium acetate, tetrabutylphosphonium acetate.acetic acid complex butyltriphenylphosphonium tetrabromo- bisphenate, butyltriphenylphosphonium bisphenate, butyltriphenylphosphonium bicarbonate, benzyltrimethylammonium chloride, tetramethylammonium hydroxide and mixtures thereof.

The advancement reaction between the aforementioned copolymerization product of the prereaction product (step A) of the diglycidyl ether of a divalent phenol and a compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group and the monomer mixture (step B) with a divalent phenol (formulas VI, VII) and a diglycidyl ether of a diol or a phenolic capped adduct of a diglycidyl ether of a diol is carried out in the presence of an advancement catalyst using methods previously described.

It may also be possible, although less preferred, to carry out the advancement reaction of the aforementioned copolymerization product of the prereaction product of the diglycidyl ether of a divalent phenol combined with the diglycidyl ether of a diol and a compound containing both a group reactive with a epoxide group (step A) and a polymerizable ethylenically unsaturated group and the monomer mixture (step B) with a dihydric phenol (formulas VI, VII) and a diglycidyl ether of a diol or a phenolically capped adduct of a diglycidyl ether of a diol in the presence of an advancement catalyst under application of the methods described earlier. In this particular process configuration, the previously specified required amount of diglycidyl ether of a diol is distributed between the prereaction and advancement reaction steps in any desired ratio.

After completion of either the copolymerization reaction (I) or the advancement reaction (II), it is generally useful, although not required, to subject the reaction product to a vacuum stripping step. This is done by drawing a vacuum on the reactor, whereby any materials are removed and condensed as volatiles from reaction products.

In a variant of this vacuum stripping step, various modifiers or additives, for example stone-regulating agents, gloss-regulating agents, pigments, texture-regulating additives, air release agents, mixtures thereof and the like, can be added to the reaction product before the vacuum stripping step. This enables the removal of any volatile components that are contributions from the aforementioned additives.

The powder coating mixtures according to the present invention are produced using the aforementioned epoxy resin materials and a suitable curing agent for these.

The said hardeners should be essentially non-sintering and show latency at the mixing temperatures and conditions used. Suitable such curing agents are described in the Handbook of Epoxy Resins by Lee and Neville, 1967, McGraw-Hill. Representative of these curing agents are the boron trifluorideamine complexes, the polycarboxylic acids or their anhydrides, the guanamines, the guanidines, the hydrazines, the dihydrazines, the melamines, the substituted ureas and biguanides, for example dicyandiamide or dicyandiamide derivatives. The most preferred curing agent is dicyandiamide.

Epoxy polyester hybrid powder coating mixtures according to the present invention are produced by using the previously mentioned epoxy resin materials and a suitable carboxylic acid and/or hydroxyl functional polyester as curing agent.

Mixing methods that are well known in the field are used to prepare the powder coating mixtures according to the present invention. Preparation of typical epoxy resin-based powder coating compositions is described in Fundamentals of Powder Coating by Miller and Taft, 1974, Society of Manufacturing Engineers, Dearborn, Michigan.

In the general production method, the solid epoxy resin product is flake-formed or crushed and then dry-mixed with a non-sintering curing agent, and optionally one or more curing agent accelerators or catalysts, particulate fillers, pigments, flow-regulating agents, gloss-regulating additives, texture-regulating additives and air-free remedies. The dry-blended product is then heat-melt-blended, typically using a kna-type extruder. The extruded product passes through cooled rollers and is then extracted and crushed into a coarse powder.

Further crushing to a fine powder is carried out using a high-speed hammer mill or other type of crushing equipment. The resulting fine powder is subjected to a size classification step to recover the desired range of product particle size. The desired product size distribution for the product may vary depending on the intended end use for the product, but generally sizes between 80 mesh and 325 mesh are most desired. Well-known methods contemplated for use in a size classification of powder coating mixtures include sieving and air classification.

The resulting powder coating mixture is applied to the substrate to be coated using methods well known in the art. These methods are described in detail in the aforementioned Miller and Taft reference and include powder spreading, fluidized bed processes, electrostatic powder spraying, electrostatic fluidized bed processes and others.

The powder-coated article is cured using methods and conditions that are well known in the art. This typically involves heating in a drying cabinet for a period of time sufficient to complete curing. When dicyandiamide is the curing agent and 2-methylimidazole is the curing agent accelerator used with the epoxy resin materials according to the present invention, curing times of 5-30 minutes at a reaction temperature of 150-220°C are usually sufficient.

The powder coating mixture optionally, although preferably, contains one or more hardener accelerators or catalysts. Suitable such hardener accelerators or catalysts are described in the previously mentioned literature sources Handbook of Epoxy Resins and Fundamentals of Powder Coating. Representative of these curing agent accelerators or catalysts are the amino-substituted pyridines, imidazoles, metal salts, tertiary amines, phenols and mixtures thereof. Most preferred as a hardener accelerator for use with a dicyandiamide hardener is 2-methylimidazole.

