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Environmental Resin ER-125 Use in Quickset Inks
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Environmental Resin ER-125 has been formulated
by American Gilsonite Co. for use in all types of offset inks. This resin is
soluble in aliphatic mineral distillates, compatible with phenolic and alkyd
resins, and creates varnishes with low and stable viscosities. ER-125 is almost
totally pure aliphatic hydrocarbon with less than 0.05 percent impurity content.
Environmental Resin ER-125 can provide the quickset or sheetfed ink maker with several advantages. As a result of research performed by ink consultants in Germany, it is demonstrated in Table 1 that several benefits can be achieved by replacing phenolic resins by ER-125 Resin in quickset inks. These benefits can be summarized as follows:
Three quickset varnish formulations compared in our analysis
are summarized below in Table 1. The three columns compare quickset varnish
recipes that contain 40 percent phenolic resin (Column #1), a 50 percent substitution
level of the phenolic resin with ER-125 Resin (Column #2), and a full substitution
of the phenolic resin with ER-125 Resin (Column #3).
The rosin modified phenolic resin used is Worleefen F-120.
This is a fast setting, high gloss resin from Greece, used for quickset inks.
It has a 120° C melting point and a viscosity of 1 Pascal second (30 percent
solids in linseed oil). The alkyd resin used in all cases is Worleekyd L-3,
a linseed oil content and an acid value of 15.
The aliphatic solvents used are from Haltermann Oil Co.
in Germany. The PKWF 6/9 has a boiling point range from 260° C to 290°
C, a 20 percent aromatic content and a 76° C aniline point. The PKWF 28/31
has a boiling point range from 280° C to 310° C, a 20 percent aromatic
content and an 82° C aniline point.
One objective of the varnish examinations was to produce
varnishes with approximately the same viscosity (14.5, 14.5 and 17.5 Pa.s, shown
in Table 2). Table 1 shows that the varnish recipes in Columns #2 and #3 required
extra aliphatic solvent, 6 percent and 10 percent respectively, to maintain
approximately the same initial solution viscosity. This is one demonstration
of ER-125 Resin's economic value, providing that a lower solids content yields
the same solution viscosity .
Table 2 presents the performance results from the quickset
varnishes. As mentioned above, the three varnish viscosities have been equalized
using extra PKWF 6/9 mineral distillates. Please note some very interesting
results. First, while the three viscosities are essentially equal, the varnish
yield values are greatly increased by substituting ER-125 Resin for the rosin
modified phenolic resin. This increase in yield value means that ER-125 Resin
is adding "rheological structure" to the quickset varnishes. In addition,
the ER Resin substitution considerably lowers the varnish tack level from 194
(Column #1) to 104 (Column #3) and it improves the varnish's tack stability
showing an increase of only 38 compared to an increase of 60 when using the
phenolic resin.
Table 3 represents quickset ink recipes. One premise is that each of these formulations has the same concentration of carbon black. Cabot's Elftex 415 carbon black was used; it has a jetness index of 84, a tinting strength of 125, and a surface area of 90 square meters per gram.
Each grinding recipe presented in Table 3 starts with
65 percent of the free-flow varnish produced in Table 1 and 15 percent carbon
black. Then, each finished quickset ink is made by adding more free-flow varnish,
more PKWF 28/31 and 2 percent cobalt/manganese driers to the grinding varnish.
Again, extra PKWF 28/31 is added to produce inks that have approximately the
same viscosity (32, 30 and 34 Pa.s., respectively).
Table 4 presents the performance results of the three
quickset inks produced in Table 3. The most important observations in Table
4 are the beneficial rela-
tionships between the gloss level, the tack level and the setting speed of the
ER-based quickset ink. First, the ink in Column #3 (Complete ER replacement
of the phenolic resin) gives a gloss level five points higher than that of Column
#1 (91 versus 86). While this is not such a great increase, it is achieved at
a somewhat faster setting speed (3.81 compared to 4.08). This means that the
ER-based ink will dry faster, allowing faster printing speeds and yielding a
higher gloss level of the ink at the same time. This results in a cost savings
to the ink maker who normally expects faster drying inks to have lower, not
higher, gloss levels.
In addition, Column #3's ink has the lowest tack level
(initial tack of 130 versus 210 and 144) and the smallest increase in tack (34
compared to 48 and 58). Again, ink makers prefer inks with lower tack levels
because they permit faster printing speeds but lower tack normally implies low
solubility of raw materials in the ink system which gives lower gloss levels,
two big disadvantages. The quickset ink in Column #3 is unique and proves this
theory wrong. It has a lower tack level but a higher gloss level, at the same
time.
Other benefits of the Environmental Resin-based quickset
ink are:
1. its higher gloss level at a lower solids concentration which gives the ink maker an economic advantage;
2. significantly less misting compared to phenolic resin-based
quickset ink recipes;
3. its excellent flow characteristics (935 versus 240).
One slight disadvantage of ER Resin shown in Table 4
is poorer rub resistance of Column #3 compared to Column #1 or #2. However,
none of these inks contain any wax and the ER-based recipe's rub resistance
can be greatly improved by addition of a small concentration of wax. This one
minor deficit can be easily overcome.
Finally, because of the high cost of phenolic resins, it can be shown that ER Resin replacement can reduce raw material costs by more than 20 percent for a quickset ink.
By Joseph Baldassare
American Gilsonite Company, Salt Lake City, Utah
American Ink Maker, Volume 73, No. 10, October 1995
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