U.S. patent application number 13/365596 was filed with the patent office on 2012-05-31 for deinking a cellulosic substrate using magnesium silicate.
Invention is credited to Prasad Y. Duggirala, Michael J. Murcia.
Application Number | 20120135906 13/365596 |
Document ID | / |
Family ID | 41179148 |
Filed Date | 2012-05-31 |
United States Patent
Application |
20120135906 |
Kind Code |
A1 |
Duggirala; Prasad Y. ; et
al. |
May 31, 2012 |
DEINKING A CELLULOSIC SUBSTRATE USING MAGNESIUM SILICATE
Abstract
A composition and method for deinking is disclosed. The
composition and method contain an activated magnesium silicate or a
magnesium silicate.
Inventors: |
Duggirala; Prasad Y.;
(Naperville, IL) ; Murcia; Michael J.; (DeKalb,
IL) |
Family ID: |
41179148 |
Appl. No.: |
13/365596 |
Filed: |
February 3, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12169831 |
Jul 9, 2008 |
8133350 |
|
|
13365596 |
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Current U.S.
Class: |
510/174 |
Current CPC
Class: |
D21C 5/027 20130101;
Y02W 30/64 20150501; Y02W 30/648 20150501 |
Class at
Publication: |
510/174 |
International
Class: |
C11D 3/60 20060101
C11D003/60 |
Claims
1. A composition comprising: a. activated magnesium silicate; b.
optionally a suspending agent for said activated magnesium
silicate; c. water; d. optionally an emulsifier; e. optionally
excluding caustic soda; and f. optionally excluding hydrogen
peroxide.
2. The composition of claim 1, wherein said suspending agent is a
thickening agent.
3. The composition of claim 2, wherein said thickening agent is
selected from the group consisting of: galactomannans; guar gum;
locust bean gum; xanthan gum; para gum; cellulosics; hydroxypropyl
methylcellulose; hydroxypropyl cellulose; carrageean; alginates;
sodium alginates; potassium alginates; ammonium salt alginates; and
a combination thereof.
4. The composition of claim 1, wherein said composition contains
from about 5% to about 70% of said activated magnesium silicate,
based upon weight of the composition.
5. The composition of claim 1, wherein said composition contains
from about 0.05% to about 20% of said suspending agent, based upon
weight of the composition.
6. The composition of claim 1 further comprising: an oil
7. The composition of claim 6 wherein said composition contains
from about 2% to about 55% of said oil based upon the weight of the
composition.
8. The composition of claim 1 wherein said composition contains
from about 0.5% to about 20% of said emulsifier.
9. The composition of claim 6, wherein said oil contains a fatty
acid, optionally further comprising rosin, optionally wherein the
content of rosin in the composition is from greater than 0% to
about 30% based upon weight of the fatty acid.
10. The composition of claim 9, wherein said oil is used to form an
oil and water emulsion.
11. The composition of claim 1 wherein said emulsifier is a
surfactant.
12. The composition of claim 9, wherein said fatty acid contains a
tall oil fatty acid.
13. The composition of claim 1, wherein the emulsifier is selected
from the group consisting of: sorbitol derivatives; polysorbate 80;
sorbitan monolaurate; polysorbate 20; ethoxylated alcohols; sodium
laureth sulfate; polyethylene glycol; sulfate esters; sodium lauryl
sulfate; and a combination thereof.
14. A composition comprising: a. activated magnesium silicate; b.
water; c. xanthan gum; d. tall oil fatty acid; and e. sodium lauryl
sulfate
15. The composition of claim 14 wherein the composition is
comprised of about 18% of said activated magnesium silicate; about
0.288% xanthan gum; about 22% tall oil fatty acid; and about 2%
sodium lauryl sulfate.
16. A composition comprising: a. magnesium silicate; b. a
suspending agent for said magnesium silicate; c. water; d.
optionally an emulsifier; e. optionally excluding caustic soda; and
f. optionally excluding hydrogen peroxide.
Description
[0001] This application is a divisional application of U.S. patent
application Ser. No. 12/169,831, filed Jul. 9, 2008.
FIELD OF THE INVENTION
[0002] The invention pertains to compositions and methods for
deinking a cellulosic substrate.
