Note: Descriptions are shown in the official language in which they were submitted.
~ -`` 1174011
This invention is directed to an improved
fountain solution suitable for use in a lithographic
offset printing press, which solution contains a mix-
ture of a polyol and/or glycol ether partially soluble
in water and a polyol and/or glycol ether completely
soluble in water.
Lithographic printing operations require the
use of a dampening or fountain solution to achieve
proper operation of the press so that good quality prints
are obtained.
The fountain solution is generally a blend
or mixture of water, acids, salts, solvents, and natur-
ally occurring polymeric materials, such as gum arabic,
and/or a variety of synthetic polymers. The purpose of
the fountain solution is to wet the non-image areas of
a printing plate and thus prevent ink from depositing
in these non-image areas. Should the ink deposit in
the non-image area, a poor quality print results.
Traditionally, alcohols, especially isopropanol, were
used in fountain solutions up to 30 percent volume con-
centration levels to achieve best performance in opera-
tion of the press with attendant high quality prints.
The basis for using isopropyl alcohol resides partly
in its ability to transport the fountain solution to
the printing plate by means of the inked rollers in
the press or throu~h its own roller train. This pro-
perty has been attrlbuted to the low surfa_e tension
of the aqueous solution containing the isopropyl alcohol.
This- allows the fountain solution to wet and mi~ with
the ink in the Dahlgren system or to keep ink and
2.
1~'74011
fountain solution separate as in lithographic presses
with conventional dispersin~ systems. However, when the
fountain solution is transported by the rollers in
the form of a thin film, volatile components, especially
the alcohol, are lost. Aside from the cost considerations
in losing the alcohol by evaporation, safety considera-
tions urge against its use. Thus, it is desirable
to find a substitute for the volatile alcohol which
does not have the problems associatéd with using iso-
propyl alcohol~
U.S. Patent 3,877,372 describes an attempt
to eliminate isopropanol from the fountain solution
and use a mixture of butyl ¢elloso? ~, a silicone
glycol copolymer, and a defoamer.
A commercially available fountain solution
utilizes 2-ethyl-1,3-hexanediol as a replacement for
isopropyl alcohol to provide an isopropyl alcohol
free fountain solution. The use of 2-ethyl-1,3-
hexanediol eliminates the toxic and flammable pro-
perties associated with isopropyl alcohol containing
fountain solutions. Also, fountain solutions con~ain-
ing the 2-ethyl-1,3-hexanediol provide a high quality
printed product on a lithographic press.
However, it has been found that in using
the 2-ethyl-1,3-hexanediol containing fountain solu-
tions, the appearance of tinting and/or banding in
the print is observed in many instances. Tinting is
the deposition of minute ink droplets in the non-image
area of the print resuLt~ng in the appearance of a light
tint. Banding is the appearance of narrow dark streaks
4()11
in the print. Thus, there is a desire to develop a
non-isopropyl alcohol containing fountain solution
whose use would substantially eliminate the appearance
of tlnting and/or banding in a print.
DESCRIPTION OF THE INVENTION
It has now been found that when a mixture of
a polyol and/or glycol ether partially soluble in water
arld a polyol and/or glycol ether completely soluble
in water is used in a fountain solution; tinting
and/or banding-in the resulting print is substantially
reduced and in many instances eliminated.
The use of such a mixture as a replacement
for isopropyl alcohol eliminates the toxic and flam-
mable properties of conventional isopropyl alcohol-
containing fountain solutions and provides a fountain
solution that has the other desirable properties which
provide a high quality printed product on a lithographic
plate.
~ he fountain solution contains between about
'0 0.5 and about 10 percent by volume of the mixture.
The mixture of polyols and/or glycol ethers
which is suitable for use in this invention include a
polyol and/or glycol which is partially soluble in
water, such as 2-ethyl-1,3-hexanediol, Esterdiol-204,
i.e., HOCH2CCCH3~2CH2OCOC(CH3)2CH2OH, Hexyl Cello-
solve~ i.e., C6H13OCH2CH2OH, Hexyl Carbitol~ i.e.,
C6H13OCC2H4O~2H, and the like. The polyol and/or
glycol ethers which is completely soluble in water
4.
