Anaerobically curable adhesive compositions

Abstract

An anaerobically curable composition comprising: (i) an anaerobically curable component; (ii) an anaerobic cure inducing component; and (iii) a metal (meth)acrylate where the metal is selected from the group comprising: zinc, caesium, neodymium, zirconium, aluminium, yttrium, titanium, cobalt and nickel; and / or (iv) a chelator for a metal where the metal is selected from the group comprising: zinc, caesium, neodymium, zirconium, aluminium, yttrium, titanium, cobalt and nickel. A method of curing and an assembly comprising bonded substrates are also described. These compositions provide storage stable compositions which cure to give bond strengths similar to or better than a control composition and with good high temperature performance.

Description

Anaerobically curable adhesive compositionsField

[0001] The present invention relates to anaerobically curable adhesive compositions, method of anaerobically curing such compositions and cured products thereof.Background

[0002] Anaerobically curable compositions are well known. Anaerobically curable compositions remain uncured when exposed to air (oxygen) and cure under suitable anaerobic conditions. The uses of anaerobically curable compositions are broad and continue to be developed. For example, anaerobically curable compositions can be useful as threadlockers, for gasketing, for adhesion to oily substrates, as pipe sealants, and for joint repair.

[0003] Typically, anaerobic adhesive compositions are mixtures of polymerizable acrylate ester monomers and peroxy polymerization initiators therefor. Preferably, at least a portion of the acrylate monomer is a di- or other polyacrylate ester. Suitable polyacrylate ester monomers are di-, tri- -and tetraethyleneglycol dimethacrylate; dipropyleneglycol dimethacrylate; polyethyleneglycol di methacrylate; polypropyleneglycol dimethacrylate; di(pentamethyleneglycol) di methacrylate; tetraethyleneglycol diacrylate; tetraethyleneglycol di(chloracrylate); diglycerol diacrylate; diglycerol tetramethacrylate; tetramethylene dimethacrylate; ethylene dimethacrylate; butyleneglycol dimethacrylate; neopentylglycol diacrylate; and trimethylolpropane triacrylate.

[0004] Monofunctional acrylate esters (esters containing one acrylate group) may also be used in anaerobic adhesives, and preferably the esters are those with a relatively polar alcoholic moiety. Typical examples of compounds within this category are cyclohexylmethacrylate; tetrahydrofurfuryl methacrylate; hydroxyethyl acrylate; hydroxypropyl methacrylate; t-butylaminoethyl methacrylate; cyanoethylacrylate and choroethyl methacrylate.

[0005] Another class of polyacrylate ester monomers utilized in anaerobic adhesive compositions are the isocyanatemonoacrylate reaction products described in U.S. Patent No. 3425988 (Toback / Gorman).

[0006] All anaerobic adhesives are sensitive to the presence of metal ions in their formulations, in particular Cu and Fe metal ion contaminants. There are often small (ppm) levels of metal ions present in the raw material ingredients or acquired through the processing of the formulations. A critical component of all anaerobic formulations therefore is a stabiliser which can sequester such metal ions before they begin to destabilise the anaerobic adhesive itself. Such stabilisers are known as metal chelators. At present, commercially available anaerobically curable compositions employ tetrasodium EDTA (ethylene diamine tetra-acetic acid), also referred to as Na4EDTA, as a stabiliser which is shown below:tetrasodium EDTA

[0007] It is generally known that anaerobically curable compositions can be unstable and lose adhesion performance over time. Accordingly, it is common to employ stabilisers in the composition to obtain anaerobically curable compositions with increased stability. These stabilisers, however, can reduce the performance of the anaerobically curable compositions.

[0008] European patent application no. EP 0282292 describes a metal ion chelator N-hydroxyethylenediamine triacetic acid trisodium salt (HEDTA Nas) for use in anaerobic acrylate ester sealants or adhesives.

[0009] It is desirable in all compositions including anaerobic compositions to utilise materials which are not carcinogenic, mutagenic, or toxic for reproduction (so called “non-CMR” substances).

[0010] On the other hand, it is desirable to provide anaerobic compositions which are storage stable, and / or which cure to form high strength bonds and / or which form bonds which are heat resistant at high temperatures.

[0011] Accordingly the present invention seeks to provide stable anaerobically curable compositions. It is an objective to provide anaerobically curable compositions which arestorage stable yet which cure under anaerobic conditions to give desirable bond strengths.

