The present invention provides fire-retarded rigid polyurethane foam comprising the reaction product of polyol and isocyanate foam forming components and a dialkyl phosphorus-containing compound, namely a reactive mono-hydroxyl-functional dialkyl phosphinates, as flame retardant, serving as highly efficient reactive flame retardant in said rigid polyurethane foam.

Provided is a foam sheet showing little change in dielectric constant even when exposed under a high-humidity condition. The foam sheet of the present invention includes: a foam layer; and a pressure-sensitive adhesive layer arranged on at least one side of the foam layer, wherein the foam sheet has an impact absorbability change amount [(QP)100]/P of 10 (%) or less, where P (N) represents impact absorbability of the foam layer immediately after the foam sheet has been left at rest under conditions of a temperature of 23 C. and a humidity of 50% for 2 hours, and Q (N) represents impact absorbability of the foam layer immediately after the foam sheet has been left at rest under conditions of a temperature of 60 C. and a humidity of 95% for 24 hours.

A method for producing a polyurethane foam. The method comprises a step of spraying a polyurethane foam stock solution comprising a polyisocyanate component and a polyol component in a mist form by using compressed gas. The compressed gas is heated and kept at a temperature of not less than 40 C.

A method for producing a polyurethane foam. The method comprises a step of spraying a polyurethane foam stock solution comprising a polyisocyanate component and a polyol component in a mist form by using compressed gas. The compressed gas is heated and kept at a temperature of not less than 40 C.

Provided is a foam sheet that can raise an electrostatic capacitance at the time of compression, and hence can improve sensitivity when used for an electrostatic capacitance sensor. The foam sheet includes: a foam layer; and a pressure-sensitive adhesive layer arranged on at least one side of the foam layer, wherein the foam sheet has a dielectric constant increase amount Q-P at 10% compression of 0.2 (F/m) or more, where P (F/m) represents a dielectric constant of the foam sheet immediately after the foam sheet has been left at rest under conditions of a temperature of 23 C. and a humidity of 50% for 2 hours, and Q (F/m) represents a dielectric constant of the foam sheet at a time when the foam sheet is compressed by 10% immediately after being left at rest under the conditions of a temperature of 23 C. and a humidity of 50% for 2 hours.

A foamed, opacifying element is prepared to have a light-blocking value (LBV) of at least 4. A method is carried out in a specific order with a unique series of steps including: providing a unique foamable aqueous composition; aerating that foamable aqueous composition to a foam density of at least 0.1-0.5 g/cm.sup.3; disposing the foamed aqueous composition onto a surface of a porous substrate; drying the foamed aqueous composition without substantial curing of the binder material therein, to provide a dry foamed composition on the surface, without substantial curing; densifying the dry foamed composition to provide a dry opacifying layer in a foamed, opacifying element; and curing the dry opacifying layer in the foamed, opacifying element.

A foamed, opacifying element is prepared to have a light-blocking value (LBV) of at least 4. A method is carried out in a specific order with a unique series of steps including: providing a unique foamable aqueous composition; aerating that foamable aqueous composition to a foam density of at least 0.1-0.5 g/cm.sup.3; disposing the foamed aqueous composition onto a surface of a porous substrate; drying the foamed aqueous composition without substantial curing of the binder material therein, to provide a dry foamed composition on the surface, without substantial curing; densifying the dry foamed composition to provide a dry opacifying layer in a foamed, opacifying element; and curing the dry opacifying layer in the foamed, opacifying element.

A foamed, opacifying element useful as a light-blocking article has a substrate; an opacifying layer disposed on the substrate, and a functional composition disposed over the opacifying layer. The functional composition comprises: (i) glass particles such as hollow glass particles. The presence of the glass particles provides additional heat absorption for the foamed, opacifying elements that can be formed into light-blocking materials.

A foamed, opacifying element has a substrate with opposing planar surfaces and a foamed opacifying layer disposed on one opposing surface. The foamed opacifying layer contains (a) 0.1-80 weight % of nonporous polymeric particles; (b) 10-80 weight % of a matrix material derived from a (b) binder material having a glass transition temperature of less than 40 C.; (c) 0.0001-50 weight % of certain additives; (d) less than 5 weight % of water; and (e) at least 0.002 weight % of an opacifying colorant different from all of the (c) additives. Foamable and foamed aqueous compositions can be used to provide these foamed, opacifying elements for use as light-blocking window shades, curtains, or other materials. These light-blocking articles can also have a printable outer surface that accepts ink for making printed images that are not observable from the opposite surface.

A process for manufacturing a rigid foam product includes processing a forest residue to obtain fibers having a mesh size of at most 5 mm mesh and an aspect ratio of between 0.5:1 and 20:1; preparing a slurry comprising the fibers, water, a foaming agent, and a polymer additive; foaming the slurry to yield a wet foam; and drying the wet foam to yield a rigid foam product.