Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/20—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the epoxy compounds used
  • C08G59/22—Di-epoxy compounds
  • C08G59/226—Mixtures of di-epoxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/02—Polycondensates containing more than one epoxy group per molecule
  • C08G59/04—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof
  • C08G59/06—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof of polyhydric phenols
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/02—Polycondensates containing more than one epoxy group per molecule
  • C08G59/10—Polycondensates containing more than one epoxy group per molecule of polyamines with epihalohydrins or precursors thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/182—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing using pre-adducts of epoxy compounds with curing agents
  • C08G59/184—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing using pre-adducts of epoxy compounds with curing agents with amines

Definitions

• the present invention relates to a method of making aqueous epoxy resin dispersions.
• the dispersions are useful in preparing coating compositions comprising the same.
• Epoxy resins have come into widespread use as components in coating compositions. Coatings which comprise cured epoxy resins are valued for their durability, chemical resistance, and excellent adhesion to a broad range of substrates. Particularly desirable from an environmental point of view are epoxy resins which may be applied to a substrate with either minimal or no release of volatile organic components. Toward this end, there has been much research directed to the development of aqueous dispersions and emulsions of epoxy resins.
• aqueous epoxy dispersions employs one or more additives, also known as dispersants or emulsifiers or surfactants, which are necessary to stabilize the epoxy resin in the dispersion or emulsion form.
• additives also known as dispersants or emulsifiers or surfactants
• Representative examples include an aqueous epoxy dispersion as described in U.S. Patent No. 3,301 ,804 (employing the reaction product of a boric acid ester derived from boric acid with both an alkylene glycol and a beta-dialkyl-substituted aminoalkanol as an emulsifier), U.S. Patent No. 3,634,348 (employing a phosphate ester as an emulsifying agent),
• PROX-E-141 can act as a dispersant for epoxy resin in water, but then will react along with the epoxy resin when exposed to an amine functional curing agent.
• the use of an additive to provide stability to an aqueous epoxy dispersion is preferably avoided as such additives add additional cost, formulation complexity, and may potentially interfere with the performance of a coating derived from the aqueous epoxy dispersion. It is known to prepare aqueous epoxy dispersions from self- emulsifying epoxy resins. For example, U.S. Patent No.
• 4,315,044 describes a stable epoxy dispersion composition
• a stable epoxy dispersion composition comprising (1 ) an aqueous medium; and (2) between about 50-70 weight percent of self- emulsifying epoxy resin which is the addition product of reactants comprising (a) 40-90 parts by weight of diglycidyl ether of dihydric phenol, (b) 5-35 parts by weight of dihydric phenol, and (c) 2-1 5 parts by weight of diglycidyl ether of polyoxyalkylene glycol, wherein the molecular weight of the epoxy resin is in the range between about
• the dispersion can also contain 1 -25 weight percent based on resin solids of a water-immiscible C 8 -C 20 aliphatic monoepoxide reactive diluent.
• U.S. Patent No. 4,608,406 describes stable aqueous epoxy resin dispersions comprised of (1 ) an aqueous medium; and (2) between about
• self-emulsifying epoxy resin which is the addition reaction product of (a) 40-90 parts by weight of a diglycidyl ether of a dihydric phenol; (b) 5-35 parts of a dihydric phenol; (c) 2-15 parts by weight of a diglycidyl ether of a polyoxyalkylene glycol; and (d) 2 to 15 parts by weight of an alkyl phenol-formaldehyde novolac resin wherein the molecular weight of the epoxy resin is in the range of about 1000 to about 20,000.
• the stable dispersions can be modified by the addition of about 1 to about 25 weight percent of an aliphatic monoepoxide reactive diluent.
• the stable aqueous epoxy resin dispersions can be modified by the addition of about 5-20 weight percent, based on resin solids weight, of a water-miscible solvent which, preferably, is a 2 to 8 carbon glycol or glycol ether.
• a primary object of this invention to provide a self-dispersing curable epoxy resin which may be dispersed in water without the necessity for an additive to stabilize the epoxy dispersion.
• Another object of this invention is to provide aqueous dispersions of self-dispersing curable epoxy resins which exhibit long term stability under ambient storage conditions.
• Yet another object of this invention is to provide coating compositions incorporating a self-dispersing curable epoxy resin, where the coating composition exhibits excellent properties when cured.
• a self-dispersing curable epoxy resin dispersion can be prepared by a process comprising: reducing the particle size of a mixture comprised of a self- dispersing curable epoxy resin based on a polyoxyalkyleneamine, water and an organic cosolvent and removing at least a major amount of said organic cosolvent from said mixture after said reducing.
• the self-dispersing curable epoxy resin is based on a polyoxyalkyleneamine.
• a polyoxyalkyleneamine was present as a chemical precursor of the epoxy resin or a starting material therefor.
• the self-dispersing curable epoxy resin of the invention is in the form of an aqueous dispersion. When cured, films of the self-dispersing curable epoxy resin dispersion are useful as a coating composition.
