The present invention provides a composition which is capable of forming a polyurethane foam having a high hardness and excellent sound absorption properties. [Solution] The present invention relates to a composition for forming polyurethane foam characterized in that the composition for forming polyurethane foam comprises a polyol, a polyisocyanate, and a catalyst, in which the polyol comprises a polyol (A) having a number average molecular weight of 1500 to 8000 g/mol, the catalyst comprises a trimerization catalyst, in which the polyurethane foam has an air permeability of not less than 0.1 L/sec.

A flexible gastight material for a landfill site includes a component A and a component B, the component A including: at least one of polypropylene glycol with a molecular weight of 600-4000, polytetrahydrofuran diol with a molecular weight of 1000-3000, polycaprolactone diol with a molecular weight of 1000-3000, and polycarbonate diol with a molecular weight of 1000-3000; and at least one of 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The flexible gastight material for the landfill site provided in the present application has a micro-closed-cell foam structure. The closed-cell elastic structure of the flexible gastight material may block the volatilization of toxic and harmful odors, and may cut off the diffusion path of the odors by combining with gas treatment systems at the landfill site. The flexible gastight material has excellent water blocking and gas sealing performance.

The invention relates to a method in which a polyester melt containing one or more polyesters is produced, the polyester melt being foamed by a blowing agent and a foamed granulate is produced from the foamed polyester melt. The intrinsic viscosity (IV) of the polyester melt is reduced by the blowing agent about at least 0.05 dl/g, measured according to ASTM D4603, and the IV of the foamed granulate is then increased by means of a solid phase polycondensation (SSP).

Expandable chlorinated vinyl chloride-based resin particles from which a chlorinated vinyl chloride-based resin foamed molded product achieving both high expansion ratio and excellent surface appearance are provided. The expandable chlorinated vinyl chloride-based resin particles have a porosity of not more than 5.5 (ml/100 g).

A polyurethane foam article comprises the reaction product of an isocyanate component and isocyanate-reactive composition in the presence of a blowing agent. The isocyanate component includes an isocyanate prepolymer comprising the reaction product of a first polyether polyol and a methylene diphenyl diisocyanate. The isocyanate-reactive composition comprises a second polyether polyol having secondary terminal hydroxyl groups and an amine-initiated catalytic polyether polyol having primary hydroxyl groups. A method of making the polyurethane foam article comprises the steps of reacting the first polyether polyol and methylene diphenyl diisocyanate to form the isocyanate prepolymer and reacting the isocyanate prepolymer with the isocyanate-reactive composition in the presence of the blowing agent to form the polyurethane foam article.

The invention relates to a process for producing polyurethanes using a component A comprising a polyhydrazide, a polysemicarbazide, a polysulfonyl hydrazide and/or carbodihydrazide, in particular a polyhydrazide, wherein the component A is employed in the form of a mixture C which further comprises a component B comprising a dispersion medium.

Rigid polyurethane or polyisocyanurate foams, polyester polyols used to produce them, and methods for formulating the foams are disclosed. The foams comprise a reaction product of a polyisocyanate, a polyester polyol, water, a surfactant, a catalyst and optional ingredients. The polyester polyols comprise a phthalimide-containing polyacid, a phthalimide-containing polyol, or a combination thereof. Rigid foams produced from the polyester polyols exhibit higher thermal stability and/or greater intumescence when compared with foams made from other polyester polyols. The phthalimide-containing polyester polyols should allow formulators to improve the flammability performance of rigid foams with reduced levels of flame retardants and/or lower index and should facilitate the production of thinner insulation panels.

A foam-forming composition for producing a rigid polyurethane foam including: (a) at least one isocyanate component; and (b) at least one isocyanate-reactive composition including: (bi) a rigid polyol compound; and (bii) a flexible polyol compound; (c) a catalyst package including at least one latent gelling catalyst; and (d) at least one blowing agent.

Foam wall structures and methods for making them are described. The wall structures include a frame, a foam panel overlying a front surface of the frame, and a polyurethane foam layer disposed in a cavity of the wall structure. The polyurethane foam layer has a density, as determined by ASTM D1622-14, of at least 44 kg/m.sup.3 and exhibits ASTM E84-16 Class A flame spread and smoke development characteristics. The polyurethane foam layer is the cured reaction product of a polyurethane foam-forming composition that includes a polyisocyanate, an aromatic polyester polyol having a functionality of greater than 2.5 and an OH number of at least 300 mg KOH/g, which is present in an amount of at least 50% by weight, based on the total weight of the polyurethane foam-forming composition less the weight of the polyisocyanate, a catalyst, and a blowing agent composition. The blowing agent composition includes water and a hydrofluoroolefin.

The present invention relates to a method for producing foam and foam produced thereby. The method for producing foam includes a step for producing foam by kneading and injection molding a first extrusion product and a second extrusion product, wherein the first extrusion product is obtained by extruding a first composition including an aromatic vinyl-based resin, and the second extrusion product is obtained by extruding a second composition including a polyamide resin and a foaming agent.