Activators for Two Part Cyanoacrylate Adhesives

(19) United States (12) Patent Application Publication (10) Pub. No.: US 2011/0196092 A1 US 20110196092A1 Hally et al. (43) Pub. Date: Aug. 11, 2011 (54) ACTIVATORS FOR TWO PART (60) Provisional application No. 61/107,137, filed on Oct. CYANOACRYLATE ADHESIVES 21, 2008. (75) Inventors: William Hally, Naas (IE); Emer Publication Classification Ward, Rathfarnham (IE); Patricia (51) Int CL 3- liiediilezimlf/:1: Cab¥1tfieiYh(ii%)3é . C09J 4/04 (2006.01) De ‘Wt F ii ‘:;’r°=Dan:‘g I ( IE) C09] 11/06 (2006.01) em" ' ea ey’ “ aVm( ) (52) U.s. Cl. ....... .. 524/710; 526/205; 524/755; 524/776; (73) Assignee: Loctite (R&D) Limited, Dublin 524/773 (H3) (57) ABSTRACT (21) App]. No‘; 13/090,539 There is provided a cyanoacrylate composition comprising: a cyanoacrylate; and (22) Filed, Apt 20, 2011 a 2-substituted benzothiazole or a derivative thereof wherein the 2-substituent is an alkyl, an alkene, an alkylben- . . zyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a Related U'S' Apphcatlon Data sulfenamide, a thioalkvl or a thioalkoxy group, with the pro- (63) Continuation of application No, PCT/EP2009/ v1so that an amide portion of the sulfenamide does not have a 063833, filed on Oct. 21, 2009. tert butylamino or a morpholine group. Patent Application Publication Aug. 11, 2011 Sheet 1 of 6 US 2011/0196092 A1 Bond strengths for 2-part CA's -part B 30 25 ‘E 20 Al E 15 Steel 2 1o ' 5 O I I I I I ? S — N O S \_/ N-oxidiethylene benzothiazoles-2- sulfenamide [0017] Japanese Patent Publication No. 62-022877 describes the use of aromatic amines as activators. The main associated advantage with use of these compounds being that there is no unpleasant odour and relevantly good efficient acceleration is provided, particularly when N,N-Dimethyl-p- Toluidine (DMPT) is used. / N,N-Dimethyl-p-Toluidine (DMPT) [0018] U.S. Pat. No. 6,547,917 describes superior activator compounds for accelerating hardening having the structural element —N:C—S—S—C:N—. The compounds described such as dithiopyridine, N-t-butyl-2-benzothiazole- sulfenamide, N-cyclohexyl-2-benzothiazole-sulfenarnide, dibenzothiazyl disulfide, promote hardening to occur within a few seconds. These compounds are superior since they allow a substantially longer waiting time between application of the activator and application of the adhesive and thus tend to avoid superficial hardening. [0019] However, there are some limitations associated with the state of the art. For example, deactivation of some activa- tors may occur when they are storage in clear packaging. Additional, it is doubtful that activators based on tert-butyl benzothiazole sulfenamide, N-oxydiethylene benzothiazole- 2-sulfanamide or N,N dimethyl-p-toluidine have sufiicient UV or hydrolytic stability to allow their use in clear two component packaging. Furthermore, the time between mix- ing and polymerisation for two component adhesives based on tert-butyl benzothiazole sulfenamide (European Patent No. EP 785,865) or N,N dimethyl-p-toluidine (Japanese Patent Application No. JP 62-022877) or 2,2 dithiodipyridine is typically in the range of 30s-60s. Such gel times may be insufficient where some assembly time is required, as would be the case for larger parts. A longer, reliable time between mixing and curing would be of advantage to an adhesive user and would allow mixing nozzles to be used for a longer time. [0020] Thus, it is desirable to provide additional activators for cyanoacrylate compositions which are particularly suit- able for use in two-part packs. In particular the provision of activators, which are more insensitive to UV and/ or water are desirable for example for improved storage stability. SUMMARY OF THE INVENTION [0021] According to the present invention, there is provided a cyanoacrylate composition comprising: [0022] a cyanoacrylate; and [0023] a 2-substituted benzothiazole or a derivative thereof wherein the 2-substituent is an alkyl, an alkene, an alkylben- zyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a sulfenamide, a thioalkyl or a thioalkoxy group, with the pro- Aug. 11, 2011 viso that an amide portion of the sulfenamide does not have a tert butylamino or a morpholine group. [0024] Thus, the