• the self-dispersing curable epoxy resin used as a starting material herein can be any one of several self-dispersing curable epoxy resins that are based upon a polyoxyalkyleneamine.
• the self-dispersing curable epoxy resin based on a polyoxyalkyleneamine is prepared by reacting (a) 1 .0 reactive equivalents of an epoxy resin, (b) from about 0.01 to 1 .0 reactive equivalents (e.g.
• the epoxy resin is prepared by reacting an epoxy resin with a polyoxyalkyleneamine having a molecular weight of from about 3,000 to about 15,000 in a ratio of about 0.001 to 0.060 reactive equivalents of polyoxyalkyleneamine to about 1 .0 reactive equivalents of epoxy resin.
• a polyoxyalkyleneamine having a molecular weight of from about 3,000 to about 15,000 in a ratio of about 0.001 to 0.060 reactive equivalents of polyoxyalkyleneamine to about 1 .0 reactive equivalents of epoxy resin.
• the epoxy resin composition is prepared by reacting (a) 1 .0 reactive equivalents of an epoxy resin, (b) from about
• the polyoxyalkyleneamine reactant comprises one or more amino- compounds where the amino-compound comprises both an amine group and a substantially water-soluble polyether chain.
• the polyoxyalkyleneamine reactant is soluble or at least partially soluble in water.
• Techniques to prepare suitable polyoxyalkyleneamine reactants are known in the art, and include reacting a hydroxyl group containing initiator with ethylene oxide and/or propylene oxide, followed by conversion of the resulting terminal hydroxyl group(s) to amine(s).
• Illustrative of the polyoxyalkyleneamine reactants employed in the invention are the Jeffamine (Reg. TM) brand of polyoxyalkyleneamines available from Texaco Chemical Company, Bellaire, Texas.
• Polyoxyalkyleneamines of this invention have the structural formula R r O-R 2 -CH 2 CH(R 3 )-NH 2 wherein
• R 1 designates a monovalent organic radical selected from the group consisting of C 1 to C 12 aliphatic, aiicyclic or aromatic hydrocarbons
• R 2 represents a polyoxyalkylene chain having the structural formula:
• R 4 is a monovalent organic radical selected from the group consisting of C, to C 4 aliphatic hydrocarbons,
• 'a' designates a number of ethoxy groups (CH 2 -CH 2 -O)
• 'b' designates a number of monosubstituted ethoxy groups (CH 2 -CH(R 4 )- O) where the substitution of one monosubstituted ethoxy group is independent from the substitution of any other monosubstituted ethoxy group in the polyoxyalkylene chain, the sum of 'a' and 'b' is equal to or greater than 10 but less than or equal to 200, and where the sequence of ethoxy and monosubstituted ethoxy groups within a polyoxyalkylene chain may be completely random and/or there may be blocks of ethoxy and/or monosubstituted ethoxy groups, and R 3 designates H or a monovalent organic radical selected from the group consisting of C 1 to C 4 aliphatic hydrocarbons.
• the polyoxyalkyleneamine is adducted with an aliphatic polyepoxide and the adduct is reacted with an epoxy resin.
• the preferred polyoxyalkyleneamines have R,, R 3 and R 4 each equal to methyl, and either (i) a ratio of 'a' and 'b' of about
• the most preferred polyoxyalkyleneamine is Jeffamine (Reg. TM) M-2070 from Texaco Chemical Company, Bellaire Texas. According to
• this polyoxyalkyleneamine is prepared by reacting methanol with ethylene oxide and propylene oxide followed by conversion of the resulting terminal hydroxyl group to an amine.
• the most preferred polyoxyalkyleneamine has an approximate molecular weight of 2,000 and a mole ratio of propylene oxide to ethylene oxide of 10/32.
• the polyoxyalkyleneamine is directly reacted with an epoxy resin.
• the polyoxyalkyleneamine will have a molecular weight of from about 3,000 to about 1 5,000 and will be directly reacted with the epoxy resin in a ratio of about 0.001 to 0.060 reactive equivalents of polyoxyalkyleneamine to about 1 .0 reactive equivalents of epoxy resin.
• Preferred polyoxyalkyleneamines have R 1 f R 3 and R 4 each equal to methyl, and either (i) a ratio of 'a' to 'b' of about 19: 1 (e.g.
• a ratio of 'a' to 'b' of about 9: 1 e.g. a weight ratio of about 90% by weight ethoxy to about 10% by weight iso-propoxy
• the ethoxy and iso-propoxy groups are arranged substantially in two blocks and the molecular weight of the polyoxyalkyleneamine is from about 5,000 to about 6,000, or
• a ratio of 'a' to 'b' of about 7:3 e.g. a weight ratio of about
• 8 molecular weight of the polyoxyalkyleneamine is from about 5,000 to about 6,000, or (v) a ratio of 'a' to 'b' of about 9: 1 (e.g. a weight ratio of about 90% by weight ethoxy to about 10% by weight iso-propoxy), wherein the ethoxy and iso-propoxy groups are arranged substantially in two blocks and the molecular weight of the polyoxyalkyleneamine is from about 9,000 to about 10,000 or (vi) a ratio of 'a' to 'b' of about 7:3 (e.g.