BACKGROUND OF THE INVENTION
[0003] Efficiently removing ink from secondary fiber without
impacting fiber quality is one of the major challenges in paper
recycling. Currently, the most widespread method of removing ink
from secondary fiber is an alkaline process that uses sodium
hydroxide, sodium silicate, hydrogen peroxide, surfactants and
chelants. The caustic is used to elevate the pH in the repulper
causing the fiber to swell, which assists in ink detachment, but
also yellows the fiber clue to interaction with lignin in
mechanical grades, resulting in a brightness loss. Peroxide is
added to reduce fiber yellowing, and chelant is added to prevent
peroxide degradation by metals. Surfactants are used to manage the
detached ink and prevent redeposition onto the fiber.
[0004] While the conventional method of deinking is effective for
ink removal, it has disadvantages. When the cost of the chemicals
needed to overcome the unwanted effects of caustic is considered,
the alkaline method is quite expensive. Aside from the high cost of
the chemicals used, handling caustic can be hazardous, and it is
critical to maintain the proper balance of caustic, peroxide and
silicate to produce fiber with the desired optical properties.
Moreover, any residual fiber yellowing, or chromophoric generation,
that is caused by caustic and cannot be removed with bleaching is
balanced blue dye to the fiber. While this is effective for
achieving a neutral color balance, it reduces ISO brightness,
making it difficult to reach brightness targets. In addition, a
recent study showed that fiber strength and tensile index was
reduced for secondary fiber deinked under alkaline conditions.
Finally, the elevated pH in the pulper saponifies adhesives,
thereby introducing more stickies into the papermaking system,
which cause runnability problems for the paper machine.
[0005] An improved methodology is therefore desired.
SUMMARY OF THE INVENTION
[0006] The present invention provides for a composition comprising:
(a) activated magnesium silicate; (b) optionally a suspending agent
for said activated magnesium silicate; (c) water; (d) optionally an
emulsifier; (e) optionally excluding caustic soda; and (f)
optionally excluding hydrogen peroxide.
[0007] The present invention also provides for a composition
comprising: (a) magnesium silicate; (b) a suspending agent for said
magnesium silicate; (c) water; (d) optionally an emulsifier; (e)
optionally excluding caustic soda; and (f) optionally excluding
hydrogen peroxide.
[0008] The present invention also provides for a method of removing
ink from a cellulosic containing substance comprising: (a) adding
to the substance a composition comprising: (1) activated magnesium
silicate, (2) water, (3) optionally a suspending agent for said
activated magnesium silicate, and (4) optionally an emulsifier; (b)
optionally excluding adding caustic soda to the cellulosic
containing substance; and (c) optionally excluding adding hydrogen
peroxide to the cellulosic containing substance.
[0009] The present invention further provides for a method of
removing ink from a cellulosic containing substance comprising: (a)
adding to the substance a composition comprising: (1) magnesium
silicate, (2) a suspending agent for said magnesium silicate, (3)
water, and (4) optionally an emulsifier; (b) optionally excluding
adding caustic soda to the cellulosic containing substance; and (c)
optionally excluding adding hydrogen peroxide to the cellulosic
containing substance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows residual ink data after the application of an
activated magnesium silicate and emulsified TOFA formulation to
fiber.
[0011] FIG. 2 shows ISO brightness after the application of an
activated magnesium silicate and emulsified TOFA formulation to
fiber.
[0012] FIG. 3 shows sheet yellowness after the application of an
activated magnesium silicate and emulsified TOFA formulation to
fiber.
[0013] FIG. 4 shows fiber whiteness after the application of an
activated magnesium silicate and emulsified TOFA formulation to
fiber.
DETAILED DESCRIPTION OF THE INVENTION
A. Definitions
[0014] "Suspending agent" means one or more agents that prevents
precipitation of a stabilized dispersion of colloidal particles in
solution.
[0015] "Activated magnesium silicate" means a formulation that
includes magnesium silicate plus one or more components that
provides additional deinking performance over the magnesium
silicate alone, e.g. oil added as formulation with magnesium
silicate. For example, if the magnesium silicate is mixed with an
oil and that oil meets the requirements of providing additional
deinking performance, then the magnesium silicate is an activated
magnesium silicate.