cyanoacrylate compositions of the inven- tion include an activator (the 2-substituted benzothiazoles) that can assist with cure, in particular, with rapid adhesive bond formation. [0025] Thus, certain of the compositions of the invention have the particular advantage that they are less prone to mois- ture and UV sensitivity. Certain of the activators of the inven- tion are particularly useful for storage in transparent or trans- lucent containers that may allow greater UV penetration than a comparable opaque container. Furthermore the composi- tions of the invention demonstrate good cure-through-gap properties. [0026] The present invention thus provides improved acti- vators for use in cyanoacrylate adhesive compositions and applications thereof. The invention provides such activators for use in two-part cyanoacrylate adhesive applications, which are less prone to deactivation than known activators and/or provide superior cure times. [0027] The cyanoacrylate compositions of the invention comprise 2-substituted benzothiazoles as activators/accelera- tors. Suitably, the substitutions at the 2-position of the ben- zothiazole ring include C1-C4 alkyl groups such as methyl, ethyl, propyl or butyl groups. It will be appreciated that branched propyl or butyl substituents may be used to provide particularly desirable activators in cyanoacrylate composi- tions. Most desirable are 2-substituted benzothiazole com- pounds having a methyl substituent at the 2-position of the benzothiazole ring. [0028] Suitable alkene substituents at the 2-position of the benzothiazole ring may be C1-C4 alkene groups such as an allyl, a propylene or a butylene groups. The alkene bond may be terminal to the 2-position of the benzothiazole ring or may be in an intermediate position along the hydrocarbon chain. [0029] Other advantageous compositions arise, when the activator/accelerator compounds have alkylhydroxy substitu- tions at the 2-position of the benzothiazole ring. Suitably, the alkylhydroxy substituent may be a branched or unbranched C1-C4 alkylhydroxy group, wherein the alkyl chain is substi- tuted with the hydroxyl group at any of the C1-C4 hydrocar- bon positions. [0030] Suitable ether substituents at the 2-position of the benzothiazole ring of the activators/accelerators for the com- positions of the invention may comprise ether groups. Suit- ably, the ether substituent may be a branched or unbranched C1-C10 alkylether group, a branched or unbranched C1-C10 alkylether group containing at least one double bond or branched or unbranched C1-C10 alkylether group containing at least one triple bond, in the alkyl chain. Desirably, the ether group oxygen atom is directly linked to the benzothiazole at the 2-position. [0031] Other favourable compositions result wherein the benzothiazole compounds have a sulfenamide positioned at the 2-position of the benzothiazole compounds. Suitable sulfenamide substituents include sulfenamide wherein the amide portion of the sulfenamide is a cyclohexylarnine but exclude those having an amide portion which is a morpholine or a butylamino group. [0032] The cyanoacrylate compositions of the invention may comprise benzothiazole compounds, which have a thio- alkyl substituent at the 2-position of the benzothiazole. Desir- ably, the alkyl portion of the thioalkyl substituent may com- prise a branched or unbranched C1-C20 alkyl group attached US 2011/0196092 A1 to the thioalkyl sulfur atom. The sulfur atom of the thioalkyl substituent is directly attached at the 2-position of the ben- zothiazole. Suitably, C1 -C4 thioalkyl groups may also be used as the 2-position substituent on benzothiazole ring. Such groups include thiomethyl, thioethyl, thiopropyl or thiobutyl groups, all of which provide desirable compounds for use as activators in cyanoacrylate adhesive compositions. It will be appreciated that branched thi opropyl or thiobutyl sub stituents may be used. Most desirable are compounds having a thiom- ethyl substituent at the 2-position of the benzothiazole ring. [0033] Altematively, the cyanoacrylate compositions of the invention may comprise benzothiazole compounds which have an alkylbenzyl group at the 2-position of the benzothia- zole. Suitably the alkylbenzyl group may comprise