• the most preferred polyoxyalkyleneamines are the Jeffamine (Reg. TM) polyoxyalkyleneamines from Texaco Chemical Company, Bellaire Texas. According to Texaco, these polyoxyalkyleneamine are prepared by reacting methanol with ethylene oxide and propylene oxide followed by conversion of the resulting terminal hydroxyl group to an amine.
• the most preferred polyoxyalkyleneamine has an approximate molecular weight of 3,000 and a weight ratio of ethylene oxide to propylene oxide of about 19: 1 .
• the Aliphatic Polyepoxide reactant comprises one or more compounds each having a plurality of epoxide functional groups.
• the aliphatic polyepoxide reactant has at least 2 epoxide groups present in the molecule, and may have as many as 6 epoxide groups present in the molecule.
• Techniques to prepare suitable polyepoxide compounds are known in the art, and include reacting compounds having a plurality of hydroxyl groups with epichlorohydrin in the presence of a suitable catalyst.
• Suitable aliphatic polyepoxide compounds are commercially available from Henkel Corporation, Ambler Pennsylvania under the trademarks "Capcures Reg. TM" or "Photomers Reg. TM"
• One representative class of aliphatic polyepoxide reactant according to the invention has the structural formula: R 5 (R 6 -H) c (R 6 -CH 2 -CH-CH 2 ) d
• R 5 designates a linear, branched or cyclic aliphatic or alicyclic organic radical having a valency equal to the sum of 'c' and 'd', where the sum of 'c' and 'd' is equal to or greater than 2 but no more than or equal to 6 and where 'd' is equal to or greater than 2 but less than or equal to 6.
• R 5 designates a linear, branched or cyclic aliphatic or alicyclic divalent organic radical having from 2 to 14 carbon atoms, and specifically includes the hydrocarbon portions of the dihydric alcohols ethylene glycol, butylene glycol, hexylene glycol, decanediol and dodecanediol which remain after the hydroxyl groups have been removed, and when the sum of 'c' and 'd' equals three (3), R 5 designates a linear, branched or cyclic aliphatic or alicyclic trivalent organic radical having from 3 to 14 carbon atoms, and specifically includes the hydrocarbon portions of the trihydric alcohols glycerol, 1 ,1 ,1-tris(hydroxymethyl)ethane, and 2-ethyl- 2-(hydroxymethyl)-1 ,3-propanediol which remain after the hydroxyl groups have been removed, and when the sum of '
• R 5 ⁇ esignates a linear, branched or cyclic aliphatic or alicyclic hexavalent organic radical having from 8 to 30 carbon atoms, and specifically includes the hydrocarbon portion of the hexahydric alcohol dipentaerythritol which remains after the hydroxyl groups have been removed, and
• R 6 represents a divalent polyoxyalkylene chain having the structural formula:
• R 7 is a monovalent organic radical selected from the group consisting of C, to C 4 aliphatic hydrocarbons,
• 'e' designates a number of ethoxy groups (CH 2 -CH 2 -O)
• 'f designates a number of monosubstituted ethoxy groups (CH 2 - CH(R 7 )-O) where the substitution of one monosubstituted ethoxy group is independent from the substitution of any other monosubstituted ethoxy group in the polyoxyalkylene chain, the sum of 'e' and 'V is equal to or greater than 0 but less than or equal to 10, and where the sequence of ethoxy and monosubstituted ethoxy groups within a polyoxyalkylene chain may be completely random and/or there may be blocks of ethoxy and/or monosubstituted ethoxy groups.
• the most preferred aliphatic polyepoxide compound is the reaction product of pentaerythritol, propylene oxide and epichlorohydrin, having an epoxide equivalent weight (EEW) of about 230.
• the epoxy resin used in the practice of this invention comprises one
• R 8 represents a 'g' valent C 6 -C 50 organic radical comprising at least one six-carbon aromatized ring (e.g. when g is 2, R 5 can be -CH 2 - O -0-
• C(CH 3 ) 2 -0-O-CH 2 - or R 5 can be -CH 2 - O -0-CH 2 -0-O-CH 2 - wherein 0 represents a phenyl group), and 'g' is equal to or greater than 2 but less than or equal to 6.
• epoxy resins include reacting compounds having 2 or more hydroxyl groups with epichlorohydrin in the presence of a suitable catalyst.
• Suitable epoxy resins are commercially available from a variety of sources and include EPON (Reg. TM) epoxy resins from Shell Chemical Company, Houston, Texas, and DER
• Suitable epoxy resins are:
• Polyglycidyl and poly(beta-methylglycidyl) esters obtainable by reacting a compound having at least two carboxy groups in the molecule with epichlorohydrin or beta-methyl-epichlorohydrin, respectively.
• the reaction is advantageously carried out in the presence of bases.
• aromatic poiycarboxylic acids which may be used include, for example, phthalic acid, isophthalic acid or terephthalic acid.
