PHENYLHYDRAZINE/ANHYDRIDE ADDUCTS AND ANAEROBIC CURABLE COMPOSITIONS USING SAME

Abstract

Phenylhydrazine/anhydride adducts and anaerobic curable compositions using these adducts are provided. The compositions are particularly useful as adhesives and sealants.

Claims

1. Anaerobic cure accelerator compounds within structure I ##STR00022## wherein R.sup.1 is selected from H and C.sub.1-4 alkyl; p is an integer between 1 and 5; and O represents a cycloalkyl, cycloalkenyl, bicycloalkyl or bicycloalkenyl, with or without one or more C.sub.1-4 alkyl substituents.

2. An anaerobic curable composition, comprising: (a) a (meth)acrylate component; (b) an anaerobic cure-inducing composition and (c) a compound according to claim 1.

3. The composition according to claim 2, wherein the compound is a member selected from the group consisting of: ##STR00023##

4. The composition according to claim 2, wherein the (meth)acrylate component is represented by H.sub.2C═CGCO.sub.2R.sup.10, wherein G is a member selected from the group consisting of H, halogen and alkyl having from 1 to about four carbon atoms, and R.sup.10 is a member selected from the group consisting of alkyl, cycloalkyl, aklenyl, cycloalkenyl, alkaryl, and aryl groups having from 1 to about 16 carbon atoms, with or without substitution or interruption by a member selected from the group consisting of silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbamate, amine, amide, sulfur, sulonate and sulfone.

5. The composition according to claim 2, wherein the (meth)acrylate component is a member selected from the group consisting of silicone (meth)acrylates, polyethylene glycol di(meth)acrylates, tetrahydrofuran (meth)acrylates and di(meth)acrylates, hydroxypropyl (meth)acrylate, hexanediol di(meth)acrylate, trimethylol propane tri(meth)acrylates, diethylene glycol di(meth)acrylates, triethylene glycol di(meth)acrylates, tetraethylene diglycol di(meth)acrylates, diglycerol tetra(meth)acrylates, tetramethylene di(meth)acrylates, ethylene di(meth)acrylates, neopentyl glycol di(meth)acrylates, bisphenol-A-(meth)acrylates, ethoxylated bisphenol-A-(meth)acrylates, bisphenol-F-(meth)acrylates, ethoxylated bisphenol-F-(meth)acrylates, and bisphenol-A di(meth)acrylates, ethoxylated bisphenol-A-di(meth)acrylates, bisphenol-F-di(meth)acrylates, and ethoxylated bisphenol-F-di(meth)acrylates.

6. The composition according to claim 1, further comprising a co-accelerator.

7. Reaction products of the composition according to claim 2.

8. A process for preparing a reaction product from an anaerobic curable composition, comprising the steps of: applying an anaerobic curable composition according to claim 2, to a desired substrate surface; and exposing the composition to an anaerobic environment for a time sufficient to cure the composition.

9. A method of preparing an anaerobic curable composition, comprising the step of: mixing together: a compound according to claim 1 as an anaerobic cure accelerator; and a (meth)acrylate component and an anaerobic cure-inducing composition.

10. The composition according to claim 2, wherein the anaerobic cure-inducing composition comprises the combination of a free radical initiator and a free radical co-accelerator.

11. A method of using a compound as a anaerobic cure accelerator comprising either: (I) mixing the compound with a (meth)acrylate component, an anaerobic cure inducing composition, or (II) applying onto a surface of a substrate the compound and applying thereover.