[0016] "Recycling process" means any process that involves the
handling of secondary fibers.
[0017] "TOFA" means tall oil fatty acid.
[0018] "%" means percent by weight of the composition.
[0019] B. Compositions
[0020] As stated above, the present invention provides for a
composition comprising: (a) activated magnesium silicate; (b)
water; (c) optionally a suspending agent for said activated
magnesium silicate; (d) optionally an emulsifier; (e) optionally
excluding caustic soda; and (f) optionally excluding hydrogen
peroxide. The present invention also provides for a composition
comprising: (a) magnesium silicate; (b) a suspending agent for said
magnesium silicate; (c) water; (d) optionally an emulsifier; (e)
optionally excluding caustic soda; and (f) optionally excluding
hydrogen peroxide.
[0021] In one embodiment, the suspending agent is a thickening
agent.
[0022] In another embodiment, the thickening agent is selected from
the group consisting of: galactomannans; guar gum; locust bean gum;
xanthan gum; para gum; cellulosics; hydroxypropyl methylcellulose;
hydroxypropyl cellulose; carrageean; alginates; sodium alginates;
potassium alginates, ammonium salt alginates; and a combination
thereof.
[0023] In another embodiment, the composition contains from about
5% to about 70% of said activated magnesium silicate/magnesium
silicate, based upon weight of the composition.
[0024] In another embodiment, the composition contains about 18% of
said activated magnesium silicate/magnesium silicate, based upon
weight of the composition.
[0025] In another embodiment, the composition contains from about
0.05% to about 20% of said suspending agent, based upon weight of
the composition.
[0026] In another embodiment, the composition contains about 0.3%
of said suspending agent, based upon weight of the composition.
[0027] In another embodiment, the composition comprises an oil.
[0028] In another embodiment, the composition contains from about
2% to about 55% of said oil based upon the weight of the
composition.
[0029] In another embodiment, the composition contains about 22% of
said oil based upon the weight of the composition.
[0030] In another embodiment, the oil contains a fatty acid.
[0031] In another embodiment, the oil is used to form an oil and
water emulsion.
[0032] In another embodiment, the composition contains from about
0.5% to about 20% of said emulsifier.
[0033] In another embodiment, the composition contains about 2% of
said emulsifier.
[0034] In another embodiment, the emulsifier is a surfactant.
[0035] In another embodiment, the fatty acid contains a tall oil
fatty acid.
[0036] In another embodiment, the emulsifier is selected from the
group consisting of: sorbitol derivatives; polysorbate 80; sorbitan
monolaurate; polysorbate 20; ethoxylated alcohols; sodium laureth
sulfate; polyethylene glycol; sulfate esters; sodium lauryl
sulfate; and a combination thereof.
[0037] In another embodiment, the composition comprises: (a)
activated magnesium silicate/magnesium silicate; (b) xanthan gum;
(c) tall oil fatty acid; (d) sodium lauryl sulfate; and (e)
water.
[0038] In a further embodiment, the composition is comprised of
about 18% of said activated magnesium silicate/magnesium silicate;
about 0.288% xanthan gum; about 22% tall oil fatty acid; and about
2% sodium lauryl sulfate.
[0039] In another embodiment, the composition excludes caustic
soda, optionally comprising rosin wherein the content of rosin in
the composition is from greater than 0% to about 30% based upon
weight of the fatty acid.
[0040] These compositions may be applied in methods of removing ink
from a cellulosic containing substance/substrate. In the next
section, various embodiments of these applications are
discussed.
[0041] C. Methods
[0042] As stated above, the present invention provides for a method
of removing ink from a cellulosic containing substance comprising:
(a) adding to the substance a composition comprising: (1) activated
magnesium silicate, (2) water, (3) optionally a suspending agent
for said activated magnesium silicate, and (4) optionally an
emulsifier; (b) optionally excluding adding caustic soda to the
cellulosic containing substance; and (c) optionally excluding
adding hydrogen peroxide to the cellulosic containing substance.
The present invention also provides for a method of removing ink
from a cellulosic containing substance comprising: (a) adding to
the substance a composition comprising: (1) magnesium silicate; (2)
a suspending agent for said magnesium silicate; (3) water; and (4)
optionally an emulsifier; (b) optionally excluding adding caustic
soda to the cellulosic containing substance; and (c) optionally
excluding adding hydrogen peroxide to the cellulosic containing
substance.
