INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

Case Study # 80

1. Headline: Substitution of organic solvent-based

flexographic printing ink on polyethylene to water-based

flexographic printing ink.

2. Background: Landskrona Emballage is a printing company

that mainly produces packages for food and sanitary

articles. The material printed is mostly polyethylene of

different qualities. The company has 40 employees and the

turnover in 1993 was US$ 3.8 million. The case study was

performed in 1991.

3. Cleaner Production Principal: The cleaner technology

principle involves material substitution of water-based

flexographic printing inks which are free from organic

solvents.

4. Description of Cleaner Production Application:

Process and Waste Information: The chemicals handled in

the production were used in the printing process and in

cleaning the printing equipment. The printing ink commonly

used contained 70% organic solvents, principally ethanol

and different glycols. When cleaning the equipment for the

presses, solvents were used which normally were included

in the printing ink.

It is important that the ink must be easy to remove from

press parts and yet have a short drying time during the

printing. Another important requirement is that the ink

has to be resistant to chemicals. The printing quality of

the inks free from volatile organic solvents on products

like bread packages, postal order material and sanitary

articles is now fully comparable with solvent based

printing quality. The modifications made on the equipment

also contributed to the printing quality.

The importance of good adherence between the printing ink

and the polyethylene film increases when printing with

water-based ink. An important factor is the level of

treating (ie the change of the surface tension on the

polyethylene film). Treating equipment was installed in

line on the press to achieve better control over the level

of treatment which is influenced by, for example, the

amount of slip agent and the storing time. In order to

deal with excess ozone, an ozone converter was included in

the equipment.

Traditionally, centrifugal pumps are used to pump ink from

ink fountains to an ink train. Problems, including scum

formation and packing caused by the build-up of layers of

dried ink, arise with this form of pumping when using

water based ink. The problems can be almost completely

eliminated by using peristaltic pumps. All six ink trains

in the presses were equipped with peristaltic pumps.

To limit the amount of ink transferred to a roller,

different types of blades are used to rake off ink excess.

The water-based printing technology required an effective

blade system, something which lead to the installation of

a double blade enclosed chamber system. Problems with

frothing between the rollers could in this way be avoided.

The water based printing ink dries slower than organic

solvent based ink. The drying process is therefore

important. Efforts have been made to modify and make the

drying process more effective and the drying units between

different ink trains were therefore re-built.

The solvent-based printing ink was easy to wash away with

ethanol and ethylene glycol. Since the new water-based ink

is harder to remove, it was necessary to change the

washing routines. The longer washing time can be

compensated for by less need for cleaning of the new

equipment such as the chamber blades and peristaltic

pumps. The new cleaning with water also clearly improves

the work environment.

Since 1991, all printing is being done with water-based

inks in the modified press. The emission of solvents has

in the printing line been considerably reduced from 20

tons a year to nearly zero.

Scale of Operation: The company employs 40 people and the

turnover in 1993 was US$ 3.8 million. The equipment is

available on the market

Material/Energy Balances and Substitutions:

Material Category Quantity Before Quantity After

Waste Generation

discharge of organic

solvents 20 tons nearly 0

Feedstock Use N/A N/A

Water Use N/A N/A

Energy Use N/A No increase

5. Economics: The total investment cost in technology was

US$ 304,000 (1990).

6. Advantages: Generally, the following advantages can be

ascribed to the water-based technology in relation to

solvent-based printing inks:

-Considerable reduction of the discharge of solvents

-No inflammable printing ink

-Improved working environment

-Improved environmental reputation in society and public

relations through visible environmental improvement

activities

7. Constraints: Not reported

8. Contacts

Lars Siljebratt

The Foundation of TEM,

Asumsgatan 38 275 37 Sjobo

Sweden

TEL: +46-416-273 00

FAX: +46-416-273 12

Landskrona Emballage AB

Bevergatan 1

Box 4084

261 04 Landskrona

Sweden

Tel: +46-418-169 70

9. Keywords: Sweden, printing, flexographic printing,

material substitution, ink, polyethylene, peristaltic

pump.

10. Reviewer's Comments: This case study was translated from

Swedish and submitted by the Swedish Foundation of TEM to

UNEP IE. It was edited by UNEP IE in July 1995, but has

not undergone a formal technical review.