U.S. Pat. No. 2,343,972 describes resins that are obtained  by reaction of furfuryl alcohol and formaldehyde with  heating in the presence of an acid such as lactic acid, formic  acid or chloroacetic acid. Concrete information on the  properties that are important for binders in the no-bake 5  process is not given in U.S. Pat. No. 2,343,972.  U.S. Pat. No. 5,741,914 (and correspondingly U.S. Pat.  No. 5,849,858) describes resins as binders for producing  composites, which are obtained by reacting furfuryl alcohol  with an excess of formaldehyde in the presence of an acid  with a pKa value above about 4, wherein the molar ratio of  furfuryl alcohol to formaldehyde is at least 1:2. Similar  resins are disclosed in U.S. Pat. No. 5,486,557.  DE 21 26 800 (and correspondingly CA 1 200 336)  describes a method for producing a composite object and  suitable binders therefore, wherein the binders are high› viscosity resin-like condensation products based on furan› formaldehyde, which are diluted with water.  U.S. Pat. No. 3,816,375 (and correspondingly DE 23 02  629) describes partially prepolymerised furfuryl alcohol› aldehyde binders, wherein the aldehyde is formaldehyde  and/or furfural, which are used there for forming composite  materials. When the material selected for the composite  material is glass fibre, according to U.S. Pat. No. 3,816,375  preferably a prepolymerised high-viscosity furfuryl alcohol› aldehyde binder is used, which is diluted with furfural. A  similar system is disclosed in U.S. Pat. No. 3,594,345 (and  correspondingly DE 19 27 776).  U.S. Pat. No. 2,874,148 discloses furfuryl alcohol-form- aldehyde resins that are produced by reacting furfuryl alco› hol with formaldehyde in the presence of sulphuric acid. The  physical properties of the resins obtained according to U.S.  Pat. No. 2,874,148 are very dependent on the other particu› lar reaction conditions.  Usually a mixture according to the invention for use as  binder in the no-bake process does not comprise an acid that  has a pKa value below 2 at 25°  C., and preferably does not  comprise an acid that has a pKa value below 2.5 at 25°  C.  If  in exceptional cases such acids are used, their maximum  total amount is preferably less than 5 wt. %, relative to the  total weight of the mixture. This applies to all mixtures  according to the invention described below.  Usually a mixture according to the invention for use as  binder in the no-bake process does not comprise any refrac- tory granular materials.  If  in exceptional cases refractory  granular materials are used in the mixture, their maximum  total amount is preferably less than 5 wt. %, relative to the  total amount of the mixture. This applies to all mixtures  according to the invention described below.  Usually a mixture according to the invention is a homo› geneous solution; this applies to all preferred mixtures  according to the invention described below.  Preferably a mixture according to the invention contains  less than 5 wt. % of monomeric furfural, preferably less than  3 wt. %, more preferably less than 1 wt. % of monomeric  furfural.  Preferably the mixtures according to the invention contain  less than 3 wt. % of polyvinyl acetate, preferably less than  1 wt. %, more preferably they are free from polyvinyl  acetate.  Preferably a mixture according to the invention contains  less than 5 wt. % of monomeric furfural and less than 3 wt.  % of polyvinyl acetate.  Preferably a mixture according to the invention contains  less than 1 wt. % of monomeric furfural and less than 1 wt.  % of polyvinyl acetate.  The phenolic compounds are preferably phenolic com› pounds with 6 to 25 carbon atoms and/or one, two, three or  four hydroxyl groups bound directly to an aromatic ring,  preferably selected from the group consisting of phenol,  optionally Cl-C4-alkyl-mono- or -disubstituted dihydroxy› benzenes, trihydroxybenzenes, methylphenols and bisphe› nols, particularly preferably selected from the group con- sisting  of  phenol,  o-dihydroxybenzene,  m-dihydroxybenzene  (resorcinol),  p-dihydroxybenzene,  5-methy lresorcinol, 5-ethy lresorcinol, 2, 5-dimethy lresorci- nol, 4,5-dimethylresorcinol, 1,2,3-trihydroxybenzene, 1,3,5- For this, the phenolic compound(s) can be reacted under  acidic conditions with furfuryl alcohol and formaldehyde  directly or with a furfuryl alcohol/formaldehyde pre-con› densate.  The particularly preferred organic compound that has one  or a plurality of H$_{2}$N groups is urea.  In constituent (b-2), the other compound(s) of the reaction  product with formaldehyde are preferably selected from the  group consisting of  organic compounds that have one or a plurality of H$_{2}$N  groups and/or one or a plurality of HN groups, and  phenolic compounds.  The proportion of "furan ring" units can be determined by  $^{13}$C-NMR. The proportion of "furan ring" units, calculated  as furfuryl alcohol (C5H6O2), in the reaction product (b-1)  from formaldehyde with furfuryl alcohol and optionally  further constituents is preferably in the range from 60 to 96  wt. %, preferably in the range from 70 to 95 wt. %, more  preferably in the range from 75 to 90 wt.%, and particularly  preferably in the range from 75 to 85 wt. %, in each case  relative to the total weight of constituent (b-1).  Other suitable analytical methods are $^{15}$N-NMR or $^{13}$C- NMR.  For the case when nitrogen-containing components are  present in constituent (b-2), they can be detected from the  nitrogen itself. In the case of a phenolic compound as  component in constituent (b-2) differentiation is also pos› sible based on the phenolic compound (for example deter› mination of the residual monomer content, GC-MS analy- sis).  In constituent (b-1) of a mixture according to the inven› tion, the proportion of "furan ring units" can be determined  from the furan ring, for example by $^{13}$C-NMR.  Preferably a mixture according to the invention comprises  monomeric furfuryl alcohol (constituent (a)) and 2,5-bis  (hydroxymethyl)furan (BHMF) ( as part of constituent (b-1))  in a weight ratio in the range from 3:1 to 1:3, preferably in  the range from 2:1 to 1:2, more preferably in the range from  3:2 to 2:3, particularly preferably in the range from 5:4 to  4:5.  Preferably the mixtures according to the invention com› prise, in constituent (b-1 ), 2,5-bis(hydroxymethyl)furan  (BHMF) in an amount of at least 1 wt. %, more preferably  in an amount from 5 to 40 wt. %, particularly preferably in  an amount from 10 to 35 wt. %, quite particularly preferably  in an amount from 15 to 30 wt. %, relative to the total weight  of a mixture according to the invention.  Preferably the mixtures according to the invention com› prise, as part of constituent (b-1), the compound 2,5-bis  (hydroxymethyl)furan (BHMF), preferably in an amount of  at least 2 wt. %, more preferably in an amount from 5 to 80  wt. %, particularly preferably in an amount from 10 to 70 wt.  %, in particular in an amount from 20 to 60 wt. %, in each  case relative to the total weight of constituent (b-1).  10  US 9,993,863 B2  9 