Patent GB-1098489-A (GB)
Title: Pressure-sensitive adhesives and adhesive tapes
IPC: C09J7/22
Filed: 1964-12-09
Abstract: A pressure sensitive adhesive comprises an adhesive polymer consisting of units of (A) a half-ester of at least one ethylenically unsaturated alpha, beta-dicarboxylic acid and at least one C1 to C24 alkanol, at least 50 mol per cent of the alkanols selected being non-tertiary alkanols, the average number of carbon atoms of the alkanols being no greater than 18, the alkanols which contain more than 7 carbon atoms being branched, and the alkanols selected being a mixture when they contain more than 7 carbon atoms; (B) at least one ester of acrylic or methacrylic acid and at least one C1 to C14 alkanol, at least 50 mol per cent of the alkanols selected being non-tertiary; the proportion of component (A) to component (B) being from 1:19 to 7:3 by weight and not exceeding a mol ratio of 1:1.  The adhesive may optionally contain 5 parts or more of a tackifier resin per 100 parts by weight of the adhesive polymer. Polymer component (A) may be a halfester of maleic, citraconic, fumaric or itaconic acid.  The polymer may additionally comprise units of other polymerizable compounds such as acrylic and methacrylic acid and their nitrile and amide derivatives, unsaturated dicarboxylic acids and their imides, amides and amideesters, N-alkylammonium salts and esters of unsaturated acids (other than components A and B), vinyl esters, vinyl ethers, vinyl aromatic compounds such as styrene, vinyl and vinylidene halides, olefins, diacrylates, dimethacrylates, allyl acrylate, allyl methacrylate, diallyl succinate, divinylbenzene, dimaleates, dicitraconates, diitaconates and the corresponding diamic derivatives of the polycarboxylic acids.  The polymers can be prepared by polymerizing the appropriate monomers in aqueous emulsion or suspension or in an inert solvent employing catalysts such as inorganic or organic peroxides, hydroperoxides, salts of per acids and azo compounds; the peroxy catalysts can be used in conjunction with a reducing agent such as a ferrous, cuprous, bisulphite, thiosulphate, hydrosulphite or tetrathionate salt, ascorbic acid or an amino compound; polymerization may also be initiated with U.V. light in the presence of an organic peroxide or a photosensitizer such as benzophenone.  In emulsion polymerization, anionic, nonionic or cationic emulsifiers can be used, e.g. sodium lauryl sulphate, and the polymer emulsion may be thickened with, e.g. polyvinyl alcohol, polyacrylates or water soluble cellulosic derivatives; the polymer may be coagulated from the emulsion.  Suitable tackifier resins are wood rosin, phenol-formaldehyde resins, phenolic modified terpene resins, phenol modified rosin, polyester resins and bicycloheptadiene-terpene resins.  Plasticizers may additionally be added, e.g. dialkyl phthalates, polymeric or monomeric alkyl esters of aliphatic dicarboxylic acids, polymeric condensation products of sebacic acid and propylene glycol, sucrose acetate isobutyrate, chlorinated biphenyl, tricresyl phosphate and diphenyl ether.  The adhesive polymers may also be blended with other polymers such as SBR rubber, polychloroprene rubber, cis-polyisoprene rubber and rubbery polyacrylates. Crosslinking or curing agents can also be included such as organic peroxides, epoxy compounds, formaldehyde resins, polyvalent metal compounds, polyamines, polyhydroxy compounds and polyisocyanates; crosslinking can also be effected by means of U.V. or electron beam irradiation, or by heating.  The adhesives may be applied from an emulsion or as a solution in an organic solvent, e.g. methyl ethyl ketone or toluene.ALSO:Half-esters of unsaturated dicarboxylic acids and alkanols are prepared by reacting in suitable proportions in an organic solvent an unsaturated dicaboxylic anhydride and mixtures of alkanols. Reactants specified are (1) maleic anhydride with a tridecyl oxo alcohol mixture, (2) maleic anhydride with a mixture of tridecyl oxo alcohols, an alkanol mixture averaging 16 carbon atoms and an isomeric mixture of C10 alkanols, (3) maleic anhydride with a mixture of 2 - ethyl - 1 - hexanol, 2,6 - dimethyl - 4 - heptanol, isodecanol (an isomeric mixture of C10 alkanols), 2-ethyl-butanol, 2-methyl-pentanol, 2,2,4-trimethylpentanol and 4-methyl-2-pentanol, (4) itaconic anhydride with the alcohol mixture of (2), and (5) citraconic anhydride with the alcohol mixture of (3).  Solvents specified for reactions (1) and (5) are benzene and isopropyl acetate respectively and each of these reactions was conducted in the presence of a small amount of sodium propionate.ALSO:Adhesive tapes are prepared by coating polyethylene terephthalate film with polymers whose essential components are (A) a half-ester of at least ethylenically unsaturated alpha, beta-dicarboxylic acid, e.g. maleic, citraconic, fumaric, or itaconic acid, and at least one C1 to C24 alkanol and (B) at least one ester of acrylic or methacrylic acid and at least one C1 to C14 alkanol, the polymer being applied as a solution in an organic solvent, e.g. methyl ethyl ketone or toluene, which is subsequently evaporated.  The solution may optionally contain other components such as tackifier resins, plasticisers, rubbery polymers and crosslinking or curing agents.