Process for tire manufacture with on-line determining of carbon black concentration and distribution in rubber compounds and other carbon black containing materials

Process for manufacturing pneumatic tire for vehicle wheels, comprising the steps of:

• preparing at least one rubber compound by mixing together at least one polymeric material with other ingredients, including carbon black, according to prefixed quantitative ratios between said ingredients established in a given recipe;
• forming from said rubber compound at least one semi-finished component for said tire;
• assembling together a plurality of said semi-finished components to build up a raw carcass to be molded and vulcanized in a curing mold, wherein this process further comprises the steps of:
• quantitatively detecting, on-line, the quantity of carbon black contained in said at least one rubber compound to thereby monitor in real time a dispersion degree and a homogeneity of the carbon black in said rubber compound, by taking respective first and second measurements:
• wherein each of the first and second measurements is made by directing a laser of a laser apparatus at the rubber compound to thereby produce a plasma, detecting radiation from the plasma, producing a spectrum from the radiation, measuring intensities of spectral lines of the spectrum;
• and wherein, in said first measurement, said measuring of said intensities of said spectral lines is carried out at a first time delay from actuation of the laser apparatus for causing the plasma whose radiation is measured in the first measurement, and in said first measurement, the intensities of spectral lines of carbon and at least approximately all other analysis constituents of the rubber compound forming the spectrum are measured;
• and in said second measurement, the measuring of said intensities of said spectral lines is carried out at a second time delay from actuation of the laser apparatus for causing the plasma whose radiation is being measured in the second measurement, with the first and second time delays for the first and second measurements being substantially different from one another and, in the second measurement, the spectral lines of carbon and at least one of the other analysis constituents is measured;
• determining the quantity of carbon black in said at least one rubber compound using the intensities measured in the first and second measurements, in conjunction with stored values of intensities of known rubber compound samples;
• controlling the quantity of carbon black which is being mixed into said polymeric material during said mixing step, by using said on-line detection of carbon black to achieve the prefixed quantitative ratios of ingredients.