[0043] The performance of a deinking process can be measured in a
variety of ways. Typically, optical properties such as brightness
(B), whiteness (L), red/green color balance (a) and yellow/blue
color balance (b*) are measured on a sheet formed from the
resulting deinked fiber.
[0044] In addition to optical properties, an ink speck count
measurement is used to evaluate the efficiency with which the ink
is removed. Residual ink can be expressed in terms of specks/unit
area, percent coverage of ink specks on an area, or effective
residual ink concentration (ERIC), which is commonly expressed in
ppm.
[0045] In one embodiment, the cellulosic substance is located
anywhere in a recycling process up through one or more flotation
accepts.
[0046] In another embodiment, the emulsifier is added separately to
the cellulosic containing substance.
[0047] In another embodiment, the suspending agent is a thickening
agent.
[0048] In another embodiment, the thickening agent is selected from
the group consisting of: galactomannans; guar gum; locust bean gum;
xanthan gum; para gum; cellulosics; hydroxypropyl methylcellulose;
hydroxypropyl cellulose; carrageean; alginates; sodium alginates;
potassium alginates, ammonium salt alginates; and a combination
thereof.
[0049] In another embodiment, the composition contains from about
5% to about 70% of said activated magnesium silicate/magnesium
silicate, based upon weight of the composition.
[0050] In another embodiment, the composition contains about 18% of
said activated magnesium silicate/magnesium silicate, based upon
weight of the composition.
[0051] In another embodiment, the composition contains from about
0.05% to about 20% of said suspending agent, based upon weight of
the composition.
[0052] In another embodiment, the composition contains about 0.3%
of said suspending agent, based upon weight of the composition.
[0053] In another embodiment, the composition further comprises: an
oil. In another embodiment, the composition contains from about 2%
to about 55% of said oil based upon the weight of the
composition.
[0054] In another embodiment, the composition contains about 22% of
said oil based upon the weight of the composition.
[0055] In another embodiment, the composition contains from about
0.5% to about 20% of said emulsifier.
[0056] In another embodiment, the composition contains from about
2% of said emulsifier.
[0057] In another embodiment, the oil contains a fatty acid.
[0058] In another embodiment, the oil is used to form an oil and
water emulsion.
[0059] In another embodiment, the emulsifier is a surfactant.
[0060] In another embodiment, the fatty acid contains a tall oil
fatty acid.
[0061] In another embodiment, the emulsifier is selected from the
group consisting of: sorbitol derivatives; polysorbate 80; sorbitan
monolaurate; polysorbate 20; ethoxylated alcohols; sodium laureth
sulfate; polyethylene glycol; sulfate esters; sodium lauryl
sulfate; and a combination thereof
[0062] In another embodiment, the composition excludes caustic
soda.
[0063] In another embodiment, the composition further comprises
rosin, optionally wherein the content of rosin in the composition
is from greater than 0% to about 30% based upon weight of the fatty
acid.
[0064] In another embodiment, the method of removing ink from a
cellulosic containing substance comprises: (a) adding to the
substance a composition comprising: (1) activated magnesium
silicate/magnesium silicate, (2) xanthan gum, (3) tall oil fatty
acid, (4) sodium lauryl sulfate, and (5) water; (b) optionally
excluding adding caustic soda to the cellulosic containing
substance; and (c) optionally excluding adding hydrogen peroxide to
the cellulosic containing substance.
[0065] In further embodiment, the composition is comprised of about
18% of said activated magnesium silicate/magnesium silicate; about
0.288% xanthan gum; about 22% tall oil fatty acid; and about 2%
sodium lauryl sulfate.
[0066] The methodologies of the present invention can be applied to
a paper recycling process, when deinking is desired.
[0067] In one embodiment, the composition is added to a paper
recycling process in at least one of the following locations: a
pulper; dilution stage; flotation cell thickening stage; and a
kneader.
[0068] In another embodiment, the composition is added in a pulper
of a paper recycling process.
[0069] In another embodiment, the composition is added at a
dilution stage of a paper recycling process.