[0012] International Patent Publication No. WO 00 / 17241 A1 discloses an air-activatable polymerisable composition useful, for example, in the field of adhesives, sealants, surface coatings, moulding resins and composite matrices, comprises: a) at least one free-radically polymerisable monomer, b) an activator system for effective polymerisation of the free-radically polymerisable monomer, said activator system comprising at least one auto-oxidisable compound which is a beta diketone, c) a soluble ionic salt, particularly a transition metal salt, d) and a weak acid or a latent weak acid, with the proviso that the composition does not contain a peroxide, or a peroxide precursor which produces peroxide in the absence of air, or any ingredient which is a significant source of radicals in the absence of air.

[0013] US Patent No. 4460760 discloses an anaerobically curable composition which comprises per 100 parts of a polymerizable methacrylate, 0.1 to 5.0 parts of the salt of o-benzoic sulfimide and a specified aromatic amine, 0.1 to 5.0 parts of an acid amide, and 0 to 3.0 parts of a gelling stabilizer.

[0014] US Patent Publication No. 2022 / 275259 discloses a one-component (1K) anaerobic curable composition comprising, based on the weight of the composition:from 15 to 35 wt. % of: a1) at least one (meth)acrylate monomer represented by Formula I: H2C DGCO2R1; wherein: G is hydrogen, halogen or a C1-C4 alkyl group; and, R1is selected from C1-C30 alkyl, C3-C30 cycloalkyl, C2-C20 alkenyl and C2-C12 alkynyl; from 5 to 25 wt. % of: a2) at least one (meth)acrylate monomer represented by Formula II: H2C DQCO2R2wherein: Q may be hydrogen, halogen or a C1-C4 alkyl group; and, R2may be selected from Ce-Cis aryl, alkaryl and aralkyl;from 35 to 75 wt. % of: a3) at least one (meth)acrylate-functionalized oligomer; from 0.1 to 10 wt. % of b) at least one cure initiator;from 0.1 to 5 wt. % of c) at least one cure accelerator;from 1 to 5 wt. % of d) at least one cellulose mixed ester of which all of said ester groups are selected from C1-C6 ester groups; and,from 1 to 5 wt. % of e) fumed silica.

[0015] CN Patent Publication No. 115595096 discloses an anaerobic adhesive and a preparation method thereof. The anaerobic adhesive comprises a monomer-polymerization inhibitor mixture; the initiator is selected from one or more of organic peroxides; the first accelerant and the second accelerant are respectively selected from one or more of first amine, hydrazine and derivatives thereof or first organic dibasic acid; the auxiliary accelerant is selected from one or more of saccharin salt or second organicdibasic acid; wherein the mass ratio of the monomer-polymerization inhibitor mixture to the initiator to the first accelerant to the second accelerant to the auxiliary accelerant is 100 to (0.4 to 0.5) to (1.8 to 2.0) to (0.005 to 0.006) to (0.4 to 0.5).

[0016] International Patent Publication No. WO 2006 / 028806 discloses a system wherein a curative is incorporated into a solid or semi-solid carrier material whereby mere fracturing or failure of the capsule wall encapsulating such cure systems will not provide for or allow sufficient release of the curative.Summary

[0017] The present invention provides an anaerobically curable composition comprising:(i) an anaerobically curable component;(ii) an anaerobic cure inducing component; and(iii) a metal (meth)acrylate where the metal is selected from the group comprising: zinc, caesium, neodymium, zirconium, aluminium, yttrium, titanium, cobalt and nickel.

[0018] The present invention thus provides anaerobically curable compositions which are storage stable yet which cure under anaerobic conditions to give desirable bond strengths.

[0019] It is to be understood in the context of the present invention that the metal (meth) acrylate is a different component from component (i) which is an anaerobically curable component. While the anaerobically curable component may be a meth(acrylate) it is not a component that has a metal within its structure and it is not a metal (meth)acrylate.

[0020] It will be appreciated that the compositions of the invention include those where there are combinations of different metal (meth)acrylates.

[0021] It is surprising that compositions of the invention are storage stable, as exposure to metal, such as transition metal, induces cure of anaerobically curable compositions. Thus exposure to metal such as transition metal would be expected to make anaerobically curable compositions unstable. Given that exposure to metals is undesirable in terms of storage stability, inclusion of metals (in the form of metalcontaining compounds) within the composition would be expected to substantially compromise storage stability.

