Use of hydrophilic polymer dispersion containing a colloidal silica or an inorganic flocculant as retention and drainage aids in papermaking process.
Field of Invention
The present invention is in the technical field of papermaking. In particular, this invention relates to improved papermaking process utilizing hydrophilic polymer dispersion containing a colloidal silica, or an inorganic flocculant as retention aids and drainage aids.
Background of the invention
In the manufacture of paper, an aqueous cellulosic suspension or slurry is formed into a paper sheet. These three aspects in the below is extremely important for the cost effective papermaking.
1) Drainage:
The cellulosic slurry generally contains less than 1% solids contents (dry weight basis) whereas the finished sheet is required to have more than 94% solid contents. The most cost effective dewatering process is drainage. Also used, yet less cost effective, are felt blanket, blotting, pressing, evaporation, pressing, vacuum etc. as dewatering methods. Since the drainage is the most cost effective and the very first step of dewatering, any improvement of performance of drainage greatly affects the cost and efficiency of dewatering in papermaking.
2) Retention:
The paper furnish contains cellulosic fibers (2-3 millimeter in size), mineral fillers (added to enhance brightness, opacity and other paper characteristics, typically a few micrometers in size), small particles, and other furnish components.
Maximum retention of cellulosic fiber, mineral filler, and other small particles on the fiber mat leads to numerous benefits for papermakers.
A) Retention of Mineral Fillers:
Most widely used mineral fillers, such as Calcium Carbonate, Clay are often less expensive than fibers. These mineral fillers are a good substitute for cellulosic fibers when retained properly in the papermaking process. These mineral fillers also often required to be used to achieve a certain sheet properties (brightness, opacity, optimum interaction with printing ink).
B) Retention of other furnish components, particularly small particulates: As the fiber mat is formed on the wire (typically 200 mesh), these small particulates are not retained and pass through the spaces (pores) between cellulosic fibers in the fiber mat being formed on the wire in papermaking process. The maximum retention of these small particulates is most desired in papermaking process because they can be attached to additives, such as sizing agents, dyes and others, in significant portion, further prohibit the effective performance of these additives. Many papermills recycle their Whitewater. With continuous recycle of Whitewater back into the furnish, the amounts of small particulates increase in the furnish. These further levels prohibit, to a large degree, the effective performance of expensive functional additives, such as Titanium oxide upon recycling of Whitewater. The increased concentration of small particles in the furnish in Whitewater can cause deposit problems, which leads to poor runnability, and poor product quality. An effective retention of mineral fillers, and small particles in the furnish leads to (1) reduced usage of cellulosic fiber, (2) enhanced performance of functional additives, such as sizing agent, and Titanium Oxides, (3) enhanced performance of mineral fillers, (4) reduction in waste material and its disposal, (5) raw material cost saving, (6) enhanced processing, runnability, product quality, and (7) cleaner Whitewater, which will contribute to lower the papermaking cost in overall.
3) Formation:
It relates to level of uniform density and thickness of paper and paperboard both on any particular point of the sheet and across the width of the sheet. When retention and drainage aids are applied to form a floe in wet end, the size of the floe is to do with the formation, retention, and drainage. Large floe may be good for retention and drainage, but leads to poor formation. Small floes may bring much better formation, however it may adversely affect retention and drainage. As the retention increase to higher level over 75%, it is known that the formation becomes an apparent problem in papermakings.
In order to improve retention and drainage in papermaking, various approaches have been made.
U.S. Patent No. 4,388,150 discloses the use of a combination of cationic starch followed by colloidal silica to increase the amount of material retained on the web by charge neutralization and adsorption of smaller agglomerates.
U.S. Patents Nos. 5,098,520 and 5,185,062 disclose to add high molecular weight cationic polymer and then a medium molecular weight anionic polymer (which includes ionizable sulfonate) to papermaking cellulosic slurry, to improve drainage and retention.
U.S. Patents Nos. 4,753,710 and 4,913,775 teach, in order to improve retention and drainage, to add to an aqueous cellulosic papermaking suspension (1 ) a high molecular weight linear cationic polymer before shearing the suspension, followed by the addition of (2) bentonite after shearing. The shearing is generally provided by one or more of cleaning, mixing, pumping of papermaking process. The shearing breaks down the large floes formed by the high molecular weight polymer into microflocs, and further agglomeration then ensues with the addition of bentonite clay particles.
U.S. Patent No. 6,238,521 teaches to add coagulants (such as starch, low molecular weight cationic synthetic polymers, alum), to add a cationic dispersion polymer which is a copolymer comprising about 30 mole % of DADMAC (diallydimethylammoniumchloride) and about 70 mole % Acrylamide before shearing. Either before or after the a cationic dispersion polymer in the above is added, microparticles selected from the group consisting of copolymer(anionic) of acrylic acid and acrylamide, bentonite, dispersed silica are added.
