Standardization

Responsible handling of the resources, such as energy, water, and air, and the two most important primary products ink and paper, as well as the other substances required, is one of the most important tasks of the printing industry, the manufacturers of printing systems, the sub-contracting industry, and waste disposal firms.

To this day many successful environmental protection measures have been implemented in the printing industry. The following are some examples:

• In printing inks, substances are used that are as environmentally compatible as possible and do not endanger human health. In 1993, ink manufacturers voluntarily pledged to refrain from using certain pigments, colorants, solvents, softeners, and toxic substances. Today, the inks used in sheet-fed offset presses consist of more than 60% renewable raw materials; ink manufacturers are working to increase replacement of mineral oils by vegetable oils (soybean oil). In the case of gravure inks, the toluene used may not contain more than 0.1% benzene. The chlorine content of inks is less than 0.5% on average. Only small amounts of heavy metals are still contained in certain types of inks, for instance, iron and manganese in mineral pigments, cobalt as a drying agent, and copper in organic blue and green pigments, and these amounts can be considered environmentally safe.

• To reduce VOC (Volatile Organic Compounds) emissions, an initiative was launched by the German printing industry. Printing press manufacturers, manufacturers of wash-up devices, and roller manufacturers pledged to use low-emission cleaning agents in all wash-up devices built after 1995. An independent testing institute (FOGRA at present) checks cleaning agents for non-toxicity, compliance with safety regulations, and environmental and material compatibility and issues a test certificate. Solvent emissions from washing operations have decreased markedly since 1995. At the initiative’s regular meetings, which are organized by the Berufsgenossenschaft Druck und Papierverarbeitung (German Institution for Statutory Accident Insurance and Prevention in the Printing and Paper Converting Industry), other subjects are also discussed, such as alcohol reduction in the dampening solution for offset printing, or reduction of the powder used for delivery-pile dusting (to prevent the unwanted transfer of ink that is still not completely dry). Expansion of the initiative to other European countries began in 1998.

• Paper almost always consists of wood fiber. Other substances such as filler and pigments can make up as much as 35% of the contents.Wood is a renewable raw material and about 8% of all the wood felled worldwide is used for paper production. Tropical wood is not used in the paper industry because its fibers are unsuitable. For years the printing industry has called for and supported woodfelling based on the conservation requirements of any particular wooded area. The voluntary pledge made by the paper industry in 1994 to increase waste paper recycling to 60% by the year 2000 was more than fulfilled when 83.1% was reached as early as 1997. In papermaking, until a few years ago, elementary chlorine was used to bleach the wood-pulp. Owing in particular to waste water contamination, most European papermakers have converted their bleaching processes to oxygen and hydrogen peroxide.

• Returnable systems (which are returned for reuse) for containers and cleaning cloths have already been widely established in many countries, or are in the setup phase. Standardized containers are used, which are put in circulation in the recycling system based on payment of a deposit refundable on return of the container after use. Practising Environmental Protection In the general processes in a printing plant are illustrated in a diagram. First of all, the recycling processes will be explained in more detail. Recycling is to be understood as the reuse and processing of products or parts of products in a circulatory system .Recycling produces secondary raw materials and in this way resources are saved. The reduction in the quantity of waste means that less demand is placed on available dumping-ground capacities.

Diagram of material flow in a printing plant

The term use is characterized by retention of the product structure and a minor loss of value.Reusing involves the product being used for the same purpose (e.g., returnable cleaning cloths or reusable canisters for printing chemicals), and further use means that the product is used for another purpose (e.g., one-way canister for collecting hazardous liquid wastes).

The term processing is characterized by the conversion of the product structure, which means that there is a greater loss of value. In the reprocessing process, waste material or returned production material is reused in a production process similar to the one it has been passed through before (e.g., recycling of used cleaning agents). Further processing generates secondary raw materials (e.g., waste paper recycling, the recycling of aluminum printing plates or empty ink canisters).

Incineration (e.g., of washing cloths or ink residues) for the production of energy is another type of recycling.

Environmental aspects are explained in more detail below with reference to offset printing, the most widely- used printing process. The other printing processes are then considered somewhat more briefly.

Methods of photographic reproduction in prepress require the use of developing and fixing baths with which the silver-based film is treated as a master for the printing plates. The service life of the developing bath can be extended by developer-saving systems and longlife chemicals. In this way, the quantity of used developer requiring disposal, which is classified as hazardous waste that must be closely monitored, is reduced considerably. In the case of the fixer, circulatory systems with electrolytic desilverization extend its service life substantially; in this way the mass of hazardous waste can be reduced here, too. The recovered silver is recycled.

Recycling of recovered silver is also possible for films and photographic papers with a blackening factor of more than 30%. On the other hand, when blackening is less than 30% or in the case of mounting films, we are dealing with non-hazardous waste for recycling (household waste).

