NOVELTY - Manufacture of sealing material sheet involves molding sealing material composition comprising heat-resistant composition material containing polyethylene-type resin having density of 0.88-0.94 g/cm3, adhesive composition material, and compatibility composition material, obtaining unbridged sealing material sheet, crosslinking unbridged sealing material sheet by irradiation of ionizing radiation, and obtaining bridged sealing material sheet. The melt flow rate of compatibility composition material is higher than the melt flow rate of heat-resistant composition material.    USE - Manufacture of sealing material sheet used for back surface protection sheet of solar cell module.    ADVANTAGE - The method enables manufacture of sealing material sheet with excellent durability, adhesiveness, film-forming property, and heat resistance.    DETAILED DESCRIPTION - Manufacture of sealing material sheet involves molding sealing material composition comprising heat-resistant composition material containing polyethylene-type resin having density of 0.88-0.94 g/cm3 at 190 degrees C measured based on JIS K7210 and melt flow rate of 2-4 g/10 minutes measured using a load of 2.16 kg, adhesive composition material containing polyethylene-type resin having density of 0.87-0.91 g/cm3 and melt flow rate of 11-25 g/10 minutes, and compatibility composition material containing polyethylene-type resin having different melt flow rate and density of 0.87-0.94 g/cm3 by melting, obtaining unbridged sealing material sheet, crosslinking the unbridged sealing material sheet by irradiation of an ionizing radiation, and obtaining bridged sealing material sheet. The melt flow rate of compatibility composition material having lower melt flow rate among the compatibility composition materials is 3 times or less, which is higher than the melt flow rate of heat-resistant composition material. The melt flow rate of adhesive composition material is 3 times or less, which is higher than the melt flow rate of compatibility composition material having high melt flow rate among the compatibility composition materials.    DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional view of the laminated constitution of solar cell module.    Solar cell module (1)    Clear glass substrate (2)    Front sealing material layer (3)    Solar cell element (4)    Back surface sealing material layer (5)