U.S. Patent No. 6,059,930 discloses adding of an effective amount of a hydrophilic dispersion polymers (preferably a copolymer of DMAEA.MCQ- dimethylamonoethyl acrylate methyl chloride quaternary and acrylamide) to an aqueous cellulosic papermaking slurry to improve retention and drainage.
However, there is a strong demand for the retention and drainage system with better performance which utilize a water soluble, cationic dispersion polymer containing a colloidal silica or inorganic flocculant for the better performance with these benefits.
1 ) Water soluble, contains no unwanted oils.
2) Easy of handling — simple static mixing. No aging, no conditioning often associated with an inverse water in oil emulsion polymer, is required.
3) Enhanced performance over water-soluble dispersion polymer which does not contain a colloidal silica or an inorganic flocculant.
Summary of the invention
The method of the invention calls for forming an aqueous cellulosic papermaking slurry, adding an effective amount of a hydrophilic dispersion polymer containing a colloidal silica or an inorganic flocculant to the slurry with adding microparticle (bentonite) after a polymer is added to slurry.
The hydrophilic dispersion polymer comprises (1) Colloidal Silica or (2) Inorganic flocculant.
Brief Description of the Drawings
Fig. 1 shows drainage performance of (Polymer P + Bentonite) or
(Polymer A + Bentonite) over ablank;
Fig. 2 shows drainage performance of (Polymer P + Bentonite) or (Polymer A + Bentonite) over blank;
Fig. 3 shows retention performance in terms of turbidity reduction improvement (%);
Fig. 4 shows drainage performance of (Polymer P + Bentonite) over blank; Fig. 5 shows drainage performance of (Polymer P + Bentonite) over blank
Fig. 6 shows retention performance in terms of turbidity reduction improvement (%);
Fig. 7 shows drainage performance of (Polymer R or Q + Bentonite) over blank; Fig. 8 shows retention performance in terms of turbidity reduction improvement (%);
Fig. 9 shows drainage performance of (Polymer A or K + Bentonite) over blank,
Fig. 10 shows drainage performance of (Polymer A or K + Bentonite) over blank;
Fig. 11 shows retention performance in terms of turbidity reduction improvement (%);
Fig. 12 shows a schematic illustration of Retention Drainage Analyzer-
Hand Sheet Former.
Detailed Description of the invention
An aqueous cellulosic slurry is first formed by any conventional means generally known to those skilled in the art.
The next step of this invention is to add to the slurry a hydrophilic dispersion polymer which contains a colloidal silica or inorganic flocculant.
The hydrophilic dispersion polymer in this invention is formed by the polymerization process of
i) mixing 1.0-25 wt % of acrylamide, 0-2 wt % of anionic monomer selected from the group consisting of acrylic acid, methacrylic acid and itaconic acid, 1.0-30 wt % of cationic monomer mixture of compound of formula I and formula II, 0.5-5 wt % of polymer selected from the group consisting of homopolymer of compound of formula I, homopolymer of compound of formula II and copolymer of compound of formula I and formula II, 10-30 wt % of anionic salt, 0.5-10 wt % of colloidal silica, 0.01-1 wt % of nonionic surfactant, 0.05-2 wt % of dispersion stabilizer and 40-75 wt % of water; ii) 1st-polymerizing the mixture in addition to 0.001-0. 1 wt % of polymerization initiator to said mixture; iii) 2nd-polymerizing the 1 st-polymerized mixture containing unreacted monomers completely; and iv) adding and mixing 10-30 wt % of anionic salt to obtained polymers.
formula I
wherein
R1 is hydrogen atom or methyl;
R2 and R3 are each independently alkyl group having 1 to 3 carbon atoms;
A1 is oxygen atom or NH;
B1 is alkylene group having 2 to 4 carbon atoms or hydropropylene; and
X1 is anionic counter ion.
formula II
wherein
R4 is hydrogen atom or methyl;
R5 and R6 are each independently alkyl group having 1 to 2 carbon atoms; R7 is hydrogen atom or alkyl group having 1 to 2 carbon atoms;
A2 is oxygen atom or NH;
B2 is alkylene group having 2 to 4 carbon atoms or hydropropylene; and X2 is anionic counter ion.
a) Colloidal silica has 10-30 nm of diameter. b) Anionic salt is selected from the group consisting of ammonium sulfate, ammonium chloride, sodium sulfate, magnesium sulfate, aluminium sulfate, ammonium hydrogenphosphate, sodium hydrogenphosphate, and
potassium hydrogenphosphate. c) Dispersion stabilizer is selected from the group consisting of nonionic surfactant and glycerin. d) The ratio of cationic monomer mixture of compound of formula I and formula II is in the range of 10:0 to 2:8.
