IL33800A - Highly stable polymerizable anaerobic compositions and process for preparing them - Google Patents

Description

HIGHLY STABLE POLYMSRIZABLE ANAEROBIC COMPOSITIONS AND PROCESS FOR PREPARING THEM inajn 'j^nni ma »s HIGHLY STABLE ANAEROBIC COMPOSITIONS AND PROCESS FOR PREPARING THEM NEj-liott Frauenglass and Jeremy W. Gorman ATTRACT OF THE DISCLOSURE Polymerizable ana obic compositions can be made more stable and capable of greater speed of cure by removing from the composition at least a subsc&Qtial portion of the metal contamination.

CROSS REFERENCE TO RELATED APPLICATION This is a continuation in part of copending application Ser-ial Number 796 } 572 » which veto filed on February 4,—1969.

BACKGROUND OF THE INVENTION Polymerizable anaerobic compositions are precatalyzed polymerizable compositions which cure by a polymerization process which is inhibited by oxygen. As a result they remain in an unpolymerized state as long as adequate contact is maintained with air or other oxygen-bearing materials. Cure may be instituted by removing the composition from contact with oxygen. Since such oxygen free conditions can be found between closely fitting, non-porois sur aces, such as between inter-fitting metal parts, anaerobic compositions have found great utility in the adhesives and sealants fields.

The earliest anaerobic material is that disclosed in U.S. Patent 2,628,178 to Burnett and Nordlander, issued February 10, 1953. A more technically advanced and the first commercially important type of anaerobic composition is that disclosed in United States Patent 2,895,950 to Krieble, issued July 21, 1959. Typical examples of disclosures relating to improved anaerobic compositions of this latter type may be found in the following United States Patents: 3,043,820 to Krieble, issued July 10, 1962; 3,046,262 to Krieble, issued July 24, 1962; 3,218,305 to Krieble, issued November 16, 1965; and 3,425,988 to Gorman and Toback, issued February 4, 1969.

Improvements in the chemistry of anaerobic systems permitted the incorporation of polymerization accelerators which, while not destroying the stability of the composition over significant periods of time, such as six months or more, did provide increased speed of cure at the time of intended use. However, as more of the accelerator was added, or if a stronger accelerator was used, the incidence of spurious polymerization of the composition prior to the time of intended use increased. It also was found that these anaerobic compositions were far more sensitive to outside influences, such as temperature, and their performance was less predictable. For reasons not completely known, the number of compositions which would cure during processing or immediately after manufacture also increased.

In an attempt to solve these problems, larger amounts of conventional polymerization inhibitors (such as mentioned stability problems. More powerful polymerization inhibitors were discovered, but were not found to be the complete solution to the problem. Even with these inhibitors, the stronger types of polymerization accelerators could not be used with safety, particularly at concentrations which would produce highly desirable speeds of cure.

It is the purpose of this invention to provide anaerobic compositions which can be formulated with increases in either or both stability and speed of cure, as well as to provide a process for producing anaerobic compositions having such capabilities.

THE INVENTION This invention concerns anaerobic compositions having a reduced content of metal contamination. As used herein, "metal contamination" is intended to encompass metal which is present in any form within the anaerobic composition. The most common of these is metal which is present in the form of free metal ions. However, organic and inorganic metal compounds also commonly are included in such compositions as well. The presence of such contamination is traceable to impurities in the starting materials, generally due to their methods of manufacture, and on occasion traceable in part to contamination from the processing equi-pment in which the anaerobic composition is made. Metal contamination in the starting materials is by far the most troublesome source of contamination. than 0.1 parts per million by weight, a level which was ex- ' ceeded by prior art anaerobic compositions due to the inherent metal contamination in the starting materials as discussed above. While numerous metals contribute to the contamination, iron constitutes the bulk of such contaminants and if the iron content is reduced below the above level, significant increases in desirable properties are achieved. For optimum results, the iron content should be reduced to less than 0.05 parts per million by weight. Other common metal contaminants, such as copper, nickel and manganese, generally are removed in significant quantities along with the iron, although the efficiency with which a given metal contaminant is removed will vary to some extent with the specific method of removal, as is more fully discussed below.

'The invention also contemplates anaerobic compositions prepared by a process which includes the step of reducing the content of metal contamination. The metal contamination may be removed from the final anaerobic composition or from starting materials or intermediates therefore. While significant improvements are achieved when any significant proportion of the metal contamination is removed, it commonly is desirable to remove at least 50 percent by weight of such metal contamination.

DESCRIPTION OF THE INVENTION AND ITS PREFERRED EMBODIMENTS A. THE PRODUCT Anaerobic compositions which are the subject of the free-radical polymerizable monomer whose polymerization is inhibited by the presence of oxygen; and (b) a redox activated latent initiator of free radical polymerization, which is capable of polymerizing the monomer of (a) above, in the absence of oxygen. This combination of ingredients can be place in an oxygen containing atmosphere such as a half filled bottle (preferrably polyethylene or other material which will permit penetration of atmospheric oxygen) , and will remain in the liquid, unpolymerized state at normally encountered temperatures, such as 70°F. to 100°F . , for a period of several months or longer.

As indicated above, this invention deals with anaerobic compositions wherein the latent initiator of free radical polymerization is redox activated. "Redox activated" refers to activation by a process which includes an oxidation-reduction reaction, wherein one of the products is or forms a free radical. The most important class of initiators in this category is the class of hydroperoxides. While applicants do not wish to be bound to any particular theory, it is believed that such initiators co-act with metal contamination to produce stability problems in the anaerobic composition, apparently by overcoming the inhibiting effect of the oxygen. It is quite surprising to find that the low levels of metal contamination which applicants find are inherent in the starting materials for anaerobic compositions could cause the significant problems which have been traced to such contamination. Even more surprising was the size of the increase in the performance of While again not wishing to be bound by any particular , theory, it is believed the metals which co-act with hydroperoxides to cause the stability problem discussed above are transition metals which have contiguous multivalances (at least two available valance s ates which differ by only one number) . This includes essentially all transition metals (those elements in classes 3b, 4b, 5b, 6b, 7b, 8b and lb on the periodic chart). Examples of transition metals which do not have contiguous multivalances are platinum, gold, zirconium and hafnium. It appears that transition metal with contiguous multivalances combine with hydroperoxides to form a redox system frequently capable of initiating polymerization of the monomer in the anaerobic composition even in the presence of oxygen.

The most desirable monomers for use in anaerobic systems are polymerizable acrylate esters^ When used in the , . . preferably , _ process of this invention , -prefer^^ly- at least a portion of the acrylate monomer is a di- or other polyacrylate ester.

These poly-functional monomers produce cross-linked polymers, which serve as more effective and more durable sealants and adhesives, the most common uses for the anaerobic compositions.

The most highly preferred acrylate esters which can be used in the compositions disclosed herein are polyacrylate esters which have the following general formula: wherein R represents a radical selected from the group con atoms, hydroxy alkyl of from 1 to about 4 carbon atoms, and 0 II -CH2~0-C-C=CH2 I R2 2 R is a radical selected from the group consisting of hydro¬ gen, halogen, and lower alkyl of from 1 to about 4 carbon 3 atoms; R is a radical selected from the group consisting of hydrogen, hydroxyl, and m is an integer equal to at least 1, e.g., from 1 to about 15 or higher, and preferrably from 1 to about 8 inclusive; n is an integer equal to at least 1, e.g., 1 to about 20 or more, and preferrably between about 2 and about 6; and p is one of the following: 0, 1.

The polymerizable polyacrylate esters utilized in accordance with the invention and corresponding to the above general formula are exemplified by, but not restricted to, tetra. the following materials: di- , tri- and -tsti/ethyleneglycol dimethacrylate; dipropyleneglycol dimethacrylate; poly-ethyleneglycol dimethacrylate; di(pentamethyleneglycol) dimethacrylate; tetraethyleneglycol diacrylate; tetraethyl-eneglycol di(chloroacrylate) ; diglycerol diacrylate; diglycerol tetramethacrylate; tetramethylene dimethacrylate; ethylene dimethacrylate; neopentylglycol diacrylate; and trimethylol-propane triacrylate.

