US 2018/0235218 Al  3  Aug. 23, 2018  Combination E: propionic acid, lactic acid, acetic acid,  sodium benzoate  Combination F: tartaric acid, propionic acid, acetic acid,  lactic acid, sodium benzoate.  [0057]  Particularly preferred embodiments of the concen› trate according to the invention are the following composi› tions:  aromatic alcohols, no metal ions and no combinations of  these antimicrobial active ingredients.  [0063]  Surprisingly, it is possible using the disinfectant  according to the invention to already achieve, just through  addition of organic acids without further antimicrobial  active ingredients, a sufficient microbicidal efficacy against  a broad spectrum of microorganisms after two minutes, five  minutes or 15 minutes. Moreover, the combination of mul› tiple organic acids that is in accordance with the invention  represents, surprisingly, a synergistic composition owing to  differently combined mechanisms of action and allows a  sufficient, pathogen-killing action.  [0064]  The list of organic acids suitable as active ingre› dients of disinfection compositions comprises:  formic acid, ascorbic acid, benzoic acid, dehydroacetic acid,  acetic acid, fumaric acid, glycolic acid, lactic acid, mandelic  acid, phenylacetic acid, propionic acid, salicylic acid, tar› taric acid, zinc stearic acid, citric acid, present in each case  as free acid, salt and in any combination, preferably acetic  acid, lactic acid, propionic acid, tartaric acid, sodium ben› zoate/benzoic acid or mixtures thereof.  [0065]  Preferably, the disinfectant concentrates according  to the invention contain organic acids having 2 to 8 carbon  atoms, preferably 3 to 7 carbon atoms.  [0066]  In one embodiment, the disinfectants according to  the invention and the disinfectant concentrates according to  the invention additionally contain nonionic surfactants, cat› ionic surfactants, amphoteric surfactants, or a combination  of these, and preferably no anionic surfactants.  [0071]  Surprisingly, the organic acids in combination can  be used effectively according to the invention against micro› organisms, since the following mechanisms of action appar› ently accumulate synergistically:  [0070]  The organic acids preferred according to the inven› tion have the following pKa values (at 20°  C.)  pKa tartaric acid: 3.04  pKa lactic acid: 3.87  pKa benzoic acid: 4.17  pKa acetic acid: 4.76  pKa propionic acid: 4.88.  [0069]  Preferably, the disinfectant according to the inven› tion and the disinfectant concentrate according to the inven› tion comprise, as antimicrobial active ingredient (active  component), exclusively organic acids having a pKa  between 2 and 6, preferably having a pKa between 3 and 5.  [0068]  Organic acids can have an antimicrobial action  owing to their acid function and their structure. Thus, a  long-chain fatty acid can, owing to its hydrophilic and  hydrophobic moiety, also have an antimicrobial character as  surface-active  substance,  comparable  to  surfactants,  whereas a short-chain acid can act through the lowering of  pH. The acidity can be deduced from the pKa value. The  pKa corresponds to the negative common logarithm of the  acid constant Ka and provides information about the equi› librium position of an acid which reacts with water. The pKa  therefore serves as a measure of the strength of an acid, with  a small value meaning a strong acid.  [0067]  There are many compounds which belong to the  group of organic acids and which can differ in structure and  mode of action. One way of characterizing organic acids is  the degree of dissociation in the aqueous medium. The  dissociation constant of an organic acid (Ka) decreases with  increasing chain length; the acid dissociates more weakly.  [0062]  Preferably, the disinfectants according to the inven› tion and the disinfectant concentrates according to the  invention contain, as sole antimicrobial active ingredient,  organic acids and no further antimicrobial active ingredi› ents. Particularly preferably, the disinfectants according to  the invention contain no quaternary ammonium compounds,  no aldehydes, no guanidines, no active chlorine, no amines,  no oxygen-releasing agents, no monohydric alcohols, no  [0061]  Preferably, the disinfectants according to the inven› tion and the disinfectant concentrates according to the  invention contain, as solubilizers, glycols selected from  propylene glycol and monoethylene glycol and/or glycol  ethers selected from methyl carbitol, butyl carbitol and  hexyl carbitol, particularly preferably a combination of  propylene glycol and hexyl carbitol.  [0060]  Hexyl carbitol and/or propylene glycol are prefer› ably used at a weakly acidic pH in aqueous disinfectants  containing sodium benzoate. The quantity ratio of sodium  benzoate to hexyl carbitol is preferably between 4: 1 and 1 :4,  particularly preferably 3:1. If propylene glycol is used, the  quantity ratio of sodium benzoate to propylene glycol is  between 4: 1 and 1 :4, particularly preferably  1:  1.5. Particu› larly preferably, the combination of hexyl carbitol with  propylene glycol in the presence of sodium benzoate is in a  preferred ratio of sodium benzoate:hexyl carbitol:propylene  glycol=3/1/5 or 3/5/5. Further solubilizers which can be  used at pH<7.0 are: methyl carbitol, butyl carbitol, mono› ethylene glycol and combinations of these.  [0059]  The disinfectant concentrates according to the  invention can contain, as auxiliaries, solubilizers and/or pH  regulators and/or surfactants. Suitable solubilizers are, for  example, diethylene glycol mono-n-hexyl ether (hexyl car› bitol) and/or 1,2-propanediol (propylene glycol), as well as  methyl carbitol, butyl carbitol, monoethylene glycol. Further  auxiliaries, which are less preferred according to the inven› tion, are corrosion inhibitors, foam regulators, dispersants,  dyes, perfume or mixtures thereof.  [0058]  The disinfectant according to the invention prefer› ably has a pH of 1.0 to 7.0, particularly preferably ;;,;2.0-s6.0.  The pH can be adjusted by addition of low amounts of pH  regulators, such as strong bases or strong acids, for example  sulfuric acid, potassium hydroxide, sodium sulfite. Prefer› ably, the use of a pH regulator is dispensed with.  *Marlipal 1618/25, nonionic surfactant manufactured by Sasol Germany GmbH  Concentrates  [%]  [%]  [%]  [%]  [%]  Lactic acid  15  Tartaric acid  6  Acetic acid  15  15  15  30  5  Propionic acid  15  15  15  30  15  Sodium benzoate  6  13  6  13  Sodium acetate  Propylene glycol  10  12  10  10  10  Hexyl carbitol  10  14  10  10  10  Demineralized water  29  31  44  13.5  46  Linear alcohol ethoxylate*  0.5 