a branched or unbranched C1-C4 alkyl chain, which is further substituted with a benzyl group at any of the C1 -C4 positions. Desirably, the compound has the benzyl group at the terminal carbon in the hydrocarbon chain. [0034] Other desirable compound arise wherein the ben- zothiazole compound comprises a alkylamino substituent at the 2-position. Suitable alkylamino substituents include a branched or unbranched C1-C4 alkyl group, which is further substituted with at least one amine group at any one of the C1 -C4 positions. The amine may be a primary amine (—NH2) or a secondary amine (—NHR1, wherein R1 may be a C1-C4 alkyl group), or a combination thereof. [0035] Suitably, the cyanoacrylate compositions of the invention may comprise benzothiazole compounds which comprise an alkoxy substituents at the 2-position of the ben- zothiazole ring. Desirably, C1-C4 alkoxy groups such as methoxy, ethoxy, propoxy or butoxy groups are the substitu- ent. It will be appreciated that branched propoxy or butoxy substituents may be used. [0036] Desirable activator/accelerators compounds of the invention include those having C1-C4 thioalkoxy groups at the 2-position of the benzothiazole. Suitably, thiomethoxyl, thioethoxy, thiopropoxy or thiobutoxy groups may be the favoured substituent. It will be appreciated that branched thiopropoxy or thiobutoxy substituents may be used. [0037] Desirably, the benzene ring of any of the 2-substi- tuted benzothiazole compounds of the invention may be sub- stituted with at least one halo, thioalkyl, haloalkyl, ether, alkyl, alkoxy or hydroxyl substituent. [0038] Suitably, the halo substituent on the benzene ring of the benzothiazole compound may be Cl, Br or F, or combi- nations thereof. Benzothiazole compounds having at least one Cl substituent on the benzene ring of the benzothiazole provides compounds which are particularly desirable as acti- vators in cyanoacrylate compositions. Most desirable of all are compounds having Cl at the 5 -position of the benzene ring of the benzothiazole compound. Particularly desired as such compounds where there is a methyl sub stituent at the 2-posi- tion of the benzothiazole compound. [0039] Altematively the benzene ring of the benzothiazole compounds may be substituted with at least one thioalkyl substituent. Desirably, the alkyl portion of the thioalkyl sub- stituent may comprise a branched or unbranched C1-C4 alkyl group attached to the thioalkyl sulfur atom. The sulfur atom of the thioalkyl substituent is directly attached to the benzothia- zole benzene ring. Such groups include thiomethyl, thioethyl, thiopropyl or thiobutyl groups at any of the positions of the benzothiazole benzene ring. It will be appreciated that branched thiopropyl or thiobutyl substituents may be used. Aug. 11, 2011 [0040] Altemative desirable compounds are benzothiaz- oles having a thiomethyl substituent on the benzothiazole benzene ring. In particular, it is desirable to have a thiomethyl substituent at the 5-position of the benzene ring of the ben- zothiazole compound. A particularly desirable compound has a thiomethyl substituent at the 5-position of the benzene ring of the benzothiazole compound and is substituted at the 2-po- sition of the benzothiazole ring with a methyl group. [0041] In compounds wherein there is provided a haloalkyl substituent on the benzene ring of the 2-substituted ben- zothiazole, it is desirable that such a haloalkyl substituent is a trifluoromethane group. [0042] Other favourable compounds for use in the compo- sition of the invention include 2-substituted benzothiazoles, which comprise ether substituents on the benzene ring of the benzothiazole compound. Suitable substituents comprise ether groups wherein the ether substituent is a branched or unbranched C1-C10 alkylether group, a branched or unbranched C1-C10 alkylether group containing at least one double bond or branched or unbranched C1-C10 alkylether group containing at least one triple bond in the alkyl chain. Desirably, the ether group oxygen atom is a methylether group on the benzene ring of the benzothiazole compound. Particularly preferred are such compounds where the meth- ylether group is at the 4-position of the benzene ring of the benzothiazole