While di- and other polyacrylate esters -- and parti- acrylate esters (esters containing one acrylate group) also may be used. When dealing with monofunctional acrylate esters, it is preferrable to use an ester which has a relatively polar alcoholic moiety. Such materials are less volatile than low molecular weight alkyl esters and, more important, the polar group tends to provide intermolecular attraction in the cured polymer, thus producing a more durable sealant or adhesive.

Most preferrably the polar group is selected from the group consisting of labile hydrogen, heterocyclic ring, hydroxy, amino, cyano, and halogen polar groups. Typical examples of compounds within this category are cyclohexylmethacrylate, tetrahydrofurfuryl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, t-butylaminoethyl methacrylate, cyanoethylacrylate , and chloroethyl methacrylate.

Other acrylates can be used in the anaerobic compositions, such as the isocyanate-monoacrylate reaction products described in the above mentioned United States Patent 3,425,988. However, when other acrylates are used, they preferrably are used in combination with one or more members from either or both of the above described classes of poly-acrylate and monoacrylate monomers. Most preferrably, poly-acrylates having the chemical formula (1) , given above, comprise at least about fifty percent by weight of the acrylates used since these monomers have been found clearly superior in anaerobic sealants, as is more fully described below.

An indicated above the anaerobic compositions as discussed herein are prepared by mixing a hydroperoxide catalyst with one or more acrylate esters as described above. Hydrogen- initiators are the. organic hydroperoxides. Included within this definition are materials such as organic peroxides or organic peresters which decompose or hydrolyze to form organic hydroperoxides in situ. Examples of such peroxides and peresters are cyclohexyl hydroxycyclc¾e¾t peroxide and t-butyl perbenzoate, respectively.

While the nature of the organic hydroperoxides is not critical to the broad concept of this invention, the general class of hydroperoxides can be represented by the formula R 4OOH, wherein R4 generally is a hydrocarbon group containing up to about 18 carbon atoms, and preferrably is an alkyl, aryl or aralkyl hydrocarbon group containing from about 3 to about 4 12 carbon atoms. Naturally R can contain any substituent or linkage, hydrocarbon or otherwise, which does not affect the hydroperoxide adversely for the purpose disclosed herein.

Typical examples of such organic hydroperoxides are cumene hydroperoxide, tertiary butyl hydroperoxide, methylethylketone hydroperoxide, and hydroperoxides formed by oxygenation of various hydrocarbons such as methylbutene, cetane, and cyclohexene, and various ketones and ethers, including certain compounds represented by the general formula (1) above. The organic hydroperoxide initiators which are used commonly comprise less than about 10 percent by weight of the combination of polymerizable monomer and initiator, since above that level adverse effects on the strength and durability of the cured composition may be experienced. Preferrably the hydroperoxide initiator comprises from about 0.1 percent to about 5 percent by weight of the combination. polymerizable monomer and latent polymerization initiator, such as quinone or polyhydric phenol stabilizers, thickeners, plasticizers , dyes, adhesive agents, thixo ropic agents, etc. Such materials can be used in such combinations and proportions as is desired, provided they do not affect adversely the anaerobic nature of the composition. These materials generally do not comprise more than about 50 percent by weight of the total composition:, and preferrably not more than about 20 percent by weight of the composition.

While the benefits of this invention are achievable in all anaerobic compositions in the form of increased stability, they are seen most clearly in anaerobic compositions which contain polymerization accelerators. As explained above, such accelerators should be incorporated in the composition to obtain rapid cure at the time of intended use. This avoids the need to add accelerators either to the anaerobic composition or the surfaces to be bonded, sealed, etc., at the time of use.

The most efficient of the polymerization accelerators are those which are redox activated. These frequently create stability problems when used to prepare anaerobic compositions in the prior art fashion because of the presence of metal contamination as discussed above. When used as disclosed herein, the redox activated accelerators can be used safely, and even can be used at higher levels to produce greater speed of cure. It is in this respect that some of the most important advantages of this invention are realized.

In addition, the removal of metal contamination inhibitors, such as those of the quinone-type , did not have a measureable effect on the speed of cure by less sophisticated accelerators, but such has not been found to be the case when dealing with the more sophisticated accelerator systems, such as those disclosed in the above mentioned United States Patent 3,218,305. When metal contamination is removed, the inhibitor level can be reduced safely from the customary 100 to 300 parts per million by weight to about 25 to about 75 parts per million by weight. In many cases, the inhibitor can be eliminated totally. This reduction or elimination produces significant improvements in speed of cure.

The most common of the polymerization accelerators suitable for incorporation in anaerobic composition are discussed below and the benefits of the invention are achievable with any of such accelerators. It should be noted however that large numbers of polymerization accelerators are known in the art, and the broad concept of this invention is intended to encompass any polymerization accelerator which can be incorporated in the anaerobic composition without destroying the essential characteristics of such composition.

Among the earliest of the polymerization accelerators used in anaerobic composition were amines. The most commonly used are tertiary amines such as tributylamine and triethylamine. Essentially the entire class of tertiary amines can be used in such compositions, and the class may be broadly represented by the formula wherein each of , R and is a hydrocarbon group contain groups can contain any substituent or linkage which does not adversely affect the workability of the amine to perform its intended function. Preferrably, each of 5 , R6 and R7 is an alkyl , aryl or aralkyl group containing up to about 8 carbon atoms. The Ν,Ν-dialkyl aryl amines are particularly effective.

Certain secondary amines also can be used as accelerators, but care must be utlized in the selection of secondary amines since they are potent accelerators. They frequently can cause stability problems if used in too large an amount. The most desirable class of secondary amines has been found to be the class of heterocyclic secondary amines, particularly those amines wherein the heterocyclic ring is hydrogenated. Typical of such compounds are pyrrolidine, piperazine and 1,2,3,4- tetrahydroquinoline. Low levels of certain primary amines can be used in some cases, but rarely, if ever, can any advantage be shown over the other amines previously described.

Another highly successful class of accelerators is the organic sulfimides, i.e., organic compounds which contain the group Because of the extreme effectiveness of the sulfimides as accelerators for anaerobic compositions, and because of the apparent strong interaction between the sulfimides and metal contamination, the use of the invention disclosed herein with anaerobic compositions containing organic sulfimides constitutes organic sulfimides can be used successfully, the sulfimides most commonly used can be represented by the formula wherein each of Rg and Rg is a hydrocarbon group containing up to about ten carbon atoms, and preferrably up to about six carbon atoms. Naturally, Rg and Rg can contain any linkage or substituent which does not adversely affect the sulfimide for its intended use in the anaerobic composition. Further, Rg and Rg can be united to bond the sulfimide group in a heterocyclic ring, or a polynuclear heterocyclic ring system. Of the organic sulfimides, benzoic sulfimide has been found to be the most preferrable.

A good combination of shelf stability and cure speed is obtainable with this class of accelerators, but care must be taken in combining sulfimides, particularly benzoic sulfimide, with amines of the types described above. Improper combinations can cause stability problems. However certain selected classes of amines can be used in combination with the sulfimides, and exceptionally good anaerobic compositions can be prepared. A preferred composition is that which contains a sulfimide, particularly benzoic sulfimide, in combination with either a heterocyclic secondary amine as discussed above, or a tertiary Ν,Ν-dialkyl aryl amine. Typical amines within the latter class may be represented by the following general formula: R" and R are lower alkyl radicals of 1 to 4 carbon atoms; t is one of the following: 0, integer equal to from 1 to 5 12 inclusive; R is a member selected from the groups of lower alkyl and lower alkoxy radicals of 1 to 4 carbon atoms inclusive, provided that when an R radical is m the ortho position, t is greater than 1. For an expanded discussion of this type of system, reference is made to the above mentioned United States Patent 3,218,305.

