CA1227202A - Hydroxyl terminated polyfunction epoxy curing agents - Google Patents

Abstract

HYDROXYL TERMINATED POLYFUNCTIONAL
EPOXY CURING AGENTS

ABSTRACT OF THE DISCLOSURE

A polyglycidyl derivative of an aromatic diamine, aminophenol, or polyphenol and a diglycidyl ether of a bisphenol are reacted with a bisphenol, in the presence of a catalyst at elevated temperature, to yield a reaction product wherein each glycidyl group is effectively endcapped with a moiety containing a free hydroxyl group. The ratio of equivalents of polyglycidyl compound to diglycidyl compound is 1 to 4 to 1 to 1, and of bisphenol to total glycidyl compounds is 1.8 to 1 to 2.4 to 1. Said product is useful for curing solid epoxy resins. The epoxy resins cured by said product have a dense crosslinked network resulting in concomitant superior coating properties especially chemical resistance while maintaining good flexibility.

Description

~22~2 The instant invention pertains to polyfunctional finlike hydroxyl terminated hardener products and to curable solid epoxy resin compositions containing said hardeners.

.
The reaction of epoxy resins with finlike hydroxy-containing compounds in the presence of a catalyst is well known in the art. This reaction is typified by the reaction of bisphenol A (- BRA or I isopropylidenediphenol) with liquid BRA epoxy resins to form solid high molecular weight products.

U.S. Patent No. 3,931,109 teaches the termination of basic liquid BRA epoxy resins as well as epoxy novolac resins with bisphenol A to give finlike hydroxyl terminated hardeners.

U.S. Patent No. 3,931,109 also teaches curable compositions of liquid epoxy resins containing a dispersion of a solid finlike hydroxyl terminated hardener therein.

The instant polyfunctional finlike hydroxyl terminated hardener products are superior to the hardeners described in U.S. 3,931,109 in respect to curing solid epoxy resins to cured products with outstanding properties particularly in regards to I

chemical resistance. This is especially of value in the field of coatings.

The products of this invention are useful as curing agents for epoxy resins. When these items are combined with dip and polyepoxide resins and cured at elevated temperatures (e.g. 180C) a dense cross linked network is established which produces superior protective coatings. These coatings, when applied by electrostatic techniques and properly cured to produce thin films, excel in chemical resistance while maintaining flexibility.

The reason these multi functional hardeners produce their extremely good chemical resistance is through formation of a dense cross linked reticulum in the final cured coating. The difunctional BRA terminate hardeners form linear extensions, while the multi functional BRA terminated curing agents produce a web-like structure. This three dimensional network provides the tight barrier by which the cured final coating strongly resists any chemical attack.

The reaction of hydroxyl groups with liquid epoxy resins to form higher molecular weight epoxy resins is described by H. Lee and I. Seville, "Handbook of epoxy resins", ~IcGr~w Lyle, 1967, Jew York, pp. I , 2-9. Chapter 2 of Lee and evils Ilk "Handbook of Epoxy Resins" is devoted to the "Synthesis of Glycidyl-Type Epoxy Resins". This chapter describes the synthesis of high molecular weight epoxy resins based on many types of alcohols.

U.S. Patent No. 4,322,456 discloses powder coating compositions consisting of an epoxy resin, a finlike hardener and a catalyst for effecting reaction between said resin and said hardener.

The instant polyfunctional finlike hydroxyl terminated hardener products are superior to the hardeners described in U.S. 4,322,456 in respect to curing solid epoxy resins to cured products with outstanding properties particularly in respect to chemical resistance while maintaining flexibility.

U.S. Patent No. ~,288,565 pertains to epoxy molding compositions wherein triphenols such as l,1,3-tris(4-hydroxy-phenyl)propane are used as the finlike hardener component.
While both the instant hardeners and those of this reference have three or more finlike groups per molecule, the remainder of the respective hardener molecules differ widely. The prior art hardener is a relatively small molecule with the terminal finlike hydroxy groups attached to the backbone trim ethylene-(propane) chain at very close intervals. While this does not 7~2 interfere with the hardening efficacy of the molecule, the cured epoxy resin is a relatively rigid and inflexible structure due to the high cross link density (nearness together of the original finlike hydroxyl groups).

By contrast the instant hardeners, wherein the terminal finlike hydroxyl groups are relatively far removed from one another with a relatively bully linking group there between, permit good curing since the efficacy of the finlike hydroxyl groups is undiminished. However, a lower cross link density is obtained leading to a concomitant increase in flexibility with-out loss of chemical resistance.

The preponderance of hy2roxyl groups present in the instant hardeners also allows for improved adhesion of epoxy resin cured thereby.

One object of the instant invention is a polyfunctional finlike hydroxyl terminated product useful as hardener in the curing of solid epoxy resins.

