A method for producing a feeder element is described. The method includes (a) producing composite particles having a particle size of less than 2 mm in a matrix encapsulation method with the following steps: (a1) producing droplets of a suspension from at least (i) one or more refractory substances, (ii) one or more of fillers having a bulk density in the range from 10 to 350 g/L, expandants, and pyrolysable fillers, (iii) as continuous phase, a solidifiable liquid, (a2) solidifying the droplets with the refractory substance(s) and density-reducing substance(s) are encapsulated therein, (a3) treating the hardened droplets to form composite particles, (b) mixing the composite particles with a binder and, optionally, further constituents to give a feeder composition, (c) shaping and curing the feeder composition to give a feeder element. Also described are a method for producing refractory composite particles and the use of the composite particles.

What is described are isocyanate compositions comprising ?-dicarbonyl compounds and a binder system, especially for use in a process from the group consisting of polyurethane cold-box process and polyurethane no-bake process, with this isocyanate composition as polyisocyanate component.

An amount of a halloysite clay, used as an additive in a foundry mix composition having a polyurethane-based binder system, reduces the amount of smoke emitted when molds and cores formed from the composition are exposed to molten metal, as compared to when the halloysite clay is not used.

Described is a phenolic resin composition for use in the polyurethane cold-box and/or no-bake process. The phenolic resin composition comprises an ortho-condensed phenolic resol having etherified and/or free methylol groups in a total amount of 40 to 60% by weight based on the total mass of the phenolic resin composition, free formaldehyde in an amount of less than 0.1% by weight based on the total weight of the phenolic resin composition, one or more reaction products of formaldehyde with one or more CH-acidic reactant compounds, other constituents in a total amount of at least 38% by weight, wherein the amount of water in the phenolic resin composition is not more than 1.0% by weight in each case based on the total mass of the phenolic resin composition. Also described is a two-component binder system for use in the polyurethane cold-box and/or no-bake process, a use of a CH-acidic compound as a formaldehyde scavenger for producing a phenolic resin composition for use in the polyurethane cold-box and/or no-bake process, a process for producing a phenolic resin composition, a process for producing a two-component binder system and a process for producing a feeder, a foundry mold or a foundry core from a molding material mixture and finally corresponding feeders, foundry molds and foundry cores.

A binder system for refractory materials used in sand casting processes, especially two-part polyurethane-based binder systems used in the cold box or no bake process, has less metal-mold reaction when a separate third part is used. The third part is an alkyl silicate, such as tetraethyl orthosilicate (TEOS), an alkyl orthoformate, such as trimethyl orthoformate (TMOF) or triethyl orthoformate (TEOF), or combinations thereof.

An organic binder system is mixed with molding material for sand casting in the metals industry. The organic binder system has three parts, the first two of which are conventional and are used in the cold box or no bake process. The third part, which is combined with the first two parts at the time of use, contains at least an alkyl silicate and, optionally, a bipodal aminosilane. In some embodiments, an amount of hydrofluoric acid is included in one or both of the first two parts. Use of the organic binder system provides improved tensile strength in the mold, especially in high relative humidity.

This invention relates generally to a composition for silica sand cores and molds suitable for in the casting of metals. The sand core composition contains a hinder and a uniformly dispersed anti-veining additive. The mixed metal oxides collapse into a visco-plastic state when the foundry mold/core is heated by the molten metal during casting. A change in state of the MMOx from solid to a visco-plastic at the casting high temperatures provides space and lubricity within the foundry shape sufficient to compensate for the thermally-induced physical expansion of the silica grains. Thereby avoiding the mechanical forces which cause cracks and fissures in the mold or core that produce veins and other surface imperfections associated with the high coefficient of thermal expansion of silica sand.

What is described are isocyanate compositions comprising -dicarbonyl compounds and a binder system, especially for use in a process from the group consisting of polyurethane cold-box process and polyurethane no-bake process, with this isocyanate composition as polyisocyanate component.

The present invention relates to the use of closed-pore microspheres of expanded perlite as a filler for producing moldings for the foundry industry, to a composition for producing moldings for the foundry industry, comprising closed-pore microspheres of expanded perlite as a filler, and a binder, the binder being selected from the group consisting of water glass, phenol-formaldehyde resins, two-component systems comprising as reactants a polyisocyanate and a polyol component containing free hydroxyl groups (OH groups), and starch, and also to moldings for the foundry industry and to a process for producing a molding for the foundry industry.

The subject matter of the present invention is a binder system containing blocked tertiary amines or amidines as co-catalysts for a polyurethane cold-box application. It also relates to the molding material mixtures produced using such a binder system further comprising volatile tertiary amines, a method for producing the molding material mixtures, and the cores and molds made from the molding material mixtures according to the cold-box process.