US 20050000646A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2005/0000646A1 Ryan et al. (43) Pub. Date: Jan. 6, 2005 (54) ACTIVATOR COMPOSITIONS FOR Publication Classification CYANOCRYLATE ADHESIVES (51) Int. Cl." ................................ C09J 5/04; B01J 31/00 (76) Inventors: Bernard Ryan, Dublin (IE); Hanns (52) U.S. Cl. ................... 156/314; 156/331.2; 156/331.6; Misiak, Dublin (IE); James Houlihan, 502/167 Dublin (IE) Correspondence Address: (57) ABSTRACT Henkel Corporation Legal Department An activator composition for accelerating hardening and 1001 Trout Brook Crossing achieving cure-through-volume of cyanoacrylate adhesives) Rocky Hill, CT 06067 (US) comprising; (a) one or more compounds Selected from the group consisting of (i) pyrazine; or a pyrazine derivative; (21) Appl. No.: 10/495,817 Said pyrazine derivative being pyrazine Substituted with at least one electron-releasing group; (ii) pyridine N oxides (22) PCT Filed: Nov. 13, 2002 Substituted with at least one electron-releasing group; or (iii) (86) PCT No.: PCT/IE02/00157 2.6 pyridines being pyridines Substituted in the 2- and 6-positions by Substituents, at least one of the Substituents (30) Foreign Application Priority Data being electron-releasing provided that both Substituents are not methyl; and (b) a volatile solvent carrier for the com Nov. 14, 2001 (IE)........................................ S2001/0987 pound. US 2005/0000646 A1 Jan. 6, 2005 ACTIVATOR COMPOSITIONS FOR Solvents used for Such dilute Solutions of activators are CYANOCRYLATE ADHESIVES generally low-boiling organic Solvents, So that they may be readily evaporated, leaving the activator on the Substrate FIELD OF THE INVENTION and/or on the adhesive. 0001. This invention relates to activator compositions, 0008 Japanese Patent Application Nos. JP-A-62 022 particularly well Suited for accelerating the hardening of 877, JP-A-03 207 778 and JP-59-66471 propose the use of cyanoacrylate adhesives. The invention further relates to a Solutions of various amines in Solution as accelerators for proceSS for the accelerated bonding of Substrates using cyanoacrylate adhesives. U.S. Pat. No. 3,260,637 of von cyanoacrylate adhesives. Bramer discloses the use of a range of organic amines (excluding primary amines) as accelerators for cyanoacry BRIEF DESCRIPTION OF RELATED late adhesives, particularly for use on metallic and non TECHNOLOGY metallic Substrates. 0002 Adhesive compositions based upon cyanoacrylate 0009 N,N-dimethyl-p-toluidine has been widely used as esters are well known and have found extensive use, because an accelerator for the accelerated hardening of cyanoacrylate of their rapid cure Speed, excellent long-term bond strength, adhesives. This chemical provides a short duration of the and applicability to a wide variety of Substrates. They Surface activation, which does not permit long waiting times generally harden after only a few Seconds, after which the between application of the accelerator Solution beforehand joined parts exhibit at least a certain degree of initial to the Substrates to be bonded and the Subsequent bonding Strength. process. In addition, the use of N,N-dimethyl-p-toluidine in 0003) If the cyanoacrylate (CA) adhesive is convention Some countries oftentimes involves rigorous regulatory ally applied in a relatively thick layer in the joint gap or labelling requirements. relatively large amounts of adhesive are applied So that relatively large drops of adhesive protrude from between the 0010 Basicity of an accelerator Substance is not a suffi cient criterion for identifying Solutions which are acceptable parts to be joined, rapid hardening throughout the adhesive in practice in terms of application technology. Many Sub may rarely be achieved, i.e. cure-through-gap or cure stances, Such as alkylamines, 1,2-di-(4-pyridyl-ethane), 4,4'- through-volume (CTV) performance may be unsatisfactory. dipyridyl disulfide, 3-(3-hydroxypropyl)pyridine, 1,2-bis 0004. With certain substrates, particularly substrates hav (diphenylphosphino)-ethane, pyridazine, methylpyridazine ing acidic Surfaces, Such as wood or paper, the polymerisa or 4,4'-dipyridyl, are So basic or nucleophilic that Sponta tion reaction may be retarded, often times to an unmanage neous Superficial hardening takes place at the adhesive able extent. Moreover, unless the adhesive is gelled or interface (shock hardening) before the activator is able to rendered thixotropic by appropriate additives to confer Such initiate polymerisation throughout the liquid adhesive (usu properties, the wood or paper Substrates, due to their poros ally a drop or layer) by dispersion processes Such as by ity, tend to draw the adhesive out of the joint gap by capillary convection and diffusion. The result is that an often cloudy action before hardening has taken place in the gap. polymerisation occurs at the Surface only. With other com 0005. Heretofore efforts have been made to accelerate the pounds, Such as Oxazoles, the basicity is evidently too low, polymerisation of Such CA adhesives by means of certain and the