Other less active accelerators can be used in the compositions of this invention. Typical examples of such accelerators are succinimide, phthalimide and formamide.

Routine testing easily will determine the optimum amount of accelerator which can be incorporated in a given anaerobic composition. the following general guide lines may be used. With regard to tertiary amines, large amounts may be used if desired, up to a maximum of about 5 percent by weight of the composition. Most preferrably these tertiary amine accelerators are used at from about 1 percent to about 4 percent by x^eight of the anaerobic composition.

The succinimide, phthalimide and formamide accelerators also can be used in significant amounts, up to about 5 percent by weight of the composition, and preferrably from about 1 percent to about 5 percent by weight. The sulfimide and secondary amine accelerators generally are used at less than 2 percent by weight of the anaerobic composition. In the special case where a sulfimide is used in combination with a heterocyclic secondary amine or a Ν,Ν-dialkyl arylamine, the total of the two components should not exceed about 3 percent by weight B. THE PROCESS It will be apparent from the foregoing discussion, any process can be used which is capable of removing metal contamination at the extremely low concentrations at which it exists in anaerobic compositions, or in the starting materials, therefor. As indicated above, it has been found that the desirable properties described herein are obtained when the iron contamination in the anaerobic composition is less than that inherent in prior art anaerobic compositions, and hence the iron content should be reduced to a level less than about 0.10 parts per million by weight. Preferrably, this level is less than 0.05 parts per million, and optimum results are obtained at levels less than about 0.01 parts per million.

To accomplish the removal of metal contamination, the anaerobic composition, or at least a portion of the starting materials or intermediates therefore, are treated with an organic or inorganic compound which reacts with the metal of the metal contamination to form an insoluble metal containing precipitate. For purposes of this invention, the term insoluble metal-containing precipitate is used in its broad sense to cover chemical compounds and chemical complexes which are insoluble in the anaerobic composition.

Removal of the insoluble metal-containing precipitate may be by any conventional method. In many cases, allowing the insoluble precipitate to settle from the anaerobic composition will be adequate, even if the insoluble precipitate is not physically separated from the anaerobic composition. Preferably, physical separation is effected, and standard methods or removal In a suitable process, the materials to be treated are passed through an ion exchange resin. Resins specifically designed for the removal of metal contamination, and particularly iron contamination, are available from a number of commercial sources. Because of the extremely low concentrations of metal contamination which are involved, extended colums of the resin should be used. Alternatively, the resin, in fine granules, can be mixed with the anaerobic materials or ingredients for a sufficient period of time to allow the metal to form an insoluble metal complex. A suitable ion exchange resin is that sold under the tradename "Dowex-50", a cationic resin of the sulfonate type, supported in a styrene-divinylbenzene matrix.

In another suitable process within the scope of the invention, the treatment agent is one which removes the metal contamination by complexing or adsorbing the metal onto its surface. A suitable treatment agent of this type is elemental sulfur An exceptionally good method of metal contamination removal within the scope of the invention described herein has been found to be the use of insoluble chelators. Unexpectedly, it was found that this process could be utilized to remove a large percentage of the extremely low concentration of metal contamination of the anaerobic composition, or the starting materials which are to be used in preparing such a composition. The use of insoluble chelators is a preferred embodiment of this invention.

As is well known in the art, chelating agents are compounds which bind available atoms into a ring structure via available electron pairs on the chelating agent. Typical and beta diketones ; in these compounds the pair of nitrogen , or oxygen atoms generally is separated by three carbon atoms. In this arrangement, the available electron pairs on the nitrogen or oxygen atoms are readily available for binding the metal atom into a six member, and hence quite stable, heterocyclic ring.

With other chelating agents , rings may be formed having from five to seven atoms or twelve or more atoms.

For an expanded treatment of chelation and the chelating agents, reference is made to Dwyer and Mellor, "Chelating Agents and Metal Chelates", Academic Press, New York, 1964.

Generally, chelating agents are categorized by their "donor atoms", e.g., the atoms in the agent which "donate" electron pairs to bind the metal atom into the ring structure. The most common donor atoms in chelating agents are oxygen, nitrogen and sulfur. The most highly preferred chelating agents are those which utilize a nitrogen atom and an oxygen atom in forming the chelated ring structure. Examples of such chelating agents are ethylenediamine tetraacetic acid, o-aminophenol , and sodium salts of either of these.

Chelating agents other than those having one each of oxygen and nitrogen donor atoms can be used successfully.

Typical examples of such compounds are the following: sodium acetylacetonate ; polyvinyl alcohol; sodium dimethyIglyoximate; sodium salicaldehyde; sodium diethyldithiocarbamate ; disodium dithioxamidate; disodium pyrocatecholate ; and sodium quino- linolate.

Still another class of treating agents which can be is that class of compounds which will react with metal contamination to form metal salts which are insoluble in the anaerobic composition-, or its starting materials, as the case may be.

Typical treating agents of this class which can be used successfully are as follows: potassium ferricyanate ; sodium citrate; sodium pyrophosphate; sodium silicate; disodium oxalate; phosphomolybdic acid; sodium cyanide; sodium stearate; tribasic sodium phosphate; and sodium sulfate.

The amount of treating agent, such as those described in the preceding paragraphs , which should be used to remove metal contamination from the anaerobic composition, or the starting materials therefore, easily can be determined with a minimum of routine testing. The optimum amount depends upon a large number of factors, such as the amount of metal contamination in the material, the percent removal required for the specific anaerobic composition involved, the time available over which chelation can take place, etc. In many cases it may be advantageous to use a combination of treating agents, particularly when dealing with chelating agents, or compounds used to form insoluble metal salts. Frequently, certain treating agents are particularly effective in removing certain metals, and hence a combination of agents may be more effective than any single one. As a general guideline, the minimum amount of insoluble treating agent which should be used is about 0.5% by weight of the materials to be treated; the maximum amount is about 107<> by weight. Below this minimum, threatment time becomes unduly long, and above this maximum, little if any additional benefit is obtained. The preferred range is from about 1% to 570 treating In some cases, the amount of treating agent used can b< materially reduced by performing the treatment step at a tempera ture at which the treating agent is at least slightly soluble in the material being treated, and allowing the reaction product of the treating agent and the metal contaminats to separate at a temperature at which the reaction product is insoluble.

In this case, concentrations of treating agents as low as about 50 to 100 parts per million by weight of the material to be treated can be used. A demonstration of this technique is presented in the examples below.

The amount of time required for the treatment process of this invention can, be several days or more, or it can be reduced by, e.g., the use of large amounts of the chelating agent. It generally is undesirable under any processing conditions to mix the treating agent and the material to be treated for less than about one to two hours. Longer mixing times are desirable if the length of treatment time is not critical since the efficiency of removal of the metal contamination increases with treatment time. Treatment may proceed for up to several weeks if desired; excessive time may be wasteful or cumbersome, but will not adversely affect the process described herein.

As a practical matter, it is desirable to test the stability of the product when treatment is commenced, and check the stability from time to time thereafter until a pre-deter-mined stability is reached. (A suitable test for stability is described fully in the Examples below.) At that time treatment may be stopped. may vary over a relatively wide range. It has been found that ' the efficiency of the treatment process for metal removal increases with increasing temperature. Excessively high temperatures should be avoided however since the polymerizable monomers of the anaerobic composition will polymerize even in the most stable systems at elevated temperatures. Generally treatment at temperatures greater than about 160°F. is undesirable, particularly in the absence of vigorous agitation. Preferrably the temperature does not exceed about 150°F. At the other extreme, while the treatment may be conducted at low temperatures, such as about 30°F., it generally is impractical to perform the treatment at less than ambient temperature (e.g., 70°F.). Treatment at ambient temperature has been found to be perfectly suitable and, as a matter of convenience, frequently will be the most suitable temperature. Most preferrably the treatment is conducted between about 70°F. and about 150°F.

