US 2020/0139427 Al  4  May 7, 2020  [0062]  It is mentioned in this context that the printing  temperature, i.e., the temperature of the printhead, is not  restricted to room temperature but can instead lie between  20°  C. to 80°  C., in particular 20 to 40°  C., and even higher  viscosity binders can thereby be easily printed.  [0061]  As a print medium, the resin component, as  described above, has a viscosity (Brookfield, 25°  C., spindle  21, DIN EN ISO 2555) of 2 mPas to 70 mPas, preferably 5  mPas to 60 mPas, and particularly preferably from 5 mPas  to 50 mPas at 25°  C. in each case. Also independent thereof,  the surface tension is from 10 mN/m to 70 mN/m, preferably  of 15 mN/m to 60 mN/m, particularly preferably from 15  mN/m to 55 mN/m and especially preferably from 20 mN/m  to 50 mN/m, determined using the Wilhelmy plate method  with a Kriiss Kl00 force tensiometer measured at 20°  C. To  lower the surface tension, the resin component can be  additionally modified with surface-active substances such as  cationic, anionic or non-ionic surfactants, such as with  carboxylates, sulfonates or sulfates like sodium-2-ethyl› hexyl sulfate as the anionic surfactant, quaternary ammo› nium compounds like esterquats as the cationic surfactants,  or alcohols, ethers or ethoxylates likepolyalkylene glycol  ether as the nonionic surfactants.  [0057]  To additionally dilute the above-described resin  component to a viscosity range needed for the printing  process of 2 mPas to 70 mPas, preferably from 5 mPas to 60  mPas and particularly preferably from 5 mPas to 50 mPas  (Brookfield, at 25°  C.), the resin component can contain  additional solvents such as water or organic solvents that are  not furfuryl alcohol comprising 1 to 25 carbon atoms such  as alcohols like ethanol, propanol, 5-hydroxy-1,3-dioxane,  4-hydroxymethyl-1,3-dioxolane or tetrahydrofurfuryl alco› hol, oxetanes such as trimethylolpropane oxetane, ketones  [0056]  The overall content of free phenol in the resin  component is preferably less than 1 % by weight ( determined  by gas chromatography).  [0055]  These phenols can be made to react directly with  the furfuryl alcohol and the aldehyde compound or with  their pre-condensate. Moreover, reaction products of phe› nols and formaldehyde in the form of resol resins that are  produced under alkaline conditions can be added to the resin  component.  [0060]  In addition to the components already mentioned,  the resin component can contain suitable additives such as  surface modifiers which include for example silanes (for  example according to EP 1137500 Bl). Suitable silanes are  for example amino silanes, epoxy silanes, mercapto silanes,  hydroxy silanes and ureido silanes such as gamma-hydroxy› propyl trimethoxysilane, gamma-aminopropyl trimethoxysi› lane, 3-ureidopropyl triethoxysilane, gamma-mercaptopro› pyl  trimethoxysilane,  gamma-glycidoxypropyl  trimethoxysilane,  beta-(3,4-epoxy-cyclohexyl)-trimethox› ysilane  and  N-beta-(aminoethyl)-gamma-aminopropyl  trimethoxysilane or other polysiloxanes. The added amounts  of silanes are in particular between 0% by weight to 5% by  weight, preferably between 0.01 % by weight to 2% by  weight, and particularly preferably between 0.05% by  weight to 1 % by weight, relative to the resin component in  each case.  [0054]  Suitable phenol compounds are characterized by  one or more aromatic rings and at least one hydroxy sub› stitution on these rings. In addition to phenol itself,  examples are substituted phenols such as cresols or nonyl› phenol, 1,2-dihydroxybenzene (catechol), 1,3-dihydroxy› benzene (resorcinol), cashew nut shell oil, i.e., a mixture  consisting of cardanol and cardol, or 1,4-dihydroxybenzene  (hydroquinone) or phenolic compounds such as bisphenol A  or mixtures thereof. Phenol as a phenolic component is  particularly preferable.  [0053]  The amount of nitrogen-containing compounds is  selected so that the overall nitrogen content (N) of the resin  component determined according to Kjeldahl (according to  DIN 16916-02-B2 orVDG memorandum P70), is less than  5% by weight, preferably less than 3.5% by weight and  particularly preferably less than 2% by weight so that  surface flaws in the cast part resulting from the presence of  nitrogen are reduced or avoided.  [0059]  Moreover, the resin component can contain addi› tional additives such as curing moderators or plastifiers. This  includes for example dials or polyols with 2 to 12 carbon  atoms, fatty acids, silicones or phthalates that are used in  amounts of 0% by weight to 25% by weight, preferably 0%  by weight to 20% by weight and particularly preferably in  amounts of 0.2 to 15% by weight relative to the resin  component. Glycols such as ethylene glycol as well as fatty  acids such as oleic acid are particularly preferable.  [0052]  These compounds containing nitrogen can be made  to react directly with the furfuryl alcohol or the furfuryl  alcohol derivative and the aldehyde compound or with their  pre-condensate, or in a preferred variation, added as an  independent pre-condensate, in particular in the form of urea  derivatives such as preferably urea itself, condensed with an  aldehyde, preferably formaldehyde, and optionally con› densed with preferably furfuryl alcohol or a furfuryl alcohol  derivative.  [0051]  Suitable compounds containing nitrogen are for  example urea derivatives such as urea itself, melamine or  ethylene urea, or amines such as ammonia and triethylam› ine, amino alcohols such as monoethanolamine or 2-amino- 2-methyl-1-propanol. Urea, triethyl amine or monoetha› nolamine, in particular urea, are used in a particularly  preferred embodiment.  [0058]  The amount of the solvent(s) added to the resin  component is chosen so that the overall water content of the  resin component (determined by Karl-Fischer titration  according to DIN 51777) is between 5% by weight and less  than 40% by weight, preferably 5% by weight and less than  35% by weight, and in particular 7% by weight and less than  30% by weight, and the amount of additional solvents that  are not furfuryl alcohol or water is between 0% by weight to  30% by weight, preferably 0.5% by weight to 25% by  weight, and in particular 1 % by weight to 20% by weight,  relative to the resin component in each case.  such as acetone or esters such as triacetine and propylene  carbonate. Water and ethanol as well as mixtures thereof are  particularly preferred.  [0050]  Examples are formaldehyde, for example in the  form of aqueous solutions, or polymers in the form of  trioxane or para-formaldehyde, acetaldehyde, propionalde› hyde, furfurylaldehyde (furfural), butyraldehyde, glyoxal  and mixtures thereof. Formaldehyde or mixtures containing  primarily formaldehyde (relative to the molar amount of the  aldehydes) are particularly preferable.  [0049]  Generally, aldehydes of formula R-CHO are used  as the aldehydes, wherein R is a hydrogen atom or a carbon  atom residue with preferably 1 to 8, particularly preferably  1 to 3 carbon atoms. 