A second object of the instant invention is a curable composition comprising a solid epoxy resin and a polyfunctional ~henolic hydroxyl terminated hardener of this invention.

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Still another object of this invention is a cured composition having superior properties prepared by curing a composition comprising a solid epoxy resin and a polyfunctional finlike hydroxyl terminated hardener of this invention.

The instant invention pertains to a polyfunctional finlike hydroxyl terminated hardener product useful in the curing of epoxy resins, which is the reaction product of a) a polyglycidyl compound of the formula I, II, III or IV

Tl~-N(glycidyl)2]2 (I), ,,M(glycidyl)2 To (II), O-glycidyl T3(-0-glycidyl)3 or 4 (III) or T4~glycidyl)3 (IVY

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wherein To is 1,2-phenylene, 1,3-phenylene, 1,4-phenylene or Q
where Q it alkaline of 1 to 6 carbon atoms, alkylidene of 2 to 6 carbon atoms, -S2 , -SO-, -S-, -S-S-, -O- or -CO-, To is 1,2-phenylene, 1,3-phenylene or 1,4-phenylene, To is 1,2,3-benzenetriyl, 1,2,4-benzenetriyl, 1,3,5-benzenetriyl or ( )2CHCH( I
I

To is ON\
f 1 or Jo N-KIWI/

Go Go G2~CO KEG

\/ I \ /
CO O I

where Go and Go are independently alkyd of 1 to 6 carbon atoms or are together alkaline of 4 to 5 carbon atoms, and b) a diglycidyl compound of the formula glycidyl~O-E-O-glycidyl where E is 1,2-phenylene, 1,3-phenylene, 1,4-phenylene or . L
where L is a direct bond, alkaline of 1 to 6 carbon atoms or alkylidene of 2 to 6 carbon atoms, wherein the ratio of equivalents of polyglycidyl compound (a to diglycidyl compound (b) is from 1 to 4 to 1 to 1, with (c) a bisphenol of the formula HO-El-OH
where El has the same definitions as E, but is independent of E, wherein the ratio of equivalents ox bisphenol component (c) to the total equivalents of glycidyl compounds (a) plus (b) is from 1.8 to 1 to 2.4 to 1, and where each glycidyl group is effectively end capped with a moiety containing a foe finlike hydroxyl group by reaction of components (a) and (b) with (c) in the presence of an effective amount of a catalyst for promoting said reaction at a temperature between 120 and 300C.

Another aspect of the instant invention relates to curable compositions comprising (A) a solid epoxy resin ha no more than one 1,2-epoxy group, Lo 2 (B) a polyfunctional finlike hydroxyl terminated epoxy hardener product of the instant invention or mixtures thereof, and (C) a catalytic amount of a catalyst effective in causing reaction between the epoxy groups of (A) and the finlike hydroxyl groups of (B), wherein the epoxy resin (A) and the hydroxyl terminated hardener (B) are employed in the range of 1:0.4 to 1:1.2;
preferably of 1:0.5 to 1:0.8; and most preferably of 1:0.65 to 1:0.75.

A further aspect of the instant invention pertains to cured epoxy resin compositions prepared from the curable compositions of the instant invention. Such cured compositions find utility in a host of end-use applications including moldings and electrical uses, but it is particularly in the field of coatings that the instant cured compositions find their most important use. the properties of such cured coatings are excellent, especially in rewards to chemical resistance, flexibility and adhesion.

The polyfunctional finlike hydroxyl terminated hardeners of the instant invention are prepared by reaction of a polyglycidylated aromatic Damon, amino phenol, polyphenol with functionality more than 2 or heterocyclic nitrogen compound and a diglycidyl ether of a bisphenol with a bisphenol _ g _ .

l:~Z720Z

in such amounts that about two equivalents of bisphenol are reacted with each equivalent of glycidyl moiety loading to the instant compounds containing finlike end groups on each original glycidyl moiety These polyglycidylated compounds (a) are in many cases items of Connors or may be prepared in a conventional glycidyla-tion reaction with epichlorohydrin and the commercially available aromatic dominoes, amino phenols, polyphenols or heterocyclic nitrogen compounds.

To is derived prom aromatic dominoes such as o-, m- or p-phenylenediamine or the dominoes of the formula NH Q NH2 where Q is alkaline of 1 to 6 carbon atoms, alkylidene of 1 to 6 carbon atoms, -S02-, -SO-, -S-, -S-S-, -O-or -CO-.

Preferably To is 1,3-phenylene, 1,4-phenylene or Q where Q is ethylene or -O-. Most preferably T
is I where Q is ethylene.

To is derived from o-, m- and p-aminophenols.
Preferably To is 1,4-phenylene.

72~2 To is derived from polyfunctional phenols having a functionality of 3 or 4. These polyphenols include phloroglucinol, pyrogallol, 1,2,4-benzenetriol and 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane.

