Green Printing Handbook: Requirements for Printing Enterprises and Products in Implementing Green Printing

(1) Requirements for printing raw and auxiliary materials

Restriction requirements for phthalate esters

Phthalate esters (PEs) are a class of fat-soluble synthetic organic compounds. Among them, di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP) are low-molecular-weight phthalate esters with a carbon content of 8 or less; they cause varying degrees of harm to human health and are a class of environmental pollutants. As important additives for a variety of chemical products such as plastics, rubber and coatings, they are widely used.

Phthalate esters are regulated under relevant EU directives and standards, US consumer product regulations, and other rules. The main regulatory directives and standards include: 《BSEN14372：2004》, 2005/84/EC, the Consumer Product Safety Improvement Act H.R.4040 and CaliforniaAB1108.

Considering that printing companies do not directly use phthalate esters and are passive recipients, it is not envisaged that companies control the phthalate ester content in raw and auxiliary materials themselves; instead, this is achieved through the control requirements companies place on their raw material suppliers. Based on an analysis of the main raw and auxiliary materials used in printing, the materials involving phthalate esters include inks, overprint varnishes, blankets and adhesives. Accordingly, the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing sets restriction requirements for these four types of materials.

Requirements for paper brightness (whiteness)

Lowering the brightness (whiteness) of paper can reduce the amount of bleaching agents and the number of bleaching stages for pulp, and reduce the use of chemicals such as brightening agents — that is, it reduces pollutant emissions. At the same time, paper that is too white also has adverse effects on human health.

The existing domestic requirements for paper brightness (whiteness) mainly involve 3 standards.

1. Requirements of GB/T17934.2-1999, Graphic technology — Process control for the production of half-tone colour separations, proof and production prints — Part 2: Offset lithographic processes. The brightness (whiteness) provisions are given in Table 2.
2. Requirements of GB/T18359-2001, Paper, printing quality requirements and inspection methods for primary and secondary school textbooks. The brightness (whiteness) provisions are given in Table 3.
3. Requirements of GB/T24999-2010, Paper and board — High limit of brightness (whiteness). The brightness (whiteness) provisions are given in Table 4.

At present, responsibility for paper brightness (whiteness) requirements rests mainly with paper mills, while printing companies merely put forward the demand. Therefore, in terms of standard selection, reference is made to the requirements of GB/T24999-2010, Paper and board — High limit of brightness (whiteness). Since primary and secondary school textbooks are currently controlled by a dedicated standard, the standard basis for such textbooks is the requirements of GB/T18359-2001, Paper, printing quality requirements and inspection methods for primary and secondary school textbooks. Because the brightness (whiteness) provisions have a considerable impact on the quality of current printing products, the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing does not impose stricter requirements.

Requirements for offset printing inks

Offset printing (lithographic) inks are a major source of environmental pollution in printing and printed products. Inks not only pollute the environment and endanger human health during the printing process; the organic residues on printed products will continue to pollute the environment, and these organic residues together with the harmful substances they contain, such as lead, mercury, arsenic and chromium, will also continue to harm the health of users of printed products. For this reason, the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing requires that inks for all environment-labelled printed products must meet the requirements of the HJ/T370 standard.

Requirements for overprint varnish

Overprint varnish is a colourless, transparent lacquer with two functions:

① As a transparent protective lacquer, its hardness and abrasion resistance are better than those of coloured lacquers, so it provides protection; ② As a tactile lacquer, it has excellent gloss and brightness and feels very good to the touch.

There are currently three main types of overprint varnish on the market:

1. UV overprint varnish: UV overprint varnish is mainly composed of oligomers, reactive diluents, photoinitiators and other additives.
2. Water-based overprint varnish: water-based overprint varnish is composed of 45% synthetic resin and 55% water.
3. Solvent-based overprint varnish: contains 50% solvent, toluene, ethyl ester and butyl ester.

Solvent-based varnishes are hazardous materials and are greatly restricted in their production and use. Because some of their solvents are benzene-based solvents such as toluene and ethylbenzene, and the evaporation of large amounts of such solvents causes significant harm to the environment, the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing prohibits the use of solvent-based varnishes in environmentally labeled printed products.

