In­dus­tri­al clean­ing rep­re­sents a very im­por­tant and eco­nom­i­cal­ly promis­ing fu­ture mar­ket for clean­ing ser­vice com­pa­nies. The clean­ing of print­ing ma­chine hous­ings is a typ­i­cal ex­am­ple: To en­sure high qual­i­ty print­ing, not only the clean­li­ness of the rub­ber rollers and cylin­ders lo­cat­ed in the print­ing ma­chine, but also the clean­li­ness of the ma­chine hous­ing has be­come a cen­tral el­e­ment in qual­i­ty man­age­ment in re­cent years.

There­fore, the de­mands on clean­ing of print­ing ma­chine hous­ings in­crease con­tin­u­ous­ly. Both in sheetfed off­set print­ing with UV inks and heat­set web off­set and news­pa­per print­ing with con­ven­tion­al print­ing inks aerosols are de­posit­ed on print­ing ma­chine hous­ings. These de­posits can cause print de­fects due to a car­ry­over of ink on the sur­face to be print­ed.

How­ev­er, the cur­rent­ly used clean­ing meth­ods for re­moval of ink have se­ri­ous draw­backs: Ex­ten­sive use of or­gan­ic sol­vents for soil re­moval caus­es ex­pen­sive mea­sures re­gard­ing work safe­ty and en­vi­ron­men­tal pro­tec­tion. More­over, the large frac­tion of man­u­al work re­sults in very money, human re­sources and time-con­sum­ing clean­ing pro­ce­dures. The es­sen­tial pre­req­ui­site to open up this mar­ket po­ten­tial for ex­ter­nal clean­ing com­pa­nies is an eco­log­i­cal and eco­nom­ic clean­ing pro­ce­dure for strong­ly ad­her­ent inkjet colours.

There­fore, tar­get of the pro­ject was the de­vel­op­ment of a re­new­able soil re­lease coat­ing which is ap­plied as tem­po­rary pro­tec­tion resp. sac­ri­fi­cial layer be­tween ma­chine hous­ing and print­ing ink. The pro­tec­tion layer is sup­posed to be re­moved to­geth­er with de­posed soil­ings on top of the layer by a water based clean­ing pro­cess with­out ap­pli­ca­tion of or­gan­ic sol­vents. After de­vel­op­ment of suit­able thixotrop­ic soil-re­lease-hy­dro­gels and suit­able ap­pli­ca­tion pro­cess­ing for rel­e­vant sur­face ma­te­ri­als, var­i­ous metal sur­faces were soiled with typ­i­cal print­ing inks. Fi­nal­ly, a clean­ing pro­cess and treat­ment rec­om­men­da­tions were worked out. This in­clud­ed amongst oth­ers, the ob­ser­va­tion of the mi­gra­tion be­hav­ior of the inks into the coat­ing, the ef­fect of water con­tent, the oc­cur­rence of cor­ro­sion and the ef­fect of foun­tain so­lu­tion on me­chan­i­cal sta­bil­i­ty.

The de­vel­oped soil-re­lease-hy­dro­gel was proved suc­cess­ful­ly under prac­ti­cal con­di­tions in three com­pa­nies. Even after 6 weeks with strong soil­ing (re­sult­ing in closed lay­ers) the de­posit­ed ink could be re­moved to­geth­er with the sac­ri­fi­cial layer suc­cess­ful­ly from the ma­chine parts using the de­vel­oped wa­ter-based clean­ing pro­cess. The amount of time need­ed for clean­ing with the new wa­ter-based pro­cess is com­pa­ra­ble to the con­ven­tion­al sol­vent-based clean­ing pro­cess. How­ev­er, the ac­cord­ing in­curred costs are lower and no or­gan­ic sol­vents are used em­ploy­ing the newly de­vel­oped clean­ing pro­cess. The re­search work was per­formed by the wfk – Clean­ing Tech­nol­o­gy In­sti­tute in Krefeld in co­op­er­a­tion with the Fo­gra-In­sti­tut e.V., Mu­nich

Der Forschungsbericht ist auf Anfrage bei der FRT erhältlich.