12. The composition of claim 1, further comprising acrylic acid.

13. Compounds selected from the group consisting of: ##STR00024##

Description

BRIEF DESCRIPTION OF THE FIGURES

[0022] FIG. 1 depicts a bar chart, showing breakaway strength on steel nut/bolt assemblies after curing for 15 minutes, 1 hour and 24 hours, for anaerobic curable compositions based on PEGMA (Formulation 1) with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0023] FIG. 2 depicts a bar chart, showing prevail strength on steel nut/bolt assemblies after curing 15 minutes, 1 hour and 24 hours, for anaerobic curable compositions based on PEGMA (Formulation 1) with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0024] FIG. 3 depicts a bar chart, showing breakaway strength on stainless steel nut/bolt assemblies after curing for 15 minutes, 1 hour and 24 hours, for anaerobic curable compositions based on PEGMA (Formulation 1) with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0025] FIG. 4 depicts a bar chart, showing prevail strength on stainless steel nut/bolt assemblies after curing 15 minutes, 1 hour and 24 hours, for anaerobic curable compositions based on PEGMA (Formulation 1) with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0026] FIG. 5 depicts a bar chart, showing tensile strength on steel pin/collar assemblies after curing 15 minutes, 1 hour and 24 hours, for anaerobic curable compositions based on PEGMA (Formulation 1) with APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0027] FIG. 6 depicts a bar chart showing breakaway strength on steel nut/bolt assemblies after curing for 5 minutes, 1 hour and 24 hours for anaerobic curable compositions based on PEGMA (Formulation 2) and acrylic acid with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0028] FIG. 7 depicts a bar chart showing prevail strength on steel nut/bolt assemblies after curing for 15 minutes, 1 hour and 24 hours for anaerobic curable compositions based on PEGMA (Formulation 2) and acrylic acid with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0029] FIG. 8 depicts a bar chart showing breakaway strength on stainless steel nut/bolt assemblies after curing for 5 minutes, 1 hour and 24 hour for anaerobic curable compositions based on PEGMA (Formulation 2) and acrylic acid with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0030] FIG. 9 depicts a bar chart showing prevail strength on stainless steel nut/bolt assemblies after curing for 15 minutes, 1 hour and 24 hours for anaerobic curable compositions based on PEGMA (Formulation 2) and acrylic acid with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

[0031] FIG. 10 depicts a bar chart showing tensile strength on steel pin/collar assemblies after curing for 15 minutes, 1 hour and 24 hours for anaerobic curable compositions based on PEGMA (Formulation 2) and acrylic acid with one of APH/MA, SPH, THPH or HHPH as a cure accelerator.

DETAILED DESCRIPTION

[0032] The present invention provides anaerobic cure accelerators, having the linkage —C(═O)—NH—NH— and a carboxylic acid functional group on the same molecule. The addition of such compounds as cure accelerators into anaerobic curable compositions as a replacement for some or all of the amount of conventional cure accelerators surprisingly provides at least comparable cure speeds and physical properties for the reaction products formed.

[0033] The inventive anaerobic cure accelerators may be represented below with reference to structure I:

##STR00008##

where R.sup.1 is selected from hydrogen or C.sub.1-4 alkyl; p is an integer between 1 and 5; and O represents a cycloalkyl, cycloalkenyl, bicycloalkyl or bicycloalkenyl, with or without one or more C.sub.1-4 alkyl substituents.

[0034] Particular examples of such accelerators within structure I include:

##STR00009##

[0035] NPH represents nadic phenylhydrazine and NMPH represents nadic methyl phenylhydrazine. THPH, HHPH and MHPH are denoted above.

[0036] The inventive anaerobic cure accelerators may be prepared generally from phenyl hydrazines and anhydrides within the following respective structures:

##STR00010##

where R.sup.1 is selected from hydrogen or C.sub.1-4 alky; p is an integer between 1 and 5; and O represents a cycloalkyl, cycloalkenyl, bicycloalkyl or bicycloalkenyl, with or without one or more C.sub.1-4 alkyl substituents. A more detailed description of the synthesis is set forth below in the examples. Specific anhydrides include:

##STR00011##

[0037] These anhydrides are tetrahydrophthalic anhydride (“THPA”), hexahydrophthalic anhydride (“HHPA”), methylhexahydrophthalic anhydride (“MHHPA”), nadic anhydride (“NA”), and nadic methyl anhydride (“NMA”).

[0038] (Meth)acrylate monomers suitable for use as the (meth)acrylate component in the present invention may be chosen from a wide variety of materials, such as those represented by H.sub.2C═CGCO.sub.2R.sup.10, where G may be hydrogen, halogen or alkyl groups having from 1 to about 4 carbon atoms, and R.sup.10 may be selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, aralkyl or aryl groups having from 1 to about 16 carbon atoms, any of which may be optionally substituted or interrupted as the case may be with silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbonate, amine, amide, sulfur, sulfonate, sulfone and the like.