Since numerous possible components of anaerobic compositions are solids, it frequently is necessary to process the anaerobic composition as a whole, or to dissolve the solid component or components in a solvent for treatment. After the insoluble metal containing precipitate is separated, the solvent is removed by stripping or otherwise. Also, when viscous anaerobic compositions or components therefor are treated, it frequently is desirable to add sufficient solvent to reduce the viscosity to e.g., 1000 centipoises and preferrably to about 500 centipoises, before commencing the treatment process.

When a suitable amount of the metal contamination has been separated from the anaerobic composition or the starting indicated above, measurable benefits are obtained from the ^ process described herein when any significant amount of metal contamination is removed. Generally, at least about 50%, by weight of the metal contamination should be removed, based on the total weight of metal contaminants in all ingredients used. Preferably at least about 80% by weight is removed, optimum results are achieved when at least about 95% by weight is removed.

The processing equipment which is used in the chelation process described herein should be constructed from passivated surfaces (surfaces which are essentially free of reactive metals, and particularly of those metals described herein as detrimental to anaerobic compositions) . While certain grades of highly passivated stainless steel frequently can be used without substantial adverse effect, it is preferrable for the appropriate surfaces to be coated with glass, epoxy, polyethylene, teflon, or other such non-metallic surface.

Upon completion of the processing described herein, the anaerobic compositions may be packaged in standard polyethylene bottles or other suitable containers, and are ready for use directly. If the starting materials for the anaerobic compositions are processed separately, the treated .components simply need mixing prior to packaging and shipment.

EXAMPLES The following Examples are given to demonstrate product:; and processes within the scope of the invention disclosed herein and are not intended to be limitations upon the invention. Unless stated to the contrary all ratios and percentages in the Examples are on a weight basis.

Standard Stability Test Where the Examples contained herein make reference to the "stability" of a composition, the results of the following tests are involved. A standard 10 centimeter test tube is filled approximately half-full with a sample of the composition in question. The tube is then suspended in a constant temperature water bath which is maintained at 82°C. The length of time in minutes from the placing of the test tube in the bath to the time when the first solid or jelled material appears in the tube is noted. This length of time is used as a measure of the stability of the composition. It lias been found that the relative stability as determined by this test reflects with reasonable accuracy the relative lengths of -time for which the compositions may be stored at room temperature without spurious polymerization taking place. While a suitable stability for a given composition will vary some what from one composition to the next, the relative figures do give a sound basis for comparing related products.

Example I An approximate two pound sample of polyethyleneglycol dimethacrylate (average molecular weight =330) (hereinafter called "PEGMA") was separated into two approximately equal portions. To one of the portions \vas added 1 percent by weight ethylenediamine tetraacetic acid, and the mixture was agitated vigorously for one hour. The agitation was conducted in a 4 r equipped with a teflon coated shaft and blade. After the agitation the chelator was allowed to settle and the treated PEGMA was separated by decantation.

The treated and untreated portions of the PEGMA were used to prepare anaerobic compositions by adding to each 0.3 percent by weight dimethylparatoluidine , 0.4 percent by weight benzoic sulfimide, 3 ¾ by weight cumene hydroperoxide and 50 parts per million by weight quinone. The stability of each formulation then was determined and it was found that the anaerobic composition formulated from the untreated PEGMA was 4 minutes, whereas the composition formulated from the chelator- treated PEGMA was 12 minutes.

Fifty milliliters of each of the two anaerobic compositions were placed in separate polyethylene bottles and stored at room temperature. After two weeks it was found that the compositions prepared from untreated PEGMA had polymerized, whereas that prepared from the chelator- treated PEGMA was still liquid and had experienced no loss of stability.

Example II The process in Example I was repeated except that the disodium salt of etJiylenediamine tetraacetic acid was used as a chelating agent at a concentration of 2 percent by weight Of the material to be treated. The material treated was 94 percent by weight PEGMA, made slightly more viscous by the addition of 6 percent by weight of a polychlorophenol resin (ASTM E-28 softening point = 208°-220°F), sold under the trade name "Aroclor 5460". As in Example I, the mixing time was one hour. Upon completion of the mixing operation, the treated mixture was allowed to stand overnight to permit settling of the chelating agent, after which time the treated liquid was removed by decan ψ chlorophenol resin were used to prepare anaerobic compositions by the addition of the same ingredients, in the same concentrations, specified in Example I.

The stability of the two anaerobic compositions were determined and it was found that the composition prepared from the untreated material was 2 minutes, whereas that prepared from the chelator- treated material was 9 minutes.

Example III A two pound sample of PEGMA was mixed with 3 percent by weight cumene hydroperoxide and 100 parts per million by weighs quinone. To this was added 4.3 percent by weight of the disodium salt ethylenediamine tetraacetic acid. The mixture was agitated as described in Example I above, for a period of 4 days. The mixture then was allowed to stand over night to permit settling of the chelator, following which the treated liquid was removed by decantation.

An anaerobic composition was prepared from this treated material by adding to it 0.3 percent by weight dimethylpara-toluidine and 0.4 percent by weight benzoic sulfimide. The stability of this material was determined and found to be 12 minutes Example IV Approximately 50 cubic centimeters of dimethylpara-toluidine was mixed with 5.6 % by weight of the disodium salt of ethylenediamine tetraacetic acid, and agitated in a 250 cubic centimeter glass beaker for 48 hours. Approximately 50 cubic centimeters of cumene hydroperoxide were mixed with 5 percent by weight of the same chelating agent, and agitated in a second beaker for 16 hours. Approximately 50 cubic centimeters of PEGMA containing about 5 percent by weight of benzoic sulfimide were mixed with 5 percent of the same chelating agent and mixed in a the chelating agent, following which the treated liquids were removed by decantation.

A sufficient amount of the PEGMA-benzoic sulfimide mixture was added to a portion of the chelator treated PEGMA from Example I to produce a benzoic sulfimide concentration in PEGMA of 0.4 percent by weight. To this was added 0.3 percent by weight of the dimethylparatoluidine treated in this Example, and 3 percent by weight of the cumene hydroperoxide, also treated in this Example. To the final mixture was added 100 parts per million by weight quinone.

The stability of this anaerobic composition then was determined and found, to be 15 minutes.

Example V Ten percent by weight eth lenediamine tetraacetic acid was added to approximately 50 cubic centimeters of acrylic acid and the mixture was agitated for 2 hours, essentially as described in the above Examples. Thereafter the chelator was allowed to settle, and the chelator- treated liquid was removed by decantation.

Six percent by weight of the acrylic acid so treated was added to an anaerobic composition essentially identical to those described in Example I above (stability 11 minutes). The stability of the final mixture was tested and found to be 13 minutes .

To a second sample of the same anaerobic composition was added 6 percent by weight acrylic acid which had not been chelator- treated . The stability of this mixture was measured and found to be 4 minutes.

Example VII A polymerizable acrylate monomer was prepared by the reaction product of 2 moles of toluene diisocyonate and 1 mole of hydrogenated diphenyldimeth lmethane , 100 parts by weight of this monomer were mixed with 50 parts by weight dich-loromethane and 15 parts by weight ethylenediamine tetraacetic acid. This mixture was agitated for 72 hours, essentially as described in the preceding Examples. After the chelator had settled, the liquid was removed by decantation and the dich-loromethane was allowed to evaporate.

Six percent by weight of the treated acrylate monomer of the preceding paragraph was added to an anaerobic composition essentially identical to those described in Example I (stability 16 minutes) . The stability of the final mixture was measured and found to be 19 minutes.

Six percent of the same acrylate monomer which had not been treated as described above in this Example, was added to a portion of the same anaerobic composition described in the preceding paragraph. The stability of this final mixture was measured and found to be eleven minutes.

Example VIII An anaerobic composition essentially identical to those described in Example I, above, \>;as prepared, except that the level of benzoic sulfimide was increased to 1.6% by weight. The composition immediately was mixed with 5% by weight of ethylenediamine tetraacetic acid and agitated for 18 days.

