“Designer” Nucleating Agents for Polypropylene

Abstract

We report the discovery of a family of organic compounds, substituted 1,3,5-benzenetrisamides, thatsdepending on subtle details of their chemical structuresare capable of selectively and extremely efficiently nucleating the growth of the common R-crystal modification of the major industrial polymer isotactic polypropylene (i-PP), rendering this normally turbid material highly transparent ("clarified") at exceedingly low concentrations (as low as a weight fraction of 0.0002), inducing the mechanically distinct, tough i-PP β-polymorph, or promoting growth of hybrids of both crystallographic modifications with heretofore unknown combinations of the above desirable optical-mechanical properties. In addition, these trisamide-based compounds exhibit excellent thermal stability and do not feature absorption of visible light, adding to a most favorable set of characteristics that provides marked benefits over the presently employed nucleating/clarifying agents.

Effect of the Molecular Structure of the Polymer and Nucleation on the Optical Properties of Polypropylene Homo- and Copolymers

“…These latter additives dissolve in the polymer generating a microcrystalline structure and improve haze considerably [10][11] . In the last decade a relatively new family of nucleating agents based on trisamide derivatives appeared as the competitor of sorbitol clarifiers [12][13][14][15] . However, the efficiency of the clarifier depends very much also on the characteristics of the polymer used and on processing conditions, as mentioned above.…”

“…Two different soluble clarifiers were used for the modification of optical properties, a sorbitol type additive and the recently developed and marketed trisamide product of BASF 12 .…”

A New Class of Ultra‐Efficient Supramolecular Nucleating Agents for Isotactic Polypropylene

“…[ 11 , 12 ] In recent years, a new class of supramolecular nucleating agents based on 1,3,5-benzenetrisamides was developed that circumvents the above disadvantages. Many compounds of this family were found to raise the crystallization temperatures of i -PP and some of them promoted so-called clarifying, that is, drastic reduction of haze and increasing clarity, at concentrations as low as 0.02 wt%, [ 13 ] which is one order of magnitude lower than for rosin-type [ 14 ] and sorbitol clarifi ers. [ 15 ] In addition of being soluble in the polymer melt permitting ultra-fi ne dispersion, [ 15 ] 1,3,5-benzenetrisamides exhibit outstanding thermal stability.…”

“…From these X-ray data, k -values were calculated according to standard procedures given in the literature. [ 13 ] The k -value thus is proportional to the content of the β -crystal modifi cation in the sample.…”

“…The ability to promote nucleation of the α -phase of i -PP was determined and is expressed as the k -value, which is proportional to the content of the β -modifi cation in the sample. [ 13 ] All 2,4,6-trimethyl-1,3,5-benzenetrisamides/ i -PP compounds-with exception of derivative 1 (R: i -propyl, k = 0.31)-form predominantly the α modifi cation of i -PP This is indicated by the low k values between 0.10 and 0.17.…”