compound. [0043] Suitably, the compounds of the invention may have at least one alkyl substituent on the benzene ring of the ben- zothiazole compound. Suitable alkyl substituents include C1-C4 alkyl groups such as methyl, ethyl, propyl or butyl groups. It will be appreciated that branched propyl or butyl substituents may be used to provide particularly desirable as activators in cyanoacrylate compositions. Most desirable are compounds having at least one methyl substituent on the 5-, 6-or 7-position of the benzothiazole benzene ring. The most desirable compounds have at least one methyl substituent on the 5-, 6- or 7-position of the benzothiazole benzene ring and a methyl group at the 2-position of the benzotriazole com- pound. [0044] Other desirable compounds of the invention are 2-substituted benzothiazoles having at least one alkoxy sub- stituent on the benzene ring of the benzothiazole ring. Suit- ably, such alkoxy groups include C1 -C4 alkoxy groups such as methoxy, ethoxy, propoxy or butoxy groups. It will be appre- ciated that branched propoxy or butoxy substituents may be used as the substituent. A methoxy substituent on the aro- matic of the benzothiazole provide particularly desirable compounds for use as activators in cyanoacrylate composi- tions. It is particularly desirable to have such methoxy sub- stituents at the 5- and 6-positions of the benzothiazole com- pound. The most desirable compounds have are 2-methyl benzothiazole compounds having methoxy groups in the 5- or 6-positions of the benzothiazole benzene ring. [0045] Suitably the benzene ring of the benzothiazole com- pound may be substituted with at least one hydroxyl group to provide desirable compounds for use as activators in cyanoacrylate compositions. Particularly advantageous com- pounds arise wherein a 2-methyl benzothiazole compound is substituted with a hydroxyl group. Most favoured is a 2-me- thyl benzothiazole compound, which is substituted with a hydroxyl group at the 5-position. [0046] The compounds of the invention are particular use- ful as activators for cyanoacrylate adhesive compositions. The compounds of the invention provide a good range of gel US 2011/0196092 A1 Aug. 11, 2011 5 times while being less prone to moisture sensitivity and/or ultraviolet ageing. An advantage therefore is that the -continued cyanoacrylate compositions of the invention, comprising the N\ O\/§ compounds of the invention may be packed in clear, UV Y transparent or opaque packaging since ultraviolet light sen- S sitivity is reduced. It may be possible that the compositions of 2_(aHylOXy)_1,3_benZOthiaZOle the invention may have a longer shelf life. S N [0047] The 2-substituted benzothiazoles or derivatives / Y thereof of the invention may be selected from : S 2-methyl-5 - (methylthio)- l ,3 -benzothiazole NH2 NY S V N \ CH3 3 S 2- (ethylthio)- l ,3-benzothiazole F N O 2- [(te1t-butyla.mino)thio]- l ,3-benzothiazol-5-ol Y Br N S Y 2-(heXyloXy)- l ,3 -benzothiazole S N O \ 5 -bromo-2-methyl- l ,3 -benzothiazole Cl N S Y 2-(l ,3 -dimethylbutoXy)- l ,3-benzothiazole S N S C1 Y \/\1.;— 5,6-dichloro-2-methyl- l ,3-benzothiazole S N \ 2-(Octadecylthio)benzothiazole N O S \ Br 6-bromo-2-methyl- l ,3 -benzothiazole S N 2-(l-ethylbutoXy)- l ,3-benzothiazole \ N O Y s Cl S Cl 6,7-dichloro-2-methyl- l ,3-benzothiazole F NY S 2-(octyloXy)- l ,3-benzothiazole 2-(l-methylbutoxy)-l ,3 -benzothiazole 5-fluoro-2-methyl-l ,3-benzothiazole N O Y F F N S \ 2-(2-phenylethoxy)-l ,3-benzothiazole S N O F Y Y\/\/\ S F 4,5 ,6,7-tetrafluoro-2-methyl- l ,3-benzothiazole _ 2- [(1 -methylheptyl)oXy]- l ,3 -benzothiazole CF3 NY N S s 2,5-dimethyl-l ,3 -benzothiazole 2_aHy1_1 3_beHZOthiaZOle US 2011/0196092 A1 Aug. 11, 2011 -continued -continued N O Y W/K/XX S . N S 2-[(1-methylheXyl)oXy]-l,3-benzothiazole Y Cl S N O Y \ 2-(nudecylthio)-l,3-benzothiazole S [0048] Particularly desirable cyanoacrylate compositions of the invention comprise activators based on 2-substituted N\ O benzothiazoles or derivatives thereof, which may be selected \|/ from: S 2- (3-methylbutoxy)-l ,3-benzothiazole N MeO N C1 \>? CH3 \ \>? CH3 N\ O\% S S Y 2-methyl- l ,3-benzothiazole 5-methoXy-2-methylbenzothiazole S H3C N N 4-chloro-2- (ethynyloxy)-l ,3 -benzothiazole \>:CH3 : \>: