Curable composition

A polyurethane foam produced from a curable composition comprising:

• an isocyanate group-containing urethane pre-polymer (I) that has an oxyalkylene ether skeleton and no siloxane skeleton;
• and
• an isocyanate group-containing urethane pre-polymer (II) that has a siloxane skeleton and an oxyalkylene ether skeleton, represented by the following formula (2),
• wherein each R1 is independently a monovalent hydrocarbon group, each R2 is independently a straight-chain or a branched-chain alkylene group having 1 to 6 carbon atoms, each R3 is independently an oxyalkylene group represented by a formula —[R6—O]m—, wherein R6 represents a straight-chain or a branched-chain alkylene group having 1 to 6 carbon atoms and m represents an integer of 1 to 55, R4 represents —O— or —NH—, R5 represents a divalent aliphatic hydrocarbon group, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, and n represents an integer of 1 to 100,
• wherein the urethane pre-polymer (I) has 0.5 to 10% by mass of the NCO content measured according to JISK0113 using a potentiometric titration method, and the urethane pre-polymer (II) has 0.5 to 10% by mass of the NCO content measured according to JISK0113 using a potentiometric titration method, and
• wherein the content of the siloxane skeleton in the urethane pre-polymer (II) is 0.001 to 0.5% by mass relative to 100% by mass of the total amount of an overall NCO group-containing compound contained in the curable composition,
• wherein the foam is a closed cell foam, and
• wherein
• the cells have a mode average diameter <150 μm, or
• five or fewer cells per 4 mm2 have a cell diameter ≥250 μm.

A polyurethane foam produced from a curable composition comprising:

• an isocyanate group-containing urethane pre-polymer (I) that has an oxyalkylene ether skeleton and no siloxane skeleton;
• and
• an isocyanate group-containing urethane pre-polymer (II) that has a siloxane skeleton and an oxyalkylene ether skeleton, represented by the following formula (2),
• wherein each R1 is independently a monovalent hydrocarbon group, each R2 is independently a straight-chain or a branched-chain alkylene group having 1 to 6 carbon atoms, each R3 is independently an oxyalkylene group represented by a formula —[R6—O]m—, wherein R6 represents a straight-chain or a branched-chain alkylene group having 1 to 6 carbon atoms and m represents an integer of 1 to 55, R4 represents —O— or —NH—, R5 represents a divalent aliphatic hydrocarbon group, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, and n represents an integer of 1 to 100,
• wherein the urethane pre-polymer (I) has 0.5 to 10% by mass of the NCO content measured according to JISK0113 using a potentiometric titration method, and the urethane pre-polymer (II) has 0.5 to 10% by mass of the NCO content measured according to JISK0113 using a potentiometric titration method, and
• wherein the content of the siloxane skeleton in the urethane pre-polymer (II) is 0.001 to 0.5% by mass relative to 100% by mass of the total amount of an overall NCO group-containing compound contained in the curable composition,
• wherein
• the foam is flexible, or
• the curable composition has a volume and the polyurethane foam has a volume, expansion ratio of the polyurethane foam volume to curable composition volume ranges from 3:1 to 4:1.

A closed-cell polyurethane foam produced from mixing components consisting of:

• a gas selected from the group consisting of air, carbon dioxide, nitrogen, oxygen, argon, and krypton,
• a filler,
• a curing agent,
• a plasticizer, and
• a curable composition comprising:
• an isocyanate group-containing urethane pre-polymer (I) that has an oxyalkylene ether skeleton and no siloxane skeleton;
• and
• an isocyanate group-containing urethane pre-polymer (II) that has a siloxane skeleton and an oxyalkylene ether skeleton, represented by the following formula (2),
• wherein each R1 is a methyl group, each R2 is independently a propylene group, each R3 is independently an oxyalkylene group represented by a formula —[R6—O]m—, wherein R6 represents an ethylene group or a propylene group and m represents an integer of 1 to 55, R4 represents —O— or —NH—, R5 represents a divalent aliphatic hydrocarbon group, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, and n represents an integer of 1 to 100;
• wherein the closed cell foam cells have a mode average diameter of <150 μm;
• wherein five or fewer cells per 4 mm2 have a cell size ≥250 μm;
• wherein the foam is free of hydrofluorocarbons (HFCs) and/or chlorofluorocarbons (CFCs);
• and
• wherein the foam has water sealing properties.