Washing and Cleaning Solutions for Offset Printing

Function

Washing and cleaning solutions for use in offsetprinting are mixtures of different, chemicalcompounds such as hydrocarbons, solvent naphthas,oils, tensides, corrosion inhibitors and others.The different compositions of the washing solutionsare adjusted to the specific intended use.

Adjusted to printing inks Conventional printing inksUV-curing inksHybrid inksDispersion varnishes

Adjusted to fields of applicationSheet-fed offset printingColdsetHeatset

Adjusted to special applications Rubber materials EPDM, NBRDamping rollersBrush rollersImpression cylindersCleaning of parts

A material compatibility of the washing solutionsmust be guaranteed for contact with all systemcomponents such as machine parts, machine coatings,tubes, seals, rubber materials and printing plates.

Application

The regular cleaning and maintenance of the printingmachine is one of the most important conditions forthe trouble-free production course at the end ofwhich a satisfying printing result is expected.

The washing solution will etch printing inkcomponents. Washing solutions mixed with water willremove the water-soluble accumulated dirt (such aspaper components) together with the printing ink.

Automatic washing units (s. illustration) such as brushor blanket washing units are meanwhile standardequipment for the cleaning of blankets. A considerableamount of time, expenditure and washing solutions isthe result when they are used.

For use in heatset printing further regulations are tobe observed for the washing solution, as the inks areheated in the continuous-flow drier far above the flashpoint of their solvents. Up to 85% of the solvents willevaporate. Oxygen will get into the interior of the

drier throughthe opening andwill mix withthe vapours. Inorder to avoidthe risk of anexplosion theair is suckedout.The washingsolution and

the maximum throughput when washing the blankethave to be adapted to the exhaust volume of theventilation of the drier.

Inking rollers or ink fountains are cleaned with un-diluted washing solution as in this case only inks willhave to be dissolved. In addition it is recommendedto use roller cleaning paste especially in case of an inkchange from dark to lighter colour tones in order toachieve a fast and effective cleaning.

The use of a cylinder cleaning paste is recommendedfor cleaning soiled metal surfaces.The paste willremove all residues and will protect the surface of thecylinder against resoiling.

In the courseof time com-ponents ofpaper and inkwill deposit onthe rollerswhich can causeconsiderable

trouble in the printing process. Especially calciumcarbonate will considerably influence the emulationbehaviour and ink transport. Special cleaning solutionsadjusted to this task will be able to remove residuesof this kind.

Washing and Cleaning Solutionsfor Offset Printing

Conscious use of washing solutions

The use of cleaning solutions is connected withdangers and risks for the human being in theenvironment in many cases. The data on the technicaldata sheets, safety data sheets and product labelsshould therefore always be observed.

Environment and health

Due to its high degree of volatility VOC-containingwashing solutions are criticised to an increasingdegree. The environmental consciousness increased,the natural resources decrease.

This is why leading producers and suppliers ofwashing solutions, printing machines, printing inks,printing rollers, blankets and blanket washing units andthe employer's liability insurance association “Printingand Paper Converting” signed the“Trade initiative for reducing solvent emissions in offsetprinting” already in 1995.

They explicitly aimed at the following: Reduction ofthe emissions in offset printing by recommendationand offering alternative washing and cleaning solution.

The success is something to be proud of. If theamounts of the different washing solutions used noware compared with those used in 1995, a clear trendto washing solutions with a higher flash point can beseen and this means the aims aimed at were realized.

On 3rd October 2002 the ordinance regulating theworking safety came into force. It replaces theordinance on combustible liquids, the ordinance onthe use of work equipment and the ordinance on theuse of electrical installations in hazardous locations.Combustible liquids are differentiated only accordingto characteristics of hazard according to the lawsconcerning hazardous material. The classification inclasses of hazard according to the ordinance oncombustible liquids into AI, AII, AIII and B is dropped(s. table).

Flash point Hazardous characteristic according Former classed pf harzard according Typeto ordinance on hazardous material to the ordinance on combustible liquids

< 0°C Highly inflammable AI Special grades of petroleum spirit

< 21°C Easily inflammable AI Special grades of petroleum spirit

21°C – 55°C Inflammable AII White spirit

55°C – 100°C None AIII White spirit

> 100°C None --- High-boiling

> 150°C None --- Cleaning solution on vegetable oil basis

Consumption of washing solutionsTrend of developments 1995 to 2006

1995 2006

Source: Federal Association Printing and Media e.V.

This positive development continues.

Advantages of certified washing and cleaningsolutions:

■ Improved health protection.A clearly reducedpollution of the air we breathe.

■ Improved safety by reduction of fire and explosionrisks.

■ Environmental and user friendliness by reducedVOC-emissions.

■ Protection against corrosion.■ Reduced consumption.■ Possibility of processing and reutilization.■ Less costs.

Recycling of used washing solutions

The trend to recycle used washing solutions isincreasing. This is mainly done by vacuum destillationor different possibilities of filtering.Most of our washing agents can be processed bydestillation or filtration. If you have got any questionsconcerning this topic, we’d be please to give youadvice.

www.SchwegmannNet.de

Technical release of cleaning solvents

Since 1995 the following criteria are valid for therelease tests of washing solutions in offset printing:■ Flash point > 55°C■ Benzole content < 0,1 % ■ Toluol and Xylol content < 1%■ Aromatic compounds (> C9) < 1%

The following substances must not be contained anymore:■ Halogenated hydrocarbon■ Terpenes■ n-Hexane■ secondary amines and amides■ toxic and dermatological questionable substances.All washing solutions corresponding to the above-mentioned criteria are certified by the FOGRAinstitution after having been thoroughly tested andare then released by the machine manufactures foruse with their machines and plants.

