Interlayer film for laminated glass, and laminated glass

An interlayer film for laminated glass comprising:

• a first layer containing a polyvinyl acetal resin and a plasticizer;
• a second layer containing a polyvinyl acetal resin and a plasticizer;
• and
• a third layer containing a polyvinyl acetal resin and a plasticizer,
• wherein the first layer is arranged on a first surface side of the second layer, and the third layer is arranged on a second surface side opposite to the first surface side of the second layer,
• each of the glass transition temperatures of the first layer and third, layer is higher than or equal to 31° C.,
• the content of the plasticizer contained in the second layer relative to 100 parts by weight of the polyvinyl acetal resin contained in the second layer is larger than the content of the plasticizer contained in the first layer relative to 100 parts by weight of the polyvinyl acetal resin contained in the first layer, and
• the content of the plasticizer contained in the second layer relative to 100 parts by weight of the polyvinyl acetal resin contained in the second layer is larger than the content of the plasticizer contained in the third layer relative to 100 parts by weight of the polyvinyl acetal resin contained in the third layer, and
• wherein the interlayer film for laminated glass satisfies at least one of (b1) and (b2):
• (b1) an acetalization degree of the polyvinyl acetal resin contained in the first layer is greater than or equal to 55% by mole and less than or equal to 71% by mole and the half-value width of the hydroxyl group of the polyvinyl acetal resin contained in the first layer is greater than or equal to 257.3 cm−1 and less than or equal to 267.0 cm−1, and an acetalization degree of the polyvinyl acetal resin contained in the third layer is greater than or equal to 55% by mole and less than or equal to 71% by mole and the half-value width of the hydroxyl group of the polyvinyl acetal resin contained in the third layer is greater than or equal to 257.3 cm−1 and less than or equal to 267.0 cm−1;
• (b2) an acetalization degree of the polyvinyl acetal resin contained in the first layer is greater than or equal to 55% by mole and less than or equal to 66% by mole and the half-value width of the hydroxyl group of the polyvinyl acetal resin contained in the first layer is greater than or equal to 257.3 cm−1 and less than or equal to 274.8 cm−1, and an acetalization degree of the polyvinyl acetal resin contained in the third layer is greater than or equal to 55% by mole and less than or equal to 66% by mole and the half-value width of the hydroxyl group of the polyvinyl acetal resin contained in the third layer is greater than or equal to 257.3 cm−1 and less than or equal to 274.8 cm−1.