US 2020/0139427 Al  1  May 7, 2020  METHOD FOR PRODUCING  THREE-DIMENSIONALLY LAYERED  SHAPED BODIES  Object of the Invention  SUMMARY OF THE INVENTION  [0016]  The furane resin is characterized in that it is  constructed from aldehyde compound(s ), in particular form› aldehyde, with furfuryl alcohol and possibly with additional  monomers such as in particular urea, furfuryl alcohol deriva› tives (by definition, the furfuryl alcohol derivatives therefore  do not comprise furfuryl alcohol itself) and/or phenol  derivatives. In this case, the furane resin is constructed in  particular of furfuryl alcohol and formaldehyde as mono› mers by more than 60% by weight, preferably more than  70% by weight, and particularly preferably more than 80%  by weight overall relative to all of the monomers used. With  this binder, the so-called job box of the 3-D printer can be  used spatially with greater efficiency, i.e., shaped bodies can  be produced closer to each other in space since a "fusion" of  the shaped bodies is prevented given the reduced tendency  [0009]  In particular, the acid/furane resin system has the  disadvantage that shaped bodies produced according to this  [0008]  In particular, the system of acid/furane resin cor› responding to EP 1638758 Bl and the system of ester/  alkaline phenol resin corresponding to DE 102014106178  Al have been accepted somewhat in practice in the layer› by-layer construction of molded bodies and are used in the  development of new cast parts and in the production of  individual parts or small series when conventional produc› tion with molding tools would be too complicated and  expensive, or respectively only describable with a compli› cated core package.  [0007]  A method is described in DE 102014106178 Al in  which a basic mold material is hardened in layers by means  of an alkaline phenol resin, an ester, and optionally an  inorganic additive.  [0006]  In EP 1638758 Bl, the sequence of addition is  reversed. First, the basic mold material is premixed with a  hardener, and then the resin component is selectively applied  layer-by-layer. Inter alia, acids such as aqueous para-tolu› enesulfonic acid are described as the hardener and once  more inter alia furane resins are described as the resin  component, although again, if further specified, using a  furane resin with at least 50% furfuryl alcohol.  [0005]  According to EP 1509382 Bl, the resin component  of the binder is not applied layer-by-layer by means of a  printhead, but rather is mixed directly with the basic mold  material and applied layer-by-layer together with the basic  mold material. This mixture consisting of the resin compo› nent and basic mold material is then cured by the selective  application of the hardener.  [0015]  The present invention therefore comprises a binder  comprising an acid and a resin component comprising at  least one furane resin, and containing monomer furfuryl  alcohol of, on the one hand, more than 5% by weight,  preferably more than 10% by weight, and particularly pref› erably more than 15% by weight furfuryl alcohol, and on the  other hand less than 50% by weight, preferably less than  45% by weight, and particularly preferably less than 40% by  weight monomer furfuryl alcohol relative in each case to the  resin component.  [0014]  These and other objects are achieved by the subject  of the independent claims; advantageous developments are  the subject of the dependent claims or are described below.  significantly reduces the problem of adhesions by a non› printed mixture consisting of acid and the basic mold  material, or the resin component and basic mold material, to  the shaped bodies produced in this manner.  [0011]  It was surprisingly found that a binder comprising  at least:  [0013]  (b) an acid  [0012]  (a) a resin component containing at least one  furane resin obtainable by reacting at least one alde› hyde compound, in particular formaldehyde, with fur› furyl alcohol, and possibly with additional monomers,  as well as more than 5% by weight, preferably more  than 10% by weight, and particularly preferably more  than 15% by weight, as well as less than 50% by  weight, preferably less than 45% by weight and par› ticularly preferably less than 40% by weight monomer  furfuryl alcohol relative to the resin component, and  [0010]  The object of the present invention is to provide a  binder for the layer-by-layer construction of three-dimen› sional shaped bodies that permits the layer-by-layer produc› tion of three-dimensional shaped bodies that can be freed  easily and with a sharp contour from a non-printed, adhering  mixture consisting of the basic mold material and the acid or  resin component. Beyond the significant time savings, the  reduced exposure to solvent and binder vapors is an addi› tional advantage in this case.  [0004]  EP 1268165 Bl varies this method in that both the  liquid binder, inter alia also a furane resin that is not  described further as well as a liquid hardener are applied  selectively and layer-by-layer sequentially in the sequence  of resin component and then hardener to the sections to be  cured.  [0003]  WO 2001/068336 A2 discloses various binders for  layer-by-layer construction. Inter alia, the use of a furane  resin (not described further) with at least 50% furfuryl  alcohol and at most 4% ethylene glycol is also cited as  binder components. The resin component of the binder is  sprayed layer-by-layer over the entire working surface of the  loose basic mold material and then is also cured layer-by› layer, but with the selective application of a hardener such  as an organic acid.  [0002]  Various methods are known for the layer-by-layer  construction of three-dimensionally shaped bodies. With the  assistance of these methods, bodies with even the most  complicated geometries can be produced directly layer-by› layer by 3D printing from the CAD data without molding  tools. This is not possible with conventional methods requir› ing molds.  [0001]  The invention relates to a method for producing  three-dimensionally layered shaped bodies by means of  layer-by-layer construction using a resin component which  contains at least one furane resin, and more than 5% by  weight and less than 50% by weight monomer furfuryl  alcohol, and an acid. The shaped bodies produced in this  manner are suitable inter alia as casting molds and casting  cores for metal casting.  method must first be freed in an involved manner from an  adhering and non-printed mixture consisting of the basic  mold material and acid or resin component. Individuals who  perform this task are exposed to dusts and solvent and binder  vapors. 