Pollution Prevention in a Lithographic Pressroom
by Lyle I. Van Vleet
The Companyp> Commercial Lithographing Company is a sheetfed offset lithographic printer. The company was established in 1923 by a group of trades people including Mr. Fred Pfeiffer, who in his early career had operated the first offset lithographing press in Kansas City. In 1926 the company moved to its present location at 13th and Chestnut in Northeast Kansas City, Missouri.
Under the guidance of Fred Pfeiffer's four sons, and the current management, the third generation of Pfeiffers, the company has grown to one of the major offset lithographers in Kansas City. We currently employ 150 people and reside in a 150,000 square foot building complex. The company produces high quality printing for major corporate clients. We specialize in greeting cards and other social expression products, labels, packaging, and general commercial printing.
What is sheetfed offset lithography?
Lithography is the most common of the five major printing processes, encompassing about 60% of all printing. It is used in commercial printing/publishing, in-plant print shops, folding carton operations, and quick printers. In the United States there are about 122,000 facilities which employ over 2-million people.
The offset lithographic process utilizes a photo-sensitive printing plate where the image area is distinguished from the non-image area by the chemical treatment of the plate. The image area, usually a photo sensitive polymer, is "grease loving" and will attract the lithographic paste inks. The non-print areas, usually the aluminum plate metal, is "water loving" and is kept clean and free of ink with a slightly acidic water solution, called the fountain solution.
The ink and fountain solution are applied to the plate, and the inked image is printed from the plate onto a rubber blanket, which in turn prints on the substrate. Thus the term "offset". Because of the offset blanket, lithography can be used to print on almost any type of substrate: all types of paper, foils, plastics, and sheet metal.
The sheetfed lithographer utilizes equipment which prints on sheeted stock as opposed to roll stock. The paste inks are oil based, and cure by oxidation and polymerization. The flat sheets from the press can be cut, folded, and bound to almost any configuration desired.
Pollutants from the litho pressroom materials included hazrdous chemicals and volatile organic compounds (VOCs), which can participate in the formation of ozone. For the most part, these pollutants are fugitive air emissions. Many pose a potential health hazard to the equipment operators.
There are three major areas in the lithographic printing process where hazardous materials have been used: the ink; the fountain solution; and clean-up solution.
The ink is a mixture of pigment, resins, petroleum oils, and vegetable oils. In the past, hazardous heavy metals such as chromium were used as pigments. Today, due to the efforts of the ink makers, the exposure to many of these metals has been eliminated. For example, last year Commercial used 330,000 pounds of ink. That ink contained about 4000 pounds of cobalt and manganese compounds as catalyst for the curing process, and 2700 pounds of barium compounds, copper, and zinc as pigments. These materials were not emitted to the air, but became part of the printed product.
Sheetfed litho paste inks also contain various oils, which in the state of Missouri are counted as VOCs. However test have shown that 95% of these VOCs are trapped in the paper and ink film. This fact is recognized by the EPA and many other states, including Kansas.
The fountain solution is a mixture of water, acid, gum arabic or synthetic gum, buffers, and wetting agents. Typically, at most lithopgraphic print shops, the wetting agent of choice was 15 to 25% isopropyl alcohol (IPA). IPA reduced the surface tension of the fountain solution which allowed it to flow over the plate. IP Alcohol evaporated readily witout leaving residue in or on the rollers, or on the printed substrate. The evaporation also helped cool the surface of the rollers and plate. However IPA is 100% a VOC, and can participate in the formation of ground level ozone. It is also very flammable.
Cleaning is a major part of the printing process. The majority of cleaning solutions are used to clean the ink rollers and the printing blankets. Lithographers have used various blends of solvents to accomplish these tasks. The solvent blends were generally 100 percent VOCs and many contained hazardous materials
Today I am going to talk about Commercial Lithographing Company's accomplishments in reducing pollution and hazards in our pressroom. We have concentrated on two process areas, the fountain solution and the cleanup solutions, which were our major sources of emission. I will discuss the elimination of Isopropyl alcohol from the fountain solution and review how we eliminated the hazardous chemicals and reduced the VOCs from our cleaning solutions.
Fountain Solution... Isopropyl Alcohol
Under the leadership of Bill Pfeiffer, Jr. and Mike Pfeiffer, a company policy was implemented to minimize the hazards in our printing operation. One of the early objectives was to eliminate the negative environmental affects associated with isopropyl alcohol in the fountain solution.
In 1990, IP Alcohol was a necessity to our business. We operated 41 lithographic units with dampening systems designed to be used with alcohol. We printed a very high quality product using some very unique inks.
