Abstract: There is disclosed an improved process for the manufacture of a foundry core or mould, comprising forming into the foundry core or mould a composition comprising a granular filler, a synthetic resin which cures under the action of an acid and a desensitized ketone peroxide composition and treating said formed composition with sulphur dioxide, wherein the improvement comprises using as the desensitizing agent a dialkyl ester of an aliphatic dicarboxylic acid of the general formula ##STR1## wherein n=1-7 and R.sub.1 and R.sub.2 =a branched or non-branched alkyl group having 3 to 5 carbon atoms.

Abstract: Novel peroxyketals having the general formula ##STR1## are provided, wherein R.sup.1 represents a tert. alkyl group having 4-12 carbon atoms and R.sup.2 represents a branched or a non-branched alkyl group having 1-12 carbon atoms or a substituted or unsubstituted cycloalkyl group having 5-12 carbon atoms. The peroxyketals can be used to advantage for initiating the copolymerization reaction of ethylenically unsaturated compounds such as unsaturated polyester resins containing both an unsaturated polyester and an ethylenically unsaturated monomer such as styrene.

Abstract: A process for copolymerizing unsaturated polyester resins is disclosed wherein said resin is copolymerized in the presence of a perketal and an acid or acid-releasing compound.

Abstract: A process for the preparation of a curable molding or coating compound containing an unsaturated polyester resin is disclosed. The process comprises substantially uniformly incorporating into said resin effective amounts of a cerium promoter and a catalytically active tertiary butyl peroxy ester or a tertiary amyl peroxy ester of a non-.alpha.-branched aliphatic or aromatic, mono- or dicarboxylic acid.

Abstract: Novel peroxyketals having the general formula ##STR1## are provided, wherein R' represents a tert.alkyl group having 4-12 carbon atoms and R.sup.2 represents a branched or a non-branched alkyl group having 1-12 carbon atoms or a substituted or unsubstituted cycloalkyl group having 5-12 carbon atoms. The peroxyketals can be used to advantage for initiating the copolymerization reaction of ethylenically unsaturated compounds such as unsaturated polyester resins containing both an unsaturated polyester and an ethylenically unsaturated monomer such as styrene.

Abstract: A copolymerizable composition containing an unsaturated polyester resin and a metal accelerator, suitable for copolymerization with an ethylenically unsaturated monomer, has incorporated therein as a peroxide initiator composition an alkylaldehyde peroxide which may be unsubstituted, or alkyl- or aryl-substituted, the alkylaldehyde peroxide containing not more than 20 carbon atoms and at least 1.5 active oxygen atoms per carbonyl group of said alkylaldehyde.

Abstract: A copolymerizable composition containing an unsaturated polyester resin and a metal accelerator, suitable for copolymerization with an ethylenically unsaturated monomer, has incorporated therein as a peroxide initiator composition an alkylaldehyde peroxide which may be unsubstituted, or alkyl- or aryl-substituted, the alkylaldehyde peroxide containing not more than 20 carbon atoms and at least 1.5 active oxygen atoms per carbonyl group of said alkylaldehyde.

Abstract: A copolymerizable composition containing an unsaturated polyester resin and a metal accelerator, suitable for copolymerization with an ethylenically unsaturated monomer, has incorporated therein as a peroxide initiator composition an alkylaldehyde peroxide which may be unsubstituted, or alkyl- or aryl-substituted, the alkylaldehyde peroxide containing not more than 20 carbon atoms and at least 1.5 active oxygen atoms per carbonyl group of said alkylaldehyde.

Abstract: A process for the polymerization of vinyl or vinylidene-group-containing esters in the presence of a free radical generating compound as an initiator and a metal compound as an accelerator comprising, as an initiator, an organic peroxidic composition consisting essentially of a compound having the general formula ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 may be the same or different and each represents hydrogen, branched or unbranched alkyl, if desired substituted by hydroxy, alkoxy, alkoxycarbonyl or halogen, aryl, if desired substituted by alkyl, hydroxy, alkoxy or halogen, or aralkyl wherein the aryl group may be substituted by alkyl, hydroxy, alkoxy or halogen, and wherein R.sub.1 together with R.sub.2, R.sub.3 together with R.sub.4, and R.sub.1 together with R.sub.4 form a branched or unbranched alkylene group, and R.sub.1 together with R.sub.2 and R.sub.3 form a branched or unbranched alkylylidene group.

Abstract: A process for stabilizing an ultraviolet light curable unsaturated polyester resin mixture containing a benzoin compound as a photosensitizer is disclosed. A stabilizing amount of a compound of the formula ##SPC1##Wherein A is a methyl group, B is a hydrogen atom or A and B together represent a substituted or non-substituted benzo group is added to the mixture which can also contain a filler, a quaternary ammonium compound and a copper or iron compound soluble in the unsaturated polyester resin. The composition and cured product are also disclosed.