• Polyglycidyl or poly(beta-methylglycidyl) ethers obtainable by reacting a compound having at least two free phenolic hydroxy groups with epichlorohydrin or beta-methyl-epichlorohydrin, respectively, under alkaline conditions, or in the presence of an acid catalyst and with subsequent alkali treatment.
• the epoxy compounds of this type may be derived from mononuclear phenols, such as, for example, resorcinol or hydroquinone; or they are based on polynuclear phenols, such as, for example, bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 1 , 1 ,2,2-tetrakis(4- hydroxyphenyDethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5- dibromo-4-hydroxyphenyl) propane, and from novolacs obtainable by condensation of aldehydes, such as formaldehyde, acetaldehyde, chloral or furfuraldehyde, with phenols, such as phenol, or with phenols that are substituted in the nucleus by halide atoms or C C 18 (preferably C,- C 9 ) alkyl groups, such as,
• epoxy resins that have an epoxy content of from 2 to 10 equivalents/mole and that are glycidyl ethers or glycidyl esters of aromatic or alkylaromatic compounds.
• Especially preferred epoxy resins are polyglycidyl ethers of bisphenols, such as, for example, of 2,2-bis(4- hydroxyphenyOpropane (bisphenol A) or bis(4-hydroxyphenyl)methane (bisphenol F), or novolacs formed by reacting formaldehyde with a phenol.
• bisphenol A 2,2-bis(4- hydroxyphenyOpropane
• bisphenol F bis(4-hydroxyphenyl)methane
• novolacs formed by reacting formaldehyde with a phenol for reasons of cost and availability, the most preferred epoxy resins are polyglycidyl ethers based on bisphenol A.
• Preferred epoxy resins have an epoxide equivalent weight of less than about 400 grams/equivalent, e.g. from about 100 grams/equivalent to about 350 grams/equivalent, more preferably from about 1 50 grams/equivalent to about 225 grams/equivalent, e.g. DER 331 available from Dow Chemical at
• the polyhydric phenol reactant comprises one or more compounds each having a plurality of hydroxyl groups covalently bonded to one or more six-carbon aromatized rings.
• the polyhydric phenol reactant may contain substituents such as alkyl, aryl, sulfido, sulfonyl, halo, and the like.
• the polyhydric phenol is represented by the structural formula:
• R 9 represents an 'h' valent C 6 -C 50 organic radical comprising at least one six-carbon aromatized ring, and 'h' represents a number of phenolic hydroxyl groups where 'h' is equal to or greater than 2 but less than or equal to 6.
• Suitable polyhydric phenol compounds are commercially available from Dow Chemical Company, Midland, Michigan, and Shell Chemical Company, Houston, Texas.
• Suitable polyhydric phenols are 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-bromo-4-hydroxyphenyl)- propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 2,2-bis(3-chloro-4- hydroxyphenyDpropane, bis(4-hydroxyphenyl)-methane, bis(4- hydroxyphenyDsulfone, bis(4-hydroxyphenyl)sulfide, resorcinol, hydroquinone, phenol-formaldehyde novolac resins, and the like.
• the most preferred dihydric phenols are 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) and bis(4-hydroxyphenyl)methane (bisphenol F) for reasons of cost and availability.
• the preparation of certain of the self-dispersing curable epoxy resins of the invention proceeds through an amine-epoxy adduct, where the amine- epoxy adduct is subsequently reacted with an epoxy resin and, optionally, a polyhydric phenol.
• the structure of the amine-epoxy adduct is dependant on the structures of the polyoxyalkyleneamine and the aliphatic polyepoxide used in the preparation of the amine-epoxy adduct, as well as the relative ratio of the reactants.
• An adduct formed by reacting 1 .0 equivalents of an aliphatic polyepoxide and from about 0.3 to 0.9 reactive equivalents, preferably from about 0.6 and 0.8 reactive equivalents of a polyoxyalkyleneamine will produce compounds having the structural formula: ((CH 2 -CH-R 6 ) (d . 1 ) (H-R 6 ) c R 5 R 6 -CH(OH)CH 2 -N-
• 'V indicates a number of repetitive units where 'i' is equal to or greater than zero (0) but less than or equal to about fifty.
• the adduct is formed by reacting 1 .0 equivalents of an aliphatic polyepoxide with from greater than about 1 .0 equivalents (preferably from about 1 .01 to about 2.5) reactive equivalents of a polyoxyalkyleneamine, the adduct will have the structural formula:
• 'V indicates a number of repetitive units where 'i' is equal to or greater than zero (0) but less than or equal to about fifty, typically from about 10 to about 20.
• the self-dispersing curable epoxy resins of the invention can be prepared by reacting an amine-epoxy adduct with a polyhydric phenol and an epoxy resin.
• the structure and composition of the self-dispersing curable epoxy resin will depend on the identity of the amine-epoxy adduct, the identity of the epoxy resin, the identity of the polyhydric phenol and the relative ratio of the reactants.