At the end of that period, the stability of the composition was found to be 60 minutes. Iron analysis indicated that the total iron content was less than 0.10 parts per million by weight. faster than any of the compositions prepared in Examples I through VII above.

Example IX A sample of PEGMA was split into three portions. To the first portion was added ten percent by weight of elemental sulfur, and the mixture was agitated at room temperature for twenty hours. After the sulfur had settled, the treated PEGMA was separated by decantation.

To the second portion of the PEGMA was added ten percent by weight of an acid form cation exchange resin of the sulfonate type, sold under the tradename "Dowex 50 " . The mixture was agitated for twenty hours at 150°F, after which the temperature was allowed to return to room temperature and the ion exchange resin allowed to settle. The treated PEGMA was separated thereafter by decantation.

Three anaerobic formulations were prepared consisting of PEGMA containing three percent by weight cumene hydroperoxide, 0.2 percent by weight benzoic sulfimide, and 0.05 percent by weight dimethylparatoluidine . Formulation A was prepared from the untreated portion of PEGMA, Formulation B from the sulfur treated portion of PEGMA, and Formulation C from the ion exchange resin treated portion of PEGMA. The stabilities of the three Formulations were determined and found to be as follows: Formulation Stability, Mins .

A 8 B 75 C ^ 75 Example X Samples of PEGMA were mixed with five percent by weight two different temperatures. After the treatment the PEGMA samples were separated from the settled solids by decantation, and anaerobic formulations were prepared, using the same ingredients in the same percentages as described in Example IX, above. The stabilities of the various formulations were determined and found to be as follows: Treatment T Stability (Minutes) after Treatment (Flours ) 70°F 150°F 27 A control sample made from untreated PEGMA had a stability of eight minutes .

Example XI To demonstrate an alternate method of separation of the metal containing precipitate which is insoluble in the PEGMA, PEGMA was treated with ten percent by weight of a 50/50 weight solution of tetrasodium eth lenediamine tetraacetic acid in water The mixture was vigorously agitated for one hour, after which the water layer was allowed to separate. A sample was drawn from the PEGMA layer and formulated into an anaerobic composition using the same ingredients in the same percentages described in Example IX, above. The stability of the formulation was found to be twenty minutes, whereas the stability of a control sample prepared from untreated PEGMA was found to be eight minutes.

Example XII In this Example various samples of PEGMA were treated with 300 parts per million by weight of various chelating agents.

The agent was added in a three percent by weight water solution. Treatment was at 150°F. for one hour with moderate stirring.

After cooling to room temperature, an insoluble precipitate was seen at the bottom of the mixture. The treated PEGMA samples then were used to prepare anaerobic formulations, using the same ingredients in the same percentages described in Example IX, above. The stabilities of the various formulations, referenced to the chelating agent used in the treatment process, are given below.

Chelating Agent Stability (Minutes) Sodium Acetylacetonate 19 Sodium Salicaldehyde 37 Sodium o-Aminophenolate ^ 75 Disodium Pyroca.^echolate 45 Sodium Quinolinolate 36 Additional chelating agents were used in the same test as described in this Example, except that mixing of the chelating agent and PEGMA was continued for sixteen hours. The results of these tests are given below.

Chelating Agent Stability (Minutes) Polyvinyl Alcohol 70 Disodium Dithioxamidate 32 Sodium Dime th lglyoximate 28 Sodium Diethyldithiocarbamate S 75 Example XIII The exact procedure of Example XII, above, was repeated using the one hour mixing time, except that the chelating agents were replaced with insoluble metal salt forming compounds. In each case, the presence of an insoluble precipitate was detected at the bottom of the treated PEG A sample after cooling to room temperature. The stabilities, referenced to the treating agents used, for the resultant anaerobic compositions were as follows: Treating Agent Stability -(Minutes) Sodium Thiosulfate 18 Potassium Ferricyanate 15 Sodium Citrate 19 Sodium Pyrophosphate 2.8 Sodium Silicate 19 Disodium Oxalate 26 Sodium Cyanide 20 Sodium Stearate 17 Example XIV Each of the anaerobic compositions of Examples I through XIII, above, the whole or a. portion of which was treated and prepared in accord with the invention disclosed herein, was tested and found to be an effective anaerobic sealant. When pla-ced on the threads of a steel bolt, and the bolt assembled with a mating nut, the sealant was found to harden in a short time to bond the nut and bolt firmly together.

Further, the anaerobic composition prepared and treated according to this invention are capable of greater cure speed since higher le\>"els of polymerization accelerators may be used therein, compared to their prior art counterparts which have not been so treated. Particularly good results were achievab e in compositions which contained less than 0.1 parts per million iron, by weight o£ the final anaerobic composition, and most particularly when this level was less than 0.05 parts per million HIGHLY STABLE FOLYMSRIZABLE ANAEROBIC COMPOSITIONS AND PROCESS FOR PREPARING THEM mairar? ma's' isa ηΐ'ηιτ.κ nunyn injjn i»» nni ma>»aV The earliest anaerobic material is that disclosed in U.S. Patent 2,628,173 to Burnett and Nordlander, issued first that issued July 21, 1959. Typical examples of disclosures relating to improved anaerobic compositions of this latter type may be found in the following United States Patents: 3,043,820 to Krieble, issued July 10, 1962; 3,046,262 to Krieble, issued July 24, 1962; 3,218,305 to Krieble, issued November 16, 1965; and 3,425,988 to Gorman and Toback, issued February 4, 1969.

Improvements in the chemistry of anaerobic systems permitted the incorporation of polymerization accelerators which, while not destroying the stability of the composition over significant periods of time, such as six months or more, did provide increased speed of cure at the time of intended use. However, as' more of the accelerator was added, or if a stronger accelerator was used, the incidence of spurious polymerization use increased. It also was foundJ^iai -t¾s~e~liin^ tions were far more sensitive to outside influences, such as temperature, and their performance was less predictable. For reasons not completeJ-y_known,—the-number - of compositions which would cure during processing or immediately after manufacture also increased— / In an attempt to solve these problems, larger amounts of conventional polymerization inhibitors (such as mentioned stability problems. More powerful polymerization inhibitors were discovered, but were not found to be the complete solution to the problem. Even with these inhibitors, the stronger types of polymerization accelerators could not ■ I ■*' be used with safety, particularly at concentrations which' would produce highly desirable speeds of cure.

It is the purpose of this invention to provide anaerobic compositions which can be . formulated with increases in either or both stability and speed of cure, as well as to provide a process for producing anaerobic . compositions having such capabilities.

THE INVENTION compositions having a reduced content of metal contamination. As used herein, "metralT'contamination" is intended to encompass metal which is present in any form within the anaerobic composition. The most common of these is metal which is present in the form of free metal ions. However, organic and inorganic metal compounds also commonly are included in such compositions as well. The presence of such contamination is traceable to impurities in the starting materials, generally due to their methods of manufacture, and on occasion traceable in. part to contamination from the processing equipment in which. the5 anaerobic cpmpositio is made. Metal contamination in the starting materials is by far the most troublesome source of contamination. than 0.1 parts per million by weight,, a level which was ex- r ceeded by prior art anaerobic compositions due to the inherent metal contamination in the starting materials as discussed above. While numerous metals contribute to the contamination, iron constitutes the bulk of such contaminants and if the iron content is reduced below the above level, significant increases in desirable properties are achieved. For optimum results, the iron content should be reduced to less than 0.05 parts per million by weight.. Other as copper, nickel and manganese, generally are removed in significant quantities along with the iron, although the efficiency with which a given metal contaminant is removed will Vary to some extent with the specific method of removal, as is more fully discussed_beLow_, •'The invention also contemplates anaerobic compositions prepared by a process which includes the step of reducing the content of metal contamination. The metal contamination may be removed from the final anaerobic composition or from starting materials or intermediates therefore. While significant improvements are achieved when any significant proportion of the metal contamination is removed, it commonly is desirable to remove at least 50 percent by weight of such metal contamination. ' DESCRIPTION OF THE INVENTION AND ITS PREFERRED EMBODIMENTS A. THE PRODUCT Anaerobic compositions which are the subject of t ree-radical polymerizable monomer whose polymerization is inhibited by the presence of oxygen; and (b) a redox activated latent initiator of free radical polymerization, which is capable of polymerizing the monomer of (a) above, in the absence of oxygen. This combination of ingredients can be I bottle preferrab y po yet y ene or ot er mater a w c w permit penetration of atmospheric oxygen) , and will remain in the liquid, unpolymerized state at normally encountered for a period of several months or longer.