At that time our fountain solution contained 15 to 20% IPA in the mixture. The company was purchasing 2000 gallons of IPA every 4 to 6 weeks. We were emitting over 60 tons of VOCs into the air due to the IP Alcohol in the fountain solution. The emissions were fugitive, and were emitted into the pressroom before they found their way outside. The well being of our operators had to be considered.
The management was determined to reduce the amount of alcohol used by the presses. In conjunction with our suppliers and the press manufactureror we embarked on a program to test fountain solution additives. As with other printers throughout the country, it was a program of trial and error. By the end of 1991, we were able to see positive results on the 40 inch presses.
In December of 1991, the state of Missouri promulgated a RACT regulation for offset lithography in Kansas City, in which IPA was to be limited to 10% of the fountain solution. We now had a regulatory concern added to our other reasons to continue reducing alcohol emissions.
The company tested additives, alcohol substitutes, magnetic devices, and electronic devices, all to aid in the reduction of alcohol. At the same time, we were operating a business to produce a high quality product. The costs were high due to excess man-hours, excess press-hours, and excess printed waste.
Eliminating alcohol was a unique problem. It had been used in the lithographic printing process for over 20-years. It was the ideal material for the job, and it was relatively inexpensive. The press operators understood how to maintain the ink and "water" balance to obtain the highest quality printing. Reducing and then eliminating the alcohol made it necessary to relearn the process. Without the dogged perseverance and commitment of management it would have been an almost impossible problem.
By the end of 1992 all our presses were operating with less than 10 percent alcohol in the fountain solution. By the end of 1994 the pressroom was operating alcohol free.
After 5 years of experimentation, successes and failures, we have settled on the alcohol replacement chemistry from two manufacturers. One uses a combination of Propylene glycol, dipropylene glycol monoethyl ether, and tripropylene glycol n-butyl ether. The other uses ethylene glycol monobutyl ether. The benefits from this new combination of chemicals include:
- Approximately 5 percent VOCs in the fountain solution.
- No evaporation: vapor pressure is less than 1 mmHg, so there is no loss in the system prior to printing.
- Non-flammable material, which is safer and easier to handle.
- Meets current regulations.
|40" Printing Units||23||42|
|60" Printing Units||18||16|
|IP Alcohol (lbs.)||123,250||1,400|
|Alcohol Substitute (lbs.)||0||7,900|
|Fountain Solution VOCs||125,450 lbs.||9,700 lbs.|
Results, 1996 compared to 1990:
- Near elimination of IP Alcohol.
- Elimination of a flammable liquid from the pressroom.
- A 97% reduction of VOCs from the fountain solution.
- 20% reduction in cost for fountain solution materials.
At Commercial Lithographing in 1990, the majority of our cleanup was accomplished with a solvent blend we called "type wash". "Type wash" was a combination of methyl alcohol, acetone, and toluene. This solvent was a great blanket wash; it readily dissolved the ink, it evaporated quickly eliminating any manual drying, and it did not leave an oily residue on the rubber blanket.
The problem with "type wash" was that all the constituents were "bad actors", all were listed as hazardous materials, all were suspected health hazards, and all were hazardous air emissions.
|Methyl Alcohol||20,400 lbs.|
In 1991. Bill Pfeiffer, Jr. and Mike Pfeiffer directed the elimination of hazardous chenicals as constituents of our main cleaning solvent, the "type wash.
The approach was very simple. We went to our solvent supplier and asked them to formulate a blanket wash which would closely match the characteristics of "type wash" without using "313" listed hazardous chemicals. The new blanket wash was tested and by the end of 1991 was accepted as a substitute for "type wash".
This was a good-news bad-news situation for the operators. They understood and appreciated the need to eliminate the potential hazards present with "type wash. On the other hand, this new combination of solvents did not clean as well as the toluene rich solvent. The more stubborn cleaning jobs would take additional effort, but they were not impossible to clean.
The blanket wash formula is a blend of ethyl-acetate, n-propyl alcohol, and petroleum naphtha. The vapor pressure at 37 mmHg is down from that of "type wash" at 85 mmHg, and the flash point at 40O F is up from 4O F. Although "blanket wash" is still a very flammable material, it has eliminated the "bad actors" from the pressroom.
|Methyl Alcohol||88 lbs.|
Cleaning Solvents... VOC Reduction
Reduction of the VOC air emissions from cleaning materials has been an ongoing management objective at Commercial. As we saw it, there were two ways we could attack the problem: first, reduce the amount of evaporation; and second, eliminate the materials which contain VOCs.
The majority of our cleaning is done manually with 100 % VOC solvents. In order to reduce evaporation of the solvent, management enforced the following good operating practices:
- Solvents are maintained in closed containers.
