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Description  |
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BACKGROUND OF THE INVENTION
Dry toner electrostatic printing inks, including laser and xerographic
inks, are important and growing contaminants in the area of waste paper
recycling. Traditionally, paper has been printed with water or oil-based
inks which were adequately removed by conventional deinking procedures. In
these methods, secondary fiber is mechanically pulped and contacted with
an aqueous medium containing a surfactant. Ink is separated from pulp
fibers as a result of mechanical pulping and the action of the surfactant.
The dispersed ink is separated from pulp fibers by such means as washing
or flotation.
Conventional deinking processes have shown minimal success in dealing with
dry toner electrostatic printing inks, with the necessary chemical and
mechanical treatments of the furnish proving to be time consuming and
often rendering a furnish which is unacceptable for many applications. The
development of a deinking program for office waste contaminated with
electrostatic printed copy will make this furnish more amenable to the
recycling process.
The ability to recycle office waste will prove commercially advantageous
and will have a significant impact on the conservation of virgin fiber
resources. Although electrostatic printed waste has not reached the volume
of impact printed waste commonly seen in the industry, indications are
such that usage of electrostatic print is increasing steadily and that
waste copies available to the recycling industry will also increase.
The present invention enhances the agglomeration and subsequent removal of
electrostatic toner particles through centrifugal cleaners by using
specific commercially available raw materials. It is believed that this
can be accomplished at a wide range of pH levels (5.0 to 11.0) and will
render a furnish that is virtually free of electrostatic printing ink
after subsequent mechanical treatment. The invention allows for the
separation of ink particles and associated binder from pulp fibers, and
causes the particles to agglomerate to a critical range of size and
density, which affords their most efficient removal from the pulp slurry
by centrifugal cleaners.
The present invention demonstrates that specific surfactants with low HLBs
enhance the agglomeration of electrostatic toner particles, allowing
removal through centrifugal cleaning and/or screening. HLB is an
abbreviation for hydrophile-lipophile balance as related to the oil and
water solubility of a material. A high HLB indicates that the hydrophilic
portion of the molecule is dominant, while a low HLB indicates that the
hydrophobic portion of the molecule is dominant. The water solubility of
materials increases with increasing HLB. Traditional deinking processes
utilize a wide variety of high HLB (generally greater than 10) nonionic
and/or anionic surfactants or dispersants to wet and disperse ink
particles to a range of size (about 0.5 to 15 microns) which allows for
their most efficient subsequent removal by washing and/or froth flotation
processes.
Agglomeration is anticipated to be seen at pH levels ranging from 5.0 to
11.0, with no significant deposition of ink expected to be present on
pulping equipment. The advantage of the present invention is that it
allows for agglomeration at an ambient pH, alleviating the need for
caustic or acid tanks in the mill environment.
SUMMARY OF THE INVENTION
The components of the present invention comprise individual surfactants
with hydrophile/lipophile balances of less than or equal to 10.0. It is
expected that these components will also be effective when combined with
aliphatic petroleum distillates (solvents). (The solvents are saturated
hydrocarbons having carbon numbers in the range of C9-C12.) All components
are commercially available.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present inventors have discovered that the addition of an ethoxylated
surfactant, propoxylated surfactant, esterified surfactant or alkanolamide
surfactant to the pulper significantly enhances the agglomeration of
electrostatic toner particles, allowing for their separation from fiber
through centrifugal cleaning and/or screening. This agglomeration is
anticipated to be seen at pH levels ranging from 5.0 to 11.0, with no
significant deposition of ink expected to be present on pulping equipment.