As indicated above, this invention deals with i anaerobic compositions- wherein the latent initiator of free radical polymerization is redox activated. "Redox activated11 refers to activation by a process which includes an oxidation- reduction reaction, wherein one of the products is or forms a free radical. The most important class of initiators in this category is the class of hydroperoxides. While applicants do not wish to be bound to any particular itheory, it is believed that such initiators co-act with metal contamination to produce stability problems in the anaerobic composition, apparently by overcoming the inhibiting effect of the oxygen. It is quite surprising to find that the low levels- of metal contamination- which applicants find are inherent in the starting materials for anaerobic compositions could cause the significant problems which have been traced to such contamination. Even more surprising was the size of the increase in the performance of cms, hydroxy alkyl of from 1 to about 4 carbon atoms, and R Is a radical selec ed-from the group consisting of hydro¬ gen, halogen, and lower alkyl of from 1 to about 4 carbon 3 atoms; R is a radical selected from the group consisting of hydrogen , hydroxyl , and 0 m is an integer equal to at least 1, e.g., from 1 to about 15 or higher, and preferrably from 1 to about 8. inclusive; n is a integer equal to at least 1, e.g., 1 to about 20 or more, and preferrably between about 2 and about 6; and p is one of the following: 0, 1.

The polymerizable polyacrylate esters utilized in accordance with the invention and corresponding to the above general formula are exemplified by, but not restricted to, I the following materials: di- , tri- and -tat¾/ethyleneglycoi dimethacrylate; dipropyleneglycol dimethacrylate; poly- ethyleneglycol dimethacrylate; di(pentamethylenegly'col) dimethacrylate; tetraethyleneglycol diacrylate; tetraethyl-I eneglycol di(chloroacrylate) ; diglycerol diacrylate; diglycero tetramethacrylate; tetramethylene dimethacrylate; ethylene dimethacrylate; neopentylglycol diacrylate; and trimethylol- propane triacrylate. acryiauG es on 'aiiiing one acrylate group) also may be used. When dealing with monofunctional acrylate esters, it Is preUerrable to use an ester which has a relatively polar alcoholic moiety. Such materials are less volatile than low molecular weight alkyl esters and, more important, the polar group tends to provide interrnolecular attraction in the cured polymer, thus producing a more durable sealant or adhesive.

Most preferrably the polar group is selected from the group consisting of labile hydrogen, heterocyclic ring, hydroxy, amino, cyano, and halogen polar groups. Typical examples of compounds within this category are cyclohexylmethacrylate, tetrahydrofurfuryl methacrylate, hydroxyethyl acrylate, hydroxy ropyl methacrylate, t-butylaminoethyl methacrylate, cyanoethylacrylate, and chloroethyl methacrylate.

Other acrylates can be used in the anaerobic compositions, such as the isocyanate-monoacrylate reactio products described in the above mentioned United States Patent 3,425,988. However, -when other acrylates are used, they preferrably are used in combination with one or more members from either or both of the above described classes of poly-acrylate and monoacrylate . monomers . Most preferrably, poly-acrylates having the chemical formula (1) , given above, comprise at least about fifty percent by weight of the acrylates used since these monomers have been found clearly superior initiators are the organic hydroperoxides. Included within this clefi l ^ir~s '( ~i^e l ls such as organic peroxides or organic peresters which decompose or hydrolyze to form organic hydroperoxides in situ. Examples of such peroxides and peresters are cycJLohexyl- hydt-oxycyclo¾e½£l- peroxide and t-butyl perbenzoate, respectively.

While the nature of the organic hydroperoxides is not critical to the broad concept of this invention, the general class of hydroperoxides can be represented by the formula generally is a hydrocarbon group containing up to about 18 carbon atoms, and preferrably is an alkyl, aryl or aralkyl hydrocarbon group containing from abou 3 to about 4 12 carbon atoms. Naturally R can contain any substituent or linkage, hydrocarbon or otherwise, which does not affect the hydroperoxide adversely for the purpose disclosed herein.

Typical examples of such organic hydroperoxides are cumene hydroperoxide, tertiary butyl hydroperoxide, me hyle hyIke ne hydroperoxide, and hydroperoxides formed by oxygenation of various hydrocarbons such as methylbutene, cetane, and cyclohexene* and various ketones and ethers, 'including certain compounds represented by. the general formula (1) above. The organic hydroperoxide initiators which are used commonly comprise less than about 10 percent by weight of the combination of polymerizable monomer and initiator,^ since above that level adverse effects on the strength and durability of the cured composition may be experienced. Preferrably the hydroperoxide initiator comprises from about 0.1 percent to about 5 percent oolymerizable monomer and latent polymerization initiator, such as quiiione or polyhydric phenol stabilizers, thickeners, •plasticizers, dyes, adhesive agents, thixotro ic agents, etc. Such materials can be used in such combinations and proportions as is desired, provided they do not affect adversely the anaerobic nature of the composition. These materials generally do not comprise more than about 50 percent by weight of the total composition, and preferrably not more than about 20 'ϊ groups can contain any substituent or linkage which does not adversely affect the workability of the amine to perform its 6 7 intended function. Preferr bly, each of R , R and R is an alkyl, aryl or aralkyl group containing up to about 8 carbon ' atoms. The Ν,Ν-dialkyl aryl amines are particularly . foefive Certain secondary amines also can be used as , accelerators, but care must be utlized in the selection;of secondary amines since they are potent accelerators. They j frequently can cause stability problems if used in too large an amount. been found to be the class o heterocyc ic secon ary amines, particularly those amines wherein the heterocyclics ring is hydrogenated. Typical of such compounds are pyrrolidine, piperazine and 1,2,3,4- tetrahydroquinolxne. Low levels of certain primary amines can be used in some cases, but rarely, if ever, can any advantage be shown over the other amines pre¬ viously described.

Another highly successful class of accelerators is the organic sulfimides, i.e., organic compounds which contain the group O H O II I ' ll -S- -G- il ; * 0 Because of the extreme ef ectiveness of the sulfimides as accelerators for anaerobic compositio s^ / apparent strong interaction between the sulfimides and metal contamination, the use of the invention disclosed herein with organic sulfimides ca be used successfully, the sulfimides most commonly used can be represented by the formula iwherein each of g and R^ is a hydrocarbon group containir up to about ten carbon atoms, and preferrably up to about six carbon atoms. Naturally, g and Rg can contain any linkage or j substituent which does not adversely affect the sulfimide for its intended use in the anaerobic composition. Further, Rg and can be united to bond the sulfimide group in a heterocyclic ring, or a polynuclear heterocyclic ring system. Of the organic sulfimides, benzoic sulfimide has been found to be the most j In some cases, the amount o£ treating agent used can be materially reduced by performing the treatment step atJ tem erature at which the treating agent is at least slightly soluble in the material being treated, and allowing the- reaction product of the treating agent and the metal contaminats to separate at a temperature at which the reaction product is insoluble.

In this case, concentrations of treating agents as low as about 50 to 100 parts per million by weight of the material is presente n t e examp es e ow.