Spray powder is an indispensable process in modern high-speed multicolor offset printing. Its main function is to prevent back-side soiling of printed products and to improve printing quality and efficiency. Spray powder is made from mineral and plant powders refined through modern science, with spherical, crystal-clear, smooth-surfaced particles (particle size 10–25μm). The fine particles undergo special surface treatment and offer excellent dispersibility and flowability, preventing set-off, without hardening or clogging. They fully deliver anti-setoff and anti-static effects while in no way affecting printing results or the transparency of the film, and also possess water resistance without caking under changes in temperature and humidity;

On the premise of improving the four main technical indicators of ink (drying performance, transfer performance, drying speed, and post-printing suitability), printed product quality is enhanced and post-printing processes are ensured to proceed smoothly. Because plant-based spray powder poses no harm to personnel in contact and brings no environmental problems, the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing requires that only plant-based spray powder be used.

Requirements for Fountain Solution

Traditional fountain solutions are alcohol-containing products, and the alcohols currently used are generally methanol, ethanol, isopropyl alcohol, propanol, butanol, isoamyl alcohol, etc. Methanol is widely known for its toxicity: ingestion of more than 4 grams can cause poisoning reactions; accidental consumption of a small cup exceeding 10 grams can cause blindness in both eyes; and a large intake can cause death, with a lethal dose of more than 30 milliliters. Methanol is not easily excreted from the body and can accumulate; its oxidation in the body produces formaldehyde and formic acid, both of which are also toxic. The Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing prohibits the use of methanol as a fountain solution.

Requirements for Lamination Adhesives

Lamination adhesive is the glue required for paper-plastic lamination of printed products. Paper-plastic lamination technology can extend the preservation time of products. Currently, two main categories of adhesives are used domestically: solvent-based adhesives and water-based adhesives. Among these, solvent-based adhesives mainly use benzene-based solvents, which are highly toxic and harmful; therefore, the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing prohibits the use of solvent-based lamination adhesives in lamination.

(II) Restriction Requirements for Printed Products

Requirements for Soluble Elements

Based on the characteristics of offset printed products and the products involved, and with reference to GB6675, the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing sets restriction requirements for eight soluble elements in printed products: Sb, As, Ba, Pb, Cd, Cr3+, Hg, and Se.

Since this requirement is formulated according to the characteristics of children, its indicators can ensure user safety. Therefore, the implementation of these indicators represents a certain level of advancement. Requiring element control for all printed products is a first in China; considering that enterprises are still in an exploratory stage, the indicators in this standard are not tightened this time. Under volatile substance requirements, the odor of finished printed products and its impact on human health have always been a focus of attention, with the main influencing factors coming from certain compounds with pungent odors. These compounds mainly originate from chemicals used in printing processes such as inks, lamination adhesives, and varnishes. Because some compounds are toxic and harmful substances, such as benzene, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, ethyl acetate, isopropyl acetate, n-butanol, propylene glycol methyl ether, n-propyl acetate, 4-methyl-2-pentanone, toluene, n-butyl acetate, ethylbenzene, xylene, cyclohexanone, etc. Therefore, it is necessary to control them.

At present, foreign restrictions on volatile organic compounds (VOCs) in printed matter have been stipulated only for toy products. Research shows that the test methods specified therein are relatively complex and are intended for testing simple products; therefore, they are not suitable for testing bound books and hardcover books. As for standards limiting VOCs in printed matter, especially in books, neither foreign countries nor China has yet formulated any. A standard that can be referenced at present is the "Limits of Volatile Organic Compounds in Cigarette Carton and Box Packaging Paper" (YC263-2008). The scope of this standard covers the specialty paper for packaging cartoned cigarettes into cartons and the specialty paper for packaging cigarettes into boxes. Such products belong to the packaging decoration category of lithographic printed products; therefore, this standard can be referenced when formulating limits on volatile organic compounds for lithographic printing products. The method may be revised later after further in-depth study of the standard.

Using the test method specified in that standard, "Determination of Volatile Organic Compounds in Cigarette Carton and Box Packaging Paper — Headspace-Gas Chromatography" (YC/T207-2006), the samples currently collected were tested, and the pass rate was 60%, indicating that the limits are advanced.

(3) Environmental Behavior Evaluation Requirements for Raw and Auxiliary Materials for Printing

1. Sustainable forest certification requirements.

In the 1980s, forest problems became increasingly prominent. In particular, the massive export of timber from tropical countries caused a sharp reduction in local forest area, intensified forest degradation and severe environmental deterioration. This drew the attention of some environmental non-governmental organizations in Europe. In order to eliminate the forest crisis in tropical countries, Europe and North America launched a movement to restrict imports of tropical timber, making it impossible for tropical countries to export their timber to consumer countries. Through this movement, consumers in consumer countries generally formed the perception that the quality of timber from tropical countries was inferior to that from non-tropical countries.