Preferably To is ( )2CHCH( I

To is derived from nitrogen heterocyclic compounds including triglycidyl isocyanurate or triglycidyl bis-hydantoins of the formula Go Go G2.~--fo f (32 glycidyl-N /-CH21CHCH2-N 7--glycidyl CO O CO
glycidyl where Go and Go are independently alkyd of 1 to 6 carbon atoms, - preferably methyl, or Go and Go are together alkaline of 4 to 5 carbon atoms.

Preferably To is derived from triglycidyl isocyanurate.

The diglycidylated derivatives of bisphenols are also items of commerce or may be prepared by the conventional glycidylation reaction with epichlorohydrin and commercially available bisphenols.

The diglycidylated compounds (b) have the formula glycidyl-O-E-O-glycidyl and are derived, for example, from catcall, resorcinol, hydroquinone, o,o'-biphenol, pup'-biphenol, bist2-hydroxyphenyl)methane, bis~4-hydroxyphenyl~-methane and 2,2-bis(4-hydroxyphenyl)propane. E is thus 1,2-phenylene, 1,3-phenylene, 1,4-phenylen0 or - L-where L is a direct bond, al}~ylene of l to 6 carbon atoms or alkylidene of 2 to 6 carbon atoms.

Preferably E is L where L is isopropylidene.

The bisphenols (c) have the formula HO-El-OH
where El has the same definitions as E given above, but E and El are independent or one another. Examples of suitable bisphenols are delineated swooper.

The reaction of the polyglycidylated and diglycidylated compounds with the bisphenol to make the instant polyfunctional finlike hydroxyl terminated hardener is carried out in the ~:;272~Z

presence of a catalytic amount of a catalyst effecting the reaction between an epoxy or glycidyl group and a finlike hydroxyl group.

Suitable catalysts which are employed to effect the reaction between the glycidyl group and the finlike hydroxyl groups include the phosphonium salts of organic and inorganic acids, imidazoles, imidazolines, qua ternary ammonium compounds and the live. Any catalyst which will effectively promote the reaction between a 1,2-epoxide group and a finlike hydroxyl group can suitably be employed in the present invention.

The catalysts are generally employed in quantities of from about 0.001% to about 10~ and preferably from about 0.05%
to about 5% by weight based upon the combined weight of the reactants, i.e. the weight of glycidyl-cGntaining compound plus the weight of the finlike hydroxyl-containing compound.

The inorganic and organic phosphonium compounds which are employed in the process of the present invention, as catalysts, include phosphonium salts of an acid, acid ester or ester of an element selected from the group consisting of carbon, nitrogen, phosphorus, sulfur, silicon, chlorine, bromide, iodine and boron which are represented by the general formula:

~l2;~7~

Al R4- P R2 em I m wherein Al, R2, R3 and R4 are independently selected from the group consisting of hydrogen, aliphatic hydrocarbon radicals containing from about 1 to 20 carbon atoms, aromatic hydrocarbon radicals, alkyd substituted aromatic hydrocarbon radicals and radicals represented by the formula Rosy wherein Us is an aliphatic hydrocarbon radical having from about 1 to about 20 carbon atoms and Y is a member selected from the group consisting of Of, Bra I, NO, H and OH and where X is the union portion of an acid, ester or acid ester of an element selected from carbon, nitrogen, phosphorus, sulfur, silicon, chlorine, bromide, iodine and boron and wherein m is the valence of the anion X.

;, .
` Particularly suitable catalysts include ethyltriphenyl phosphonium iodide, ethyltriphenyl phosphonium chloride, ethyltriphenyl phosphonium thiocyanate, ethyltriphenyl phosphonium acetate acetic acid complex, tetrabutyl phosphonium iodide, tetrabutyl phosphonium bromide, and tetra~utyl phosphonium acetate acetic acid complex.

. ' I

These and other phosphonium catalysts are more fully described in U.S. Patent No. 3,477,990 and U.S. Patent No.
3,341,580.

Suitable imidazoles which may be employed as catalysts in the present invention include, for example,

2-styrylimidazole, 1-benzyl-2-methylimidazole, 2-methylimidazole, 2-butylimidazole, mixture thereof and the like. These and other suitable catalysts are disclosed in Lee and Seville, "Handbook of Epoxy Resins", McGraw Hill, 1967, New York, pp. 11-14.

The imidazole catalysts are particularly preferred in the preparation of the instant hardeners.

It is noted that the catalysts described above which are useful in -the preparation of the instant hardeners are the very same catalysts which may be used as component (C) in the curable compositions of the instant invention.

These curable compositions comprise (A) a solid epoxy resin hazing more than one 1,2-epoxy group, (B) a polyfunctional finlike hydroxyl terminated epoxy hardener of this invention, and ~2~Z~7;~0~
(C) a catalytic amount of a catalyst effective in causing reaction between the epoxy groups of (A) and the finlike hydroxyl groups of (B).