hardening is often too slow for practical purposes. additives. Addition of accelerators directly to the adhesive 0011 German Patent DE-A-22 61 261 proposes accel formulation is possible to only a very limited extent, how erator Substances containing the Structural element ever, Since Substances having a basic or nucleophilic action, -N=C-S-, including 2,4-dimethylthiazole. U.S. Pat. which would normally bring about a pronounced accelera Nos. 5,567,266 (Liu) and U.S. Pat. No. 5,643,982 (Liu) tion of the polymerisation of the cyanoacrylate adhesive, are describe accelerator compositions comprising amine com generally used, it is usually at the expense of the Storage pounds. EP 0822 242 and U.S. Pat. No. 5,749,956 (Fisher stability of Such formulations. et al.) describe non-Ozone depleting non-flammable co 0006 Addition of such accelerators shortly before appli Solvent useful for carrying inter alia accelerators. cation of the adhesive results in Virtually a two-component 0012 European Patent Publication No. 0271 675 A2 of (two-part) System-in other words the adhesive and the Three Bond Co. Ltd. describes a primer for CA adhesive for accelerator are Stored apart-the accelerator would not use in bonding non-polar or highly crystallized resins Such normally be mixed with the adhesive for Storage purposes. as polyolefins, polyethyleneterephthalates, nylons, fluorine However, Such method has the disadvantage that the work containing resins, soft PVC films and the like which are ing life is limited after the activator has been mixed in. In notorious as being ordinarily difficult to bond. The primer addition, with the Small amounts of activator that are comprises (A) a compound selected from the group consist required, the necessary accuracy of metering and homoge ing of benzene ring compounds having aldehyde groups and neity of mixing are difficult to achieve. Moreover, use of nitrogen or oxygen atom-containing heterocyclic com Such a two-part System is often seen as cumberSome to the pounds having aldehyde groups (such as 2-pyridine car end user, and Sometimes only modestly improves the boxylaldehyde, 2,6-pyridine carboxylaldehyde and pyrrole intended result. 2-carboxylaldehyde), and (B) an organic amine compound. 0007 Activators are also used in the form of a dilute The EP 675 publication states that in bonding non-polar or Solution which is either applied beforehand onto a Substrate highly crystallized resins using a CA adhesive the primer Such as a part which is to be bonded, and/or is applied onto instantaneously exhibits a high bonding Strength at ambient the adhesive where it is still liquid (before the adhesive has temperature by Simply applying Such primer onto a Surface fully cured) after the substrates have been joined. The of one of the resins, applying the CAadhesive onto a Surface US 2005/0000646 A1 Jan. 6, 2005 of the other resin and bringing both Surfaces into contact least one of the Substituents being electron-releas with each other, thus achieving "Zero gap' and an instanta ing provided that both Substituents are not methyl, neous high bonding Strength. and 0013 British Patent Specification No. 1 230 560 of 0024 (b) a volatile solvent carrier for the com International Chemical Company Limited (ICC) describes pound. CA adhesive compositions containing certain Substituted 0025 In the groups (i) to (iii) above (the groups (i) to (iii) heterocyclic compounds as accelerators. The compositions are used for convenience and mixtures of compounds within may be presented in a two-part form, the first part compris a designated group and/or between groups is encompassed ing the CA adhesive and the Second part comprising at least by the use of the phrase "at least one') the electron releasing one of the Substituted heterocyclic compounds, preferably in effect of the Substituent is measured relative to hydrogen Solution in an organic Solvent. In the compositions in which in other words a Substituent which is considered more the heterocyclic compound is an iminoethylene-Substituted electron-releasing than a hydrogen Substituent is desired. triazine or pyrimido-pyrimidine, the heterocyclic compound Usually the electron-releasing effect would be manifested in is invariably present in one part of a two-part composition a net increase in the base Strength of the Substituted com because iminoethylene-Substituted triazines and pyrimido pound compared to the corresponding Substituted com pyrimidines accelerate the polymerisation So rapidly they pound. Such a net increase in the base Strength of the must be kept apart from the CA composition before use. Substituted compound compared to the corresponding 0.014) Japanese Patent Abstract Publication No. unsubstituted compound is desirable for all compounds of 62018485 of Alpha Giken KK also describes a primer for a groups (i) to (iii) above. CA adhesive and is not concerned with an activator for good 0026. This base strength effect is particularly desirable CTV performance. for the Substituted pyrazines of group (i) and the pyridine 0.015 Activator solutions are often applied by spraying.