But by the 1990s, this perception met with strong opposition from non-governmental organizations in northern timber-producing countries (mainly the Nordic and North American countries). They believed that their own forest management was by no means entirely sustainable, and that if this continued, it would inevitably cause great damage to their forest resources and undermine the local ecological environment. At the same time, forests in tropical countries did not entirely fail to meet the standards of sustainable management, and those countries also had a demand for timber exports.

Therefore, some non-governmental organizations in consumer countries launched another campaign, attempting to change consumers' previous perception — namely, that no matter where timber comes from, as long as it originates from a sustainably managed forest, it can be accepted and used; otherwise, it should be banned. This required a set of widely recognized methods and standards so that consumers could know and trace the origin of timber, and thus forest certification came into being.

Forest certification falls into two categories: ForestManagementCertification (FMC) and ChainofCustody (CoC) certification. Forest management certification is certification carried out on forest management units. An independent certification body audits the forest management unit in accordance with certification principles and standards (including forest inventory, management planning, silviculture, harvesting, forest infrastructure, and the related environmental, economic and social aspects). If its forest management activities meet the requirements of the certification standards, a certificate can be issued and the unit is allowed to use the certification mark, proving that the timber it produces comes from a sustainably managed forest or a well-managed forest.

Simply put, forest management certification is the certification of forests. Chain of custody (CoC) certification, by contrast, is certification carried out on the commercial organizations that process and sell forest products; it tracks the source of raw materials for forest product processing and the entire process of product storage, transport and sale — that is, the whole process from the forest to the consumer. In the overall process of forest product certification, that is, from the forest to the end consumer, products certified through CoC can be labeled with the certification mark, telling consumers that the wood used to produce the product comes from a certified forest.

Simply put, chain of custody certification is the certification of forest products, ensuring that the main raw materials of all certified products come directly or indirectly from well-managed forests — that is, forests that have obtained forest management certification. In order to ensure the effective and sustainable use of forest resources, the "Technical Requirement for Environmental Labeling Products — Printing Part: Lithographic Printing" encourages printing companies to purchase sustainably certified paper for printing.

1. Requirements for recycled paper.

Because China is relatively short of papermaking fiber resources, its supply capacity can no longer meet the needs of capacity expansion, and fiber raw material has become a bottleneck constraining the development of China's paper industry. China's papermaking raw materials present a tripartite structure: according to estimates by the China Paper Association, wood pulp currently accounts for 23% of total raw materials, non-wood pulp 15%, and waste paper pulp 62%. In recent years, the proportions of wood pulp and waste paper pulp have continued to rise while the share of non-wood raw materials has continued to fall. In 2009 alone, the proportion of wood pulp rose by 1% over the previous year, that of waste paper pulp by 2%, while the share of non-wood raw materials dropped by 3%.

China's wood pulp papermaking consumes about 10 million cubic meters of wood each year. Today, an average of 4,000 square kilometers of forest disappears from the earth every year. Forests supply oxygen to mankind, absorb carbon dioxide, prevent climate change, conserve water, check wind and fix sand, and maintain ecological balance. Protecting forests and reducing logging requires cutting demand for wood. Recycled paper is made from waste paper as its raw material, which is broken up and de-inked to make pulp and then processed through a variety of complex procedures into paper. Part of its raw material comes from recovered waste paper, with some virgin pulp added to improve the strength of the paper product. Recycling 1 tonne of waste paper yields 800 kg of recycled paper pulp, equivalent to cutting 17 fewer large trees, saving 9.6 tonnes of standard coal in papermaking energy consumption, and reducing water pollution by 35%.

Waste paper papermaking, as a model representative of the circular economy, has gained the support of the Chinese government. The National Development and Reform Commission and the Ministry of Science and Technology have successively given policy support to the recycling and utilization of domestic waste paper. As a representative example, Jiangsu Zhilian Renewable Resources Co., Ltd., with the support of the National Development and Reform Commission, has built more than ten waste paper recycling plants, and many large enterprises have also established their own waste paper recycling systems. These recycling systems serve two purposes: first, they use specialized equipment to improve the quality of recovered waste paper; second, they concentrate waste paper resources previously scattered among other small and medium-sized enterprises into the hands of large enterprises, enabling resources to be redistributed.

According to the draft of the 12th Five-Year Plan for the paper industry, the forthcoming plan is also very likely to introduce supportive policies for recycled paper producers. Abroad, environmental organizations are also paying attention to the promotion of recycled paper; under the FSC-RECYCLED requirements, at least 85% of paper raw material must be post-consumer recycled material, and up to 15% may be mill broke from papermaking enterprises. To ensure the effective and sustainable use of forest resources, the Technical Requirement for Environmental Labeling Products — Printing Part: Lithographic Printing encourages printing enterprises to purchase recycled paper for printing.

