Storage-stable polyisocyanate composition and preparation method therefor

A method for preparing a storage-stable polyisocyanate composition, comprising:

• carrying out a polymerization reaction on an isocyanate monomer in the presence of a catalyst system;
• after an appropriate conversion rate is reached, terminating the reaction to obtain a polyisocyanate reaction solution;
• carrying out heat treatment on the obtained polyisocyanate reaction solution to obtain a heat-treated polyisocyanate mixture, and a time of the heat treatment is 5-30 min;
• and then carrying out separation treatment on the heat-treated polyisocyanate mixture to remove unreacted isocyanate monomers in the system to prepare the polyisocyanate composition;
• wherein a temperature of the heat treatment is 10-30° C. higher than a heat-sensitive temperature of the obtained polyisocyanate composition;
• wherein the appropriate conversion rate is defined as:
• a preset conversion rate for the polyisocyanate composition to be prepared, which is calculated and reflected by controlling NCO % value of the system;
• wherein the heat-sensitive temperature is defined as:
• the polyisocyanate composition is heated within a temperature range of 100-200° C., the temperature range of 100-200° C. is evenly divided into multiple temperature intervals, a viscosity of the heated polyisocyanate composition is measured within these temperature intervals, the measured viscosities and their corresponding temperatures are drawn as a viscosity-temperature curve, and in the drawn curve, a temperature at which a viscosity of the polyisocyanate composition doubles is defined as the heat-sensitive temperature;
• wherein the obtained polyisocyanate composition satisfies the following conditions (1) and (2) after being stored at 50° C. for 30 days:
• (1) in the stored polyisocyanate composition, the increase of a content of an isocyanate monomer is less than or equal to 0.1 wt %;
• and
• (2) in the stored polyisocyanate composition, the increase of a viscosity of the polyisocyanate composition is less than or equal to 15% of an initial viscosity of the polyisocyanate composition.