Abstract: The invention relates to compositions for producing polymethacrylimide foams having reduced pore size. The inventive method allows production of a microporous foam with an especially homogeneous pore size distribution without having to use insoluble nucleation agents.

Abstract: The invention relates to compositions for producing polymethacrylimide foams having reduced pore size.

Abstract: The invention relates to an improved method for producing foamed material, especially poly(meth)acrylimide foams, which are foamed from polymer plates produced according to the casting method. The two-step method consists of a pre-heating step and at least one foaming step. The product obtained has a significantly smaller compressive strain, measured according to DIN 53425(ASMD 621), than prior art products.

Abstract: The invention relates to processes for preparing derivatized and partially derivatized polymethacrylimides. The properties of the material can be adjusted by appropriate selection of the derivatization, in terms of number and type.

Abstract: The invention relates to an improved method for producing foamed material, especially poly(meth)acrylimide foams, which are foamed from polymer plates produced according to the casting method. The two-step method consists of a pre-heating step and at least one foaming step. The product obtained has a significantly smaller compressive strain, measured according to DIN 53425(ASMD 621), than prior art products.

Abstract: A diaphragm for an electroacoustic transducer has a) a core layer containing poly(meth)acrylimide foam and b) at least one cover layer. The diaphragm is produced by laminating the cover layer with the core layer, using a pressure of 0.4 MPa and a temperature of 160° C., whereby at least the side of the core layer which comes into contact with the cover layer is compressed. The resultant composite is subsequently cooled to a temperature below 80° C., before the pressure is reduced to the ambient pressure. The process can be carried out as a single-step process. The diaphragms produced by this process demonstrate an excellent stability, whereby the cover layers in particular are highly resistant to separation.

Abstract: Polymethacrylimide foams are prepared by a method, comprising:preparing a mixture consisting of(a) a monomer mixture of 40-60 wt. % methacrylonitrile, 60-40 wt. % methacrylic acid, and, optionally, up to 20 wt. %, based on the sum of methacrylic acid and methacrylonitrile, of other monofunctional, vinyl-unsaturated monomers,(b) 0.5-8 wt. % of a propellant mixture of formamide or monomethyl formamide and a univalent C.sub.3-8 -aliphatic alcohol,(c) a cross-linking agent system, which consists of(c.1) 0.005-5 wt. % of a vinyl-unsaturated compound which can be radically polymerized, with at least two double bonds in the molecule, and(c.2) 1-5 wt. % magnesium oxide, dissolved in the monomer mixture, and at least one radical initiators and optionally at least one additive, shaped in the form of a sheet;polymerizing the monomers in the sheet;subsequently foaming the polymerizate sheet at temperatures from 200-260.degree. C.; and thenheat treating the sheet in two steps, at a first step of 2-6 hours at 100-130.

Abstract: The present invention relates to combined insulation layers (ISS), preferably for use in shipbuilding, encompassing (i) an outer layer (AS) consisting of sheet metal, combined with (ii) a melamine layer (MSS), (iii) a sheet aluminum layer, (iv) a core layer of a hard foam material (HSS), coated on both sides with a phenolic resin prepreg (PNP).