Suitable solid epoxy resins which are employed as component (A) in the present invention include the aromatic based epoxy resins represented by the following general formulae including mixtures thereof.

CH2-CH-CH2-0-~A~0-~ -CH-CH2-O,~_A_~ CH2-CH-cH2 X X OH X n wherein A is a diva lent hydrocarbon group having from about 1 to about 6 carbon atoms, O O O
. . I I' 11 .
-C-, -O-, -S-, -S-S-, -S- or -S-, each X is independently hydrogen, chlorine or bromide, and n has an average value of from about 1 to about 12 and preferably from about 3 to about 7.

- I

~22~0~

- o-cH2-c~l2 o-cH2-cH-\H2 o- cH2-cH-~k2 - OH- R X

wherein R is hydrogen or an alkyd group having from about 1 to about 4 carbon atoms, n has an average value of from about O to about 8, and X is hydrogen, chlorine, bromide or a lower alXyl group having from 1 to about 4 carbon atoms.

The epoxy resins employed in the present invention may be prepared by any of the well known methods such as the reaction of a bisphenolic compound with an epi.halohydrin in the presence of suitable catalysts or by the reaction of a liquid polyepoxide with a bisphenol in the presence of such compounds as qua ternary ammonium compounds, tertiary amine, phosphonium compounds and the like. These methods are discussed in Chapter 2 of Handbook of Epoxy Resins by Lee and Seville, McGraw Hill Book Co., 1967 and in U.S. Patent Jo. 3,477,990.

Any solid aromatic based epoxy resin which has more than one 1,2-epoxy group is suitable for use in the present invention.

I

Suitable hardeners which may be used as component (B) in the instant invention are the polyfunctional finlike hydroxyl terminated hardeners described above and being the reaction product of a polyglycidyl compound of formula I, II, III or IV, a diglycidyla-ted compound of formula glycidyl-O-E-O-glycidyl, end a bisphenol of formula HO-El-OH.

Preferably, component (B) is a hardener derived from a polyglycidyl compound of formula I, II or III where To is - - SHEA - -, To is 1,4-phenylene, To is (- -)2CHCH(- -)~, from a diglycidyl compound and from a bisphenol where and El are respectively both _ -C(CH3)2- -Those skilled in the ark will readily recognize thrush of epoxy compound to finlike 'nydroxyl-containing compound required to produce a product of desired molecular weight or simple experimentation can be employed to arrive at the desirable ratio for any desired molecular weight.

The instant curable compositions may find utility in a host of end-use applications including moldings and electrical uses. However, it is in the field of powder coatings that these curable compositions find their most advantageous use.

~;227~

The instant curable compositions may contain, if desired, dyes, pigments, flow aids and other suitable additives. The compositions in powder form may be used to coat suitable substrates by depositing said powder on the substrate followed by subsequent heating of the powder coated substrate to effect the catalyzed curing reaction between the solid epoxy resin, component (A), and the poly~unctional finlike hydroxyl terminated hardener, component (B), in the presence of the catalyst, component I

The curing reaction is effected by heating the coated substrate to effect the reaction between (A) and (By usually between about 120 to about 300C and preferably from about 140C to about 300C for from about 10 seconds to about 60 minutes and preferably from about 10 seconds to about 30 minutes or applying said composition to a substrate preheated to a temperature of from about 120 to about 300C, preferably from about 140C to about 300C, the cure thereby being obtained by the transfer of heat from the heated substrate to the coating.

The substrates which are employed in the process of the present invention are metallic substrates such as steel, aluminum, etc. but any substrate which Will withstand temperatures of at least about 130nC can be employed.

~227%~

Pigments, fillers, dyes, flow control agents and other modifier compounds may also be employed in the coating compositions employed in the coating process or method of the present invention.

In the present invention, the coated substrates are subjected to temperatures which will effect the reaction between the epoxy resin and the finlike hydroxyl containing compound. The time employed is of course, dependent upon the temperature, the mass of the coated substrate, etc. For example, thin metallic substrates subjected to a temperature of 3007C would require only a few seconds to effect and complete the reaction whereas automobile bodies subjected to a temperature of 120C would require upwards to 60 minutes to effect and complete the reaction between tune epoxy resin and the finlike hydroxyl-containing compound.

The coatings of the present invention can be employed as-coatings for such articles as automobiles, machinery, appliances, containers and the like.

The following examples are presented for the purpose of illustration only and are not to be construed to limit the nature or scope of the instant invention in any manner whatsoever.

-- I --.

~2~72~

PREPARATION OF THE HYDROXYL TERMINATED CURING AGENTS
Example 1 A three-necked round-bottomed flask equipped with a heating mantle, mechanical stirrer, thermometer, and nitrogen inlet tube is charged with 66.5 g (0.627 en.) of N,N,0-tri-glycidyl-p-aminophenol, 141.25 g (0.743 en.) of 2,2-bis(4-glycidyloxyphenyl)propane (or the diglycidyl ether of bisphenol A, equivalent weight is 190), 285 g (2.5 en.) of bisphenol A, and 40 ppm of 2-isopropylimidazole.