[0039] Additional (meth)acrylate monomers suitable for use herein include polyfunctional (meth)acrylate monomers, such as di-or tri-functional (meth)acrylates like polyethylene glycol di(meth)acrylates, tetrahydrofuran (meth)acrylates and di(meth)acrylates, hydroxypropyl (meth)acrylate, hexanediol di(meth)acrylate, trimethylol propane tri(meth)acrylates, diethylene glycol dimethacrylate, triethylene glycol dimethacrylates, tetraethylene glycol di(meth)acrylates, dipropylene glycol di(meth)acrylates, di-(pentamethylene glycol) di(meth)acrylates, tetraethylene diglycol di(meth)acrylates, diglycerol tetra(meth)acrylates, tetramethylene di(meth)acrylates, ethylene di(meth)acrylates, neopentyl glycol di(meth)acrylates, and bisphenol-A mono and di(meth)acrylates, such as ethoxylated bisphenol-A (meth)acrylate, and bisphenol-F mono and di(meth)acrylates, such as ethoxylated bisphenol-A (meth)acrylate.

[0040] Still other (meth)acrylate monomers that may be used herein include silicone (meth)acrylate moieties, such as those taught by and claimed in U.S. Pat. No. 5,605,999 (Chu), the disclosure of which is hereby expressly incorporated herein by reference.

[0041] Other suitable monomers include poly(meth)acrylate esters represented by the formula:

##STR00012##

where R.sup.4 is a radical selected from hydrogen, halogen or alkyl of from 1 to about 4 carbon atoms; q is an integer equal to at least 1, and preferably equal to from 1 to about 4; and X is an organic radical containing at least two carbon atoms and having a total bonding capacity of q plus 1. With regard to the upper limit for the number of carbon atoms in X, workable monomers exist at essentially any value. As a practical matter, however, a general upper limit is about 50 carbon atoms, such as desirably 30, and desirably about 20.

[0042] For example, X can be an organic radical of the formula:

##STR00013##

where each of Y.sup.1 and Y.sup.2 is an organic radical, such as a hydrocarbon group, containing at least 2 carbon atoms, and desirably from 2 to about 10 carbon atoms, and Z is an organic radical, preferably a hydrocarbon group, containing at least 1 carbon atom, and preferably from 2 to about 10 carbon atoms.

[0043] Other classes of useful monomers are the reaction products of di- or tri-alkylolamines (e.g., ethanolamines or propanolamines) with (meth)acrylic acids, such as are disclosed in French Patent No. 1,581,361. Oligomers with (meth)acrylate functionality may also be used. Examples of useful (meth)acrylate-functionalized oligomers include those having the following general formula:

##STR00014##

where R.sup.5 represents a radical selected from hydrogen, lower alkyl of from 1 to about 4 carbon atoms, hydroxy alkyl of from 1 to about 4 carbon atoms, or

##STR00015##

where R.sup.4 is a radical selected from hydrogen, halogen, or lower alkyl of from 1 to about 4 carbon atoms; R.sup.6 is a radical selected from hydrogen, hydroxyl, or

##STR00016##

m is an integer equal to at least 1, e.g., from 1 to about 15 or higher, and desirably from 1 to about 8; n is an integer equal to at least 1, e.g., 1 to about 40 or more, and desirably between about 2 and about 10; and p is 0 or 1.

[0044] Typical examples of (meth)acrylic ester oligomers corresponding to the above general formula include di-, tri- and tetraethyleneglycol dimethacrylate; di(pentamethyleneglycol)dimethacrylate; tetraethyleneglycol diacrylate; tetraethyleneglycol di(chloroacrylate); diglycerol diacrylate; diglycerol tetramethacrylate; butyleneglycol dimethacrylate; neopentylglycol diacrylate; and trimethylolpropane triacrylate.

[0045] Another useful class of materials are the reaction product of (meth)acrylate-functionalized, hydroxyl- or amino-containing materials and polyisocyanate in suitable proportions so as to convert all of the isocyanate groups to urethane or ureido groups, respectively. The so-formed (meth)acrylate urethane or urea esters may contain hydroxy or amino functional groups on the nonacrylate portion thereof. (Meth)acrylate esters suitable for use have the formula

##STR00017##

where X is selected from —O— and

##STR00018##

where R.sup.9 is selected from hydrogen or lower alkyl of 1 through 7 carbon atoms; R.sup.7 is selected from hydrogen, halogen (such as chlorine) or alkyl (such as methyl and ethyl radicals); and R.sup.8 is a divalent organic radical selected from lower alkylene of 1 through 8 carbon atoms, phenylene and naphthylene. These groups upon proper reaction with a polyisocyanate, yield a monomer of the following general formula:

##STR00019##

where n is an integer from 2 to about 6; B is a polyvalent organic radical selected from alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkaryl, alkaryl and heterocyclic radicals both substituted and unsubstituted, and combinations thereof; and R.sup.7, R.sup.8 and X have the meanings given above.