The powder coating mixture optionally, although preferably, contains one or more particulate fillers. Fillers are used in powder coatings for a wide range of purposes, and primarily for economic reasons, i.e. as a less expensive diluent. Other properties provided by fillers may include one or more of the following: handling and processing properties, impact modification, dimensional stability, moisture and chemical resistance, flame resistance, modified thermal conductivity, modified electrical properties, modified rheology, color modification and texture modification . -Suitable such fillers are described in Non-Fibrous Fillers for Epoxy Resin Formulations presented at the 7th Electrical Insulation Conference in Chicago, Illinois, October 15-19, 1967 by D.A. Shimp. Representative of these fillers are barytes (BaSCM), titanium dioxide, carbon black (carbon black), silicon dioxide flour, calcium carbonate and mixtures thereof. The particle size distribution, shape, chemical composition, surface area and level of use, i.e. ratio of resin to filler, can be adjusted individually or collectively to change the resulting cured powder coating. Simple preliminary tests within the normal knowledge of the person skilled in the field are ordinarily carried out to help with the choice of filler.

The powder coating mixture optionally contains one or more pigments. Said pigments are typically used to add color to the hardened powder coating. Suitable such pigments are described in Pigments for Coloring Epoxy Powder Coatings by Maltman and Deverell-Smith in Pigment and Resin Technology, November 1973, pages 15-19.

The powder coating mixture optionally, although preferably, contains one or more flow regulating agents. Flow regulating agents are used in powder coating to adjust the rheological properties of the total powder coating mixture and thus ensure uniform coating film thickness, "wet-out" and coating of edges. Suitable such flow control agents are described in Acrylic Flow Control Agents for the Coating Industry by Skora in Polymers Paint and Color Journal, September 5, 1979, pages 867-870. Most preferred as flow regulating agents are the polyacrylates, for example ethyl acrylate and 2-ethylhexyl acrylate copolymer and poly(butyl acrylate).

The powder coating mixture optionally contains one or more texture-regulating additives. Texture-regulating additives are used in powder coatings to modify the surface characteristics of the hardened powder coating. The material providing smooth or rough surface finish can be used. Glass microspheres, metal powders and polymeric powders are examples of the types of additives that have the ability to modify the powder coating surface into a textured finish.

The powder coating mixture optionally contains one or more air-releasing agents. Said agents are used in powder coatings to dampen surface defects, for example pinpricks in the hardened powder coating, induced by air entrapment. A most preferred air release agent is benzoin, as described in Surface Coatings, vol. 2 - Paints and Their Application by The Oil and Color Chemists' Association, Australia, published by Chapman and Hall, 1984, page 598.

The powder coating mixture optionally contains one or more gloss-regulating additives. Gloss control additives are used to reduce the high degree of reflected light from the typical cured epoxy resin surface. Suitable such gloss control agents are certain types of amorphous silica, silicic acid, and the curing agent system consisting of a salt of a polycarboxylic acid and a cyclic amidine, as taught in U.S. Patent No. 3,947,384.

Other additives or adjuvants may be incorporated into the powder coating compositions of the present invention for their known and intended use therein. Such an additive is a release aid, as described in the aforementioned reference Surface Coatings.

The cured product according to the present invention is a powder coating over a substrate such as steel, which provides a smooth finish, low gloss surface and high impact resistance.

The following examples are illustrative of the present invention and should not be understood as limiting its scope in any way.

EXAMPLE 1

Polystyrene-modified epoxy resin with 5% of the diglycidyl ether of bisphenol A substituted with polypropylene glycol diglycidyl ether during the prereaction.

A diglycidyl ether of bisphenol A (575g, 3.144 epoxide equivalents) of commercial grade (D.E.R. R 383, The Dow Chemical Company) with epoxide equivalent weight (EEW) of 182.9, a polypropylene glycol diglycidyl ether (49.14g, 0.166 epoxide equivalent) of commercial grade grade (D.E.R. R 732, The Dow Chemical Company) with an EEW of 296 and glacial methacrylic acid (2.86 g, 0.033 mol) was placed in a 2-liter 5-neck round-bottomed flask equipped with a water cooler, nitrogen purge, addition funnel, thermometer and stirrer. Heating to 150°C was initiated on the stirred solution. 44 minutes later the reactor temperature reached 145°C and nitrogen purging was initiated. 2 minutes later the temperature of 150°C was reached. The first aliquot of monomer mixture, a mixture of styrene (249.65 g, 2.39 mol) ice-methacrylic acid

(2.15 g, 0.025 mol) and tert-butyl perbenzoate (6.24 g, 0.031

mol) was placed in the addition funnel and added dropwise to the stirred solution. After 44 minutes, the addition of the first aliquot of monomer mixture was complete, and the second aliquot, a mixture of styrene (249.65 g, 2.39 mol) glacial methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate ( 6.24 g, 0.031 mol) was added to the addition funnel and added dropwise to the stirred solution. The reactor temperature was maintained between 145°C and 155°C throughout the monomer mixture addition. 47 minutes later, the addition of the second aliquot of monomer mixture was complete. The post-reaction of the stirred solution was continued for 30 minutes at 150°C. After 30 minutes at 150°C, tert-butyl perbenzoate (1.25 g, 0.0062 mol) was added to the stirred solution. After a further 30 minutes at 150°C, a vacuum was drawn to remove unreacted styrene and other light substances. During the vacuum stripping, 2.0 ml of unreacted styrene and other light substances were recovered in an overflow cold trap. After 30 minutes of vacuum stripping at 150°C, bisphenol A (162.8 g, 0.71 mol) was added to the stirred solution. 3 minutes later, the reactor's temperature had dropped to 133°C with complete dissolution of bisphenol A in the resin solution. An advancement catalyst (ethyltriphenylphosphonium acetate.acetic acid complex,

lg, 70% in methanol) was added to the reactor, which was then reheated to 150°C. 7 minutes later the reactor reached 150°C and heating was stopped. A maximum exotherm of 180°C resulted 6 minutes later. The reactor was allowed to cool to 175°C and was held there for 1 hour after the maximum exotherm. The polystyrene modified epoxy resin product was recovered as a pale yellow colored, slightly opaque, brittle solid with a final epoxy equivalent weight of 721.

