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AIR3-CT94-2272
Assessment and Improvement of the Recycling Characteristics of Vegetable Oil Based Inks for use with Newsprint and Laser Printed Papers |
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Proposal No: | AIR3-CT94-2272 |
| Date Prepared: | April 1998, September 1999 | |
| Source: | Third year technical report summary July 1997
Final Progress Report |
Introduction
The issue of volatile organic compound (VOC)
emissions and the utilisation of new forms of agricultural products are key
European environmental issues. With approximately 2% of total European VOC
emissions coming from the printing industry, with a high proportion of this
coming from mineral oil degradation, alternatives to these oils within printing
inks was required. Past research had indicated that the use of vegetable oil
based printing inks cause a reduction in VOC emissions. Along with the
increasing demand for recycling secondary fibre and decreasing numbers of
landfill disposal sites, development of good eco-friendly inks is an important
priority.
The AIR programme has funded fundamental research into the recycling characteristics of two main process printing inks to address the above mentioned environmental and agricultural issues. Four partners were involved within the research programme: Pira International (UK); project co-ordinator and de-inking experts for newsprint inks Centre Technique du Papier (France); de-inking experts for sheet fed inks Kao Corporation SA (Spain); de-inking chemical experts Trenal (Belgium); ink formulation experts.
Previous developments of vegetable oil based inks have been restricted within Europe; this was based on previous studies that de-inkability and printability of such inks is poor compared to mineral oil based inks. The overall objectives of the AIR project was to assess and improve the de-inking characteristics of vegetable oil based sheet fed and newsprint inks. The objectives were to be achieved through fundamental studies which would determine the de-inking characteristics of such inks and their individual components in comparison to conventional and commercially available inks. Information generated from the research was used to develop vegetable oil based inks which were more compatible to the recycling process and chemical and mechanical systems capable of dealing with newly formulated inks. The work programme was based on 8 principal tasks as follows:
Summary of Results and conclusions
In summary, the newly formulated vegetable oil based inks have shown
improved de-inking properties when compared to a similar quality mineral oil
based ink. The innovative points that have come from the research will be used
to inform relevant industrial sectors of the benefits of vegetable oil printed
material from a de-inking perspective throughout its life as a potential
resource for recycling. On the basis of the information generated by this
research project, the following conclusions have been made:
Newsprint inks
Sheet fed inks
Summary of results on a task by task basis
Task 1
de-inking assessment of commercially available vegetable
oil based newsprint and sheet fed inks compared to similar quality mineral oil
based inks. Task 1 was divided into two work areas. The first being a study of
the suitability of commercially available surfactants to de-ink vegetable oil
based sheet fed inks. Secondly, various commercially available vegetable and
mineral oil based sheet fed and newsprint printing inks were assessed for their
de-inking characteristics and the effect of natural ageing on their
de-inkability. Part of the study also included the effect of resin concentration
within two commercially available mineral oil based inks to investigate
individual ink component effects on de-inkability.
Newsprint inks
From brightness measurements taken from the
de-inked samples, the inks containing vegetable oils showed promising de-inking
results when compared to a typical mineral oil based ink of similar quality. As
these inks were commercially available inks, not all information was known on
the exact formulations, so it was difficult to assess effects of individual ink
components on de-inkability; this was incorporated into the task 2 study. In
summary, the task 1 study indicated that the vegetable oil based inks
commercially available on the market showed good de-inking properties on
comparison to the mineral based inks.
Sheet fed inks
The commercially available vegetable oil based
sheet fed inks showed the most promising de-inking characteristics for the inks
that were evaluated. As these inks were commercially available inks, not all
information was known on the exact formulations, so it was difficult to assess
effects of individual ink components on de-inkability; this was incorporated
into the task 2 study.
Task 2
ink component evaluation The following investigations
were carried out to assess effects of individual ink components on
de-inkability:
Newsprint
The following trials were incorporated:
Drying rates of vegetable oils within newsprint inks clearly effects de-inkability. Non-drying oils showed the better de-inking characteristics, followed by semi-drying and then the drying oils that showed the poorest de-inkability. Although non-drying oils showed the most promising de-inkability their use within newsprint inks would be restricted due to costs of manufacture and would increase the cost of such inks beyond the acceptable levels for users of newsprint inks. Semi-drying oils would be a more cost effective oil to develop within newsprint inks. It should be noted that if manufacturing costs of non-drying oils are significantly reduced then these oils can realistically be used in newsprint ink formulation. The adverse effects natural ageing can have on ink removal has been restricted for some of the vegetable oil inks that were formulated for this study. For a period of six months effects of natural ageing were minimal for some of the vegetable oil based inks; this means that "older" material entering the recycling chain will not have adverse de-inking effects, as well as being able to source older material if it is printed with these modified vegetable oil based newsprint inks. Resin concentration did not effect de-inking characteristics, but resin type clearly effects the de-inking characteristics of newsprint inks. No differences in de-inking behaviour was seen for the different newsprint furnishes studied.
Sheet fed
The following trials were incorporated:
High siccativity of the oil induces good brightness, but ink detachment is poor, as well as speck contamination which is significantly higher when compared to the low siccativity oils. The amount of resin used has no influence on de-inkability. The type of drier within the ink formulation governs the future attachment of the ink to the fibres. A drier that induces drying at the surface of the ink shows good de-inking characteristics. A drier which induces drying in the centre of the ink will contribute to a strong attachment of the ink onto the fibres. Resistance to natural ageing effects has been observed for some of the newly formulated vegetable oil based sheet fed inks.