(A pH higher than 11.0 or lower than 5.0 is also believed to be
effective). The individual surfactants allow for agglomeration at an
ambient pH, alleviating the need for caustic or acid tanks in the mill
environment. The raw materials which are expected to be effective in this
invention include:
1. Ethoxylated octylphenols
2. Ethoxylated nonylphenols
3. Dodecylphenol ethoxylates
4. Dialkylphenol ethoxylates
5. Ethoxylated polyoxypropylene glycols
6. Propoxylated polyoxypropylene glycols
7. Primary alcohol ethoxylates
8. Secondary alcohol ethoxylates
9. Glycerol esters of fatty acids
10. Ethoxylated fatty esters
11. Propoxylated fatty esters
12. Sorbitan esters
13. Fatty acid diethanolamides
14. Ethoxylated tertiary amines
15. Polyethoxylated and polypropoxylated polydimethyl siloxanes
The chemical structures of the raw materials are as follows:
Ethoxylated Octylphenols
C.sub.8 H.sub.17 --C.sub.6 H.sub.4 O(CH.sub.2 CH.sub.2 O).sub.n H
n=1-5
Ethoxylated Nonylphenols
C.sub.9 H.sub.19 --C.sub.6 H.sub.4 O(CH.sub.2 CH.sub.2 O).sub.n H
n=1-5
Dodecylphenol Ethoxylates
C.sub.12 H.sub.25 --C.sub.6 H.sub.4 O(CH.sub.2 CH.sub.2 O).sub.n H
n=1-6
Dialkylphenol Ethoxylates
##STR1##
n=1-9
R.sub.1 =R.sub.2 =C.sub.8 H.sub.17, C.sub.9 H.sub.19 or C.sub.12 H.sub.25
Ethoxylated Polyoxypropylene Glycols
##STR2##
n=1-45
m=14-77
Propoxylated Polyoxyethylene Glycols
##STR3##
n=14-77
m=1-45
Primary Alcohol Ethoxylates
CH.sub.3 --(CH.sub.2).sub.x --CH.sub.2 O(CH.sub.2 CH.sub.2 O).sub.n H
x=4-16
n=1-10
Secondary Alcohol Ethoxylates
##STR4##
n=1-8
m=9-12
Glycerol Esters of Fatty Acids
##STR5##
R=R.sup.1 =R.sup.2 =caprylic, capric, lauric, myristic, palmitic,
palmitoleic, stearic, oleic, linoleic, linolenic, alpha-eleostearic,
ricinoleic, gadoleic, arachidonic, behenic, pelargonic, iso-oleic,
iso-stearic
R.sup.1 =R.sup.2 =--H
R.noteq.--H
Ethoxylated Fatty Esters
##STR6##
n.ltoreq.9
R=R.sup.1 =caprylic, capric, lauric, myristic, palmitic, palmitoleic,
stearic, oleic, linoleic, linolenic, alpha-eleostearic, ricinoleic,
gadoleic, arachidonic, behenic, pelargonic, iso-oleic, iso-stearic
R.sup.1 =--H
R.noteq.--H
Propoxylated Fatty Esters
##STR7##
n=2-10
R=R.sup.1 =caprylic, capric, lauric, myristic, palmitic, palmitoleic,
stearic, oleic, linoleic, linolenic, alpha-eleostearic, ricinoleic,
gadoleic, arachidonic, behenic, pelargonic, iso-oleic, iso-stearic
R.sup.1 =H
Sorbitan Esters
##STR8##
R=caprylic, capric, lauric, myristic, palmitic, palmitoleic, stearic,
oleic, linoleic, linolenic, alpha-eleostearic, ricinoleic, gadoleic,
arachidonic, behenic, pelargonic, iso-oleic, iso-stearic
Fatty Acid Diethanolamides
##STR9##
R=caprylic, capric, lauric, myristic, palmitic, palmitoleic, stearic,
oleic, linoleic, linolenic, alpha-eleostearic, ricinoleic, gadoleic,
arachidonic, behenic, pelargonic, iso-oleic, iso-stearic
##STR10##
Ethoxylated Tertiary Amines
##STR11##
R=caprylic, capric, lauric, myristic, palmitic, palmitoleic, stearic,
oleic, linoleic, linolenic, alpha-eleostearic, ricinoleic, gadoleic,
arachidonic, behenic, pelargonic, iso-oleic, iso-stearic, rosin
x=y=1-6
Polyethoxylated and polypropoxylated polydimethyl siloxanes (molecular
weight=600-20,000), as well as sorbitan ester ethoxylates are also
anticipated to be effective surfactants in the agglomeration of
electrostatic toner particles.
For the application of electrostatic toner particle agglomeration, the
effective hydrophile--lipophile balance of the tested surfactants is less
than or equal to 10. It is believed that the effective temperature range
for the agglomeration of electrostatic toner particles is from
110.degree.-190.degree. F.
A beaker test method was utilized to determine the impact of various raw
materials on toner agglomeration without the presence of fiber. This
method allowed for the visual evaluation of toner configuration after
treatment and permitted the particles to be sized using the Brinkmann
Particle Size Analyzer. When raw materials were screened using this
method, those demonstrating significant particle agglomeration were
advanced to the Deinking/Repulping Apparatus (the pulper) for an
evaluation of performance in the presence of fiber.
The experimental procedure was as follows: Approximately 0.01 grams of
toner was added to a beaker containing 100 milliliters of deionized water.
Each solution of toner and water was mixed on a magnetic stirrer at a pH
of 7.0, a temperature of 150.degree. F. and a contact time of 60 minutes.