EXAMPLE 2

Polystyrene-modified epoxy resin with 5% of diglycidyl ether

of bisphenol A substituted with polypropylene glycol diglycidyl ether after monomer mixture addn.

A diglycidyl ether of bisphenol A (575 g, 3.144 epoxide equivalents) of commercial grade (D.E.R.<R>383, The Dow

Chemical Company) with an epoxide equivalent weight (EEW) of 182.9 and glacial methacrylic acid (2.86 g, 0.033 mol) was charged to a 2-liter, 5-necked round-necked flask equipped with a water cooler, nitrogen purge, addition funnel, thermometer and stirring. Heating to 150°C was initiated on the stirred solution. 47 minutes later, the reactor temperature reached 145°C, and nitrogen purging was initiated. 3 minutes later the temperature of 150°C was reached. The first aliquot of monomer mixture, a mixture of styrene (249.65 g, 2.39 mol), ice-methacrylic acid (2.15 g, 0.025

mol) and tert-butyl perbenzoate (6.24 g, 0.031 mol) were added to the addition funnel and added dropwise to the stirred solution. After 50 minutes, the addition of the first aliquot of monomer mixture was complete, and the second aliquot, a mixture of styrene (249.65 g, 2.39 mol) glacial methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate ( 6.24 g, 0.031 mol) was placed in the addition funnel and added dropwise to the stirred solution. The reactor temperature was maintained between 145°C and 155°C throughout the addition of the monomer mixture. 43 minutes later, the addition of the second aliquot of monomer mixture was complete. Post-reaction of the stirred solution was continued for 30 minutes at 150°C. After 15 minutes at 150°C, tert-butyl perbenzoate (1.25 g, 0.0062 mol) was added to the stirred solution. After a further 15 minutes at 150°C, a vacuum was drawn to remove unreacted styrene and other light substances. During the vacuum stripping, 7.5 ml of unreacted styrene and other light substances were recovered in an overflow cold trap. After 60 minutes of vacuum stripping at 150°C, a commercial grade polypropylene glycol diglycidyl ether (49.14 g, 0.166 epoxide equivalent) (D.E.R. R 732, The Dow Chemical Company) with an EEW of 296 and bisphenol A (162.8 g, 0. 71 mol) added to the stirred solution. 6 minutes later, the reactor's temperature had dropped to 130°C with complete dissolution of bisphenol A in the resin solution. An advancement catalyst (ethyl triphenylphosphonium acetate.acetic acid complex 1 g, 70% in methanol) was added to the reactor which was then reheated to 150°C. 8 minutes later the reactor reached 150°C and heating was stopped. A maximum exotherm of 180°C resulted in 7 minutes (420 s)

later. The reactor was allowed to cool to 175°C where it remained

held for 1 hour after the maximum exotherm. The polystyrene-modified epoxy resin product was recovered at room temperature as a pale yellow colored, slightly opaque, brittle solid with a final epoxy equivalent weight of 737.

EXAMPLE 3

Polystyrene-modified epoxy resin with 5% of the diglycidyl ether of bisphenol A substituted with polypropylene glycol diglycidyl ether during the advancement step post-reaction.

A diglycidyl ether of bisphenol A (575 g, 3.144 epoxide equivalents) of commercial grade D.E.R.<R>383, The Dow Chemical Company) with an epoxide equivalent weight (EEW) of 182.9 and glacial methacrylic acid (2.86 g, 0.033 mol ) was placed in a 2-liter, 5-neck round-necked flask equipped with a water cooler, nitrogen purge, addition funnel, thermometer and stirrer. Heating to 150°C was initiated on the stirred solution. 42 minutes later, the reactor temperature reached 145°C, and nitrogen purging was initiated. 3 minutes later, the temperature of 150°C was reached. The first aliquot of monomer mixture, a mixture of styrene (249.65 g, 2.39 mol), glacial methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate (6.24 g, 0.031 mol) was charged to the addition funnel and added dropwise to the stirred solution. After 45 minutes, the addition of the first aliquot of monomer mixture was complete, and the second aliquot, a mixture of styrene (249.65 g, 2.39 mol) glacial methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate ( 6.24 g, 0.031 mol) was added to the addition funnel and added dropwise to the stirred solution. The reactor temperature was maintained between 145°C and 155°C throughout the addition of the monomer mixture. 43 minutes later, the addition of the second aliquot of monomer mixture was complete. Post-reaction of the stirred solution was continued for 15 minutes at 150°C. After 15 minutes at 150°C, tert-butyl perbenzoate (1.25 g, 0.0062 mol) was added to the stirred solution. After a further 45 minutes at 150°C, a vacuum was drawn to remove unreacted styrene and other light substances. During the vacuum stripping, 2.7 ml of unreacted styrene and other light substances were recovered in an overflow cold trap. After 42 minutes of vacuum stripping at 150°C, bisphenol A (162.8 g, 0.71 mol) was added to the stirred solution. 3 minutes later, the reactor temperature had dropped to 130°C with complete dissolution of bisphenol A in the resin solution. An advancement catalyst (ethyl triphenylphosphonium acetate.acetic acid complex, 1 g 70% in methanol) was added to the reactor which was then reheated to 150°C. 9 minutes later the reactor reached 150°C and heating was stopped. A maximum exotherm of 181°C resulted 7 minutes later. The reactor was allowed to cool to 175°C where it was held for 45 minutes after the maximum exotherm. A - commercial grade (D.E.R. R 732, The Dow Chemical Company)