CH3 3 MeO S 4-chloro-2-methoXy- l ,3-benzothiazole 2,5-dimethylbenzothiazole 6-methoxy-2-methylbenzothiazole N Cl N HO N \ \ \ CH3 CH3 S s s 2,5,5_mmethy1_1,3_benZ0thiaZ01e 5-chloro-2-methylbenzothiazole 2—methyl—5—benzothiazolol N \O \ S > \ S E S 2-[(cylcoheXyla.mino)thio]—benzothiazole (Santocure CBS) N S 4-methoxy-2,7-dimethyl-l ,3-benzothiazole \ 3 CH3 5,6-dimethoxy-2-methyl-benzothiazole NY M60 NY 2—(methylmercapto) benzothiazole HO N S S MeO \>—S \ S N H 2,5,7-trimethyl-l ,3-benzothiazole 2-[(te1t butyla.mino)thio]benzothiazole N S W Y N S S \ N [W 2-(butylthio)- l ,3-benzothiazole S K/) Cl N s N / \/ \ 2-(morpholin-4-ylthio)-l,3-benzothiazole (Santocure MBS) >—cH3 s s 5-chloro-2-(ethylthio)-l,3-benzothiazole 2-methyl-l,3-benzothiazole [0049] other desirable Compositions Ofthe invention Com" prise activators based on 2-substituted benzothiazoles or derivatives thereof, and may be selected from: US 2011/0196092 A1 :\>*S\N_ H 2- [(cy1cohexy1a.rnino)thio]-benzothiazole (Santocure CBS) S 0. 2- (morpho1in-4-y1thio)- 1 ,3-benzothiazole (Santocure MBS) HO N \>j S \ S N H 2-[(te1t butylamino)thio]benzothiazo1e Compositions comprising these particular activators have been found to be sensitive to environmental degradation, such as UV ageing. Thus, it is desirable to maintain compositions of these activators in packaging that is resistant to environ- mental contaminants. For instance, it is desirable to provide those in packaging that has UV blocking properties. That is, the pack should be sufiiciently opaque to UV light so as to prevent any substantial deterioration of the ability of the activator to activate a cyanoacrylate composition. This is useful as it is desirable that the activator does not deteriorate significantly over time and maintains the ability to activate substantially well. For two-part compositions it is desirable that at least the activator part of the composition is retained in a UV opaque container. [0050] Particularly desired cyanoacrylate compositions of the invention comprise activators based on 2-substituted ben- zothiazoles or derivatives thereof, which may be selected from: N C1 N \>?CH3 \ \>}CH3 S S 2-methy1- 1 ,3-benzothiazole 5 -chloro-2-methylbenzothiazole N\ MeO N s>—S\cH3 s\>— CH3 2-(methylmercapto) benzothiazole 5-methoxy-2-methylbenzothiazole N H3C N \>~CLy3 E; \>/CH3 MeO S S 2,5-dimethylbenzothiazole N \>:CH3 S 2-methyl-5-benzothiazolol 6-methoxy-2-methylbenzothiazole HO Aug. 11, 2011 These activators are particularly useful in the compositions of the invention, since compositions comprising these com- pounds as activators are still curable after exposure to accel- erated ageing by exposure to UV light. Thus cyanoacrylate adhesive compositions comprising these compounds may be packaged in regular UV transparent packaging, which is not required to be UV blocking. Thus, the invention provides improved activators, which are particularly resistant to the effects of UV exposure and/or ageing, and will still function sufficiently well to provide a sufficient cure, after the effects of UV exposure and/or ageing. The invention provides improved activators that are not so moisture sensitive as prior art activators and which still functional well after storage, where there may be some ingress of moisture into a storage container. Compositions of the invention may contain such activators, which may be selected from: N\ C1 N\ S>_CH, 2-methy1- 1 ,3-benzothiazole 5-chloro-2-methylbenzothiazole N \>—s \ NS S K/O 2-(moipholin-4-ylthio)-1,3-benzothiazole (Santocure MBS) :\>: S\CH 2-(methylmercapto) benzothiazole 3 [0051] In general, the 2-substituted benzothiazole is carried by a carrier component. Thus the 2-substituted benzothiazole is present with, or may be supplied with, a suitable carrier. Suitably, the carrier component may be comprise a plasticizer selected from triacetin, dioctyl phthalate, dibutyl phthalate, trioctyl trimellitate, dioctyl adipate, dioctyl glutarate, butyl cyanoacetate, trimethyl trimellitate, diethylene glycol diben- zoate, diethyl malonate, triethyl-O-acetyl citrate, benzylbutyl phthalate, dipropylene glycol dibenzoate, diethyl adipate, tributyl-O -acetyl citrate, dimethyl sebacate, tributyl-O- acetyl citrate (TBAC), triethyl-O-acetyl