[0022] While the skilled person will understand that under normal storage conditions an anaerobically curable composition is not exposed to anaerobic conditions the inclusion of metals (in the form of metal-containing compounds) within the composition would beexpected to substantially compromise storage stability even under such non-anaerobic conditions.

[0023] In an anaerobically curable composition of the invention the metal may be zinc.

[0024] The metal (meth)acrylate may be a mono acrylate or a mono methacrylate.

[0025] The metal (meth)acrylate may be a diacrylate or a dimethacrylate.

[0026] The metal (meth)acrylate may be in the form of a salt.

[0027] In an anaerobically curable composition of the invention the metal (meth)acrylate may be: zinc (meth)acrylate; caesium (meth)acrylate; neodymium (meth)acrylate; zirconium (meth)acrylate; aluminium (meth)acrylate; yttrium (meth)acrylate; titanium (meth)acrylate; cobalt (meth)acrylate and; nickel (meth)acrylate.

[0028] In an anaerobically curable composition of the invention the metal (meth)acrylate may be: zinc di(meth)acrylate; caesium di(meth)acrylate; neodymium di(meth)acrylate; zirconium di(meth)acrylate; aluminium di(meth)acrylate; yttrium di(meth)acrylate; titanium di(meth)acrylate; cobalt di(meth)acrylate; and nickel di(meth)acrylate.

[0029] One desirable component is zinc dimethacrylate.

[0030] The metal (meth)acrylate may be present in an amount from about 0.1% to about 20% by weight based on the total weight of the composition.

[0031] The metal (meth)acrylate may be present in an amount from about 1% to about 15% by weight based on the total weight of the composition.

[0032] In any composition of the invention it is desirable to include a chelator (a chelating agent) for the metal of the metal (meth)acrylate.

[0033] One suitable chelator is N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine, particularly where the metal of the metal (meth)acrylate is zinc.

[0034] An anaerobically curable composition desirably includes a chelator which is N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine and a metal (meth)acrylate which is zinc dimethacrylate.

[0035] The anaerobically curable composition of the invention may be an anaerobically curable adhesive composition.

[0036] The anaerobically curable composition of the invention is formulated as a one-part composition. It is storage stable as a one-part composition.

[0037] In any anaerobically curable composition of the invention the chelator for chelating the metal of the metal (meth)acrylate suitably is present in an amount from about 0.001% to about 1% by weight based on the total weight of the composition

[0038] In any anaerobically curable composition of the invention the chelator for chelating the metal of the metal (meth)acrylate suitably is present in an amount from about 0.01 % to about 0.5% by weight based on the total weight of the composition.

[0039] The invention also provides an anaerobically curable composition comprising:(i) an anaerobically curable component;(ii) an anaerobic cure inducing component; and(iii) a chelator for a metal where the metal is selected from the group comprising: zinc, caesium, neodymium, zirconium, aluminium, yttrium, titanium, cobalt and nickel.

[0040] The present inventors have made the surprising discovery that firstly a metal (meth)acrylate may be included within an anaerobically curable composition and secondly that a chelator for the metal of the metal (meth)acrylate may be included within an anaerobically curable composition. Desirably the chelator is N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine and the metal is zinc, for example where the metal (meth)acrylate is zinc dimethacrylate.

[0041] The invention also provides a method of bonding first and second substrates to each other, the substrates having respective bonding surfaces to be bonded together, the method comprising:(i) applying, to the bonding surface of at least one of the substrates, an anaerobically curable composition of the invention; and(ii) mating the bonding surfaces.

[0042] The invention also provides an assembly comprising first and second substrates bonded together by an anaerobically curable composition of the invention or by a method of bonding of the invention.Brief Description of the Figures

[0043] Figure 1A and Figure 1B are the results of Example 1 plotted as the lapshear bond strengths in MPa v. temperature (°C) in Figure 1A and as “% retention” v. temperature (°C) in Figure 1B.

[0044] Figure 2A and Figure 2B are the results of Example 2 plotted as the “pin and collar” bond strengths in MPa v. temperature (°C) in Figure 2A and as “% retention” v. temperature (°C) in Figure 2B.

[0045] Figure 3A and Figure 3B are the results of Example 3 plotted as the “pin and collar” bond strengths in MPa v. temperature (°C) in Figure 3A and as “% retention” v. temperature (°C) in Figure 3B.Description

[0046] Compositions of the invention can be useful as threadlockers, for gasketing, for adhesion to oily substrates, as sealants such as pipe sealants, and for joint repair.