of a polypropylene glycol diglycidyl ether (49.14 g, 0.166 epoxide equivalent) was added to the advanced resin mixture. The reactor was held at 175°C for 15 minutes after the addition

of polypropylene glycol diglycidyl ether. The polystyrene-modified epoxy resin product was recovered at room temperature (25°C) as a pale yellow colored, slightly opaque, brittle solid with a final epoxy equivalent weight of 733.

EXAMPLE 4

Polystyrene-modified epoxy resin with 5% of the diglycidyl ether of bisphenol A substituted with bisphenol A-covered polypropylene glycol diglycidyl ether after monomer mixture addition.

A. Synthesis of phenolic capped aliphatic epoxy resin

A portion of a commercial grade (D.E.R. R 732, The Dow Chemical Company) of diglycidyl ether of polypropylene glycol (59.20 g, 0.20 epoxide equivalent) with an epoxide equivalent weight (EEW) of 296 was added to a reactor and heated to 150° C with stirring under a nitrogen atmosphere. Bisphenol A (68.49 g,

0.60 hydroxyl equivalent) was added to the reactor, followed by cooling to 100°C. At this point, ethyltriphenylphosphonium bromide became. acetic acid complex catalyst (0.192 g, 0.15 wt%) was added to the reactor, followed by heating to 180°C over a 16 minute period. As soon as the temperature of 180°C was reached, the reactor was allowed to cool within 10 minutes to 150°C and then held at this temperature for 64 minutes. The product was recovered as a light yellow colored transparent solid at

room temperature (25°C) with a residual percent epoxy content of 0.34 (12.647 EEW).

B. Synthesis of a polystyrene-modified epoxy resin by

using a portion of the phenolic coated aliphatic epoxy resin.

A commercial grade (D.E.R. R 383, The Dow Chemical Company) of diglycidyl ether of bisphenol A (489.72 g, 2,679 epoxide equivalent with an epoxide equivalent weight (EEW) of 182.8 g) and glacial methacrylic acid (2.86 g, 0, . nitrogen purge was initiated. 2 minutes later the temperature of 150°C was reached. The first aliquot of monomer mixture, a mixture of styrene (212.58 g, 2.04 mol), glacial methacrylic acid (1.82 g, 0.021 mol) and tert .butyl perbenzoate (5.315 g, 0.027 mol) was charged to the addition funnel and added dropwise to the stirred solution. After 46 minutes, the first aliquot of monomer mixture addition was complete, and the second aliquot, a mixture of styrene (212.58 g, 2.04 mol), glacial methacrylic acid (1.82 g, 0.021 mol) and tert-butyl perbenzoate (5.315 g, 0 .027 mol) was added to the addition funnel and added dropwise to the stirred solution. The reactor temperature was maintained between 145°C and 155°C throughout the addition of monomer mixture. 42 minutes later, the second aliquot of monomer mixture addition was complete. Post-reaction of the stirred solution was continued for 30 minutes at 150°C. After 30 minutes at 150°C, tert-butyl perbenzoate (1.06 g 0.0054 mol) was added to the stirred solution. After a further 30 minutes at 150°C, a vacuum was drawn to remove unreacted styrene and other light substances. During the vacuum stripping, 4.85 ml of unreacted styrene and other light substances were recovered in an overflow cold trap. After 30 minutes of vacuum stripping at 150°C, 90 g of the phenolic-capped aliphatic epoxy resin product (part A) was added to the stirred solution concurrently with bisphenol A (90.28 g, 0.394 mol). 10 minutes later the reactor temperature had dropped to 134°C with complete dissolution of bisphenol A in the resin solution. An advancement catalyst (ethyltriphenylphosphonium acetate.acetic acid complex, 0.84 g, 70% in methanol) was added to the reactor, which was then reheated to 150°C. 6 minutes later the reactor reached 150°C and heating was stopped. A maximum exotherm of 180°C resulted 5 minutes later. The reactor was cooled to 175°C where it was held for 1 hour after the maximum exotherm. The polystyrene-modified epoxy resin product was recovered at room temperature (25°C) as a pale yellow colored, slightly opaque, brittle solid with a final epoxy equivalent weight of 738.

EXAMPLE 5

Polystyrene modified epoxy resin with 10% of the diglycidyl ether of bisphenol A substituted with polypropylene glycol diglycidyl ether during the prereaction.