The flask and contents are heated to 100C and held at that temperature for one hour, after which the temperature is increased to 125C and held for another hour. The 25C
increments with a subsequent hold at temperature for one hour are continued until the reaction temperature of 175C is reached. The flask and contents are held at 175C for two hours. The flask is discharged after two hours and the reaction product is cooled to room temperature. The hydroxyl terminated product is then characterized by a Gardner-Holdt viscosity at 25C of U-V (ASTM D-445), a molting point of 102-103C, and a theoretical combining weight of 444 g.

This product is designated AA.

Example 2 Using the general procedure of Example 1, 162.1 (1.29 en.) ofN,N,N',N'-tetraglycidyl-4,4-diaminodiphenylmethanee, 293.6 g (1.54 eke of 2,2-bis(4-glycidyloxyphenyl)propane, 768.6 g (6.74 en.) of bisphenol A, and 40 ppm of 2-isopropylimidazole are reacted. The addition product is characterized by viscosity at 200C of 0,72 Pays, a melting point of 90C, and a theoretical combining weight of 308 g.

This product is designated BY.

Example 3 Using the general procedure of Example 1, 112.2 g. (0.60 en.) of 1,1,2,2-tetrakis(p glycidyloxyphenyl)ethane, 152.0 g (0.80 en.) of 2,2-bis(4-glycidyloxyphenyl)propane, 364.8 g (3.2 en.) of bisphenol A, and 40 ppm of 2-isopropylimidazole are reacted. The addition product is characterized by an viscosity at Coffey pus, ameltingpointof likened a theoretical combining weight of 349 g.

This addition product is designated CC.

I
Example 4 Using the general procedure of Example l, 122 g (l en.) of crossly novolac resin hardener having the structure SHEA OH -where n is 3.1, 228 g (2 en.) of bisphenol A, 188 g (l en.) of 2,2-bis(4-glycidyloxyphenyl)propane, and 40 ppm of issue-propylimidazole are reacted. The addition product is kirk-towered by a Gardner-Holdt viscosity at 25C of U, a melting point of 95-96C and a theoretical combining weight of 269 g.

This addition product is designated DUD.

PREPARATION OF CURED EPOXY RESINS
USING THE HYDROXYL TERMINATED CURING AGENTS
.

Example 5 Thy product AA, prepared in Example 1, is used as 2 multi functional hydroxy terminated curing agent in an epoxy resin formulation as is seen below.

.

Component Material g 1,1,2,2-tetrakis(p-glycidyloxypnenyl)etnane OWE
PA 88.2 Flow Aid t"MODAFLOW", Monsanto)* 2.25 2-methylimidazole 0.3 Red Iron Oxide 15.0 * "MODAFLOW" flow control agent or flow aid is a poly~2-ethyl-Huxley acrylate) sold by Monsanto.

This formulation is 2-roll milled at 70C for 6 minutes. The melt mixed formulation is then cooled, ground, sieved through a 140 mesh screen (105 microns maximum size), and applied by electrostatic techniques to cold rolled steel panels. These coated test panels are then tested for their physical characteristics as is seen in Example 14.

This formulation is designated HE.

Example 6 As a control, a difunctional hydroxy terminated curing event, similar to those described in U.S. 3,931,109, is used as a curing agent in an epoxy resin formulation. The difunctional curing agent is prepared by the reaction of two equivalents of bisphenol A with one equivalent of Boyce-glycidvloxyphenyl)propane and is designated DFCA.

The epoxy resin control formulation is as phase.

- I -Component Material g 1,1,2,2-tetrakis(p-gl~cidyloxyphenyl)ethane 78.75 DFCA 55.18 Flow Aid 1.125 Red Iron Oxide 15.0 This formulation is processed and applied as in Example 5. The resulting coated panels are then used for testing of physical characteristics as seen in Examples 14 and 18.

This formulation is designated OF.

Example 7 Product AA, prepared in Example 1, is formulated with a commercially available solid bisphenol A-based epoxy resin having an epoxy content of 1,38-1,48 equivalents/kg. The formulation is as follows:
Component Material g_ Solid bisphenol A-based epoxy resin 50.5 AA 27.5 Flow Avid ("MODAFLOW")1.5 2-methylimidazole 0.5 Red Iron Oxide 15.0 The formulation is processed and applied as in Example 5 and the resulting coated panels are jested for physical characteristics as seen in Example 16.

This formulation is designated GO.

