Crystalline form of tetrakis-(2,4-di-t-butylphenyl)-4,4'-biphenylene

#The present invention relates to a new crystalline form of tetrakis-(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite.

#More specifically, the present invention relates to a new crystalline form of tetrakis-(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite and its use as a stabilizer in organic polymers.

#A further object of the present invention relates to polymeric compositions stabilized with the above diphosphonite.

#FIG. 1 shows the spectrum relating to the X-ray diffractometric analysis of powders in Example 1.

#FIG. 2 shows the spectrum relating to the X-ray diffractometric analysis of powders in Example 2.

#FIG. 3 shows the gas-chromatographic analytic dosagin of 2,4-di-t-butylphenol released during the oven treatment in Example 3.

#The present invention therefore relates to a tetrakis-(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite having the formula: ##STR3## in crystalline form, with a melting point of 185.degree. C.-186.degree. C.

#The above tetrakis-(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite was characterized by spectrometry (.sup.31 P-NMR and .sup.1 H-NMR), DSC ("Differential Scanning Calorimetry") and X-ray diffractometry carried out with a Philips goniometer for powders using CuK.alpha. radiation and nickel filter (XRD).

#The results of the spectrometric analyses (.sup.31 P-NMR and .sup.1 H-NMR) and DSC are shown in the examples, the results of the diffractometric analyses (XRD) are shown in Table 1 and FIG. 1.