About 514 parts of raw material per million parts of solution was added to
the beaker. Upon completion of contact time, particle configurations were
noted, and solutions were filtered and held for size evaluation using the
Brinkmann Particle Size Analyzer.
The pulper was then used to evaluate selected raw materials. This apparatus
consists of a Waring blender jar with the blades reversed to provide a
mixing action of the fibers. The stirring of the blender is controlled by
a motor connected to a Servodyne controller. Temperature of the pulp in
the blender is provided by a heating mat attached to a temperature
controller. The typical furnish consistency in the laboratory pulper is
5%, and a stirring speed of 750 rpm is used to simulate the mechanical
action of a hydropulper.
Electrostatic printed wood-free fiber was used as the furnish. Twenty
pounds of raw material per ton of fiber were added to the pulper, at a
temperature of 150.degree. F., a pH of 7.0, and a pulping time of 60
minutes. In Table 1, toner particle agglomeration or the lack thereof
through the use of individual surfactants is listed.
TABLE 1
__________________________________________________________________________
TONER PARTICLE
FUNCTIONAL GROUP HLB APPEARANCE*
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NONIONIC HYDROCARBONS
Ethoxylated Octylphenols
3.6 agglomerated
n = 1.5
15.8 no effect n = 10.0
Ethoxylated Nonylphenols
4.6 agglomerated
n = 1.5
12.9 no effect n = 9.5
17.2 no effect n = 49
Ethoxylated Polyoxypropylene
0.5 agglomerated
n = 9 m = 69
Glycols 1.0 agglomerated
n = 13 m = 56
18.5 no effect n = 3 m = 15
1.0 agglomerated
n = 13 m = 56
12.0 no effect n = 3 m = 16
Primary Alcohol Ethoxylates
4.6 agglomerated
n = 2.0 X = 16
12.2 no effect n = 9.0 X = 16
6.0 agglomerated
n = 4.0 X = 6-8
Glycerol Esters of Fatty Acids
0.8 agglomerated
R = R.sup.1 = Oleic
1.6 agglomerated
R = Oleic, R.sup.1 = H
2.5 agglomerated
R = Oleic, R.sup. 1 = H
2.7 agglomerated
R = Oleic, R.sup.1 = H
2.7 agglomerated
R = Stearic, R.sup.1 = H
2.9 agglomerated
R = Isostearic, R.sup.1 = H
2.8 agglomerated
R, R.sup.1 = fatty acid
Ethoxylated Fatty Esters
8.0 agglomerated
n = 5 R = Oleic, R.sup.1 = H
13.5 no effect n = 14 R = Oleic, R.sup.1 = H
2.0 agglomerated
n = 1 R = Stearic, R.sup.1 = H
3.0 agglomerated
n = 1 R = Stearic, R.sup.1 = H
18.0 no effect n = 40 R = Stearic, R.sup.1 = H
Propoxylated Fatty Esters
1.8 agglomerated
R = Stearic, R.sup.1 = H (monoester)
1.8 agglomerated
R = Stearic, R.sup.1 = H and Stearic
(at least 95% monoester)
3.5 agglomerated
R = Stearic, R.sup.1 = H and Stearic
(at least 67% monoester)
Sorbitan Esters 1.8 agglomerated
R = Trioleic
2.1 agglomerated
R = Tristearic
2.7 agglomerated
R = Sesquioleic
14.9 no effect R = Stearic
Fatty Acid Diethanolamides
1-7 agglomerated
##STR12##
>10.0
no effect R = Coco R.sup.1 = R.sup.2 =
CH.sub.2 CH.sub.2 OH
>10.0
no effect R = Coco R.sup.1 = R.sup.2 =
CH.sub.2 CH.sub.2 OH
CATIONIC HYDROCARBONS
Ethoxylated Tertiary Amines
5.0 agglomerated
R = tallow x + y = 2
12.0 no effect R = tallow x + y = 7
ANIONIC HYDROCARBONS
Organic Phosphate Esters
13-15
no effect
13-15
no effect
SILOXANES
Polyethoxylated and polypropoxylated
5.0 agglomerated
polydimethyl siloxanes
9.0 agglomerated
17.0 no effect
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*agglomeration: particle size > approx. 10 microns
no effect: particle size > approx. 10 microns
While this invention has been described with respect to particular
embodiments thereof, it is apparent that numerous other forms and
modifications of this invention will be obvious to those skilled in the
art. The appended claims and this invention generally should be construed
to cover all such obvious forms and modifications which are within the
true spirit and scope of the present invention.
* * * * *
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