Production of moldings for foundry purposes

Abstract

A process for producing a mold includes introducing a composition including a particulate, refractory material and a binder into a hollow model having an interior cavity which determines contours of all surfaces of the mold or a mold part, wherein the model includes at least two separate parts to permit removal of the mold, and applying a second composition containing at least one organosilicon component and at least one solvent to at least one of the separable parts before use.

1 - 28 . (canceled) 
     
     
         29 . A process for producing a mold comprising:
 introducing a composition comprising a particulate, refractory material and a binder into a hollow model having an interior cavity which determines contours of all surfaces of the mold or a mold part, wherein the model comprises at least two separate parts to permit removal of the mold; and   applying a second composition containing at least one organosilicon component to at least one of the separable parts before use.   
     
     
         30 . The process as claimed in  claim 29 , further comprising:
 introducing a composition comprising the particulate, refractory material and the binder through at least one feed opening into the interior cavity;   curing the binder; and   removing the mold.   
     
     
         31 . The process as claimed in  claim 29 , wherein the composition comprising the organosilicon component is applied such that walls of the interior cavity are partly or completely covered with a layer of the composition. 
     
     
         32 . The process as claimed in  claim 29 , wherein the composition comprising the organosilicon component is cured after introduction into the interior cavity. 
     
     
         33 . The process as claimed in  claim 32 , wherein curing the composition is effected thermally. 
     
     
         34 . The process as claimed in  claim 29 , wherein the particulate, refractory material is sand. 
     
     
         35 . The process as claimed in  claim 29 , wherein the organosilicon component is at least one member selected from the group consisting of crosslinkable silanes, siloxanes and silicone compounds. 
     
     
         36 . The process as claimed in  claim 29 , wherein the composition containing the organosilicon component comprises at least one alkoxysilane. 
     
     
         37 . The process as claimed in  claim 36 , wherein the composition containing the organosilicon component comprises trimethylethoxysilane or trimethylmethoxysilane. 
     
     
         38 . The process as claimed in  claim 29 , wherein the organosilicon component comprises at least one silane having halogen-containing side chains. 
     
     
         39 . The process as claimed in  claim 38 , wherein the silane having halogen-containing side chains is at least one alkylalkoxysilane having fluorine-containing side chains. 
     
     
         40 . The process as claimed in  claim 39 , wherein the silane having halogen-containing side chains is tridecafluoro-1,1,2,2-tetrahydrooctyl-1-triethoxysilane. 
     
     
         41 . The process as claimed in  claim 29 , wherein the composition containing the organosilicon comprises at least one further crosslinkable organic component which is not an organosilicon. 
     
     
         42 . The process as claimed in  claim 41 , wherein the at least one further crosslinkable organic component is a polyester component. 
     
     
         43 . The process as claimed in  claim 41 , wherein the organosilicon component and the one further crosslinkable organic component are present as silicone polyester resin in the composition. 
     
     
         44 . The process as claimed in  claim 29 , wherein the composition containing the organosilicon component has at least one mold release agent. 
     
     
         45 . The process as claimed in  claim 43 , wherein the mold release agent is a polysiloxane of the formula RO—[R′ 2 Si—O] n —R, where R and R′ are each, independently of one another, an alkyl radical having from 1 to 8 carbon atoms or an aromatic radical having from 6 to 20 carbon atoms. 
     
     
         46 . The process as claimed in  claim 29 , wherein the composition containing the organosilicon component has inorganic particles. 
     
     
         47 . The process as claimed in  claim 29 , wherein the inorganic particles have particle sizes in the nanosize range. 
     
     
         48 . The process as claimed in  claim 46 , wherein the particles are silicate particles. 
     
     
         49 . The process as claimed in  claim 29 , wherein the composition containing the organosilicon component has at least one component suitable as a crosslinker. 
     
     
         50 . The process as claimed in  claim 49 , wherein the crosslinker is triethoxysilane (TEOS). 
     
     
         51 . The process as claimed in  claim 29 , wherein the composition containing the organosilicon component has at least one catalyst. 
     
     
         52 . The process as claimed in  claim 51 , wherein the catalyst is an acid. 
     
     
         53 . The process as claimed in  claim 29 , wherein the composition containing the organosilicon component has at least one organic solvent. 
     
     
         54 . An apparatus for producing molds for foundry purposes, in particular mask molds or sand cores, comprising at least one part which is provided with an organosilicon layer or coating. 
     
     
         55 . The apparatus as claimed in  claim 54 , wherein the layer or coating has a thickness in the range from 1 μm to 100 μm. 
     
     
         56 . The apparatus as claimed in  claim 54 , wherein the layer or coating has an organosilicon matrix in which inorganic particles are embedded.