Patent GB-1242098-A (GB)
Title: Polymerisable acrylate ester composition and process for bonding surfaces
IPC: C08F4/00
Filed: 1968-12-24
Abstract: 1,242,098. Polymerisable adhesive systems. LOCTITE CORP. 24 Dec., 1968 [28 Dec., 1967], No. 61292/68. Heading C3P. An adhesive composition suitable for bonding abutting surfaces comprises (a) a polymerizable ester of acrylic acid or an α-substituted acrylic acid; (b) a peroxy polymerization initiator; and (c) an organic bonding accelerator having a group of the formula or For storage purposes, the adhesive composition is put in the form of a multi-part system wherein components (a) and (b) are stored in one container, and component (c) in a separate container. The acrylate-based adhesives are generally of the anaerobic curing type. Component (a) is preferably an ester of the formula wherein R<SP>1</SP> is H, C 1 -C 4  alkyl or hydroxyalkyl, or the group -CH 2 -O-OC-CR<SP>2</SP>=CH 2 ; R<SP>2</SP> is H, halogen or C 1 -C 4  alkyl; R<SP>3</SP> is H, OH or the group -O-OC-CR<SP>2</SP>=CH 2 ; m and n are each integers of 1 or more; and p is 0 or 1. Such esters include di-acrylates, -methacrylates and -chloroacrylates of monoglycols and polyglycols, diglycerol diacrylate or tetramethacrylate, and trimethylolpropane triacrylate. Another suitable class of ester monomers comprises the reaction product of (i) an acrylate ester containing a suitably active hydrogen atom (e.g. the hydrogen in a hydroxy group or primary or secondary amino group) in the alcohol moiety and (ii) an organic polyisocyanate. A third class of suitable acrylate esters includes compounds of the formula or wherein R<SP>1</SP>, R<SP>2</SP>, m and n are as defined above and R<SP>5</SP> is H or an alkyl or aralkyl radical having up to 10 carbon atoms. Monoacrylate esters can also be used, e.g. hydroxyethyl, cyanoethyl, t-butylaminoethyl, glycidyl or isobutyl (meth)- acrylate. Suitable as peroxy initiators (b) are are organic hydroperoxides having up to 18 carbon atoms; hydrogen peroxide, organic peroxides and organic peresters can also be used. Suitable accelerators (c) include compounds of the formula or wherein X and Z are each H or R, where R is a monovalent hydrocarbon radical containing up to 10 C atoms, Y is H, R, -SX, -NXZ or -N=R<SP>11</SP>, where R<SP>11</SP> is a divalent hydrocarbon radical with up to 10 C atoms, and Q is H, R, -SX or or alternatively X and Y can be joined together to form a heterocyclic ring with the adjacent N and C atoms. Exemplified as bonding accelerators are thioacetamide, tetramethylthiuram disulphide, thiocarbanilide, copper dimethyldithiocarbamate, thiourea, N,N<SP>1</SP> - dicyclohexylthiourea, 1 - allyl - 2 - thiourea, striazole - 3 - thiol, 2 - mercaptothiazoline, 2- mercaptobenzothiazole, N - cyclohexylbenzothiazole - 2 - sulphonamide, N - oxydiethylene benzothiazole - 2 - sulphonamide and 5 - amino- 2-benzimidazole thiol. Other materials may be included with the acrylate ester and peroxy initiator, e.g. quinone or hydroquinone stabilizers, tertiary amine or imide accelerators, thickeners, colouring agents, plasticizers, e.g. tetraethyleneglycol di - 2 - ethylhexoate, and comonomers, e.g. acrylic acid (see the examples). The bonding accelerator is preferably used in the form of a solution or dispersion in a volatile organic solvent, or in an aerosol; the accelerator can then be applied to at least one of the surfaces to be bonded, and the acrylate/initiator combination then applied to at least one of the surfaces to be bonded. The adhesives are particularly useful in bonding metal surfaces, e.g. as in nuts and bolts.