[0047] The composition of the invention will typically include a cure system for anaerobic cure typically a redox cure system.

[0048] The anaerobically curable component may be present in an amount from about 5 wt% to about 90 wt% based on the total weight of the anaerobically curable composition, suitably in an amount of from about 10 wt% to about 80 wt%, such as about 70 wt% based on the total weight of the anaerobically curable composition.

[0049] The curing component for curing the anaerobically curable component may be present in an amount of from about 0.1 to about 10 wt% such as from about 1 to about 5 wt%, based on the total weight of the anaerobically curable composition.

[0050] The composition of the invention may include an initiator (of free radical polymerization) selected from the group consisting of: cumene hydroperoxide ("CHP"), para-menthane hydroperoxide, t-butyl hydroperoxide ("TBH"), t-butyl perbenzoate, benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide, butyl 4,4-bis(t-butylperoxy)valerate, p-chlorobenzoyl peroxide, 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, t-amyl hydroperoxide, 1,2,3,4-tetramethylbutyl hydroperoxide and combinations thereof. The initiator of free radical polymerisation may comprise an encapsulated peroxide.

[0051] A composition of the invention may also include a cure accelerator, for example saccharin and / or acetyl phenyl hydrazine (“APH”).

[0052] Additionally or alternatively the cure accelerator comprises one or more metallocenes, such as ferrocene, suitably, n-butyl ferrocene; and / or a cure accelerator embraced bywherein X is CH2, O, S, NR4, CR5R6or C=O; R is one or more of hydrogen, alkyl, alkenyl, alkynl, hydroxyalkyl, hydroxyalkenyl, or hydroxyalkynl; R1- R6are each individually selected from hydrogen, halogen, amino, carboxyl, nitro, alkyl, alkenyl, alkynyl, hydroxyalkyl, hydroxyalkenyl, hydroxyal kynyl, or alkaryl; R7is hydrogen or CHR8R9, wherein R8and R9are each individually selected from hydrogen, halogen, amino, carboxyl, nitro, alkyl, alkenyl, alkynyl, hydroxyalkyl, hydroxyalkenyl, hydroxyal kynyl, or alkaryl; and n is 0 or 1.

[0053] The anaerobically curable component may be a (meth)acrylate component.

[0054] For example the anaerobically curable component may be a (meth)acrylate monomer component which may be one or more selected from those having the formula:H2C=CGCO2R8,wherein G is hydrogen, halogen or alkyl groups having from 1 to 4 carbon atoms, and R8is selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, alkaryl 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.

[0055] Suitably, the anaerobically curable component can be the reaction product of an isocyanate-containing compound, such as phenyl isocyanate, and a hydroxylalkyl (meth) acrylate, such as hydroxyethyl methacrylate (HEMA):which is 2-methacryloxylethyl urethane with a melting point of about 70-75°C.

[0056] The anaerobically curable component can also be the reaction product of 2 molar equivalents of HEMA with 1 molar equivalent diisocyanates such as isophorone diisocyanate (IPDI), 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI), or 1,5-cyclohexyl diisocyanate (CHDI). For example:which is HEMA-IPDI-HEMA with a melting point of about 72-74°C;which is HEMA-HMDI-HEMA with a melting point of about 75-85°C;which is HEMA-CHDI-HEMA with a melting point of about 75-85°C.

[0057] The anaerobically curable component can also be or include a polyurethane methacrylate resin with a molecular weight >2000 g.mol and with a semi-crystalline polyester polyol backbone. An example of such a resin is given in International patent publication WO 2017 / 68196A1 and is the reaction product of the polyol known as Dynacoll 7380 with toluene diisocyanate, followed by end capping with HEMA. These resins have a melting point in the range of 50-80°C. Commercially available (meth)acrylated polyurethane resins include those sold under the trade nameLumiset™

[0058] The anaerobically curable component can also be or include novolac vinyl ester resins which are the reaction products of novolac epoxy resins and methacrylate acids. Examples of these resins and their preparation are shown in US Patent No. 9,957,344. For examplewhere n is an integer between 2-10 and the compound has a melting point of about 70-75°C.