• the amine-epoxy adduct is the reaction product of (a) 1 .0 reactive equivalents of an epoxy resin, (b) from about 0.01 to 1 .0 reactive equivalents, preferably from about 0.4 to 0.6 reactive equivalents of a polyhydric phenol, and (c) from about
• 0.005 to 0.5 reactive equivalents typically from about 0.005 to 0.05 reactive equivalents, more typically from about 0.005 to 0.025 reactive equivalents, and preferably from about 0.005 to 0.015 reactive equivalents.
• the products of the above reaction are envisioned to be an extremely complex mixture of polymeric materials comprising two distinct groups.
• a simplified structure for each group of reaction products can be shown if it is assumed that the phenolic component is dihydric and the epoxy
• component is a diepoxide
• ']' indicates a number of repeating units, and is equal to or greater than zero (0) but less than or equal to twenty (20).
• the self-dispersing curable epoxy resin of the present invention may be any one of the present invention.
• the cosolvent serves to reduce the viscosity of the self-dispersible curable epoxy resin before its dispersion in water as well as that of the aqueous pre-emulsion of the epoxy resin and the aqueous emulsion that is formed by reduction of the particle size of the resin in the pre-emulsion.
• Another function that the organic cosolvent may perform is the prevention of agglomeration of dispersed resin particles which stabilizes the dispersion of the resin.
• a variety of organic cosolvents are considered suitable for use in this invention. Suitable
• cosolvents consist of non-solvents as well as solvents for the self-dispersible epoxy resins.
• the cosolvent may be miscible, partly miscible or immiscible with water. Mixtures of two or more organic cosolvents can also be employed in this invention.
• organic cosolvents include the lower fatty acid esters or alkyl ethers of monohydric and dihydric alcohols
• alkyl group comprises linear or branched aliphatic or alicyclic chains and lower alkyl ketones, e.g. ketones having a total of from 3 to 6 carbon atoms, preferably methyl lower-alkyl ketones, wherein said lower alkyl group has from 1 to 3 carbon atoms.
• cosolvent can affect the pot-life of the self-dispersing curable epoxy resin. For example, for a given resin it may be possible to increase the pot-life by substituting for a cosolvent such as Ektasolve EP (Eastman
• the preferred stable aqueous epoxy resin dispersions of the present invention are those which contain a water-immiscible C 8 -C 20 aliphatic
• the said monoepoxide component can contain alicyclic and aromatic structures, as well as halogen, sulfur, phosphorus, and other such heteroatoms.
• Suitable reactive diluents are available from CVC Specialty Chemicals, Inc., Cherry Hill, New Jersey.
• monoepoxide reactive diluents are epoxidized unsaturated hydrocarbons such as decene and cyciohexene; glycidyl ethers of monohydric alcohols such as 2-ethylhexanol, dodecanol and eicosanol; glycidyl esters of monocarboxylic acids such as hexanoic acid; acetals of glycidaldehyde; and the like.
• the preferred reactive diluent is glycidyl ether of monohydric C 8 -C 10 aliphatic alcohols.
• a water-immiscible C 8 -C 20 aliphatic monoepoxide reactive diluent in an aqueous epoxy resin dispersion has significant beneficial effects in addition to modifying the viscosity of the dispersion.
• the said water-immiscible reactive diluent appears to coat the particles of epoxy resin solids and thereby provide the aqueous dispersion with improved shear, freeze-thaw resistance, shelf viscosity stability, and paint gloss.
• the reactive diluent is epoxy functional, it becomes chemically bonded into the film which is formed during the subsequent room
• aqueous dispersion composition after it has been blended with a curing agent and coated on a surface.
• the total quantity of reactive diluent contributes to the calculated proportion of non-volatiles in the dispersion composition.
• an amine-epoxy adduct is first prepared by combining the
• the respective self-dispersing epoxy resin is prepared by combining the amine-epoxy adduct, the polyhydric phenol and the epoxy resin, and heating the mixture in the presence of a catalyst, e.g., potassium hydroxide, triphenyl phosphine, benzyl dimethylamine and the like, to a temperature of about 1 50° C with stirring. An exothermic reaction will then occur, and cooling is applied to maintain the reaction temperature at about 150-160°C.
• a catalyst e.g., potassium hydroxide, triphenyl phosphine, benzyl dimethylamine and the like
• the mixture is maintained at about 160°C for about one hour subsequent to the conclusion of the exothermic reaction. If the reaction has not proceeded to the desired degree of completion (as determined by the epoxide equivalent weight of the resin), the mixture is then heated to 190°C. The mixture is then maintained at 190°C for about
• the polyoxyalkyleneamine is reacted directly with the epoxy resin to prepare a self-dispersing curable epoxy resin.
• the conditions employed for such a reaction may be the similar to the conditions under which the amine-epoxy adduct is formed.
• the aqueous epoxy dispersion of the invention can be prepared by charging the self-dispersing curable epoxy resin, as a mixture with an organic cosolvent, to a reaction vessel, then heating the resin to about 50- 100°C with stirring. Water is then mixed with the mixture of organic cosolvent and self-dispersing curable epoxy resin to form an aqueous pre- emulsion which will typically be a disperse oil phase having a larger particle size.