I

Example 8 Product DFCA, described in Example 6, is formulated with the solid bisphenol A-based epoxy resin used in Example 7.
The formulation is as follows:

Component Material ` g Solid bisphenol A-based epoxy resin 57.4 DFCA 21.1 Flow Aid ("MODAFLOW") 1.5 Red Iron Oxide 15.0 The formulation is processed and applied as in Example 5 and the resulting coated panels are tested for physical characteristics as seen in Examples 16, 17 and 19.

This formulation is designated HUH.

Example 9 Product BY, prepared in Example 2, is formulated in combination with the solid bisphenol A-based epoxy resin used in Example 7. The formulation is as follows:

I

Component Material Solid bisphenol A-based epoxy resin 90.8 BY 41.7 Flow Aid ~"MODAFLOW") 2.25 2-methylimidazole 0.3 Red Iron Oxide 15.0 The formulation is processed and applied as in Example 5 and the resulting coated panels are tested for physical characteristics as seen in Examples 17.

This formulation is designated Rio Example 10 Product CC, prepared in Example 3, is formulated in combination with commercially available solid epoxy resin 1,1,2 2-tetrakis(p-glycidyloxyphenyl)ethane. The formulation is as follows:

Component Material __~__ 1,1,2,2-tetrakis(p-glycidyloxyphenyl)e'hane 46.2 CC 86.25 Flow Aid ("MODAFLOW") 2.25 2-methylimidazole 0-3 Red Iron Oxide 15.0 ~27;~
The formulatiora is processed and applied as in example 5 and the resulting coated panels are tested for physical characteristics as seen in Examples 18.

This formulation is designated JO

Example 11 Product DUD, prepared in Example 4, is formulated in combination with the solid bi.sphenol A-based epoxy resin used in Example 7. The formulation is as follows:

Component Material g Solidbisphenol Abased epoxy resin 100.0 DUD 39.0 Flow Aid ("MODAFLOW") 2.5 2-methylimidazole 0.3 Shea 28.0 The formulation is processed an applied as in Example 5 and the resulting coated panels are tested for physical characteristics as seen in Example 19.

This formulation is designated I.

I

Example 12 Product AA, prepared in Example 1, is formulated in combination with 1,1,2,2-tetrakis(p-glycidyloxyphenyl)ethane and the solid bisphenol A-based epoxy resin used in Example 7. The formulation is as follows:

Component Material g Solid his phenol A-based epoxy resin 26.5 1,1,2,2-tetrakis(p-glycidyloxyphenyl)ethane 53.25 AA 56.6 Flow Aid ("MODAFLOW") 2.25 2-methylimidazole 0.3 Red Iron Oxide 15.0 The formulation is processed and applied US in Example 5 and the resulting coated panels are tested for physical characteristics as seen in Example 15.

This formulation is designated LO.

Example 13 A formulation based on the difuncticnal DFCA curing agent, described in Example 6, is formulated with 1,1,2,2-tetrakis(p-glycid~floxypherlyl)ethane and solid bisphenol A-based epoxy resin used in Example 7. The formulation is as follows:

- I -onent Material _ g Solid bisphenol A-based epoxy resin 21.75 1,1,2,2-tetrakis(p-glycidylo~yphenyl)ethane 43.5 DFCA 57.2 Flow rid ("MODAFLOW") 2.25 Red Iron Oxide 15.0 This formulation is processed and applied as in Example 5 and the resulting coated panels are tested or physical characteristics as seen in Example 15. .

This formulation is designated MM.

TESTING OF EPOXY RESINS CURED WITH
HYDROXYL TERMINATED CURING AGENTS

Chemical resistance testing is conducted at button room temperature (23C) and at elevated temperatures (refluxing temperatures for various solvents). Sand blasted cold rolled steel panels and 1.27 cm round stock are the substrates for the testing. The films range in thickness from 3 to 4 miss (0.076 to 0.102 mm) on the panels and 12 to 16 miss (0.305 to 0.~06 mm) on the rods. The substrates are powder coated by electrostatic spray techniques at room temperature for the thinner films and at 200C for the thicker films.

- I -:

I

In order to demonstrate the superiority of the products of this invention, aggressive solvents and elevated temperatures ore used. Some or all ox the hollowing solvents are employed to demonstrate the utility of the invention:

Acetic acid (10~) Methyl ethyl kitten (ME) Ethanol Ethylene chloride Acetone Refluxing 10% sulfuric acid Refluxing sodium hydroxide solution (pi = 13.5) Boiling water Refluxing ME
.

Failures are evidenced by blister formation, delamination, softening to substrate, or total destruction of the coating.