[0059] Suitably, the curing component for curing the anaerobically curable component comprises one or more selected from the group consisting of 1-acetyl-2-phenylhydrazine, N,N-dimethyl para toluidine, N,N-diethyl para toluidine, N,N-diethanol para toluidine, N,N-dimethyl ortho toluidine, N,N-dimethyl meta toluidine, indoline, 2methylindoline, isoindoline, indole, 1,2,3,4-tetrahydroquinoline, 3methyl1, 2,3,4-tetrahydro-quinoline, 2-methyl-1,2,3,4-tetrahydroquinoline, and 1, 2,3,4-tetrahydroquinoline-4-carboxylic acid, and 1,2,3,4-tetrahydro-benzo(H)quinolin-3-ol.

[0060] The anaerobically curable component may be a (meth)acrylate component.

[0061] For example the anaerobically curable component may be a (meth)acrylate monomer component which may be one or more selected from those having the formula:H2C=CGCO2R8,wherein G is hydrogen, halogen or alkyl groups having from 1 to 4 carbon atoms, and R8is selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, alkaryl 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.

[0062] Suitably, the anaerobically curable component can be the reaction product of an isocyanate-containing compound, such as phenyl isocyanate, and a hydroxylalkyl (meth) acrylate, such as hydroxyethyl methacrylate (HEMA):which is 2-methacryloxylethyl urethane with a melting point of about 70-75°C.

[0063] The anaerobically curable component can also be the reaction product of 2 molar equivalents of HEMA with 1 molar equivalent diisocyanates such as isophorone diisocyanate (IPDI), 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI), or 1,5-cyclohexyl diisocyanate (CHDI). For example:which is HEMA-IPDI-HEMA with a melting point of about 72-74°C;which is HEMA-HMDI-HEMA with a melting point of about 75-85°C;which is HEMA-CHDI-HEMA with a melting point of about 75-85°C.

[0064] The anaerobically curable component can also be or include a polyurethane methacrylate resin with a molecular weight >2000 g.mol and with a semi-crystalline polyester polyol backbone. An example of such a resin is given in International patent publication WO 2017 / 68196A1 and is the reaction product of the polyol known as Dynacoll 7380 with toluene diisocyanate, followed by end capping with HEMA. These resins have a melting point in the range of 50-80°C. Commercially available (meth)acrylated polyurethane resins include those sold under the trade name Lumiset™

[0065] The anaerobically curable component can also be or include novolac vinyl ester resins which are the reaction products of novolac epoxy resins and methacrylate acids. Examples of these resins and their preparation are shown in US Patent No. 9,957,344. For examplewhere n is an integer between 2-10 and the compound has a melting point of about 70-75°C.

[0066] Suitably, the curing component for curing the anaerobically curable component comprises one or more selected from the group consisting of 1-acetyl-2-phenylhydrazine, N,N-dimethyl para toluidine, N,N-diethyl para toluidine, N,N-diethanol para toluidine, N,N-dimethyl ortho toluidine, N,N-dimethyl meta toluidine, indoline, 2methylindoline, isoindoline, indole, 1,2,3,4-tetrahydroquinoline, 3methyl1, 2,3,4-tetrahydro-quinoline, 2-methyl-1,2,3,4-tetrahydroquinoline, and 1, 2,3,4-tetrahydroquinoline-4-carboxylic acid, and 1,2,3,4-tetrahydro-benzo(H)quinolin-3-ol.

[0067] The initiator of free radical polymerization is one or more selected from the group consisting of: cumene hydroperoxide ("CHP"), para-menthane hydroperoxide, t-butyl hydroperoxide ("TBH"), t-butyl perbenzoate, benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide, butyl 4,4-bis(t-butylperoxy)valerate, p-chlorobenzoyl peroxide, 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, t-amyl hydroperoxide, 1,2,3,4-tetramethylbutyl hydroperoxide and combinations thereof. The initiator of free radical polymerisation may comprise an encapsulated peroxide.

[0068] The anaerobically curable composition of the invention may further comprise a cure accelerator in addition to or instead of those described above. For example, the cure accelerator may comprise one or more metallocenes such as ferrocene, suitably, n-butyl ferrocene. Advantageously, the presence of a cure accelerator facilitates cure of the anaerobically curable composition of the invention on “non-active” or “passive” substrates, such as plastic substrates.Examples

[0069] Two components: (i) zinc dimethacrylate and (ii) TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine) were added to 3 anaerobically curable compositions as set out in Examples 1-3 below. Controls with neither component present were also prepared and tested as set out in Examples 1-3 below. Also comparative compositions with zinc dimethacrylate present but without TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine) present were also prepared and tested as set out in Examples 1-3 below.