• the relative amounts of the resin, water and organic cosolvent can vary broadly, but will typically be roughly equal, e.g. the amounts of each of resin, water and organic cosolvent will range between about 20% to about 50% each, more typically from about 35% to about 45% resin, and about 25% to about 35% each of water and organic cosolvent.
• One or more reactive diluents can be mixed into the pre-emulsion prior to reduction of particle size or they can be added to the aqueous dispersion after the reduction of the particle size.
• the particle size of the oil phase in the aqueous dispersion can be modified by physical techniques to reduce the particle size.
• the particle size reduction is preferably accomplished by subjecting the aqueous dispersion to high shear, e.g. in a homogenizer such as that disclosed in U.S. Patent No. 4,533,254 (Cook et al.), the disclosure of which is incorporated herein by reference, and commercially available as MICROFLUIDIZERTM from Microfluidics Corporation, Newton, Massachusetts. Homogenizers are discussed in W. C. Griffin, "Emulsions", Encyclopedia of Chemical
• the reduction of particle size should be effective to reduce the mean (weight average) particle size of the oil phase in the aqueous dispersion to less than about 5 microns, preferably less than about 3 microns and typically less than 1 micron, e.g. typically from about 0.1 to about 3 microns.
• organic cosolvent After reduction of the particle size, at least a portion of the organic cosolvent is removed.
• the organic cosolvent is removed by volatilizing the same from the mixture. This is an evaporative process that may be considered a distillation.
• Sufficient organic cosolvent should be removed so that the aqueous dispersion will be low in volatile organic compounds, and preferably essentially free of such compounds. Typically, less than 1 %, more typically less than 0.1 % by weight of organic cosolvent remains in the
• the removal of the organic cosolvent will be facilitated by subjecting an agitated dispersion to elevated temperatures and/or reduced pressures, e.g. a vacuum distillation.
• elevated temperatures and/or reduced pressures e.g. a vacuum distillation.
• the precise temperature and pressure employed to effect removal of the organic cosolvent will, of course, depend upon the volatility of the organic cosolvent chosen, but temperatures that will cause degradation or polymerization of the resin should be avoided. Distillation is discussed in E. Hafslund, "Distillation", Encyclopedia of Chemical Technology, vol. 7, pp. 849-891 (Kirk-Othmer, eds. John Wiley & Sons,
• the aqueous dispersion of self-dispersing resin will typically exhibit excellent chemical and physical stability over an extended shelf-life, e.g. of from five to six months.
• the epoxide equivalent weight (EEW) of the aqueous dispersion of self-dispersing resin should remain essentially constant, e.g. should show no trend of increasing molecular weight, over a period of at least one month from the preparation of the aqueous dispersion.
• Epoxide equivalent weight can be determined by differential titration with perchloric acid using crystal violet as an indicator (e.g. a first sample is titrated with 0.1 N perchloric acid to an endpoint that shows the first sight of green color from the crystal violet indicator, the amine equivalent weight
• the resin should not display layer formation for a period of at least one month from the preparation of the aqueous dispersion, i.e. there should be no formation of a macro-observable water phase as a layer separate from the dispersed resin phase.
• Coating Compositions Comprising an Aqueous Dispersion of the Self- Dispersing Curable EPOXV Resin
• the coating composition of the invention is prepared by combining the aqueous epoxy dispersion with a suitable hardening agent.
• the coatings are tack free after 45 minutes and have excellent film properties.
• An aqueous epoxy resin paint composition of the present invention may further contain additives conventionally employed in coating technology, such as organic pigments, inorganic pigments, surfactants, thickeners, and the like.
• a room temperature curable water-borne coating composition is
• the ratio of active amino hydrogens to epoxy groups in the admixture is in the range of from 0.5:1 to 2:1 and, preferably, is in the range between about 0.8:1 to 1.5:1.
• the amino hydrogens must be sufficiently reactive to effect
• Suitable polyamine curing agents are those which are soluble or dispersible in water and which contain more than 2 active hydrogen atoms per molecule. Examples of such curing agents are alkylene polyamines
• alkylene polyamines include ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, propylene diamine, dibutylene triamine, hexamethylene diamine, and the like.
• polyamido amines which are reaction products of alkylene polyamines and fatty acids.
• polyamidoamines are well known in the art and are described in U.S. Pat. Nos. 2,705,223, 2,81 1 ,495 and
• polyamine curing agents are the adducts of polyamines and epoxy compounds such as those described in U.S. Pat. Nos. 2,651 ,589,
• Examples of useful curing agents also include those disclosed in U.S. patent application Serial No. 08/085,861 , filed June 30, 1 993, entitled “Curing Agents for Aqueous Epoxy Resins", by Jason Chou et al., the disclosure of which is incorporated herein by reference.