1i74Vll
includes, for exEmple, propylene glycol, ethylene
glycol, dipropylene glycol, diethylene glycol, hexylene
glycol, triethylene glycol, tetraethylene glycol, tr -
- propylene glycol, 1,5-pentanediol, methyl cellosolve.
i.e., CH30C2H40H, 6ellosolve~solvent, i.e., C2H50C2H40H,
butyl Cellosolve~solvent~ i.e., C4HgOC2H40H,ant the like-
The solubility is measured by tetermining
the percent by weight of the polyol and/or glycol ether
which is soluble in water at 20C. A polyol antlor
glycol is characterized as partially soluble in water
if its solubility in water at 20C is from about 0.99
to about 28.0 weight percent.
From about 0.08 to about 10 parts by volume
of the polyol and/or glycol ether, which is partially
soluble in water, is uset per part by volume of the
polyol ant/or glycol ether which is completely soluble
in water.
The fountain solution general;y contains
several other ingredients. These include water-soluble
polymers, in particular water-soluble gums which con-
tain carboxyl and hydroxyl groups. Gum arabic is
the oldest and most witely uset polymer. Carboxymethyl
cellulose, hytroxyethyl cellulose as well as s~yrene-
maleic anhydride copolymers, polyvinyl pyrrolidone,
and the like, may also be used. These polymers are
generally used in concentrations of from about 1
and about 10 percent by weight.
5.
` 11'74011
.
The fountain solutions are preferably used
as aqueous acidic solutions. Phosphoric acid is a
preferred acid for use in acidifying the formulation.
Other acids which can be used include inorganic as
well as organic acids, such as acetic acid, nitric
acid, hydrochloric acid, and the like. A buffering
agent, such as ammonium acetate can also be included.
The fountain solution is generally maintained
at a pH of from about 2 to about 5. ~owever, the
particular pH at which a given solution will be main-
tained will depend upon factors, such as the type of
water-soluble polymer used, other ingredients in the
solution as well as the type of substrate employed in
the lithographic printing plate, and the like.
Other additives which may be used in the
fountain solution include preservatives such as phenol,
sodium salicylate, and the like; corrosion inhibitors
such as ammonium bichromate, magnesium nitrate, zinc
nitrate, and the like; hardeners, such as chromium
aluminum, and the like; organic solvents, such as
cyclic ethers, e.g., 4-butyrolactone, and the like; low
molecular weight aldehydes, such as formaldehyde, glu-
taraldehyde, and the like. These additives are generally
used in amounts of from about 0.1 to about 10 percent
by volume.
1:17~011
EXAMPLES
The following examples sesve to illustrate
specific em~odiments of this invention and it is not
intended that the invention shall be l~mited by the
examples.
Control
The following ingredients were mixed together
to form a foun~ain solution base:
0.5 ounce gum arabic
0.5 ounce phosphoric acid (a 5% solution
in water), and
127.0 ounce water
To the formulation,which equaled one gallon
Cl28 ounces) was added 1.3 ouncesof 2-eth~l-1,3-hexane-
diol to make a 1 volume percent concentration of 2-ethyl-
1,3-hexanediol.
The fountain solution was used on a
25 inch production size press with a Dahlgren recircu-
lating dampening system. The press was run with the
damper set at speeds of 40, 50 and 60 running approx-
imately 2ûû sheets of paper at each setting. The optical
density of sheets was measured at each setting. These
optical density measurements were made with an Optical
Densi~ometer. Also, a scum cycle test was performed.
In this test the fountain solution feed was momentarily
stopped to allow the plate to become completely coated
with ink. Then the fountain solution feed was started
and the number of revolutions of the plate before it was
cleaned of excess ink was recorded. Further, visual
~174011
observations were made of the print to determine the
appearance of tinting ant banding.