- Reusable soiled shop towels are kept in closed containers.
- Minimal amounts of solvent are used on the shop towel.
- A service was employed to wring the solvent from the shop towels with acentrfuge before they were sent to the laundry.
Commercial worked with vegetable ester blanket washes. These materials are made from fatty acid derivatives which are produced from agricultural sources, such as soy oil. They are low VOC materials with high flash points. Their performance is generally acceptable, but their cost per gallon is high.
Unfortunately, we were not able to standardize on these materials for general manual blanket washing due to the cost and to the change in the blanket washing procedure. The low VOC cleaners we tested required application of the material, waiting, washing with a damp towel, rinsing, and finally drying. When we evaluated the cost, it was our determination that the time to clean a blanket, any waste by the operator, and the five fold cost per gallon over "blanket wash" would net much more than our current operating expense.
We did determine that the vegetable ester cleaners did have application in the automatic blanket washers, in three of our presses. When the low VOC washes were tested here they were successful. We have now standardized on two cleaners with less than 3 percent VOCs. The advantage of the automatic blanket washers is that it only uses what it is set for, so there is no waste, and no excess on soiled shop towels. When the blanket washer cycle is complete, the blankets may have to be dried, but in general these materials works well.
Converting to a low vapor pressure solvent has been a challenge. When the vapor pressure drops below 10 mmHg, the material doesn't seem to evaporate and the blankets have to be dried. The solvents we've tried take somewhat more physical work to clean the blankets. But there were significant advantages: the solvent did not evaporate off the rag, allowing the operators to clean more than one blanket with a single charge; the cost per gallon was less; and it improved our ability to recover solvent with the centrifuging service.
It took an aggressive management policy to finally convert our pressroom.
Today solvent usage is taken very seriously:
- Mineral Spirits is the general solvent for blanket washing and roller washing... low vapor pressure, 3.0 mmHg.
- Vegetable ester cleaners are used in the automatic blanket washers.
- The "blanket wash" is on hand for special tough jobs, and is allocated by a supervisor.
- Soiled shop towels are centrifuged, and the recovered solvent is used in fuel blending.
|40" Printing Units||23||42|
|60" Printing Units||18||16|
|"Type wash" (lbs.)||102,600||400|
|"Blanket Wash" (lbs.)||0||9,000|
|Mineral Spirits (lbs.)||20,200||41,000|
|Other Solvents (lbs.)||3,800||3,400|
|Low VOC Cleaners (lbs.)||0||110|
|Cleaning Solution VOCs||126,600 lbs.||53,910 lbs.|
The results, 1996 compared to 1990:
- Near elimination of toluene, acetone, and methanol.
- Reduction in total VOCs.
- Costs for cleaning materials were approximately the same, including the increased centrifuge and waste disposal charges.
Overall in the past 7-years Commercial Lithographing Company has improved the environment and has made the pressroom a safer work place:
- Near elimination of hazardous chemical: toluene, methanol, and acetone.
- Reduction of total VOC emissions, which could result in ground level ozone, from 150 tons in 1990 to 78 tons in 1996.
- Elimination of a highly flammable material from the pressroom.
- Reduction in potential health risks in the pressroom.
Commercial Lithographing is currently implementing projects which will result in additional pollution prevention:
- UV curable Inks and Coatings:
- Ethylene glycol antifreeze:
- Non-Piling Additive
The latest lithographic press installed at Commercial is equiped to print and coat with UV radiation curable inks. Aside from the production and product advantages, this press emits about one third the VOCs of a convential litho press. This process is still undergoing changes as inks and coatings are being developed.
Many of our presses have cooling systems which utilize antifreeze as the transfer fluid. Currently we are in the process of converting to Propylene glycol antifreeze.
Non-piling additive is a material which is added to the fountain solution when an excessive build-up of ink occurs on the rubber blanket during printing. The material lubricates the blanket and allows it to resist the build-up or piling of ink. This material also contains ethylene glycol. We are currently testing a new product which uses hexelene glycol and we are looking into methods to reduce the overall use of a non-piling additive.
- In-house Centrifuge:
- Distillation of Waste Solvent
A $15,000 to $20,000 capital investment plus the labor to operate the system: appears to have a 2 to 4-year recovery. This does not directly reduce pollution, but aids in reaping economical benefits from the changes made to the clean-up solutions.
A $10,000 to $15,000 capital investment, plus labor to operate the system. This could result in the elimination of fuel blending and the ability to reuse some of the recovered clean-up solvents.
I want to thank you for the opportunity to talk to you about Commercial Lithographing Company and our efforts as a sheetfed lithographer to improve and protect the environment.