• epoxy curing agents comprise the reaction product of reactants consisting essentially of an alkylene polyamine having less than about 12 carbon atoms, an aromatic mono-glycidyl ether having less than about 1 8 carbon atoms, and a diglycidyl ether of an aromatic diol having an average degree of oligomerization of less than about 3.5, wherein the ratio of primary amine equivalents of said alkylene polyamine to the total epoxide equivalents of said aromatic glycidyl ether and said diglycidyl ether of an aromatic diol is not essentially less than one, and the ratio of epoxide equivalents of said aromatic mono-glycidyl ether to epoxide equivalents of said diglycidyl ether of an aromatic diol is greater than one.
• Another useful curing agent is described in U.S. Serial No. 08/279,587, filed July 25, 1994, the disclosure
• an amine component consisting essentially of a mono-alkylene polyamine having less than about 12 carbon atoms (preferably a member selected from the group consisting of lower alkylene diamines, said member having from 2 to 8 carbon atoms and, more preferably, only straight-chain alkylene groups) and an alicyclic polyamine, said alicyclic polyamine being present in an amount of greater than about 10% of the amine equivalents of said amine component;
• an aromatic mono-glycidyl ether having less than about 18 carbon atoms (preferably selected from the group consisting of mono-alkylphenyl glycidyl ethers and di-alkyl phenyl glycidyl ethers having from 9 to 13 carbon atoms); and
• the molar equivalents of primary amine groups of said polyalkylene polyamine are in excess of the molar equivalents of glycidyl groups, e.g. a ratio offrom about 1.5:1 to 2.5:1 , preferably from about 1.75:1 to about 2.25:1), and (ii) the ratio of epoxide equivalents of said aromatic mono-glycidyl ether to epoxide equivalents of said diglycidyl ether of an aromatic diol is greater than one (preferably greater than 1.5, more preferably from about 2:1 to about 6:1 , and most preferably from about 3:1 to 5:1 ).
• a curing accelerator can be included in the coating composition.
• Such an accelerator will serve to reduce the time for the coating to become tack-free.
• Useful accelerators for amine curing agents include tertiary amines, e.g. N,N'-bis(dimethyl-amino- prop ⁇ l) urea.
• curing agents can be used in the composition of this invention, particularly when the coatings made from the compositions are heated to effect a cure.
• additional curing agents are the aminoplast and phenolplast resins.
• Suitable aminoplast resins are the reaction products of ureas and melamines with aldehydes further etherified in some cases with an alcohol.
• Examples of aminoplast resin components are urea, ethylene
• the aminoplast resins can be used in the alkylol form but, preferably, are utilized in the ether form wherein the etherifying agent is a monohydric alcohol containing from 1 to 8 carbon atoms.
• suitable aminoplast resins are methylol urea, dimethoxymethylol urea, butylated polymeric urea-formaldehyde resins, hexamethoxymethyl melamine, methylated polymeric melamine-
• Phenolplast resins are the reaction products of phenols and aldehydes which contain reactive methylol groups. These compositions can be monomeric or polymeric in nature depending on the molar ratio of phenol to aldehyde used in the initial condensation reaction. Examples of suitable phenols are phenol, o, m or p-cresol, 2,4-xylenol, 3,4-xylenol, 2,5-xylenol, cardanol, p-tert-butyl phenol, and the like.
• Useful aldehydes are formaldehyde, acetaldehyde and propionaldehyde.
• Particularly useful phenolplast resins are polymethylol phenols wherein the phenolic group is etherified with an alkyl, e.g., methyl or ethyl, group.
• Other epoxy resin e.g., methyl or ethyl, group.
• curing agents may also be useful, e.g. catalytic curing agents: Lewis bases (such as tertiary amines), Lewis acids (such as boron trifluoride), cationic curing agents (such as aryldiazonium salts, diaryliodinium salts, onium salts of Group Via elements, especially sulfur) and reactive curing agents:
• Lewis bases such as tertiary amines
• Lewis acids such as boron trifluoride
• cationic curing agents such as aryldiazonium salts, diaryliodinium salts, onium salts of Group Via elements, especially sulfur
• reactive curing agents such as aryldiazonium salts, diaryliodinium salts, onium salts of Group Via elements, especially sulfur
• the product amine polyepoxide adduct has 0.4 meq./gm of total amine and 0.33 meq./gm of epoxide which indicates that about 66% of the initial free epoxide groups have been reacted with the amine.
• Example 1 was repeated except 75.0 gm (0.063 equivalent) of polyethoxy amine* and 35.5 gm (0.126 equivalent) polyepoxide of propoxylated (5PO) pentaerythritol were reacted.
• the resulting adduct yielded a product containing 0.34 me*/gm of total amine and 0.54 me/gm of epoxide which represents 50% of the original epoxide moiety capped with the amine.
• Example 1 was repeated except 75 gm (0.063 equivalent) of polyethoxy amine* and 23.6 gm (0.083 equivalent) polyepoxide of propoxylated (5PO) pentaerythritol were reacted.
• the resulting adduct yielded a product containing 0.4 me/gm of total amine and 0.26 me/gm of epoxide which represents about 75% of the initial epoxide capped with the amine.