A commercial grade (D.E.R. R 383, The Dow Chemical Company) of diglycidyl ether of bisphenol A (540.99 g, 2.979 epoxide equivalents) with epoxide equivalent weight (EEW) of 181.6 a commercial grade (D.E.R. R 732, The Dow Chemical Company ) of polypropylene glycol diglycidyl ether (97.98 g, 0.331 epoxide equivalent) with an EEW of 296 and glacial methacrylic acid (2.86 g, 0.033 mol) was charged to a 2-L, 5-necked round-bottom flask equipped with a water cooler, nitrogen purge, addition funnel, thermometer and stirrer. Heating to 150°C was initiated on the stirred solution. 47 minutes later, the reactor temperature reached 145°C, and nitrogen purging was initiated. 5 minutes later, the temperature of 150°C was reached. The first aliquot of monomer mixture, a mixture of styrene (255.59 g, 2.45 mol), glacial methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate (6.39 g, 0.032 mol) was added to addition funnel and added dropwise to the stirred solution. After 38 minutes, the first aliquot of monomer mixture addition was complete, and the second aliquot, a mixture of styrene (255.59 g, 2.45 mol), ice-methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate (6 .39 g, 0.032 mol) was added to the addition funnel and added dropwise to the stirred solution. The reactor temperature was maintained between 145°C and later the second aliquot of monomer mixture addition was complete. Post-reaction of the stirred solution was continued for 32 minutes at 150°C. After 32 minutes at 150°C, tert-butyl perbenzoate (1.28 g, 0.0064 mol) was added to the stirred solution. After 28 minutes at 150°C, a vacuum was pulled to remove unreacted styrene and other light substances. During the vacuum stripping, 7.0 ml of unreacted styrene and other light substances were recovered in an overflow cold trap. After 30 minutes of vacuum stripping at 150°C, bisphenol A

(158.97 g, 0.69 mol) was added to the stirred solution. 4

minutes later the reactor's temperature had dropped to 134°C with complete dissolution of bisphenol A in the resin solution. An advancement catalyst (ethyltriphenylphosphonium acetate-acetic acid complex, 1.0 g, 70% in methanol) was added to the reactor, which was then reheated to 150°C. 7 minutes later the reactor reached 150°C and the heating was stopped. A maximum exotherm of 176°C resulted 4 minutes later. The reactor was allowed to cool to 175°C, where it was held for 1 hour after the maximum exotherm. The polystyrene-modified epoxy resin product was recovered at room temperature (25°C) as a pale yellow colored, slightly opaque, brittle solid with a final epoxy equivalent of 740.

COMPARISON EXPERIMENT A

Polystyrene modified epoxy resin - Low qlans standard

A commercial grade (D.E.R. R 383, The Dow Chemical Company) diglycidyl ether of bisphenol A (600 g, 3.31 epoxide equivalents) having an epoxide equivalent weight (EEW) of 181.6 and glacial methacrylic acid (2.86 g, 0.033 mol) is placed in a 2-litre, 5-neck round-necked flask equipped with a water cooler, nitrogen purge, addition funnel, thermometer and stirrer. Heating to 150°C was initiated on the stirred solution. 42 minutes later, the reactor temperature reached 145°C, and nitrogen purging was initiated. 3 minutes later, the temperature of 150°C was reached. The first aliquot of monomer mixture, a mixture of styrene (240 g, 2.3 mol), glacial methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate (6 g, 0.03 mol) was charged to the addition funnel and added dropwise into the stirred solution. After 47 minutes, the addition of the first aliquot of monomer mixture was complete, and the second aliquot, a mixture of styrene (240 g, 2.3 mol), glacial methacrylic acid (2.15 g, 0.025 mol) and tert-butyl perbenzoate (6

g, 0.03 mol) was added to the addition funnel and added dropwise to the stirred solution. The reactor temperature was maintained between 145°C and 155°C throughout the addition of monomer mixture. 40 minutes later, the addition of the second aliquot of monomer mixture was complete. Post-reaction of the stirred solution was continued for 30 minutes at 150°C.

After 30 minutes at 150°C, tert-butyl perbenzoate (1.2 g, 0.006 mol) was added to the stirred solution. A weak exotherm to 153°C was noted. After a further 30 minutes at 150°C, a vacuum was drawn to remove unreacted styrene and other light substances. During the vacuum stripping, 8.5 ml of unreacted styrene and other light substances were recovered in an overflow cold trap. After 30 minutes of vacuum stripping at 150°C, bisphenol A (162.8 g, 0.71 mol) was added to the stirred solution. 3 minutes later, the reactor's temperature had dropped to 138°C with complete dissolution of bisphenol A in the resin solution. An advancement catalyst (ethyl triphenylphosphonium acetate.acetic acid complex, 1 g, 70% in methanol) was added to the reactor, which was then reheated to 150°C. 3 minutes later the reactor reached 150°C and heating was stopped. A maximum exotherm of 173°C resulted 6 minutes later. The reactor was heated to 175°C, where it was held for 1 hour after the maximum exotherm. The polystyrene-modified epoxy resin product was recovered at room temperature (25°C) as a pale yellow colored, slightly opaque, brittle solid with a final epoxy equivalent weight of 708.

EXAMPLE 6

Cone and plate viscosity determination of powder coating resins.