Example 14 PHYSICAL TEST RESULTS

Formulation HE OF (control) Contains AA DFCA
Gel @ 171C 44 sec. 85 sec.
Cure Schedule 30 min. @ 200C 30 min. 200C
Appearance Smooth Smooth Thickness 3.3 to 3.5 miss 3.0 to 3.2 miss (0.084 to 0.089mm) (0.076 to 0.081mm) Closed Direct Impact >160 inch-lbs. >160 inch-lbs.
(>1.76 Kg m) (>1.76 Kg m) Mandrel Bend Pass 1/2 inch Pass 1/8 inch (1~.7mm) (3.2mm) I

CHEMICAL TEST RESULTS

Thickness 3.0 to 3.3 miss (0.076 to 0.084 mm) Acetic Acid two%) > 35 days > 35 days Methyl Ethyl Kitten > 35 days < 1 day Ethanol > 35 days < 1 day Ethylene Chloride > 35 days < 1 day Acetone > 35 days < 1 day Refluxing (ME) 24 days < 5 minutes Example 15 PHYSICAL TEST RESULTS
Formulation LO MM (control) Contains AA DFCA
Gel @ 171C 49 sec. 86 sec.
Cure Schedule 30 mix Q 200 C 30 min. @ 200~C
Appearance Smooth Smooth Thickness 3 miss 3 miss (00076mm) ~0.076mm) Closed Direct Impact >160 inch-lbs. >160 inch-lbs.
(>1.76 Kg my (>1.76 Kg m) Mandrel Bend Pass 1/8 inch Pass 1/8 inch (3.2mm) (3.2mm) CHEMICAL TEST RESULTS

Thickness 12-16 miss (0.305 to 0.406 mm) Boiling H20 - >90 days 16 days Refluxing ~2S04 (10~) ~90 days 42 days Refluxing Noah (pal = 13.5) >14 days 5 days .~.

E mule 16 PHYSICAL AND CHEMICAL TEST RESULTS
Formulation GO HUH control) Contains AA DFCA
Cure Schedule 30 min. @ 200C 30 min. @ 200C
Appearance Smooth Smooth Thickness 2.0-2.2 miss 2.0-2.5 miss (0.0508-0.056mm) (0.0508-0.0635mm) Open Reverse Impact >160 inch-lbs. >160 inch-lbs.
~>1.76 Kg my ~>1.76 Kg m) Mandrel Bend Pass 1/8 inch Pass 1/8 inch (3.2mm) (3.2mm) Methyl Ethyl Rezone 5 min. 5 min.
Refluxing H2SO4 (10%) 76 hours 30 min.

Example 17 PHYSICAL AND CHEMICAL TEST RESULTS
Formulation II HUH (control) Contains BY DFCA
Cure Schedule 30 min. @ 200C 30 min. 200C
Appearance Smooth Smooth Thickness 3.0 miss 2.0-2.5 miss ~0.076mm~ ~0.0508 to 0.0535mm) Open Reverse Impact >160 inch-lbs. >160 inch-lbs.
(>1.76 Kg m) (>1.76 Kg m) Mandrel Bend Pass 1/8 inch Pass 1/8 inch (3,2mm) (3.2mm) Methyl Ethyl Kitten 6 hours 5 min.
Refluxing H~SC4 (lo%) 174 hours 30 mint Example 18 PHYSICAL AND CHEMICAL TEST RESULTS
Formulation JO OF (control) Contains CC DFCA
Cure Schedule 30 min. @ 200C 30 min. @ 200C
Appearance Smooth Smooth Thickness 3.2-3.5 miss 3.0-3.2 miss (0.081-0.089mm) (0.076-0.081mm) Closed Direct Impact >160 inch-lbs. >160 inch-lbs.
(~1.76 Kg my ~>1.76 Kg m) Mandrel wend Pass 1/8 inch Pass 1/8 inch (3.2mm) (3.2mm) Methyl Ethyl Kitten ~14 days I min.

Example 19 PHYSICAL AND CHEMICAL TEST RESULTS
Formulation OK HUH (control) Contains DUD DFCA
Cure Schedule 30 min. @ 200C 30 min. @ 200C
Appearance smooth Smooth Thickness 2.2 miss 2.0-2.5 miss (0.056mm~ Tom) Closed Direct Impact >160 inch-lbs. >160 inch-lbs.
(>1.76 Kg my (>1.76 Kg m) Methyl Ethyl Kitten 1 day 5 mint Example 20 In order to ascertain the influence of stoichiometry on curing epoxy resins with the hydroxyl terminated hardeners of this invention and with the objective of delineating the area where flexibility and chemical resistance of the cured products would be maximized, a series of runs are carried out using the .
hardener product AA prepared in Example 1 with the epoxy resin formulations similar to LO described in Example 12 with the equivalent ratio of epoxy groups of the epoxy resin to the finlike hydroxyl groups of the hardener ranging from 1:0.4 to 1:1.2. The results of these runs are seen in the table below where the physical properties of the films prepared from the cured compositions are delineated These results show that physical properties of the cured products rewaken a maximum in terms of impact strength (toughness) and flexibility when the ratio of equivalents of epoxy to hydroxyl is in the region of lo to 1:0.~ and particularly at about 1:0.65 to 1:0.75.