[0046] Depending on the nature of B, these (meth)acrylate esters with urea or urethane linkages may have molecular weights placing them in the oligomer class (such as about 1,000 up to about 5,000) or in the polymer class (such as about greater than 5,000).

[0047] Of course, combinations of these (meth)acrylates may also be used.

[0048] The (meth)acrylate component should comprise from about 10 to about 90 percent by weight of the composition, such as about 60 to about 90 percent by weight, based on the total weight of the composition.

[0049] Recently, additional components have been included in traditional anaerobic adhesives to alter the physical properties of either the formulation or the reaction products thereof.

[0050] For instance, one or more of maleimide components, thermal resistance-conferring coreactants, diluent components reactive at elevated temperature conditions, mono- or poly-hydroxyalkanes, polymeric plasticizers, and chelators (see International Patent Application No. PCT/US98/13704, the disclosure of which is hereby expressly incorporated herein by reference) may be included to modify the physical property and/or cure profile of the formulation and/or the strength or temperature resistance of the cured adhesive. Acrylic acid may also be used in some embodiments.

[0051] When used, the maleimide, coreactant, reactive diluent, plasticizer, mono- or poly-hydroxyalkanes and/or acrylic acid, may be present in an amount within the range of about 1 percent to about 30 percent by weight, based on the total weight of the composition.

[0052] The inventive compositions may also include other conventional components, such as free radical initiators, free radical co-accelerators, and inhibitors of free radical generation, as well as metal catalysts.

[0053] A number of well-known initiators of free radical polymerization are typically incorporated into the inventive compositions including, without limitation, hydroperoxides, such as cumene hydroperoxide (“CHP”), para-menthane hydroperoxide, t-butyl hydroperoxide (“TBH”) and t-butyl perbenzoate. Other peroxides include benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide, butyl 4,4-bis(t-butylperoxy)valerate, p-chlorobenzoyl peroxide, cumene hydroperoxide, t-butyl cumyl peroxide, t-butyl perbenzoate, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di-t-butyl-peroxyhex-3-yne, 4-methyl-2,2-di-t-butylperoxypentane and combinations thereof.

[0054] Such peroxide compounds are typically employed in the present invention in the range of from about 0.1 to about 10 percent by weight, based on the total weight of the composition, with about 1 to about 5 percent by weight being desirable.

[0055] As noted, conventional accelerators of free radical polymerization may also be used in conjunction with the inventive anaerobic cure accelerators, though in amounts less than that used in the past. Such accelerators are typically of the hydrazine variety (e.g., APH), as disclosed in U.S. Pat. No. 4,287,350 (Rich) and U.S. Pat. No. 4,321,349 (Rich). MA is usually added to APH-containing anaerobic cure systems. One benefit of the present invention is that the inventive anaerobic cure accelerators render the use of such acids unnecessary in preparing anaerobic adhesive compositions.

[0056] Co-accelerators of free radical polymerization may also be used including aromatic sulfimides such as benzoic sulfimide (also known as saccharin). (See the '305 and the '349 patents.)

[0057] Stabilizers and inhibitors (such as phenols including hydroquinone and ketones including quinones) may also be employed to control and prevent premature peroxide decomposition and polymerization of the composition of the present invention, as well as chelating agents [such as the tetrasodium salt of ethylenediamine tetraacetic acid (“EDTA”)] to trap trace amounts of metal contaminants therefrom. When used, chelating agents may ordinarily be present in the compositions in an amount from about 0.001 percent by weight to about 0.1 percent by weight, based on the total weight of the composition.

[0058] The inventive anaerobic cure accelerators may be used in amounts of about 0:1 to about 5 percent by weight, such as about 1 to about 2 percent by weight, based on the total weight of the composition. When used in combination with conventional accelerators (though at lower levels than such conventional accelerators), the inventive accelerators should be used in amounts of 0.01 to 5 percent by weight, such as 0.02 to 2 percent by weight, based on the total weight of the composition.

[0059] Metal catalyst solutions or pre-mixes thereof are used in amounts of about 0.03 to about 0.1 percent by weight.