citrate (TEAC), dipropylene glycol dibenzoate (DPGDB), diethylene glycol, dibenzoate (DEGBD), benzylbutyl phthalate, dibutyl adi- pate, dibutyl sebacate, dicapryl adipate, dicapryl phthalate, diethyleneglycol dibenzoate, diethyl adipate, diethyl glut- arate, diethyl malonate, diethyl pimelate, diisononyl phtha- late, dimethyl adipate, dimethyl glutarate, dimethyl sebacate, dioctyl phthalate, diprophyleneglycol dibenzoate, ethyl caproate, glyceroltrioleate, isopropyl myristate, methyl lau- rate, methyl stearate, pentaerythritol tetraacrylate, pen- taerythriotoltetrabenzoate, poly (neopentyl glycoladipate), tributyl-O-acetyl citrate, tricapryl trimellithate, triethyl-O- acetyl cityrate, trihexyl trimellithate, tris(isopropyl phenyl) phosphate, trimethyl trimellithate, trioctyl trimellithate, organic ethers, in particular aryl or diaryl ethers, where the aromatic ring of each aryl group is directly bonded to the ethereal oxygen and monocyclic or bicyclic lactones having from 3 to 20 carbon atoms and having from 4 to 7 members in the lactone ring. US 2011/0196092 A1 [0052] When packaged in a dual barrel syringe with one chamber of the syringe having a 9 ml capacity and the other a 1 ml capacity, the cyanoacrylate compositions according to the invention generally can achieve a cure through gap when applied to or between two substrates of between 0.5 mm and 2 mm, while acting as a so-called “instant adhesive”. [0053] Desirably, the cyanoacrylate compositions of the invention may have a cure time of in some cases less than 10 seconds, and in others between 30 seconds and 300 seconds. Such composition may comprise the following 2-substituted benzothiazole compounds or combinations of compounds as accelerator/ activator: N MeO N \%CH3 \>j CH3 S S 2-methyl- l ,3 -benzothiazole H3C N N \>—CH3 / \>—CH3 S MeO S 2,5-dimethylbenzothiazole 6-methoxy-2-methylbenzothiazole HO N \>:CH3 S 2-methyl-5-benzothiazolol 5-methoxy-2-methylbenzothiazole [0054] In another aspect of the invention there is provided for the use of a 2-substituted benzothiazole as a cyanoacrylate adhesive activator and/or accelerator, wherein the 2-substitu- ent is an alkyl, an alkene, an alkylbenzyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a sulfenamide, a thioalkyl or a thioalkoxy group, as defined above. [0055] Suitably, the benzene ring of the 2-substituted ben- zothiazole may be further substituted with at least one halo, thioalkyl, haloalkyl, alkyl, alkoxy or hydroxyl substituent as defined above. [0056] The invention desirably provides a pack comprising a cyanoacrylate adhesive composition comprising [0057] a cyanoacrylate; and [0058] a 2-substituted benzothiazole or a derivative thereof wherein the 2-substituent is an alkyl, an alkene, an alkylben- zyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a sulfenamide, a thioalkyl or a thioalkoxy group, with the pro- viso that an amide portion of the sulfenamide is not a tert butylamino or a morpholine group. This pack may be con- structed from a UV transparent material or a UV blocking material. [0059] In a different aspect the invention provides a pack comprising a cyanoacrylate adhesive composition compris- mg: [0060] a cyanoacrylate; and [0061] a 2-substituted benzothiazole or a derivative thereof wherein the 2-substituent is an alkyl, an alkene, an alkylben- zyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a sulfenamide, a thioalkyl or a thioalkoxy group. Here, in order to promote an extended shelf life one may wish to choose a pack that comprises a UV opaque material or is constructed from a UV blocking material. Aug. 11, 2011 [0062] In yet a related aspect, the invention provides a pack comprising an cyanoacrylate adhesive composition compris- ing: [0063] a cyanoacrylate; and [0064] a 2-substituted benzothiazole or a derivative thereof wherein the 2-substituent is a sulfenamide wherein the amide portion is a tert-butylamino, or a morpholine group. Again, here, in order to promote an extended shelf life the pack should be constructed from a UV blocking material. [0065] In the aspects relating to packs, the 2-substituted benzothiazole may comprise a 2-substituent which may be alkyl, an alkene, an alkylbenzyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a