[0070] In the tables below the labels “2% Zinc" etc. are shorthand labels that allow correlation of the information in the table to a corresponding graph / Figure.Example 1 :

[0071] 6 compositions were made as set out in Table 1 below. Each composition is an anaerobically curable composition. Each composition has a secondary UV cure. Each composition is liquid at room temperature. It will be noted that the composition of each of the other five compositions include the same components as the Control composition but with the addition of zinc dimethacrylate (in varying amounts) or with the addition of both zinc di methacrylate and TPEN each (in varying amounts).

[0072] These compositions are detailed in Table 1 below.

[0073] The compositions were applied to mild steel lapshears, assembled with a 322.6 mm2(0.5 in2) overlap and allowed to cure for 7 days at room temperature in accordance with ASTM D1002 -05. Shear strength was then determined according toASTM D1002 -05. Shear strength was determined for the compositions at room temperature “RT” (25°C), 50°C, 80°C, 100°C, 120°C, 150°C and 180°C.

[0074] The results are plotted as the lapshear bond strengths in MPa in Figure 1A and as “% retention” in Figure 1B “% retention” is the percentage of the room temperature strength that is retained at the elevated temperature.

[0075] Table 1 :

[0076] It can be clearly seen that despite the incorporation of a metal containing compound in the compositions, the shear strength of the bond formed, though less than the control value at lower temperatures are nonetheless very acceptable.Furthermore it can be noted that the performance of the compositions of the invention, in terms of shear strength, is better than the control at higher temperatures.

[0077] For these compositions the initial strengths decrease with the addition of the Zinc dimethacrylate with or without the TPEN stabiliser, but their strengths in MPa or in % retention is significantly improved at temperatures above 100°C.

[0078] The three non-stabilised compositions, i.e. those without TPEN, are all unstable and cure at room temperature within 12 hours. The three stabilised compositions i.e. those with TPEN are stable for >24 hours at room temperature.Example 2:

[0079] 6 compositions were made as set out in Table 2 below

[0080] Each composition is an anaerobically curable composition. Each composition has a secondary activator cure. Each composition is liquid at room temperature. Each composition can be considered a retaining compound designed for the bonding of cylindrical fitting parts.

[0081] These compositions are detailed in Table 2 below.

[0082] The compositions were applied to pin and collar and cured for 7 days at room temperature in accordance with ASTM D4562. Shear strength was then determined according to ASTM D4562. Shear strength was determined for the compositions at room temperature “RT” (25°C), 50°C, 80°C, 100°C, 120°C, 150°C and 180°C.

[0083] The results are plotted as the bond strengths in MPa in Figure 2A and as “% retention” in Figure 2B “% retention” is the percentage of the room temperature strength that is retained at the elevated temperature.

[0084] Table 2:

[0085] It can be clearly seen that despite the incorporation of a metal containing compound in the compositions, the bond strength of the bond formed, is similar to that of the control value at all temperatures. Furthermore it can be noted that the performance of the compositions of the invention, in terms of shear strength, is better than or close to that of the control at higher temperatures.

[0086] For these compositions the initial strengths increase with the addition of the zinc dimethacrylate with or without the TPEN stabiliser, and their strengths remain improved throughout the temperature scale.

[0087] The three non-stabilised compositions, i.e. those without TPEN, are all unstable and cure at room temperature within 18 hours. The three stabilised compositions i.e. those with TPEN are stable for >2 weeks at room temperature.Example 3:

[0088] 6 compositions were made as set out in Table 3 below. Each composition is an anaerobically curable composition. Each composition has a secondary activator cure. Each composition is liquid at room temperature. Each composition can be considered a retaining compound designed for the bonding of cylindrical fitting parts.

[0089] These compositions are detailed in Table 3 below.

[0090] The compositions were applied to pin and collar and cured for 7 days at room temperature in accordance with ASTM D4562. Shear strength was then determined according to ASTM D4562. Shear strength was determined for the compositions at room temperature “RT” (25°C), 50°C, 80°C, 100°C, 120°C, 150°C and 180°C.

[0091] The results are plotted as the bond strengths in MPa in Figure 3A and as “% retention” in Figure 3B. “% retention” is the percentage of the room temperature strength that is retained at the elevated temperature.

