English

The green strength of polymers produced by emulsion polymerization processes is improved through the use of carboxyl containing compounds. Specifically, the compounds are half esters of unsaturated dicarboxylic acids wherein the half ester moiety renders the carboxyl containing compound hydrophobic. As a result, carboxylic copolymers can be produced in emulsion polymerizations having a basic (pH.gtoreq.7.0) aqueous medium. Heretofore, use of carboxylic acids in emulsion polymerizations have been limited to acidic mediums.

The present invention relates to toughened cyanoacrylate compositions.

This invention relates to adhesive compositions particularly adapted for forming flexible adhesive bonds and is particularly concerned with adhesive compositions comprising a mixture of at least two different esters of alpha-cyanoacrylic acid.

Disclosed are cyanoacrylate adhesive compositions containing elastomeric polymers as fillers. Preferred fillers are the acrylic rubbers. Filler concentration range from about 0.5-40% by weight of the composition. Beneficial results include improved toughness of the cured compositions, as measured by impact, peel and tensile strength properties, particularly after exposure elevated temperatures which would ordinarily severely degrade the adhesive strength.

An adhesive composition comprising a 2-cyanoacrylate and at least one member selected from the group consisting of substituted or unsubstituted aliphatic carboxylic acids having three or more carboxyl groups, anhydrides thereof, partial esters thereof, aromatic polycarboxylic acids having three or more carboxyl groups and anhydrides thereof. This composition has a high impact strength, is suitable for bonding metallic substrates to one another and is also excellent in resistance to heat, weather, and water.

2,4,6-trimethylbenzoyldiphenylphosphineoxide (TMDPO) was irradiated in dilute solutions of benzene, methanol and dichloromethane with 20 ns flashes of 347 nm light. By optical absorption measurements, a transient spectrum with a maximum at about 330 nm detected at the end of the flash was ascribed to the diphenyl phosphonyl radical . This radical is formed by the reaction. Evidence was obtained for fragment radicals being formed, to some extent at least, from triplet states. Both the singlet and the triplet lifetimes were estimated as τ < 1 ns.

An instant-setting adhesive composition comprising a 2-cyanoacrylate and at least one 1,1-disubstituted diene, the amount of said 1,1-disubstituted diene exceeding 50% by weight based on the total weight of both components. This composition is useful in the same fields as those where conventional 2-cyanoacrylate adhesives have been used, and is excellent in impact resistance, peel resistance, heat resistance and water resistance.

The condensation of active methylene compounds 1 with acetaldehyde was efficiently promoted by a catalytic amount of lithium bromide in the presence of acetic anhydride to give ethylidene malonates 2 in 77-97% yield.

An adhesive composition comprises (a) at least one polymerizable cyanoacrylate monomer, (b) 0.1 to 10% by weight of a polymerizable acrylate ester e.g. allyl methacrylate and (c) 0.1 to 20% by weight of a maleimide derivative of formula wherein R<7> and R<8> are from alkyl, cycloalkyl, aralkyl or arkaryl. The compositions may polymerize with ring-opening of the maleimide. They have excellent hot strength properties for long periods at 121 DEG C (250 DEG F) or more.