sulfenamide, a thioalkyl or a thio- alkoxy groups, as defined above. Suitably, the benzene ring of the 2-substituted benzothiazole may be further substituted with at least one halo, thioalkyl, haloalkyl, alkyl, alkoxy or hydroxyl substituent as defined above. [0066] In one desirable arrangement, the cyanoacrylate composition of the invention is provided in a two-part form. Suitably, the cyanoacrylate composition is packed in a dis- pensing pack. For two-part compositions this may be a pack that co-dispenses the two-parts (suitably in desired ratios) for mixing thereof. For example such a dispensing pack may be a dual barrel syringe. For example the cyanoacrylate adhesive composition may be held in a first compartment such as the barrel of a syringe, whereas the activator component is held in a second compartment for example a separate barrel of a syringe. It will be appreciated that any suitable dispensing pack may be used. In an additional aspect, the invention provides an activator for use in activating a cyanoacrylate composition, which is selected from a 2-substituted ben- zothiazole or a derivative thereof, wherein the 2-sub stituent is an alkyl, an alkene, an alkylbenzyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a sulfenamide, a thioalkyl or a thioalkoxy group, with the proviso that the sulfenamide is any sulfenamide other than a sulfenamide having an amide por- tion comprising a tert butylamino or a morpholine group. [0067] In another additional aspect, the invention provides a method of using a 2-substituted benzothiazole or a deriva- tive thereof as an activator for use in activating a cyanoacry- late composition, steps of which comprise in any order: [0068] providing an activator comprising a 2-substituted benzothiazole or a derivative thereof, and [0069] providing a cyanoacrylate, wherein the 2-substituent is an alkyl, an alkene, an alkylben- zyl, an alkylamino, an alkoxy, an alkylhydroxy, an ether, a sulfenamide, a thioalkyl or a thioalkoxy group, with the pro- viso that the sulfenamide is any sulfenamide other than a sulfenamide having an amide portion that is made from a tert butylamino or a morpholine group. BRIEF DESCRIPTION OF THE DRAWINGS [0070] FIG. 1: Bond Strengths for Two-Part CA’s—part B; [0071] FIG. 2: Cure time for adhesive using Composition comprising compound 2 (2-Me BT) as activator; [0072] FIG. 3: Cure time for adhesive using Composition comprising compound 2 (2-MeBT) as activator, after UV exposure; [0073] FIG. 4: Cure time for adhesive using Composition comprising compound 8 (5-Cl-2-Me-BT) as activator; [0074] FIG. 5: Cure time for adhesive using Composition comprising compound 8 (5-Cl-2-Me-BT) as activator, after UV exposure; US 2011/0196092 A1 [0075] FIG. 6: Cure time for adhesive using Composition comprising compound 9 (2-Me-mercapto BT) as activator; [0076] FIG. 7: Cure time for adhesive using Composition comprising compound 9 2-Me-mercapto BT) as activator, after UV exposure; [0077] FIG. 8: Cure time for adhesive using Composition comprising compound 10 (Santocure MBS) as activator; [0078] FIG. 9: Cure time for adhesive using Composition comprising compound 10 (Santocure MBS) as activator, after UV exposure; [0079] FIG. 10: Cure time for adhesive using Composition comprising compound 12 (Santocure CBS) as activator; [0080] FIG. 11: Cure time for adhesive using Composition comprising compound 12 (Santocure CBS) as activator, after UV exposure; [0081] FIG. 12: Cure time for adhesive using Composition comprising compound 14 (DMPT) as activator; [0082] FIG. 13: Cure time for adhesive using Composition comprising compound 14 (DMPT) as activator, after UV exposure; [0083] FIG. 14: Cure time for adhesive using Composition comprising compound 15 (2,2-Dithiodipyridine) as activator; [0084] FIG. 15: Cure time for adhesive using Composition comprising compound 15 (2,2-Dithiodipyridine) as activator, after UV exposure [0085] FIG. 16: Cure time for adhesive using Composition comprising compound 23 (2-[(tert butylamino)thio]ben- zothiazole as activator; [0086] FIG. 17: Cure time for adhesive using Composition comprising compound 23 (2-[(tert butylamino)thio]ben- zothiazole as activator, after UV exposure. DETAILED DESCRIPTION OF THE