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An epoxy resin formulation based on 1,1,2,~-tetrakis-(p-glycidyloxyphenyl)ethane is cured using either the instant hardener of Example 1 (the product AA) or the prior art harden-or having the structure OH OH OH
SHEA SHEA - SHEA

where n is 2 to 4, designated as hardener HUT

The respective formulations are designated (A) and (B) as given below. Each formulation has one equivalent ox epoxy to one equivalent of epoxy to one equivalent of finlike hydroxyl.
Formulation A
Weight Grams 1,1,2,2-tetrakis-(p-glycidyl-oxyphenyl)ethane 44.1 Product AA OWE
Flow Aid ("MODAFLO~J") 2.25 2-methylimidazole 0.3 Red Iron Oxide 15.0 Formulation 1,1,2,2-tetrakis-(p-glycidyl-oxyphenyl)ethane 87.75 Product IT 44.7 Flow Aid ("MODAFLOW") 2.25 2-methylimidazole 0.3 Red Iron Oxide 15.0 These two formulations are then processed and applied as seen in Example 5 and the resulting coated panels are tested for chemical resistance as seen in Example 14 and for physical characteristics as seen in Example 15.

.

These test data are given in the following table.

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Chemical or solvent resistance is comparable.

These data show that the instant hardeners provide improved physical properties while maintaining goon chemical resistance.

Claims (16)

WHAT IS CLAIMED IS:

1. A polyfunctional phenolic hydroxyl terminated hardener product, useful in the curing of epoxy resins, which is the reaction product of a) a polyglycidyl compound of the formula I, II, III or IV

T1[-N(glycidyl)2]2 (I), (II), T3(-O-glycidyl)3 or 4 (III) or T4(glycidyl)3 (IV) wherein T1 is 1,2-phenylene, 1,3-phenylene, 1,4-phenylene or where Q is alkylene of 1 to 6 carbon atoms, alkylidene of 2 to 6 carbon atoms, -SO2-, -SO-, -S-, -S-S-, -O- or -CO-, T2 is 1,2-phenylene, 1,3-phenylene or 1,4-phenylene, T3 is 1,2,3-benzenetriyl, 1,2,4-benzenetriyl, 1,3,5-benzenetriyl or T4 is or where G1 and G2 are independently alkyl of 1 to 6 carbon atoms or are together alkylene of 4 to 5 carbon atoms, and (b) a diglycidyl compound of the formula glycidyl-O-E-O-glycidyl where E is 1,2-phenylene, 1,3-phenylene, 1,4-phenylene or where L is a direct bond, alkylene of 1 to 6 carbon atoms or alkylidene of 2 to 6 carbon atoms, wherein the ratio of equivalents of polyglycidyl compound (a) to diglycidyl compound (b) is from 1 to 4 to 1 to 1, with (c) a bisphenol of the formula where E1 has the same definitions as E, but is independent of E, wherein the ratio of equivalents of bisphenol component (c) to the total equivalents of glycidyl compounds (a) plus (b) is from 1.8 to 1 to 2.4 to 1, and where each glycidyl group is effectively endcapped with a moiety containing a free phenolic hydroxyl group by reaction of components (a) and (b) with (c) in the presence of an effective amount of a catalyst for promoting said reaction at a temperature between 120° and 300°C.

2. A product according to claim 1 wherein T1 is 1,3-phenylene, 1,4-phenylene or where Q is methylene or -O-.

3. A product according to claim 2 wherein Q is methylene.

4. A product according to claim 1 wherein T2 is 1,4-phenylene.

5. A product according to claim 1 wherein T3 is

6. A product according to claim 1 wherein T4 is .

7. A product according to claim 1 wherein E is where L is isopropylidene.

8. The product according to claim 1 wherein E1 is where L is isopropylidene.

9. A product according to claim 1 wherein T1 is , and E and E1 are both .

10. A product according to claim 1 wherein T2 is 1,4-phenylene, and E and El are both .

11. A product according to claim 1 wherein T3 is , and E and E1 are both .

12. A product according to claim 1 made using an imidazole catalyst.

13. A product according to claim 12 wherein the catalyst is 2-isopropylimidazole.

14. A curable composition comprising (A) a solid epoxy resin having more than one 1,2-epoxy group, (B) a polyfunctional phenolic hydroxyl terminated hardener product according to claim 1 or mixtures thereof, and (C) a catalytic amount of a catalyst effective in causing reaction between epoxy groups of (A) and the phenolic hydroxyl groups of (B) wherein the equivalent ratio of epoxy groups of the epoxy resin of component (A) to the phenolic hydroxyl groups of the hardener of component (B) is from 1:0.4 to 1:1.2.

15. A composition according to claim 14 wherein the ratio is 1:0.65 to 1:0.75.

16. A coating prepared by curing the curable compo-sition according to claim 14.