[0092] Table 3:

[0093] It can be clearly seen that despite the incorporation of a metal containing compound in the compositions, the bond strength of the bond formed, is similar to or better than that of the control value at all temperatures. Furthermore, it can be noted that the performance of the compositions of the invention, in terms of shear strength, is better than or close to that of the control at higher temperatures.

[0094] For these compositions the initial strengths increase in some cases with the addition of the zinc dimethacrylate with or without the TPEN stabiliser or decreased slightly with the addition of the zinc dimethacrylate with or without the TPEN stabiliser. Their strengths at all temperatures above 80°C remain improved up to 180°C. No testing was carried out above 180°C.

[0095] The three non-stabilised compositions, i.e. those without TPEN, are all unstable and cure at room temperature within 24 hours. The three stabilised compositions i.e. those with TPEN are stable for >3 months at room temperature.

[0096] The words “comprises / comprising” and the words “having / including” when used herein with reference to the present invention are used to specify the presence ofstated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0097] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Claims

Claims1. An anaerobically curable composition comprising:(i) an anaerobically curable component;(ii) an anaerobic cure inducing component; and(iii) a metal (meth)acrylate where the metal is selected from the group comprising: zinc, caesium, neodymium, zirconium, aluminium, yttrium, titanium, cobalt and nickel.

2. An anaerobically curable composition according to any preceding claim wherein the metal is zinc.

3. An anaerobically curable composition according to any preceding claim wherein the metal (meth)acrylate is a mono acrylate or a mono methacrylate.

4. An anaerobically curable composition according to any preceding claim wherein the metal (meth)acrylate is a diacrylate or a dimethacrylate.

5. An anaerobically curable composition according to any preceding claim wherein the metal (meth)acrylate is zinc (meth)acrylate; caesium (meth)acrylate; neodymium (meth)acrylate; zirconium (meth)acrylate; aluminium (meth)acrylate; yttrium (meth)acrylate; titanium (meth)acrylate; cobalt (meth)acrylate; and nickel (meth)acrylate.

6. An anaerobically curable composition according to Claim 4 wherein the metal (meth)acrylate is zinc di(meth)acrylate; caesium di(meth)acrylate; neodymium di(meth)acrylate; zirconium di(meth)acrylate; aluminium di(meth)acrylate; yttrium di(meth)acrylate; titanium di(meth)acrylate; cobalt di(meth)acrylate and; nickel di(meth)acrylate.

7. An anaerobically curable composition according to Claim 4 wherein the metal (meth)acrylate is zinc dimethacrylate.

8. An anaerobically curable composition according to any preceding claim wherein the metal (meth)acrylate is present in an amount from about 0.1% to about 20% by weight based on the total weight of the composition.

9. An anaerobically curable composition according to any preceding claim wherein the metal (meth)acrylate is present in an amount from about 1% to about 15% by weight based on the total weight of the composition.

10. An anaerobically curable composition according to any preceding claim further comprising a chelator for chelating the metal of the metal (meth)acrylate.

11. An anaerobically curable composition according to Claim 11 wherein the chelator is N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine.

12. An anaerobically curable composition according to Claim 11 wherein the chelator is N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine and the metal (meth)acrylate is zinc dimethacrylate.

13. An anaerobically curable composition according to any of Claims 10 to 12 wherein the chelator for chelating the metal of the metal (meth)acrylate is present in an amount from about 0.001% to about 1% by weight based on the total weight of the composition14. An anaerobically curable composition according to any of Claims 10 to 13 wherein the chelator for chelating the metal of the metal (meth)acrylate is present in an amount from about 0.01 % to about 0.5% by weight based on the total weight of the composition.

15. An anaerobically curable composition comprising:(i) an anaerobically curable component;(ii) an anaerobic cure inducing component; and(iii) a chelator for a metal where the metal is selected from the group comprising: zinc, caesium, neodymium, zirconium, aluminium, yttrium, titanium, cobalt and nickel.

16. An anaerobically curable composition according to Claim 15 wherein the chelator is N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine.

17. A method of bonding first and second substrates to each other, the substrates having respective bonding surfaces to be bonded together, the method comprising:(i) applying, to the bonding surface of at least one of the substrates, an anaerobically curable composition according to any preceding claim; and(ii) mating the bonding surfaces.

18. An assembly comprising first and second substrates bonded together by an anaerobically curable composition according to any of Claims 1 to 16 or by a method of bonding according to Claim 17.

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