The results are shown in Table I.
Example 1
The following ingredients were mixed together
to form a fountain solution:
0.5 ounce gum arabic
0.5 ounce phosphoric acid (a 5% solution
in water)
127.0 ounce - water
1.3 ounce 2-ethyl-1,3-hexanediol, and
6.8 ounce propylene glycol
The formulation yielded a 1 volume percent
concentration of 2-ethyl-1,3-hexanediol and a 5 volume
percent concentration of propylene glycol.
The solution was tested as described in
Control A.
The results are shown in Table I.
Example 2
The following ingredients were mixed together
to form a fountain solution:
0.5 ounce gum arabic,
0.5 ounce phosphoric acid (a 5% solu-
tion in water),
127.0 ounce water,
1.3 ounce 2-ethyl-1,3-hexanediol, and
6.8 ounce dipropylene glycol
The solution was tested as described in Con-
trol A.
,, ... . ". . 11740~
The results are shown in Table I.
Example 3
The following ingredients were mixed together
to form a fountain solution:
0.5 ounce gum arabic,
0.5 ounce phosphoric acid (a 5% solution
in wa~er),
127.0 ounce water,
1.3 ounce 2-ethyl-1,3-hexanediol, and
6.8 ounce diethylene glycol
The solution was tested as described in Con-
trol A.
The results are shown in Table I.
Exanç~le 4
The following ingredients were mixed together
to form a fountain solution:
0.5 ounce gum arabic,
0.5 ounce phosphoric acid (a 5% solution
in water),
20 127.0 ounce water,
1.3 ounce 2-ethyl-1,3-hexanediol, and
6.8 ounce hexylene glycol
The solution was tested as described in Con-
trol A.
The results are snown in Table I.
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10 .
1174011
.. . .. . . . ....... . .... .. . . ..... . . .
The data in Table I show that generally
higher optical density values are obtained when 2-
ethyl-1,3-hexanediol is mixed with a glycol. Also,
the scum cycle values are generally lower when 2-ethyl-
1,3-hexanediol is mixed with a glycol, which means
that the addition of the glycol improves the cleansing
operation. Further, addition of glycol to 2-ethyl-1,3-
hexanediol tends to reduce tinting and banding.
Examples 5 to 9
In these Examples fountain solutions were pre-
pared using 2-ethyl-1,3-hexanediol and propylene glycol
where the concentration of propylene glycol was varied.
Example 5
The following ingredients were mixed together
to form a fountain solution:
0.5 ounce gum arabic,
0.5 ounce phosphoric acid (a 5% solution
in water),
127.0 ounce water,
1.3 ounce 2-ethyl-1,3-hexanediol, and
2.6 ounce propylene glycol
The formulation yielded a 2 volume percent
- concentrat~on c propylene glycol.
The formulations were used on the press
described in COn~rO. A~ lhese aifferent inks were
used: offset ink No. 205; heatset web offset ink No.
204; and an acrylic modified sheet offset ink. similar
to No. 205 CNational Association Printing Ink Manu-
facturers, August, 1974~. The optical density was
measured. Also, the scum cycle test was performed.
The results are shown in Table II.
11 .
1~401~
.. ~ . . . ....... . . . . ~ , . .. .
~xample 6
Example 5 was exactly repeated except that
5.2 cunces of propylene glycol were used. The formula-
tion yielded a 4 volume percent concentration of the
glycol .
The results are shown in Table II.
Example 7
Example 5 was exactly repeated except that
7.8 ounces of propylene glycol were used: The formula-
tion yielded a 6 volume percent concentration of the
glycol.
The results are show~ in Table II.
Example 8
Example S was exactly repeated except that
10.4 ounces of propylene glycol were used. The form-
ulation yielded an 8 volume concentration of the glycol.
The results are shown in Table II.
Example 9
Example 5 was exactly repeated except that
13.0 ounces of propylene glycoi were used. The form-
ulatio~ yielded a 10 volume concentration of the glycol.
The results are shown in Table II.
il~4011
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