Cone and sheet viscosity measurements were determined for the resins of Examples 1-5 and Comparative Experiment A using an I.CI. Cone and Plate Viscometer, Research Equipment (London) Ltd.

Viscosity measurements were carried out at 150°C and 175°C. One

A 0.4 g sample of each solid resin was placed on the heated plate and assessed with a size 100 cone. The cone and plate viscosity values for Examples 1-5 and Comparative Test A are given in Table I.

EXAMPLE 7

Kinematic viscosity determination of powder coating resins.

Kinematic viscosity measurements were determined for the resin of Example 1 and a standard low gloss polystyrene modified epoxy resin prepared using the procedure of Comparative Experiment A, using Cannon-Fenske Routine Viscometer size 700.

The viscosity measurements were carried out at 150°C. An 11 gram sample of each solid resin was placed in a size 700 viscometer. The viscometer was then placed in a 150°C constant temperature oil bath.

The viscometer was allowed to equilibrate at 150°C for at least 60 minutes before the viscosity measurement. The molten resin was free of all air bubbles before the viscosity measurement. The kinematic viscosity values for Example 1 and the polystyrene-modified low-gloss epoxy resin prepared by the method in comparative test A are reproduced in Table IV.

EXAMPLE 8

Preparation of powder coating mixtures

Portions of each of the epoxy resins from Examples 1-5 and Comparative Trial A were coarsely ground in a Wellex Grinder. Mixing weights according to Table II, for the epoxy resin, the dicyandiamide, a mixture of 17% by weight 2-methylimidazole and 83% by weight dicyandiamide, Modaflow II and filler, were placed in a plastic bag, closed and dry mixed to a homogeneous mixture.

The dry blends were then extruded in a Buss-Condux PLK 46 single-screw extruder (equipped with a 46 mm diameter knob screw running at 120 rpm). For the resin compositions according to Examples 1-5, zone 1 was set at 50°C and zone

2 at 100°C; for the resin mixture according to comparative test A, zone 1 was set at 60°C and zone 2 at 100°C. The extrudate was passed through BCI Chili Rolls (6 1/2" (165.1 mm) diameter, cooled and crushed). The crushed extrudate was then coarsely ground in a Brinkmann Centrifugal Grinding Mill using the 12-tooth attachment and then finely crushed by using the 12-tooth equipment and a 0.75 mm sieve over the crusher teeth; dry ice was used as a coolant to minimize sintering and resin melting in the comminution step. The comminuted extrudate was sieved through No. 140 (150 mesh, 106um) standard test sieves (wire screen). The -150 mesh powder coating compositions were electrostatically sprayed with a Gema Ag Type 710 Laboratory Unit (set at 60-70 kV) on 4" x 12" x 20 gauge (101.6 mm x 304.8 mm x 0.529 mm) cold-rolled steel, clean treatment Parker test panels (Parker Division, Hooker Chemicals and Plastics Corporation). The electrostatically coated panels were placed in a Gallenkamp convection-type oven and cured at 180°C (356°F) for 20 minutes. After removal from the oven, the panels were cooled and vu determined via the following test methods: coating thickness was determined by ASTM D1186 using a Fischer Perma-Scope ES film thickness tester. Surface gloss was determined by ASTM D523 (DIN 67530) with a Mallinckrodt Multi Gloss gloss meter. Gardner forward and reverse impact strength was determined 24 hours after injection according to ASTM D2794

using a Gardner "Coverall" Bend and Impact Tester, 46 inch (1.18 m) pipe length, 0-160 in.-lb. tester with a four pound cone (1.81 kg), a half inch (12, 7 mm). Visualization of any surface cracks at the impact points was facilitated by the application of an acidified copper sulphate (CuSO4) solution for a period of 15 minutes. The impact areas were observed for copper deposits or iron rust stains immediately after exposure to the copper sulfate solution.

Film thickness, surface gloss and Gardner impact strength values for the cured powder coatings prepared using the epoxy resins from Examples 1-5 and Comparative Test A are shown in Table II.

COMPARISON EXPERIMENT B

Preparation of powder coating mixture using epoxy resin standard and 45 parts by weight of TiO2

A commercial grade (D.E.R. R 662UH, The Dow Chemical Company) of diglycidyl ether of bisphenol A having an epoxide equivalent weight (EEW) of 714 was used to prepare a powder coating composition using the method of Example 8 using titanium dioxide (TiO 2 , DuPont R-900) instead of BaSO4 with 45% by weight of the entire mixture. Cured powder coated panels were made and tested using the methods of Example 8. The results are shown in Table III.

COMPARISON EXPERIMENT C

Preparation of powder coating mixture using standard low gloss epoxy resin and 45 parts by weight TiO2

A portion of resin from Comparative Experiment A was used to prepare a powder coating mixture using the method of Example 8, where titanium dioxide (TiO 2 , DuPont R-900) was used instead of BaSO-i at 45% by weight of the entire mixture. Hardened powder-coated steel panels were made and tested using the methods of Example 8. The results are reproduced in Table III.

EXAMPLE 9

Preparation of powder coating mixture using 45 parts by weight of TiQ2

A portion of resin from Example 5 was used to prepare a powder coating mixture using the method of Example 8, where titanium dioxide (TiO 2 , DuPont R-900) was used instead of BaSO 4 at 45 percent by weight of the entire mixture. Hardened powder-coated steel panels were made and tested using the methods from Example 8. The results are shown in the table

III.