[0060] Other additives such as thickeners, non-reactive plasticizers, fillers, toughening agents (such as elastomers and rubbers) and other well-known additives may be incorporated therein where the art-skilled believes it would be desirable to do so.

[0061] The present invention also provides methods of preparing and using the inventive anaerobic adhesive compositions, as well as reaction products of the compositions.

[0062] The compositions of the present invention may be prepared using conventional methods which are well known to those persons of skill in the art. For instance, the components of the inventive compositions may be mixed together in any convenient order consistent with the roles and functions the components are to perform in the compositions. Conventional mixing techniques using known apparatus may be employed.

[0063] The compositions of this invention may be applied to a variety of substrates to perform with the desired benefits and advantages described herein. For instance, appropriate substrates may be constructed from steel, brass, copper, aluminum, zinc, and other metals and alloys, ceramics and thermosets. The compositions of this invention demonstrate particularly good bond strength on steel, brass, copper and zinc. An appropriate primer for anaerobic curable compositions may be applied to a surface of the chosen substrate to enhance cure rate. Or, the inventive anaerobic cure accelerators may be applied to the surface of a substrate as a primer. See e.g. U.S. Pat. No. 5,811,473 (Ramos).

[0064] In addition, the invention provides a method of preparing an anaerobic curable composition, a step of which includes mixing together a (meth)acrylate component, an anaerobic cure inducing composition substantially free of acetyl phenyl hydrazine and optionally substantially free of maleic acid, and an anaerobic cure accelerator compound, having the linkage —C(═O)—NH—NH— and a carboxylic acid functional group on the same molecule.

[0065] The invention also provides a process for preparing a reaction product from the anaerobic curable composition of the present invention, the steps of which include applying the composition to a desired substrate surface and exposing the composition to an anaerobic environment for a time sufficient to cure the composition.

[0066] This invention also provides a method of using as a cure accelerator for anaerobic curable composition, compounds having the linkage —C(═O)—NH—NH— and a carboxylic acid functional group on the same molecule.

[0067] And the present invention provides a method of using an anaerobic cure accelerator compound, including (I) mixing the anaerobic cure accelerator compound in an anaerobic curable composition or (II) applying onto a surface of a substrate the anaerobic cure accelerator compound and applying thereover an anaerobic curable composition. Of course, the present invention also provides a bond formed between mated substrates with the inventive composition.

[0068] Certain compounds embraced by structure I are provided, including:

##STR00020##

[0069] In view of the above description, it is clear that a wide range of practical opportunities is provided. The following examples are provided for illustrative purposes only, and are not to be construed so as to limit in any way the teaching herein.

EXAMPLES

[0070] An investigation was performed to evaluate certain cyclic and bicyclic anyhydride/phenylhydrazines compounds, as replacements for APH in anaerobic curable compositions, particularly adhesives.

[0071] Phenyl hydrazine, tetrahydrophthalic anhydride THPA, HHPA, MHHPA, NA, and NMA, PEGMA, MA, acrylic acid (“AA”), saccharin, and APH were purchased from the Aldrich Chemical Company.

[0072] Four cyclic and bicyclic anyhydride/phenylhydrazine compounds were prepared and evaluated to determine whether inclusion thereof would obviate the use of a separate cure component in the anaerobic adhesives.

[0073] The inventive anaerobic cure accelerators were prepared in accordance with the synthetic scheme as described below.

##STR00021##

where R.sup.1 is selected from hydrogen or C.sub.1-4 alky; p is an integer between 1 and 5; and O represents a cycloalkyl, cycloalkenyl, bicycloalkyl or bicycloalkenyl, with or without one or more C.sub.1-4 alkyl substituents.

[0074] Proton and Carbon Nuclear Magnetic Resonance (“.sup.1H and .sup.13C NMR”) analyses were performed using a Varian 300 Hz Gemini Spectrophotometer. Infrared (“IR”) spectral analyses were performed on neat samples using an ATI Mattson Genesis series FTIR. Melting points were obtained on a TA Instrument 2920 Differential Scanning calorimeter.