• Example 1 was repeated except 50.0 gm polyethoxy amine* (0.0831 equivalent) and 35.0 gm (0.1245 equivalent) polyepoxide of propoxylated
• the resulting adduct contained 0.61 me/gm of total amine and 0.37 me/gm of epoxide which represents about
• Example 1 D Example 1 was repeated except 1 50.0 gm (0.102 equivalent) of polyethoxy amine* and 41 .6 gm (0.1 53 equivalent) polyepoxide of propoxylated (5PO) pentaerythritol were reacted. The resulting adduct contained 0.32 me/gm of total amine and 0.31 me/gm of epoxide which represents about 66% of the initial epoxide capped with the amine.
• reaction mixture After the exothermic reaction subsides, the reaction mixture is maintained at 160°C for an additional hour followed by a 1 5 minute period at 1 90°C. The reaction mixture is then cooled to 160°C and 14 grams of propyl cellosolve is added which immediately begins refluxing. The reaction mixture is cooled to 100°C and analyzed. The resultant self-dispersing resin, present at 87.5%
• Example 3A the reactant charge included an aliphatic glycidyl ether which is the glycidylization reaction product of mixed seven carbon aliphatic alcohols and is available from CVC Specialty Chemicals, Cherry Hill, New Jersey, as GE-7.) TABLE I
• Example 4A above is repeated except 87.47 grams (0.0735 equivalent) of Jeffamine M-2070 and 1 1 .84 grams (0.042 equivalent) of polyepoxide of propoxylated (5 moles propylene oxide per mole of) pentaerythritol is heated at 125-130°C for two hours and at 140°C for one hour. The resulting product is cooled to 70°C and analyzed. Analysis shows zero epoxide content and 0.42 meq/g of total amine value.
• the reaction mixture is heated slowly to 1 50°C with stirring whereupon an exothermic reaction is observed. Cooling is immediately applied to maintain the reaction temperature between 1 50°C and 1 60°C.
• reaction mixture is maintained at 160°C for an additional hour followed by a 1 5 minute period at 190°C.
• the reaction mixture is then cooled to 1 60°C and 14 grams of propyl cellosolve is added which immediately begins refluxing.
• the reaction mixture is cooled to 125°C and 12.0 g of the Example IA adduct is added.
• the reaction mixture is heated at 125-130°C for one hour. It is then cooled to 100°C and analyzed.
• the resulting resin is about 87.5% solids in propyl
• cellosolve has an equivalent weight (EEW) about 617 (based on solids) and 0.07 meq/g of total amine.
• EW equivalent weight
• Example 5A was repeated except 12.0 g of the amine/epoxide adduct from example 4B is used.
• the resulting self-dispersing resin is about 87.5% solids in propyl cellosolve with an EEW (epoxy equivalent weight) of 594.0.
• the reaction mixture is heated slowly to 1 50°C with stirring whereupon an exothermic reaction is observed. Cooling is immediately applied to maintain the reaction temperature between 1 50°C and 160°C.
• reaction mixture is maintained at 160°C for an additional hour followed by a 1 5 minute period at 190°C.
• the reaction mixture is then cooled to 160°C and 14 grams of propyl cellosolve is added which immediately begins refluxing.
• the reaction mixture is cooled to 125 °C and 10.32 g of Jeffamine 6940-20
• the reaction mixture is heated at 125-130°C for one hour. It is then cooled to 100°C and analyzed.
• the resulting SDR should be about 88% solids in propyl cellosolve and should have an equivalent weight (EEW) about 617 (solid) and 0.07 meq/g total
• a solution of the self-dispersing resins prepared as in Example 2 is prepared by mixing 84 parts by weight of the self-dispersing resin with 49 parts by weight of methyl ethyl ketone. The mixture is stirred and warmed to effect a homogenous mixture. This mixture is then poured into 56 parts by weight of deionized water with vigorous stirring with a high speed mixer.
• the resulting pre-emulsion is then twice passed through a Microfluidizer, Model 1 10T, at 85 psi.
• the resulting dispersion is then subjected to rotary
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 2A.
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 3.
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 3A.
• Example 7E The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 3B.
• Example 7F The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 3C.
• Example 7G
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 3D.
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 3E.
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 3F.
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 5A.
• Example 7K The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 5B.
• Example 7A The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 6A.
• Example 7M The procedure, of Example 7A is repeated, except the self-dispersing
• Example 7N The procedure, of Example 7A is repeated, except the self-dispersing resin is prepared as in Example 6C.
• Example 7A Into a 25 ml plastic cup is charged the water-borne dispersion prepared according to Example 7A followed by an equal equivalent amount of epoxy curing agent available as 8290 by HiTech (a modified diethylene triamine with a hydrogen equivalent weight of 163). Sufficient water is then added to bring the mixture to a spreadable consistency. The epoxy dispersion/curing agent blend is aged for 10 minutes then a film casting is produced by drawing the blend down on pre-sanded TRU COLD cold rolled steel panel (3 x 6 x 0.32 inches) using a #34 wire wound steel rod.
• This example can be repeated but with substitution of the self-dispersing resin prepared according to each of Examples 7B - 7N in each case for the self- dispersing resin prepared according to each of Example 7A.

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