or
i) mixing 1.0-25 wt % of acrylamide, 0-2 wt % of anionic monomer selected from the group consisting of acrylic acid, methacrylic acid and itaconic acid, 1.0-30 wt % of cationic monomer mixture of compound of formula I and formula II, 0.5-5 wt % of polymer selected from the group consisting of homopolymer of compound of formula I, homopolymer of compound of formula II and copolymer of compound of formula I and formula ll, 10-30 wt % of anionic salt, 1-10 wt % of inorganic flocculant, 0.01-1 wt % of nonionic surfactant, 0.05-2 wt % of dispersion stabilizer and 40-75 wt % of water; ii) 1 st-polymerizing the mixture in addition to 0.001-0.1 wt % of polymerization initiator to said mixture; iii) 2nd-polymerizing the 1st-polymerized mixture containing unreacted monomers completely; and iv) adding and mixing 10-30 wt % of anionic salt to obtained polymers.
R1 is hydrogen atom or methyl;
R2 and R3 are each independently alkyl group having 1 to 3 carbon
atoms;
A1 is oxygen atom or NH;
B1 is alkylene group having 2 to 4 carbon atoms or hydroxypropylene; and
X1is anionic counter ion.
wherein
R4 is hydrogen atom or methyl;
R5 and R6 are each independently alkyl group having 1 to 2 carbon atoms;
R7 is hydrogen atom or alkyl group having 1 to 2 carbon atoms;
A2 is oxygen atom or NH;
B2 is alkylene group having 2 to 4 carbon atoms or hydroxypropylene; and
X2 is anionic counter ion.
a) Inorganic flocculant is selected from the group consisting of polyaluminium chloride, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, aluminium chlorohydrate, and aluminasol. b) Anionic salt is selected from the group consisting of ammonium sulfate, ammonium chloride, sodium sulfate, magnesium sulfate, aluminium sulfate, ammonium hydrogenphosphate, sodium hydrogenphosphate, and potassium hydrogenphosphate. c) Dispersion stabilizer is selected from the group consisting of nonionic surfactant and glycerin. d) The ratio of cationic monomer mixture of compound of formula I and formula II is in the range of 10:0 to 2:8.
(The polymer hereafter refers to a water soluble cationic dispersion polymer which contain a colloidal silica or inorganic flocculant described in the above).
It is important that the polymer added to the slurry to be dispersed effectively within the slurry. The significant amount of dispersion can be accomplished by the shear. During the creation and processing the slurry, shearing is accomplished with cleaning, mixing, and pumping steps of the papermaking.
In regard to the effective dosage of the polymer to the slurry in the papermaking, no maximum dosage has been set which will start to show adverse affect on retention, drainage, and formation. In this patent application, the unit of dosage is noted as kg/ton or ppm which is
(actual weight of the polymer in kg)/(the slurry of which contains 1000 kg solid in dry weight).
As an example, 1 kg/ton dosage means 1 kg of weight polymer is used to the slurry which contains 1000 kg of solid in dry weight.
The dosage between 1 kg/ton and 10 kg/ton is proven to be effective. However, considering the cost/performance, dosage between 1 kg/ton and 2 kg/ton is preferable, specifically, when the system also employs bentonite as microparticles.
The next step of this invention is to add to the slurry bentonite as microparticle to further enhance the performance of retention and drainage. There is an outstanding advantage and superior performance in retention and drainage if bentonite as microparticle is employed after the polymer is added. Bentonite useful as microparticle for this application is (1) any material commercially referred as bentonites or bentonite-type clays, (2) bentonites described in U.S.
Patent No. 4,305,781. The amount of bentonite employed is preferably between 1 kg and 2.5 kg per the slurry which contains 1000 kg of solid in dry weight.
The next step of this invention is to drain the slurry to form a sheet and then drying it to a paper sheet. These steps are well known art within papermaking.
Examples
The following examples are intended to be illustrative of this invention and show the ordinary skill how to use and make the invention. These examples are not intended to limit the invention or its protection in anyway.
Throughout examples, these terms have following meanings.
Dispersion Polymer: Polymers made by a precipitation polymerization process which produces well defined particles, containing very high molecular weights.
RDA-HSF(Retention Drainage Analyzer-Hand Sheet Former) is shown in Figure 12: a hand sheet former which also can measure the performance of retention and drainage. It is comprised of (1) stock preparation A with six impeller (different direction) to create controlled shear, and 6 automatic chemical feeder, (2) sheet formation B (screen, wire), (3) filtrate collection tank C, (4) vacuum induction D. The data is fed to a computer with RS232C cable for plotting.
Polymer C: a water soluble cationic dispersion polymer containing a cationic colloidal silica. Cationic charge density < 10 mol %. Product viscosity < 50 cps. 3% solution viscosity: 80-200 cps. Commercially available from Green Technology Inc. as product no. GX25C. 15% active ingredient.