Task 3
de-inking chemical development. This task involved the
development of chemical systems that are capable of dealing with the newly
formulated vegetable oil based newsprint and sheet fed inks. Results indicated
that the commercially available Dl140 surfactant was the most efficient
de-inking chemical to use for the newly formulated vegetable and mineral oil
based inks used within the task 2 study
Task 4
improvement of de-inking technology through mechanical
treatment. The new improved vegetable, standard vegetable and mineral oil based
newsprint inks were subjected to conventional flotation, kneading and secondary
flotation stages under different chemical (with and without hydrogen peroxide)
and physical (temperature and kneading energy input) conditions on pilot plant
scale. The study indicated that the new vegetable oil based ink formulation
showed the better de-inking properties after a single flotation stage,
confirming the laboratory trials. Samples taken after kneading did not show any
significant variations in brightness from the first flotation stage, however
hyper washing studies indicated that the potential for further ink removal was
good. Application of a secondary flotation stage post kneading resulted in a
good brightness lift for all three inks. All inks had a similar brightness
result post the flotation stage which matched the hyper washed samples; this
therefore suggested that the majority of ink had now been removed by the
secondary flotation. The following conclusions were derived from this part of
the work.
Task 5
vegetable oil based ink development. From the results
generated within the task 2 study, the following inks were formulated:
Newsprint
A semi-drying vegetable oil with a different type of
resin to the standard vegetable oil based commercial ink was compared with a
commercially available vegetable oil based ink and a mineral oil based ink using
the same type and amount of resin.
Sheet fed
The inks were a reference vegetable oil with
dryers B, saturated vegetable oil with dryers B and a mineral oil-based ink with
dryers B.
Task 6
printability characteristics. Printability tests gave
the following results:
Newsprint
The newly modified vegetable oil newsprint ink had
higher tack (135) than the standard vegetable and mineral oil based inks (both
95). Viscosity was also different for the new ink (6.4) compared to the
reference (7.2) and mineral oil (7.8). Rub tests indicated a poorer result for
the newly vegetable oil based ink, but this was still typical of a newsprint ink
and was therefore acceptable.
Sheet fed
Slight differences between the newly formulated
vegetable oil based ink and the mineral and vegetable reference inks existed.
Tack and viscosity were slightly different but acceptable.
In summary, printability of the newly formulated inks was satisfactory, but improvements can still be made to optimise the product.
Task 7 de-inking evaluations. Task 7 confirmed that the commercially available surfactant Dl140 was the most efficient chemical for de-inking all of the types of inks tested within the study for both sheet fed and newsprint inks.
Task 8
validation of laboratory results on a semi-industrial
scale. Pilot plant trials using the 6 newsprint and sheet fed inks printed onto
industrially made paper confirmed that the newly formulated vegetable oil based
inks showed very good de-inking properties. Pulp, paper and printing parameters
of the de-inked pulps showed no significant differences between the printed
material. Although laboratory printability was poor for all of the inks, there
were no differences between the mineral, reference and new vegetable oil based
sheet fed and newsprint inks.
Conclusions
The newly formulated vegetable oil based inks have
shown improved de-inking properties when compared to a similar quality mineral
oil based inks and standard vegetable oil based inks. The innovative points that
have come from the research will be used to inform relevant industrial sectors
of the benefits of vegetable oil printed material from a de-inking prospective
throughout its life as a potential resource for recycling.
Summary
Introduction
The objective of this research programme was to study and attempt to improve the deinking characteristics of vegetable oil based printing inks for newsprint and sheet fed printing processes. The objectives were achieved through fundamental studies that determined the deinking characteristics of such inks and their individual components in comparison to conventional and commercially available inks. Information generated from the research will be used to develop vegetable oil based inks which are more compatible to the recycling process and chemical and mechanical systems capable of dealing with newly formulated inks.
The programme is divided into various principal activities, with the main investigation over the last few months of the project relating to newsprint and sheet fed printed waste deinking properties. A further study was an extension of previous work concerning the effect of dryers on deinkability of sheet fed printed material. Other work included assessment of deinking of the most promising ink formulations for newsprint printing and validation of laboratory results on a semi-industrial scale.
Activities
The project has now been completed with the following principal tasks having been investigated.
The inks from Task 2 that were the most compatible with the recycling process were formulated for further trials. This part of the investigation indicated that drying agents that give a strong drying very quickly after printing, and which induce drying in the thickness of the print, give a strong attachment of the ink onto the fibres, and cause the formation of big resistant specks which remain in the pulp after deinking.
In Task 7 a laboratory based deinking trial was used to evaluate the most promising inks with different deinking chemicals. Studies investigated the most effective deinking conditions for the newly formulated inks using different deinking surfactants using flotation and washing procedures for validation. Further investigation confirmed that the commercially available surfactant D1140 from Kao Chemicals was the better deinking chemical to use for all three ink types that were studied for both the sheet fed and newsprint printing inks.
This indicated that the vegetable oil based inks were better than the mineral oil based inks in their deinking behaviour. Pulp, paper and printing properties indicated that the recycling of the standard and modified vegetable oil based inks did not have any adverse effects on the properties of the remade sheet fed and newsprint papers used in the investigation.
© Copyright 2006 Policy Statements
Updated
by CPL Press:
03/07/2007
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