1. Requirements for natural-color paper.

Natural-color paper refers to paper that uses no chemical bleaching or dyeing agents throughout its production process. Because such paper uses no fluorescent whitening agents and has a whiteness of 70–74, it protects eyesight, and it has therefore already been widely used in textbooks and students' exercise books. This has also reversed the view that "the whiter the paper, the better." In addition, the pulp of some natural-color paper products is non-wood pulp, which provides considerable support for the protection of wood resources, while the production process uses no bleaching or dyeing reagents (especially chlorine), greatly reducing the environmental load. The Technical Requirement for Environmental Labeling Products — Printing Part: Lithographic Printing therefore encourages enterprises to use natural-color paper.

Requirements for fountain solution

The fountain solutions widely used on offset presses include alcohol fountain solution and non-ionic surfactant fountain solution. With alcohol fountain solution, high-quality fine offset products can be printed, and the optimal alcohol concentration range is 8%–25%. However, alcohol evaporates quickly; if it is not controlled, the drop in alcohol concentration will raise the surface tension of the fountain solution and weaken its wetting ability. The alcohol consumed must therefore be replenished in time, and to reduce alcohol evaporation, the temperature of the fountain solution should be kept below 10℃ as far as possible (preferably 4–9℃).

Non-ionic surfactant fountain solutions are currently mainly the various fountain powders sold on the market. To use them, simply dissolve a certain amount of the powdered fountain agent in water and add it to the fountain pan for printing. Compared with alcohol fountain solution, non-ionic surfactant fountain solution has a lower cost, is non-toxic, does not volatilize, and requires no dedicated dampening system on the offset press — the traditional oscillating water transfer device can be used.

However, when using non-ionic surfactant fountain solution, the amount of water on the plate must be strictly controlled, and the supply of fountain solution should be reduced as much as possible without causing scumming.

Reducing the use of alcohols in fountain solution is an important research topic in environmental protection efforts in various countries. Japan's eco-label standards also explicitly set forth requirements for reducing alcohol usage. With reference to Japan's eco-label standards, we have stipulated a limit requiring that the amount of alcohol added to fountain solution be less than 5%. At present, alternatives to alcohol-based fountain solutions have matured, so we also advocate the use of alcohol-free fountain solutions.

Blanket requirements

Blankets are an important raw and auxiliary material for offset printing. Ink is transferred from the printing plate to the paper via the blanket, so all offset printing requires blankets. However, during use, blankets wear out due to high-speed operation, and once worn they need to be replaced. Because some enterprises pay little attention to resource recycling, it is common for an entire blanket to be discarded. The standard therefore specifies that blankets replaced on large-format presses may be used on single-color presses or small-format presses.

Surface treatment requirements

At present, surface treatment of printed matter generally falls into two categories: laminating or varnishing, both of which are used in large quantities in the post-press finishing of books and packaging and decorative products. They are also the main source of the VOCs that ultimately affect the product. Compared with conventional solvent-based varnishing, UV varnishing and water-based varnishing used in varnishing generate lower pollutant emissions; therefore the Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing supports their use. Laminating is divided into wet lamination and pre-coated film lamination. Wet lamination is further divided into solvent-based wet lamination and water-based wet lamination. Solvent-based wet lamination is already prohibited by this standard, and water-based wet lamination produces no volatile organic compounds, so this standard supports the use of water-based wet lamination;

Because pre-coated film emits no volatile organic compounds during the post-press process, it is more environmentally friendly, and this standard therefore supports the use of pre-coated film. Special-purpose wipes are used to clean blankets (without cleaning solution). The special wipes for the automatic blanket washing devices of offset presses are a roll-type nonwoven fabric composed of fine fibers (PET 45%) and pulp (55%). They contain cleaning agent ingredients, so no cleaning solution is needed when cleaning blankets, avoiding VOC emissions from cleaning solutions and the waste (hazardous waste) previously generated after use.

Use of processless CTP plates (eliminating the development process)

Processless CTP plates for offset printing refer to plates that, after exposure and imaging on computer-to-plate equipment, require no subsequent processing steps such as chemical development and fixing and can be put on press for printing, and that generate no liquid or solid waste of any kind. However, some CTP plates, after exposure and imaging, do not require chemical development but do require certain individual non-chemical processing steps.