EXAMPLE 10 - SCRATCH PLATE - FLOW TEST

Slanted plate flow was measured for the resins from the examples

1, 4, 5 and Comparative Test A using the mixtures prepared in Example 8 and a modification of Standard Method ASTM D3451, Part 17 described herein. 0.75 g samples of each resin were pressed into 0.25" (6 mm ) thickness and 0.50" (12.7 mm) diameter pellets using a Parr 2811 Pellet Press, stainless steel die (Parr Instrument Co., Moline, Illinois. Three pellets of resin from each sample were made, 6 pellets from comparison experiment A were made and used as control samples.

A forced air constant temperature electric oven (Gruenberg Oven Co., Inc.) was set at 350°F (177°C). The inner furnace contained a sheet metal stack 5.7" (14.5 cm) x 6" (15.2 cm) which could be held either in a horizontal position or at a 65 degree angle by means of an external riser. A 4" x 12" x 20 polished (101.6 mm x 304.8 mm x 0.529 mm) was cut into two equal parts (4" x 6" x 20 polished (101.6 mm x 125.4 mm x 0.529 mm)) and placed in a preheated oven on the horizontal stacking device. The panel was allowed to equilibrate for 10 minutes at 350°F (177°C). After the panel was equilibrated at 350°F (177°C) for 10 minutes, 3 pellets, one from Example 1, one from Example 4 and one from Comparative Experiment A were placed over the top of the preheated panel. The oven door was quickly closed, 30 seconds later the stacking unit holding the heated panel and pellets was turned to 65° to the horizontal by means of the external lifter without the oven door being opened. The stacker, panel and pellets were allowed to remain in this position for 15 minutes. After 15 minutes, the panel was removed from the oven and allowed to cool to room temperature (25°C). The maximum flow, in millimeters, from the original diameter was measured. The same procedure was repeated for example 5

and Comparative Experiment A. A series of three swashplate flow tests were evaluated for each resin, and the average flow value in millimeters is given in Table V.

Claims (17)