The amount of time required for the treatment process of this invention can, be several days or more, or it - can be \ reduced--hy--¾ g77~the use of large amounts of the chelating agent. It generally is undesirable... under any processing conditions to mix the treating agent and 'the material to be treated for less -than—about one to two hours. Longer mixing times are desirable if the length of treatment time is not critical since the efficiency of removal of the- metal contamination increases with treatment time. Treatment may proceed for up to several weeks if desired; excessive time may be wasteful or cumbersome, but will not adversely affect the process described herein. i As a practical matter, it is desirable to test the stability of the product when treatment is commenced, and check the stability from time to time thereafter until a .re-deter7' mined stability is reached. (A suitable test for stability is described fully in the Examples below.) At that time treatment indic ted above, measurable benefits are obtained from the ] when the first solid or jelled material appears in the tube is no ted. This length of time is used as a measure, of th . stabi-I ity of the composition. It lias been fou th-a^-t -r-e1 a->- " hid.ity as determined by this. test reflects with reasonable accuracy the relative lengths of. -time for which the compositions may be-, stored at room temperature without spurious polymerization taking place. While a suitable stability for a given composition will vary some figures do Exam le I An approximate two pound sample of polyethyleneglycol di ethacrylate (average molecular weight =330) (hereinafter called "PEGMA") was separated into two approximately equal , portions. To, one of the portions was added 1 percent by weight ethylenediamine tetraacetic acid, 'and the. mixture was g tated vigorously for one hour. The agitation was conducted in a 4 the chelator was allowed to settle and ^the treated PEGMA was separated by decantation. . \ percent by weight dimethylparatoluid ne , 0.4 percent y we g t benzoic sulfimide, 3 ¾ by cumene hydroperoxide and 50 , parts per million by weight quinone. The stability of each formulation then was determined and it was found that the anaerc.bic composition formulated from the untreated PEGMA was ' mir.ut.es , whereas the composition formulatecft rom "the chela".... -'tieJi . PEGMA was 12 minutes. , . ' · Fifty milliliters of each of the two anaerobic ccmpo- , sitions were placed in separate polyethylene bottles and stored at room temperature. After two weeks' it -was- found ■ that the comwhereas liquid and had experienced no loss of stability.

Example II The process in Example I was repeated except that the disodium salt of ethylenediamine tetraacetic acid was used as a chelating agent at a concentration of 2 percent by weight "of the material to be treated. The material treated was 94 percent by weight PEGMA, made : slightly more viscous by the addition of 6 percent by weight of a polychlorophenol res in (ASTM.E-28 softening point = 208°-220°F), sold under the trade name "Aroclor 5460". As in Example I, the mixing time was one ho/ir. Upon completion of the mixing operation, the treated mixture was allowed to stand overnight to permit settling of the chelating ' chlorophonol resin were used to prepare anaerobic .composit ons by tire addition of the same ingredients, in the same ^o* - or :·---„ icr.s , specified in Example I. - . ..

The stability of the two anaerobic compositions were . determined and it was found that the composition prepared from the untreated material was 2 minutes, whereas that" prepared A two pound sample of PEGMA was mixed with 3 percent by weight cuiuene hydroperoxide and 100 parts per million by weigh quinone. To this was added 4.3 percent by weight of the disodium ■salt ethylenediamine tetraacetic acid. The mixture was agi iated as described in Example I above, for a period of 4 days. The mixture then was allowed to stand over night to permit settling of the chelator, following which the treated liquid was removed by decantation.

An anaerobic composition was prepared from this treated material by adding to it 0.3 percent by weight dimethylpara- toluidine and 0.4 percent by weight benzoic sulfimide. The stability of this material was determined and found to be 12 minutes E am le IV ., Approximately 50 cubic centimeters of dimethylpara- ** toluidine was mixed with 5.6 % by weight of the disodium salt of ethylenediamine tetraacetic centimeter glass beaker for centimeters of cumene hydroperoxide were mixed with 5 percent by weight of the same chelating agent, and agitated in a second beaker for 16 hours. Appxoximately-.-Si) cubic centimeters of P GMA containing about 5 percent by weight of benzoic . sulfimide .-.'ere mixed with 5 - e eit j£L-Jh^s-ame---c elatin a ent and mixed in a the chelating agent, following which the treated liquids we e emoved by docantation.

A sufficient amount of the PEG A-benzdic sulfimide mixture was added to a portion of the chelator treated PEGMA from Example I to produce' a benzoic sulfimide concentration in PEGMA of 0.4 percent by weight. To this was added 0.5 percent j by weight of the dimethyIparatoluidine treated i this "Example and 3 percent by weight of the cumene hydroperoxide ,. also trca in this Example. To the final mixture was added 100 parts per million by weight quinone.

The stability of this anaerobic composition then vas determined and found to be 15 minutes.

E ample V Ten percent by weight ethylenediamine tetraacetic ac as added to approximately SO cubic centimet^ -s-^r£^acrylic aciu and the mixture was agitated for 2 hours, essentially as descr: bed in the above Examples. Thereafter the chelator was allowed to settle, and the chelator- treated liquid was removed by decan tat ion. _____-1——' Six percent by weight of the acrylic acid so treated was added to_jiji__iia^--e½-T _^0^ essentially identical to those described in Example I above (stability 11 minutes) . The stability of the final "mixture was tested and found to be 13 minutes.

To a second sample of the same anaerobic composition was added 6 percent by weight acrylic acid which had not been chelator- treated . The stability of this mixture was measured / and found to be 4 minutes.

Example VII ;he reaction product of 2 moles of toluene diisocyonate and 1 ;ole οί: uydrogenated diphenyJ-di ethylmethane , 100 parts by > I ■/eight of this monomer were mixed with 50 parts by we_ght dich- Lorome hane and 15 parts by weight ethylenediamine tetraace ic ij acid. This mixture was agitated for 72 hours, essentially as j!described in the preceding Examples. After the chelator had {J settled, the liquid was removed by decantation and the dich- lorome.-.iane was allowed to evaporate.

Six percent by weight of the treated acrylate monomer of the preceding paragraph was added to an anaerobic composition essentially identical to those described in Example I (stability 16 minutes) . The stability of iiand found to be 19^ininutes.

Six percent of the same acrylate monomer which had not been treated as described above_ in this Example, was added to a portion of the same anaerobic composition described in the preceding pa ^ aph.-,—The—stability of this final mixture was measured and found to be eleven minutes.

Exam le VIII An anaerobic composition essentially identical to those described in Example I, above, was prepared, except that • the level of benzoic sulfimide was increased to 1.6% by weight.

The composition immediately was mixed with 5% by weight cf (l ethylenediamine tetraacetic acid and agitated for 18 days. , i · 'I At the end of that period, the stability of, the :! composition was found to be 60 minutes. Iron analysis indicated |! .;! that the total iron content was less than 0.10 parts ^ r million faster than any of the compositions prepared in Examples I through VII above.

Example IX \ . Λ sample of PEGMA was split into three portions. To the first portion- as added 'ten percent by weight of elemental sulfur, and the mixture was agitated at room temperature for twenty hours. After the sulfur had settled, the treated PEGMA was separated by decantation.

To the second portion of the PEGMA was added ten, percent by weight of an acid form cation exchange resin of the sulfonate ytype , sold under the tradename "Dowex 50 W" . The mixture was agitated for twenty hours at 150°F, after which ^t e tempera-ture was allowed to return to room temperature and the ion ex- *" change resin allowed to settle. The treated PEGMA was separated thereafter by decantation.' Three anaerobic formulations were prepared consisting of PEGMA containing three percent by weight cumene hydroperoxide, 0.2 percent by weight benzoic sulfimide, and 0.05 percent by weight dimethylpar :tjA;iidine .- Formulation A was prepared from the untreated portion of PEGMA, Formulation B from the sulfur treated ion C from the ion exchange resin treated portion- of PEGMA. The stabilities of the three Formulations wore—determined and found to be as follows: Formulation Stability, Mins .