[0070] In another embodiment, the composition is added at a
thickening stage of a paper recycling process.
[0071] In another embodiment, the composition is added in a
flotation cell of a paper recycling process.
[0072] In another embodiment, the composition is added in a kneader
of a paper recycling process.
[0073] In another embodiment, the substance contains one or more
paper fibers.
[0074] In another embodiment, the paper fibers are secondary fibers
in a paper recycling process.
[0075] The following examples are not meant to be limiting.
EXAMPLES
[0076] A formulation for the removal of ink from secondary fiber
using under neutral pH conditions can best be realized by
thickening a sample of deionized (DI) water with xanthan gum at
2.0% by weight with gentle stirring. Adding a 50/50 mixture of
polysorbate 80 and polysorbate 20 at 2.5% by weight for the
combined surfactant to the xanthan gum enables the emulsification
of tall oil fatty acid at 5.15% by weight with mixing of the
solution. While mixing, magnesium silicate particles with 1 micron
particle size are added to the emulsion at a concentration of 5.15%
by weight. To achieve a stable formulation while maintaining a
fluid viscosity capable of being pumped, the overall solids in the
formulation is in the range of 15% but can be increased to higher
solids percentages.
[0077] For example, 0.4 g of xanthan gum is added to 20 ml of DI
water with gentle stirring to assist in dissolving the powder. 0.25
g of polysorbate 20 and 0.25 g of polysorbate 80 are added to the
xanthan gum solution. 1.2 g of TOFA is added and emulsified with
gentle stirring, along with 1.2 g of magnesium silicate, resulting
in a stable emulsified slurry of activated magnesium silicate and
TOFA. The prepared sample is suitable to remove ink from 120 g of
secondary fiber.
[0078] The deinking treatment can then be added to secondary fiber
in the repulping process at a high consistency of fiber and an
elevated temperature (.about.25-100.degree. C.) where the sheets
are disintegrated into fiber. To assist in producing a sheet with
higher brightness, peroxide can be added to the pulper upon the
addition of the disclosed formulation. Traditionally, hydrogen
peroxide is added to the pulper in caustic deinking at a ratio of
0.6:1 caustic to hydrogen peroxide. In the absence of alkalinity,
hydrogen peroxide is not activated with the neutral deinking
formulation, and therefore there is no benefit seen from adding it
to the repulper.
[0079] Upon complete repulping, the disintegrated secondary fiber
is diluted and placed into a floatation cell where detached ink is
separated from the fiber using an agitator and air bubbles passing
from the bottom to the top of the cell, collecting liberated ink
particles. This creates a froth that carries the ink and is removed
from the top of the floatation cell. Typical floatation
temperatures range from .about.25-100.degree. C. Upon completion of
the floatation stage, the deinked fiber is collected and residual
ink and optical measurements are made.
Measurement Methods:
[0080] For the studies mentioned below, optical properties of
deinked fiber were measured using a Technidyne Colortouch 2 on
handsheets prepared according to TAPPI method T218. In the interest
of reducing effects of sample preparation, ink speck counts were
performed using a PAPRICAN Ink Scanner by Op-Test on the same
sheets used for optical characterization.
Sample Results:
[0081] As shown in FIG. 1, residual ink remaining after the
deinking process was measured on handsheets made from deinked
fiber. The efficacy of the activated magnesium silicate and
emulsified TOFA formulation is clear when compared to the
variations on the formulation and the conventional caustic deinking
benchmark.
[0082] As shown in FIG. 2, ISO brightness was measured on
handsheets made from secondary fiber deinked under various
conditions. The data shows that the disclosed deinking formulation
is capable of matching the conventional caustic deinking treatment
in brightness gain when a bleaching agent is added to the
repulper.
[0083] As shown in FIG. 3, sheet yellowness, as measured on
handsheets prepared from deinked fiber, is lower for the disclosed
neutral deinking formulation due to less chromophoric generation
under neutral conditions.
[0084] As shown in FIG. 4, fiber whiteness was measured on fiber
deinked with the experimental neutral formulations. Similar to the
trend observed in the brightness measurements, the proposed
invention nearly matches the conventional caustic deinking
treatment when a bleaching agent is added to the repulper.
* * * * *