This eliminates chemical treatments for plate development, fixing and cleaning, and prevents the discharge of ablation debris and developing, fixing and cleaning waste liquids (hazardous waste). Use of polyurethane (PUR) type hot-melt adhesive Use of polyurethane (PUR) type hot-melt adhesive, in terms of environmental protection requirements, has

two advantages:

1. Low consumption: for binding the same number of books and periodicals, the amount of PUR adhesive used is only 1/3 of the EVA amount.
2. The temperature for using EVA adhesive is 170 °C, while the temperature for using PUR adhesive is 120 °C. The power of the respective heating and gluing units is 25.5 kW and 7 kW, so using PUR saves more energy.

PUR adhesive has almost no odor at all during use, whereas with EVA a large amount of smoke escapes into the production environment during production and the smell is quite pungent. In comparison, PUR adhesive has the advantage of reducing gas (VOC) emissions.

(4) Requirements for environmental protection in the production process of offset printing products

The Technical Requirement for Environmental Labeling Products — Printing Part: Offset Printing sets requirements for resource conservation, energy saving and recycling and reuse involved in the environmental protection of each process, including prepress, sheet-fed and web offset printing, and post-press converting. These indicators were formulated by the standard drafting group through in-depth research at enterprises and actual calculations by the relevant participating enterprises. They cover electricity consumption, water consumption, printing paper utilization rate, waste generation and recovery rate, and so on. These indicators involve the production process of each operation, the raw and auxiliary materials used and their consumption, waste recovery, hazardous waste treatment and other items. Through these control indicators, enterprises' implementation of energy conservation and emission reduction is assessed.

III. Environmental benefits of standard implementation

Once the standard is implemented, it will have a significant impact on China's printing industry, greatly helping to advance the industry's goals of energy conservation and emission reduction and the development of a low-carbon economy, and improving and raising the level of environmental protection in China's printing industry. Because many printing companies still use traditional printing processes, some production steps continue to cause environmental problems, such as the volatilization of solvents that are toxic and harmful to human health and cause air pollution, and the discharge of wastewater that damages water quality and contaminates soil. The promotion of the environmental label standard can play a major role in the following areas.

1. Reduce the use of highly polluting inks.
2. Reduce the use of fountain solutions containing isopropyl alcohol. Fountain solution is essential to forming a hydrophilic salt layer on the non-image areas of the plate, and offset presses currently use isopropyl alcohol fountain solution systems. Because the alcohol vapor produced after isopropyl alcohol volatilizes is toxic and can cause harmful effects on human health, many developed countries have set the workplace threshold for isopropyl alcohol at only 200–400ml/m

Implementation of this standard can reduce the use of isopropyl alcohol and ultimately achieve its complete replacement in the printing industry.

At present, the annual fountain solution consumption of printing companies of all types across the country is about 160,000 tons, with a total output value of RMB 5 billion. Using the alcohol-free fountain solution CS-T18 can save 1.6 million tons of alcohol. Calculating on the basis that producing 1 ton of ethanol generally consumes 3.2–3.5 tons of grain, this can save more than 4.8 million tons of grain, ease the problem of competing with people for grain, and reduce pollution emissions at multiple stages of the manufacturing process. It can reduce carbon dioxide emissions by about 67 million tons per year (producing 1 ton of alcohol generates about 42 tons of carbon dioxide), and reduce industrial wastewater discharge equivalent to the domestic sewage produced by 30 million urban residents, cutting the cost of pollution treatment at multiple stages by RMB 5 billion.

1. Promote the application of CTP systems.

At present, platemaking in China's printing industry still mostly relies on imagesetters outputting film to make PS plates for printing on press. Film is a silver-halide photosensitive mate-

rial, which contains silver ions, and the spent fixer after fixing also contains large amounts of silver ions. If these substances enter the environment directly, they harm the aquatic environment. The waste rinse liquid from developing and fixing contains large amounts of organic matter and is hazardous waste, which the state prohibits from being discharged directly. However, there are certain deficiencies in the environmental management of domestic companies, and some companies do not attach enough importance to it. Through the environmental label, environmental management will be progressively strengthened so that companies can make environmental progress. The use of CTP direct platemaking eliminates the intermediate steps of platemaking with film (PS plates). If all of the more than 100,000 printing plants nationwide used CTP platemaking, at least 5.4 million tons of water could be saved each year.

This could solve the annual drinking water problem for about 4.4 million people in arid regions. It could reduce carbon dioxide emissions by at least 3.6 million tons per year. If processless CTP plates were used, at least 12.6 million tons of water would be saved each year. At least 8.1 million tons of carbon dioxide emissions would be reduced. More than RMB 1 billion in costs for platemaking film and chemical agents would be saved each year.

— This article is reposted from China Packaging Network (pack.cn). Original link: http://news.pack.cn/show-362015.html