Heat sealable coating compositions

A dispersion of polymer microparticles in organic liquid obtainable by a process comprising the steps of

• i) providing a mixture comprising a first polymer having functional groups capable of reacting with the carboxylic acid and/or carboxylic acid anhydride groups of a second, polypropylene polymer
• ii) causing the polymers to melt at a chosen temperature under conditions of high shear to form an intimate mixture
• iii) causing the carboxylic acid and/or carboxylic acid anhydride groups of the polypropylene polymer to react with at least some of the functional groups of the first polymer, under conditions of high shear
• iv) diluting the resulting mixture of step iii) with an organic liquid at a temperature such that a substantially homogeneous solution is formed
• v) cooling the solution to a temperature whereby the polymer microparticles of the dispersion are formed.

A process for the manufacture of a dispersion of polymer microparticles in organic liquid, comprising the steps of

• i) providing a mixture comprising a first polymer having functional groups capable of reacting with the carboxylic acid and/or carboxylic acid anhydride groups of a second, polypropylene polymer
• ii) causing the polymers to melt at a chosen temperature under conditions of high shear to form an intimate mixture of the polymers
• iii) causing the carboxylic acid and/or carboxylic acid anhydride groups of the polypropylene polymer to react with at least some of the functional groups of the first polymer, under conditions of high shear
• iv) diluting the resulting mixture of step iii) with an organic liquid at a temperature such that a substantially homogeneous solution is formed
• v) cooling the solution to a temperature whereby the polymer microparticles of the dispersion are formed.