1. Advanced epoxy resin material comprising the product resulting from (I) polymerizing in the presence of a catalytic amount of at least one suitable polymerization catalyst (A) the reaction product of (1) a mixture comprising (a) 80-99% by weight of at least one diglycidyl ether of a dihydric phenol having an epoxide equivalent weight of 111 - 350, the epoxide equivalent weight being calculated on the basis that there are no substituent groups attached to the aromatic ring other than the hydrogen and ether oxygen atoms themselves whether the aromatic rings can actually be substituted by groups other than hydrogen; (b) 1-20 weight percent of at least one diglycidyl ether of a mono-, di- or polyether diol; with (2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to 0.05 equivalent per epoxide equivalent contained in component (A-I); and (B) a monomer mixture comprising (1) at least one vinyl aromatic monomer in an amount of 31-60 percent by weight, calculated on the combined weight of components (A), (B) and (C); (2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to 0.05 equivalent per epoxide equivalent contained in component (A-I); and eventually (3) one or more of hydroxyalkyl acrylate, hydroxyalkyl methacrylate, alkyl acrylate or alkyl methacrylate in an amount from zero to 15 percent by weight based on the combined weight of components (B-1) and (B-3); and (II) advancing in the presence of a catalytic amount of at least one suitable advancement catalyst, the product resulting from (I) with (C) at least one divalent phenol in an amount of from 0.125 to 0.8 hydroxyl equivalent per epoxide equivalent in component (A-I). 2. Advanced epoxy resin as set forth in claim 1, wherein (i) component (A-l-a) is an epoxy resin or mixture of epoxy resins represented by the following formulas (I) or (II) where each A independently is a divalent hydrocarbon group having from one to 10 carbon atoms, -O-, -S-, -S-,S-, each X independently is hydrogen, bromine, chlorine or a hydrocarbyl or hydrocarbyloxy group having 1-10 carbon atoms; each R is independently hydrogen or a methyl group; m has a value from 0-5; and n has a value of 0 or 1; (ii) component (A-l-b) is an epoxy resin or mixture of epoxy resins represented by the following formula (III). where Z is a hydrocarbyl group containing 1-12 carbon atoms or a group R<1> is independently hydrogen or a hydrocarbyl group of 1-6 carbon atoms, and p has a value from 1-100; m and R are as defined previously; and (iii) component (C) is one or more divalent phenols represented by the following formulas (VI) or (VII) where X, A and n are as previously defined. 3. Advanced epoxy resin material according to claim 2, wherein (i) component (A-l-a) is a diglycidyl ether of bisphenol A, a diglycidyl ether of tetrabromobisphenol A, a diglycidyl ether of bisphenol F, or any combination thereof; (ii) component (A-l-b) is a diglycidyl ether of a polyoxypropylene glycol, a diglycidyl ether of a dipropylene glycol, a diglycidyl ether of a polyoxyethylene glycol or any combination thereof; (iii) component (A-2) is methacrylic acid, acrylic acid or any combination thereof; (iv) component (B-l) is styrene, methylstyrene or any combination thereof; (v) component (B-2) is methacrylic acid, acrylic acid or any combination thereof; (vi) component (B-3) is hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, lauryl methacrylate or any combination thereof.; and (vii) component (C) is bisphenol A, tetrabromobisphenol A, bisphenol F or any combination thereof. 4. Advanced epoxy resin material, which includes the resulting product (I) polymerizing in the presence of a catalytic amount of at least one suitable polymerization catalyst; (A) the reaction product of (1) at least one diglycidyl ether of a dihydric phenol having an epoxide equivalent weight of 111-350, where the epoxide equivalent weight is calculated on the basis that there are no substituent groups attached to the aromatic ring other than the hydrogen and ether oxygen atoms, even though the aromatic rings may actually be substituted with groups other than hydrogen; (2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to 0.05 contained in component (A-I) with (B) a monomer mixture comprising (1) at least one vinyl aromatic monomer in an amount of 31-60 percent by weight, calculated on the combined weight of components (A), (B) and (C); (2) at least one compound containing both a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group in an amount of from 0.001 to 0.05 contained in component (A-I); and eventually (3) one or more of hydroxyalkyl acrylate, hydroxyalkyl methacrylate, alkyl acrylate or alkyl methacrylate in an amount of from 0-15 weight percent calculated on the combined weight of components (B-1) and (B-3); and (II) advancing in the presence of a catalytic amount of at least one suitable advancement catalyst, the product resulting from (I) with a mixture comprising (C) at least one dihydric phenol in an amount of from 0.125-0.8 hydroxyl equivalent per epoxide equivalent in component (A-I) and (D) at least one diglycidyl ether of a mono-, di- or polyether diol or at least one phenolically capped adduct of a diglycidyl ether of a mono-, di- or polyether diol or combination thereof where the amount of the diglycidyl ether or the amount of the diglycidyl ether contained in the capped diglycidyl ether is from 1-20 percent by weight of the components (I-A-1) and (II-D). 5. Advanced epoxy resin as stated in claim 4, where (i) component (A-l-a) is an epoxy resin or mixture of epoxy resins represented by the following formulas (I) or (II) where each A is independently a divalent hydrocarbon group having from 1-10 carbon atoms, -O-, -S-, -S-S-, 0 0 0 II il It -S-, -S-, -C-; each X independently is 0 hydrogen, bromine, chlorine or a hydrocarbyl or hydrocarbyloxy group having 1-10 carbon atoms; each R is independently hydrogen or a methyl group; m has a value from 0-5; and n has a value of 0 or 1; (ii) component (C) is one or more divalent phenols represented by the following formulas (VI) or 'VII) where X, A and n are as defined previously; and (iii) component (D) is an epoxy resin or mixture of epoxy resins represented by the following formula where Z is a hydrocarbyl group containing from 1-12 carbon atoms or a group where each R<1> is independently hydrogen or a hydrocarbyl group having 1-6 carbon atoms, and p has a value from 1-100; m and R are as defined previously. 6. Advanced epoxy resin material as set forth in claim 5, wherein (i) component (A-l-a) is a diglycidyl ether of bisphenol A, a diglycidyl ether of tetrabromobisphenol A, a diglycidyl ether of bisphenol F or any mixture thereof. (ii) component (A-2) is methacrylic acid, acrylic acid or mixtures thereof; (iii) component (B-l) is styrene, methylstyrene or any mixture thereof; (iv) component (B-2) is methacrylic acid, acrylic acid or any mixture thereof; (v) compound (B-3) is hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, lauryl methacrylate or any mixture thereof; (vi) component (C) is bisphenol A, tetrabromobisphenol A, bisphenol F or any mixture thereof; and (vii) component (D) is diglycidyl ether of a polyoxypropylene glycol or any mixture thereof. 7. Thermosetting (hardenable) material comprising a material according to claim 1, 2 or 3, and a hardening amount of a suitable hardening agent for this. 8. Thermosetable (curable) material as specified in claim 7, which is a powder coating mixture containing as a curing agent for this a biguanide and optionally containing one or more adjuvants selected from the group consisting of curing agent accelerator or catalyst, particulate filler, pigment, flow -regulating additive, gloss-regulating additive, texture-regulating additive, air-releasing additive, release aid and the like. 9. Thermosetting (curable) material as specified in claim 8, characterized in that the curing agent is dicyandiamide accelerated with 2-methylimidazole. 10. Thermosetting (hardenable) material comprising a material according to claim 4, 5 or 6, and a hardening amount of a suitable hardening agent for this. 11. Thermosetting (curable) material as specified in claim 10 which is a powder coating mixture containing, as a curing agent for this, a biguanide and possibly containing one or more adjuvants selected from the group consisting of curing agent accelerator or catalyst, particulate filler, pigment , flow-regulating additive, gloss-regulating additive, texture-regulating additive, air-releasing additive, release aid and the like. 12. Thermosetting (curable) material as stated in claim 11, where the curing agent is dicyandiamide accelerated with 2-methylimidazole. 13. Product resulting from hardening of the material according to claim 7. 14. Product resulting from hardening of the material according to claim 8. 15. Product resulting from hardening of the material according to claim 9. 16. Product resulting from hardening of the material according to claim 10. 17. Product resulting from hardening of the material according to claim 11. 1.8. Product resulting from hardening of the material according to claim 12.