GB1056079A - Adhesives for making laminated structures - Google Patents

Abstract

The invention relates to adhesive vinyl addition copolymers having attached to the carbon-carbon chain monovalent radicals of the formula <FORM:1056079/C3/1> in which Z is a tetravalent saturated aliphatic hydrocarbon radical of 2 or 3 carbon atoms, R and R1 are each a hydrogen atom or a C1-C8 alkyl radical and R11 is a hydrogen atom or a non-tertiary C1-C8 alkyl radical; said monovalent radicals being present in an amount such that the copolymer has an amino nitrogen content of 0.01 to 6.6% by weight and any substituted amido or imido nitrogen atoms in the copolymer are substituted with hydrocarbon radicals. The invention also relates to adhesive compositions comprising solutions of the above copolymers in organic solvents. The defined monovalent radicals are preferably those of the formulae -COOCH2CH2NH2, -COOCH2CH(CH3)NH2 and -COOCH(CH3)CH2NH2. The copolymers may be prepared by reacting in a liquid medium (e.g. an organic solvent), if desired in the presence of a catalyst such as azo diisobutyronitrile or cumene hydroperoxide, at least two ethylenically unsaturated copolymerizable monomers, at least one of which contains free carboxyl groups, to produce a copolymer with an acid equivalent of 0.01 to 6.0 milli-equivalents per gram, and reacting the copolymer with 50 to 100% of the theoretical amount required to completely esterify the free carboxyl groups of an alkylene imine of the formula <FORM:1056079/C3/2> wherein Z, R, R1 and R11 have the meanings given above. The carboxylic acid monomer is suitably an alpha, beta-ethylenically unsaturated carboxylic acid, e.g. acrylic, methacrylic, crotonic, itaconic, citraconic and maleic acid (or anhydrides thereof which may be subsequently hydrolysed); other unsaturated acids may also be used, e.g. 3-butenoic acid. Copolymerizable monomers include esters of acrylic, methacrylic, chloroacrylic, phenylacrylic, methoxyacrilic, cyanoacrylic, methylthioacrylic, phenylsulphonylacrylic, ethacrylic, crotonic, itaconic and maleic acids, amides of such acids, nitriles, imides, vinyl esters, ethers, thioethers, sulphones, vinyl halides, N-vinyl compounds, styrene vinyl toluene, alkyl compounds, diethyl methylene-malonate, diketene, ethylene glycol ketene acetal, methylene-cyclopentane, vinylidene chloride, vinylidene disulphones, vinylene carbonate, acrolein acetals, methyl vinyl ketone, vinyl phosphonates, allyl phosphonates, vinyl trialkoxysilanes, ethylene, propylene and butadiene. The copolymers may also be prepared by polymerizing monomers which initially contain the desired amino-ester groups. Suitable solvents for the copolymers include alcohols, esters, ketones, aromatic hydrocarbons and halogenated hydrocarbons, the preferred solvent being a mixture of isopropyl alcohol and toluene. The copolymer solutions are particularly suitable as adhesives in laminating and for this purpose may include additives such as pigments, corrosion inhibitors, U.V. light absorbers and antioxidants (e.g. TiO2, carbon black and basic zinc chromate). In examples, methacrylic acid or acrylic acid are copolymerized with one or more of methyl methacrylate, styrene, butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, butadiene, acrylonitrile and ethylene, and the resulting acid copolymers are completely or partly esterified with 1,2-propylenimine, ethylenimine, N-methyl-ethylenimine, 1,3-propylenimine, N-(n-octyl)-1,2-propylenimine or 2-(n-octyl)-ethylenimine.