A. General Procedure for the Synthesis of Cyclic and Bicyclic Anhydride/Phenylhydrazine Compounds

HHPH

[0075] To a 1000 mL four-neck round bottom flask, equipped with a condenser, thermocouple, mechanical stirrer, an addition funnel, and a nitrogen inlet, was added HHPA (77.8 g, 0.505 mol), and CH.sub.3CN (500 mL) with stirring. The solution was heated to reflux. Phenylhydrazine (54.0 g, 0.50 mol) was added dropwise over a period of time of about 15-20 minutes, and the reaction was stirred at reflux for a period of time of 30 minutes. The product precipitated from solution on cooling to ambient temperature. Crude Yield=107.0 g (81%); Melting point=152° C. The product was recrystallized from CH.sub.3CN. Crystallized Yield=77.1 g (59%): .sup.1H NMR (d.sub.6-DMSO) δδ 12.0 (s, 1, OH), 9.5 (s, 1, NH), 7.6 (s, 1, NH), 7.1 (t, 2, Ar—H), 6.7 (m, 3, Ar—H), 2.8 (m, 1, CO—CH), 2.6 (m, 1, CO—CH), 1.1-2.1 (m, 8, CH.sub.2); .sup.13C NMR (d.sub.6-DMSO) 175, 173, 148, 128, 118, 112, 42, 28, 25, 24, 22; IR (neat) 2928, 1698, 1665, 1602, 1495, 1265, 1239, 750, 690 cm.sup.−1.

THPH

[0076] The same procedure as above was used with THPA (76.8 g, 0.505 mol). Crude Yield=85.8 (66%); Melting point=149° C. The product was recrystallized from CH.sub.3CN. Crystallized Yield=53.9 g (41%): .sup.1H NMR (d.sub.6-DMSO) δδ 12.1 (br s, 1, OH), 9.5 (s, 1, NH), 7.7 (s, 1, NH), 7.1 (m, 2, Ar—H), 6.7 (m, 3, Ar—H), 5.6 (m, 2, HC═CH), 2.9 (m, 2, CO—CH), 2.1-2.6 (m, 4, ═C—CH.sub.2—); .sup.13C NMR (d.sub.6-DMSO) 175, 173, 150, 128, 126, 125, 118, 38, 27, 26, 22; IR (neat) 3276, 1704, 1633, 1601, 1494, 1258, 1211, 921, 749, 690 cm.sup.−1.

B. Adhesive Formulations with Cyclic and Bicyclic Anhydride/Phenylhydrazine Compounds

[0077] THPH and HHPH were evaluated as anaerobic adhesive curatives in two model anaerobic adhesive compositions on degreased mild steel nuts and bolts, stainless steel nuts and bolts, and mild steel pins and collars, with APH/maleic acid and succinic phenylhydrazine (“SPH”) as controls.

[0078] Model formulations, which were used for the adhesive strength evaluations, are summarized in Table A. The formularies were prepared from the noted components in the listed amounts, by mixing with a mechanical stirrer in glass vials. Each sample included a chelator and naphthaquinone as stabilizers.

TABLE-US-00001 TABLE A Formulation No./Amt (phr) Materials 1 2 PEGMA 100 100 Menadione 0.42 0.42 Chelator 2.1 2.1 Saccharin 1.05 1.05 TMBP-L (peroxide) 0.9 .09 Acrylic acid — 5 Phenylhydrazine/anhydride Equimolar Equimolar curative amounts amounts 0.25-0.60 0.25-0.60

C. Physical Properties

[0079] These new cure systems were compared with control formulations containing the conventional cure components, APH/MA and saccharin, by 82° C. accelerated stability, and 15 minute/one hour/24 hour adhesion tests on nut/bolt and pin/collar specimens.

Shelf Life Stability

[0080] The 82° C. stability of the formulations was determined according to an evaluation in which the formulation is judged to have acceptable shelf stability if the adhesive formulation remains liquid for 3.5 hours or longer at 82° C. As seen from Table B below, each formulation remained liquid for greater than 24 hours.

TABLE-US-00002 TABLE B Curative Formulation 1 Formulation 2 APH/MA >24 >24 SPH >24 >24 THPH >24 >24 HHPH >24 >24

[0081] The formulations thus demonstrated acceptable shelf life stability.

15 Minute, One Hour and 24 Hour Break and Prevail Strengths, and Tensile Strengths

[0082] For the break/prevail adhesion tests, the specimens were cured at ambient temperature for 15 minutes, 1 hour and 24 hours after assembly and were tested as follows.