Flp. 55°C - 100°C29 %

Flp. 21°C - 55°C34 %

Flp. < 0°C - 21°C27 %

VCA2 %HCA

8 % Flp. 21°C - 55°C12 %

Flp. < 0°C - 21°C6 %

VCA1%

HCA16 %

Flp. 55°C - 100°C65 %

Our product range

The users of our products will profit from long yearsof intensive development work and our compre-hensive know-how. When choosing the raw materialswe will consider the efficiency of the final product butalso the in each case latest findings concerning thesafety of the user and the environmental compatibility.We regularly exchange views with users, machinebuilders, employer’s liability insurance associations, theFOGRA institution and raw material manufacturersand use their findings and requirements in thedevelopment or our products.

Our range of products includes both standardwashing solutions (Schwego® Mat, Schwego® Clean),and special cleaning agents for blanket and printingrollers (Schwego® Plus, Schwego® Cream), metalsurfaces (Schwego® Super, Schwego® Dur) or printingplates (Schwego® Aktiv).

Future challenges

On the one hand crude oil is something you cannotdo without as universal raw material in the industrialsociety of the 20th and 21st century. On the otherhand crude oil is a transitory resource.This is why wekeep on working on alternatives for washing solutionsbased on mineral oil in the field of washing andcleaning solutions for the printing industry.

Vegetable oils have been used in a limited scope forquite a number of years now. Alternatives such asmicroemulsions or neutral and alkaline, aqueouscleaning solutions are quite promising. The up to nowpositive scope of effectiveness of these cleaningsolutions is continuously developed further by us.

When developing our products we considerenvironmental compatibility, working safety andmaterial compatibility apart from efficiency asimportant cornerstones. Our most important aim isthe reduction and substitution of harmful substances.This is why we always endeavour to adapt thecomposition and handling to the lastest findings whenchoosing our raw materials, producing our productsup to the use of packaging materials.

Washing and Cleaning Solutionsfor Offset Printing

Examples for the evaporation (volatility) of offset washing solvents:

Washing solution on the basis of Flash point Evaporation numberSpecial grades of petroleum spirit 0° C 2,6

White spirit 40° C 35,4

White spirit 60° C 154,5

High-boling solvent 100° C 2751,5

Cleaning solvent on vegetable oil basis > 150° C > 3100,0

Remark: The smaller the evaporation number, the faster the volatility of the washing solution.Tip: By the fast evaporation of a washing solution with low flash point the quantity used will increase!

Our washing and cleaning agents meet the EC-Detergent ordinance

On 08th October 2005 the ordinance (EC) No.648/2004 of the European Parliament and Council of31st March on detergents came into force. Tenside-containing washing and cleaning solutions are calleddetergents in the sense of this ordinance. Amongthem are also washing and cleaning agents for sheet-fed and web offset.The tensides contained in ourwashing and cleaning solutions meet the requirementsof biodegradation as laid down in the ordinance (EC)No. 648/2004 on detergents.

Bernd Schwegmann GmbH & Co. KG · Wernher-von-Braun-Straße 14 · 53501 Grafschaft-Gelsdorf · GermanyPhone: +49 (0) 22 25 / 92 26-0 · Fax: +49 (0) 22 25 / 92 26-33 · E-mail: info@SchwegmannNet.de · www.SchwegmannNet.de

Terms often used in connection with washingsolutions

Flash pointThe flash point (Flp.) indicates the lowest temperatureat which a solvent vapour/air mixture can be inflamedby means of a pilot light.

VOCVolatile Organic Compounds. All volatile, organiccompounds which will evaporate in the atmosphere.According to the VOC-guideline all those compoundsare included which have got a steam pressure of atleast 0.01 kPa at a temperature of 20°C,

Evaporation numberDimension number for the volatility of liquids.

Vapour pressureThe pressure which the steam (liquid of solid phase)exercises on the surrounding walls in a closedcontainer.

Workplace limiting value The workplace limiting value is the limiting value forthe chronologically important average concentrationof a substance in the air at the workplace withreference to a given reference period. It will indicateat which concentration of a substance in general noacute or chronic hazardous effects on health can beexpected.

Explosion limitFlammable gazes or vapours mixed with air arepotentially explosive within a certain range ofconcentration. This range of concentration isdetermined by the lower explosion limit and theupper explosion limit. Each effective ignition sourcecan trigger an explosion within this range ofconcentration.

Aromatic compoundsCollective term for aromatic hydrocarbons, especiallybenzoles and alkylbenzenes. The efficiency of awashing solution is increased by the use of aromaticcompounds. At the same time, however, the risk forthe user’s health will increase.

Foto

s:K

oeni

g &

Bau

er A

G,M

AN

Rol

and

Dru

ckm

asch

inen

AG

,Hei

delb

erge

r D

ruck

mas

chin

enA

G,

Bald

win

Ger

man

y G

mbH

© Bernd Schwegmann GmbH & Co. KGAny reprinting or reproduction of the contents even in extracts is only permitted with written consent of Bernd Schwegmann GmbH & Co. KG