When computer to plate or computer to press systems are used, the need for photochemicals and photomaterials is partly or even completely eliminated.An annual input/output summary (25 orders per day, 250 workdays, one-shift operation) for a direct imaging press printing in A3 format (Heidelberg’s Quickmaster DI 46-4, see figs. 4.4-8 and 4.4-9), in which thermoplates are imaged by IR laser diodes, revealed that about 3500 liters of photochemicals and 55000 liters of waste washing water are eliminated, which (if the permitted limit values are exceeded) are classified as hazardous wastes and must be disposed of at high cost. Also eliminated are about 4000 m2 of silver halide-based repro film material and the dampening solution together with its disposal, since the machine uses a dry offset printing process. The used PE-based plate may be disposed of as household waste.

Liquid wastes from small offset printing systems, residues of deletion fluid, and plate cleaning agent, as well as used plate developing solutions, must be disposed of as hazardous wastes. Through the use of longlife developers/de-coaters for metal plates made of aluminum, the mass of waste can be reduced. Today, dichromate-coated printing plates, which cause heavy waste-water contamination, are no longer used, while multi-metal plates are now only seldom used.

The process-induced emissions occurring in offset printing are VOC (volatile organic compounds) emissions and result mainly from evaporation of the IPA (isopropyl alcohol) contained in the dampening solution, to which it is frequently added as an 8 to 15%dosage,and from the cleaning agents for the rollers, rubber blankets, and other press components. These emissions can be effectively diminished by reducing the alcohol content through the use of suitable substitutes (e.g., glycol) and/or the use of hydrophilic dampening rollers and other technical improvements (e.g., reverse-osmosis water processing, inking system temperature control) to between 4 and 8% or even further, as practised in some companies. The emissions from volatile cleaning agents can be reduced in most cases when these are replaced by highly viscous and therefore low-emission, high-boiling mineral oils or chemically refined vegetable oils. Information on suitable cleaning agents can be obtained from printing press and wash-up device manufacturers. In addition, the FOGRA Institute in Munich publishes up-to-date lists of released cleaning agents at “http://www.fogra.org” on the Internet.

New accurate IPA measuring instruments (e.g.,measuring the IR absorption spectra in the gaseous phase or measurement of the acoustic velocity), which have been commercially available for some little time, can replace the inaccurate “alcohol stabilizer” (which is based on the density measuring principle) used in present- day additive metering units. Only then is controllable IPA reduction possible.

In waterless offset printing the need for a dampening solution is eliminated, and therefore there is no IPA; in addition, considerably fewer developing chemicals are required when using thermal plates.

The inks used in offset printing (sheet-fed offset and coldset web offset) are VOC-free, because the oils used as solvents do not evaporate at ambient temperature. The UV inks that are sometimes used are VOC-free, too.However, older UV dryers emit ozone if no exhaust system is provided downstream. In web offset (heatset), 99%of the solvents evaporating when hot-air dryers are used are incinerated in a state-of-the-art afterburning process. Through the use of heat exchangers, the hot, purified waste air can be used for heating purposes, including water heating. It is also possible to use catalytic or regenerative afterburning processes for waste air purification. Empty metal ink containers are recycled via the scrap trade. Ink containers whose contents have not been entirely consumed are to be disposed of as hazardous waste. Through the use of large containers, ink pumps, and ink cartridge systems, or through the use of fresh inks, the mass of waste can be substantially reduced. Waste sheets and reel cores may be transported to waste paper dealers for recycling.Through appropriate automation, such as ink key presetting systems, control station technology, register control systems, or color measuring systems, the generation of waste is reduced to a minimum and in this way paper and energy are saved.

Residual dampening solution with or without alcohol is (if the permissible limit values specific to the location are exceeded) to be disposed of as hazardous waste. Residual cleaning agent from the wash-up devices is hazardous waste. In large printshops these remnants, especially those from brush-type wash-up devices, are recovered through filtration. They can then be recycled, generally with the addition of a suitable additive, but sometimes without. Soiled filters, one-way cleaning cloths, and washing cloths from the wash-up devices must be disposed of as hazardous waste. Returnable cleaning cloth systems (rental service) offered by various service providers enable cleaning cloths to be reused.

Aluminum or multi-metal printing plates can be transported to scrap dealers for recycling; polyesterbased printing plates can be disposed of as domestic waste.

In print finishing, which includes the operations of coating, cutting, folding, stitching, gluing, packaging, and so on, the environmental repercussions are considered to be slight. For coating, dispersion and UV varnishes are mostly used. The environmental effects are similar to those of printing.Waste sheets, paper cutting and die-cutting waste, and packaging materials are recycled. In gluing, dispersion, hot-melt, and polyurethane adhesives predominate. In the processing of these adhesives, removal of the vapors by suction is recommended in the case of unpleasant odors.Hardened adhesive residues are classified as household waste, and non-hardened adhesive residues as hazardous waste.