[0083] Ten nut and bolt specimens of steel and stainless steel (having been deprimed) were assembled in the same manner as for the torque test for each formulation. The break and prevail torque strengths were then recorded for half of the specimens after one hour at ambient temperature and after 24 hours at ambient temperature for the remaining specimens. The torque strengths were measured on a calibrated automatic torque analyzer.

[0084] Adhesive strength data for the phenylhydrazine curatives in Formulation 1 are given in Tables 1-4 below and shown graphically in FIGS. 1-4.

TABLE-US-00003 TABLE 1 15 min. 60 min. 24 hrs. APH/MA 12 65 180 SPH 5 13 63 HHPH 6 23 42 THPH 0 53 39

TABLE-US-00004 TABLE 2 15 min. 60 min. 24 hrs. APH/MA 2 145 218 SPH 5 119 222 HHPH 5 140 166 THPH 0 150 215

TABLE-US-00005 TABLE 3 15 min. 60 min. 24 hrs. APH/MA 6 10 26 SPH 0 26 29 HHPH 0 26 8 THPH 12 22 23

TABLE-US-00006 TABLE 4 15 min. 60 min. 24 hrs. APH/MA 3 117 215 SPH 0 58 171 HHPH 0 174 212 THPH 24 193 212

[0085] Each of these formulations was also applied to fifteen replicates of steel pins and collars (having been degreased), and maintained at ambient temperature for 15 minutes, 1 hour, and 24 hours at room temperature (25° C.) and 45-50% relative humidity, respectively. Table 5 and FIG. 5 capture the data and show the data in bar chart form.

TABLE-US-00007 TABLE 5 15 min. 60 min. 24 hrs. APH/MA 596 2022 2348 SPH 63 1428 2013 HHPH 229 1603 1915 THPH 332 1515 1308

[0086] With reference to Tables 1-2 and FIGS. 1-2, modest improvements in strength development after curing on steel for 1 hour at room temperature may be seen with the inventive composition when contrasted to the control composition containing SPH as an accelerator. And with reference to Table 4 and FIG. 4, more significant improvements may be seen for the inventive composition after curing on stainless steel for 1 hour and 24 hours at room temperature when contrasted to the control composition.

[0087] Adhesive strength data for the phenylhydrazine based curatives in Formulation 2 are given in Tables 6-10 below and shown graphically in FIGS. 6-10.

TABLE-US-00008 TABLE 6 15 min. 60 min. 24 hrs. APH/MA 28 41 114 SPH 10 30 47 HHPH 44 38 77 THPH 14 67 105

TABLE-US-00009 TABLE 7 15 min. 60 min. 24 hrs. APH/MA 67 200 248 SPH 5 198 187 HHPH 122 178 205 THPH 7 224 235

TABLE-US-00010 TABLE 8 15 min. 60 min. 24 hrs. APH/MA 21 21 22 SPH 6 28 12 HHPH 27 9 13 THPH 15 14 20

TABLE-US-00011 TABLE 9 15 min. 60 min. 24 hrs. APH/MA 41 201 209 SPH 4 168 247 HHPH 40 247 206 THPH 94 225 258

[0088] Each of these formulations was also applied to fifteen replicates of steel pins and collars (having been degreased), and maintained at ambient temperature for 15 minutes, 1 hour, and 24 hours at room temperature (25° C.) and 45-50% relative humidity, respectively. Table 10 and FIG. 10 capture the data and show the data in bar chart form.

TABLE-US-00012 TABLE 10 15 min. 60 min. 24 hrs. APH/MA 1557 2436 2423 SPH 167 1894 2029 HHPH 1308 1947 2124 THPH 1253 1350 1572

[0089] With reference to Table 6 and FIG. 6, improvement on strength development may be seen with the HHPH-containing composition as contrasted to the SPH-containing control composition when cured on steel nuts and bolts, even modestly after 15 minutes or 1 hour and significantly after 24 hours at room temperature. Table 7 and FIG. 7 show improvement in strength development with the inventive compositions as contrasted to the SPH-containing composition when cured at room temperature on steel nuts and bolts after 15 minutes. Table 9 and FIG. 9 show improvement in strength development with the inventive compositions as contrasted to the SPH-containing composition when cured at room temperature on steel nuts and bolts after 1 hour. Table 10 and FIG. 10 show improvement in strength development with the inventive compositions as contrasted to the HHPH-containing composition when cured at room temperature on steel pins and collars after 15 minutes.