INVENTION [0087] As an investigation into activator deactivation, the Inventors tested a two-part product containing cyanoacrylate based “A Part” (LOCTITE 431) and activator based “B Part” which comprised N-tert-butyl-2-benzothiazole sulfenamide and triacetin as a control (all Loctite products are available from Henkel Ireland Limited, Tallaght, Dublin 24). It was observed that gel times drifted on some unique samples stored at room temperature (RT) and this was particularly noticeable on samples provided in clear packaging. It appeared that UV exposure resulted in deterioration of the adhesive cure prop- erties. [0088] Further investigation showed that for the samples for which gel time increased, the active N-tert-butyl-2-ben- zothiazole sulfenamide activator concentration was signifi- cantly decreased from the initial value. The initial activator component concentration was 0.0455M. The reduction in cure performance and concentration of activator would seem to indicate that loss of activator detrimentally affects the adhesive cure performance. [0089] The aim was to find replacement activators for N-tert-butyl-2-benzothiazole sulfenamide that would provide for better cure times and/ or activators which will not be UV or water sensitive. [0090] Thus, the activator “B Part” was substituted with individual compounds as shown in Table l and mixed with triacetin before mixing with “A Part”. [0091] Compounds investigated as possible activators are shown in Table 1. Aug. 11, 2011 TABLE 1 Compounds Investigated Activator N \>: C1 S 2-chloro- l ,3- benzothiazole N\ S>j CH3 2-methyl- l ,3- benzothiazole N HO > S O l,3-benzothiazole- 6- carboxylic acid N \>—NH2 o2N S 2-a.mino-6-nitro- benzothiazole Cl N \>7SH S 5-chloro-2- mercapto-benzothiazole :\>—S\/\oH 2(2-benzothiazolylthio)etha.nol N \>: OH S 2-hydroxybenzothiazole Cl N \>—cH3 s 5-chloro-2- methylbenzothiazole US 2011/0196092 A1 Aug. 11, 2011 10 TABLE 1-continued Com ounds Investi ated Activator N\ S? s \ CH3 2-(methylmercapto) benzothiazole 10 N/>:S\ S 2-(morpho1iH-4-y1thio)- 1 ,3- benzothiazole (Santocure MBS) 11 N 3\%S\3{/N S mercaptobenzothiazyl disulfide (Perkacit MBTS) 12 N \>—s \ S N H 2- [(cyc1oheXy1amiHo)thio]- benzothiazole (Santocure CBS) OH CH3 2,6-di-te1t-butyl-4-methylphenol 14 H3C \N/ CH3 CH3 N,N,4-trimethylaniline (DMPT) 2,2-Dithiodipyridine ‘O O 16 17 18 19 20 21 22 23 TABLE 1-continued Compounds Investigated Activator o3N N \>—CH3 s 2-methy1-5- Hitrobenzothiazole \>:C1 C1 3 2,6-dichlorobenzothiazole MCO N \>7 CH3 S 5-methoXy-2- methylbenzothiazole \>7 CH3 MeO S 6-methoXy-2- methylbenzothiazole H3C N \>7 CH3 S 2,5-dimethylbenzothiazole Ho N \>:CH3 S 2-methy1-5- benzothiazolol N \>:CH3 S 2-methy1-beta- Hapthothiazole N /> S\ s N H 2-[(te1t buty1amiHo)thio] benzothiazole US 2011/0196092 A1 [0092] These samples were evaluated with 2 part syringes (10:1, A:B) being packed as follows: [0093] Part A: LOCTITE 431 (a medium viscosity cyanoacrylate); [0094] Part B: Triacetin (99.89%) and activator (0.1098%), which were stirred together at RT for 30 minutes. [0095] All evaluated activators were soluble in triacetin and gave clear solutions with the exception of 2-amino-6-nitro benzothiazole (4) and 2-methyl-[3-napthothiazole (22), each of which were yellow in solution at the concentration used. [0096] Samples were evaluated in terms of gel times. Gel times were measured by dispensing 1 g of material into a dish Aug. 11, 2011 using a static mixer (containing 16 elements) and using a stopwatch to record the time taken for the material to cure. If curing had not occurred within 5 minutes, the material was given a gentle stir using an applicator stick. The tests were repeated to ensure reproducibility. Results of the adhesive testing are provided in Table 2 which provides details of the gel times for the compositions comprising the individual activator compounds tested. Composition which did not cure within 20 minutes of mixing have been denoted “DNC” which means they did not cure and were not subjected to further testing. TABLE 2 Gel times for 2- art CA’s Appearance Activator (Part B) as cures Gel time 1 Gel time 2 N >20 mins >20 mins \ 20 mins >20 mins \> 20 mins \ 20 mins \ 20 mins >20 mins \ 20 mins \ 20 mins >20 mins \ 20 mins