Single component, heat curing compositions which are stable when stored at room temperature and which comprise polymers containing anhydride groups and powdered crosslinking agents, and their method of manufacture and use

A liquid composition, which is stable in storage at room temperature and which crosslinks under the action of heat, comprising:

• a liquid binder polymer containing acid anhydride groups and at least one powdered crosslinker with a melting point above 60.degree. C. having more than one anhydride-reactive group per molecule dispersed in said liquid composition, said anhydride-reactive groups being not inactivated by inactivation of surface-reactive groups of the powdered crosslinker, said crosslinker being inactive and not soluble in the binder polymer at ambient conditions, and said crosslinker being able upon application of heat to said crosslinker to crosslink the binder polymer containing the anhydride groups at temperatures of 80.degree. C. and above,
• wherein the powdered crosslinker is selected from the group consisting of:
• b1) solid di- or polyols with primary or secondary hydroxyl groups selected from the group consisting of mannite, sorbite, sucrose, lactose, erythrite, pentaerythrol, di-pentaerythrol, tri-pentaerythrol, solid pentaerythrol derivatives with ester groups and on average at least two free hydroxyl groups, solid pentaerythrol derivatives with ether groups and on average at least two free hydroxyl groups, neopentylglycol, hydroquinone-bis-(2-hydroxyethyl) ether, oxoethylated bisphenol A, oxoethylated terephthalic acid bisamide, tris-(2-hydroxyethyl)isocyanurate, N,N'-bis-(2-hydroxyethyl)piperazine, solid polyesters containing hydroxyl groups, reaction products of di- or polyisocyanates with short chain dioles or amino alcohols and solid polymers or copolymers containing hydroxyl groups;
• b2) solid di- or polyamines selected from the group consisting of sterically hindered, aromatic diamines, ethyleneglycol-di-p-aminobenzoic ester, trimethylenglycol-di-p-aminobenzoic ester, 4,4'-diaminobenzophenone, 4,4'-diaminobenzanilide, 4,4'-diaminophenylsulphone, N,N'-di-anilino-urea, piperazine, solid reaction products of short chain mono- and diamines on diisocyanates or polyisocyanates, solid reaction products of short chain mono- and diamines on diepoxides or polyepoxides and solid reaction products of monomeric anhydrides and polyamines;
• b3) solid di- or polyepoxides;
• b4) solid compounds which carry different anhydride reactive groups;
• and
• b5) mixtures thereof.