A 8 B 75 C 7-5 Example X two different temperatures. After the treatment the PEGMA sam les were separated from the settled solids by decantation, r.r.d anaerobic formulations were prepared, using the same ingredients in the same percentages as described in Example IX, above. The stabilities of the various formulations were determined and found to be as follows: Treatment Time Stability (Minutes) after Treatment (Hours) 70°F 150°F 1 2 4 25 35 24 27 75 A control sample made from untreated PEGMA had a sj^h-i-l-i ty of eight minutes .

Example XI To demonstrate an alternate method of separation of the metal containing precipitate which is insoluble in the PEGMA, PEGMA~Av-a-s—trrclTted with ten percent by weight of a 50/50 weight solution tetraacetic The one hour, after which -the water layer was allowed to separate. A sample was drawn from the PEGMA layer and formulated into an anaerobic comp osition using the same ingredients in the same percentages described in Example IX, above. The stability of the formulation was found to be twenty minutes, whereas the stability of a control sample prepared from untreated PEGMA was, found. to be eight minutes.

Exam le XII In this Example various- samples of PEGMA were treated i'ho a en was added in a three percent by weight water solution.

Trea ment at 150°F.' for one hour with moderate sti rin After cooling to room temperature, an insoluble precipitate was seen at the bottom of the mixture. The treated PEGMA samples then were used to prepare anaerobic formulation^, using the same ingredients in the same percentages described in Example IX, above. The stabilities of the various formulations, referenced to the chelating agent used in the treatment process, are given below.

Chelating Agent Stability (Minutes) Sodium Acetylacetonate Sodium Salicaldehyde .

Sodium o-Aminophenolate Disodium Pyroca£echolate Sodium Quinolinolate Additional chelating agents were_used in the s'aae test as described in'this Example, except that mixing, of the chelating · agent and PEGMA was continued for sixteen hours. The results of these tests are given below.

Chelating Agent Stability (Minutes) Polyvinyl Alcohol 70 Disodium Dithioxamidate 32 Sodium Dimethylglyoximate 23 Sodium Die thyldithiocarbamate 75 Example XIII The exact procedure of Example XII, above, was •repea c; wore replaced with insoluble metal salt forming compounds. In each case, the presence of an insoluble precipitate w s detected j j at the bottom of the treated PEG A sample after cooling to room temperature. The stabilities, referenced to the treating agents used, for the resultant 'anaerobic compositions were as follows: Treating Agent Stability -(Minutes) Sodium Thiosulfate 18 Potassium Ferricyanate 15 Sodium Citrate 19 Sodium Pyrophosphate 23 Sodium Silicate! 19 Disodium Oxalate 26 Sodium Cyanide Sodium Stearate Example XIV · Each of the anaerobic compositions of Examples I through X111 , above- flie-whole or a., portion of which was treated and prepared in accord with the invention discloses herei , w s tested and "found to be an effective anaerobic sealant. When pla-ced on the threads of a steel bolt, and the bolt assembled with a mating nut, the sealant was found to harden in a short time to bond the nut and bolt firmly together. j Further, the anaerobic composition prepared and treated j according to this invention are capable of greater cure speed ·. / j since higher levels of polymerization accelerators may be used j therein, compared to their prior art . counterparts which 1: Ό no: j been so treated. Particularly good resultis were achievable in j ' ·

Claims (1)

1. A polymerizable anaerobic composition having an iron content of less than about 1 parts per million by said anaerobic composition a free radical polymerizable acrylate the polymerization of which is inhibited by and a redox activated latent initiator of free radical tion capable of polymerizing said monomer in the absence of The composition of claim 1 wherein the monomer is an acrylate ester and the latent initiator is a T he composition of claim 2 wherein the iron content is less than about 05 parts permillion by weight T he composition of claim 3 wherein the latent initiator is an organic and the monomer is a polyacrylate ester monomer of the wherein R represents a radical selected from the group consisting of lower of from 1 to about 4 carbon hydroxy alky of from 1 to about 4 carbon and 2 2 R2 2 R is a radical selected from the group consisting of and lower alkyl of from 1 to about 4 carbon R is a radical selected from the group consisting of and O II m is an integer equal to at least n is an integer equal to at least and p is one of the The composition of claim 2 which additionally contains an organic sulfimide polymerization The composition of Claim 2 which additionally contains a redox activated polymerization accelerator which comprises the combination an organic sulfimide containing the group O i o and a tertiary amine having the formula wherein E represents a carbocyclic aromatic nucleus selected from the group consisting oi phenyl and and are lower alkyl radicals 1 to 4 carbon t is one of the 12 integer equal to from 1 to 5 R is a member selected from the groups consisting of lower alkyl and lower alkoxy radicals of 1 to 4 12 ccaarrbboonn aattoommss pprroovviiddeedd that when an R radical is in the ortho position t is greater than The process for preparing an anaerobic composition as claimed in claim which includes the step of reducing the content of metal ions and metal containing compounds and complexes in the starting The process for preparing an improved anaerobic composition as claimed in claim 1 which includes the step of removing at least by weight of the metal contamination from the composition or the starting materials The process of Claim 8 wherein at least about by weight of the metal contamination is The process of Claim 9 wherein the anaerobic compositioi a free radical polymerizable acrylate the polymerization of which is inhibited by oxygen and a redox activated latent initiator of free radical The process of Claim 10 wherein the latent initiator is a The process of Claim 11 wherein the latent initiator is an organic and the monomer is a polyacrylate ester monomer of the 1 wherein represents a radical selected from the group consisting of lower alkyl of from 1 to about 4 carbon hydroxy alkyl of from 1 to about 4 carbon and 2 R is a radical selected from the group consisting of halogen and lower alkyl of from 1 to about 4 carbon is a radical selected from the group consisting of and O m is an integer equal to at n is an integer equal to at least and p is one of the The process of claim 11 wherein the composition additionally contains an organic sulfimide polymerization The process of Claim 11 wherein the composition additionally contains a redox activated polymerization accelerator which comprises the combination oft an organic sulfimide containing the group O O and a tertiary amine having the formula wherein E represents a carbocyclic aromatic nucleus selected from the group consisting of phenyl and naphthyl R and are radicals of 1 to 4 carbon t is one of the integer equal to from 1 to 5 12 R is a member selected from the groups consisting of lower alkyl and lower alkoxy radicals of 1 to 4 carbon atoms 12 pprroovviiddeedd tthhaatt when an R radical is in the ortho position t is greater than 35 The process of preparing an improved anaerobic composition of claim 1 which includes the step of treating at least one of the components of the composition with an agent which coacts with metal contamination in said components to form a metal containing precipitate which is insoluble in said thereby producing components having a reduced content of metal ions and metal containing compounds and The process of Claim 15 wherein at least about by weight of the metal ions and metal containing compounds and complexes in the based upon the weight of the final anaerobic are The process of Claim 15 wherein the agent used to remove the metal ions and metal containing compounds and complexes is a chelating The process of Claim 17 wherein the donor atoms of the chelating agent are selected from the class consisting essentially of oxygen and sulfur The process of Claim 15 wherein the process is conducted between about and about and for a minimum of about one The process of Claim 15 wherein the insoluble metal containing precipitate subsequently is removed from contact with the components of the anaerobic Agents for 36 XcPP t dp X b P 1 C b y Op OodooooA ocb ooo Ptoo P Xc o p 2 pp of 2 o ooXAp Abo P CO CO f p CO I 4 A 1 to h p up Ac of CO AocCO X 4 O Ood O OO spOsd do o of oddddoosdd issodoo ddOS so sd d f ooo oss p OOpd OOdl od of Ooodsos s ospod to i d f oOS df scops fssd d OO a s a d OS OSS a ooaaoaaaa aa C oa m I aaaa of Claim ai m a fat ai a ileal of la bp aro oaoa laaaaa of radical at a o p fpaaaa p a C fo oo a a a ffa a off ai laaaaa i about m o fooaa ca foomo about 4 insufficientOCRQuality