Polymer A: a water soluble cationic dispersion polymer containing an anionic colloidal silica. Cationic charge density < 10 mol %. Product viscosity < 50 cps.
3% solution viscosity: 80-200 cps. Commercially available from Green Technology Inc. as product no. GX25A. 15% active ingredient.
Polymer P: a water soluble cationic dispersion polymer containing a poly aluminum chloride. Cationic charge density < 10 mol %. Product viscosity
< 50 cps. 3% solution viscosity: 80-200 cps. Commercially available from Green Technology Inc. as product no. GX25P. 15% active ingredient.
Polymer K: a water soluble cationic dispersion polymer containing a cationic and an anionic colloidal silica. Cationic charge density < 10 mol %. Product viscosity
< 50 cps. 3% solution viscosity: 80-200 cps. Commercially available from Green Technology Inc. as product no. GX25K. 15% active ingredient.
Polymer T: a water soluble cationic dispersion polymer containing an inorganic flocculant (Poly aluminum chloride). Cationic charge density < 25 mol %. Product viscosity < 100 cps. 3% solution viscosity: 80-200 cps. Commercially available from Green Technology Inc. as product no. GX30P. 18.5% active ingredient.
Polymer Q: a water soluble cationic dispersion polymer containing an anioic colloid silica. Cationic charge density < 50 mol %. Product viscosity< 100 cps. 3% solution viscosity: 100-200 cps. Commercially available from Green Technology Inc. as product no. GX57A. 20% active ingredient.
Polymer R: a water soluble cationic dispersion polymer containing an anionic colloid silica. Cationic charge density < 25 mol %. Product viscosity < 100 cps. 3% solution viscosity: 100-200 cps. Commercially available from Green Technology Inc. as product no. GX40A. 20% active ingredient.
Blank — Furnish with no addition of polymer and bentonite.
Measuring Drainage performance
1. A vacuum pressure (being reduced continuously) is applied to fiber mat on the wire where wet sheet is formed on RDA-HSF unit. The more effective the drainage aid is, the less amount of vacuum pressure may be needed at any given time (it drains water fast), or the less it would take to reach to any given vacuum pressure applied. Data is read and fed (200 per second) to a computer and plotted.
2. The dewatered wet sheet is pressed and dried according to TAPPI Standard method.
3. Various vacuum pressure has been applied to drain the water from the fiber mat and record the time required to drain all the water from the filtrate per types of polymer added. Data is compared with furnish with no polymers added and plotted as time required and each vacuum pressure applied.
Measuring retention performance
1. Measure turbidity and Suspended Solid of Whitewater (filtrate) sample collected. This will give accurate and concise understanding of retention aids performance with formation analysis information.
2. The turbidity of filtrate is measured in FAU (Formazin Turbidity Unit).
3. The greater retention performance is, the less turbidity is measured. (Better retention will retain more suspended particles, small particles as well as more mineral fillers etc.).
4. The turbidity values (in FTU) that were determined were converted to "Percent Improvement" values with this formula:
Percent reduction (Turbidity-%) = 100 X (Turbidity before addition - Turbidity after addition )/Turbidity before addition.
Example 1
750 gram of 100 % recycled linerboard pulp of which concentration is 0.62 % (i.e. 4.65 gram of solid in this furnish). Add 2.3 cc of polymer P or A (polymer solution concentration is 0.2 %). This is the same as adding 1 kg/ton polymer to furnish. Also add 2 kg/ton of bentonite (actual amount added is 1.5 gram).
Retention and Drainage test on 100% recycled fiber linerboard papermaking of which furnish condition is
Item Data
Paper Grade 180 g/m
Furnish 100 % recycled Linerboard pH 6.90
Ca++ 272 ppm
Concentration 0.62 %
Process Sequence Description
0 seconds Start shear stirring at 600 rpm 0-3 seconds Conditioning at 600 rpm 3-6 seconds Add polymer (1 kg/ton or 1000 ppm) at 800 rpm 6-9 seconds Add bentonite(2 kg/ton or 2000 ppm) at 1000 rpm 9-13 seconds Reaction at 800 rpm 13-18 seconds Conditioning at 1300 rpm 18-28 seconds *Draining with decreasing vacuum pressure.
Measure the vacuum pressure data (200 data per second) - Drainage
28 seconds **Stop draining. Measure the turbidity of filtrate. -
Retention
Drainage performance
Figure 1 shows drainage performance of (Polymer P + Bentonite) or (Polymer A + Bentonite) over blank. As an example, at vacuum pressure of 150 mmHg, it takes to complete the drain 1147/200 = 5.735 seconds when polymer A or P is added with bentonite vs. 1468/200 = 7.34 seconds with no (polymer + bentonite) added. At vacuum pressure of 150 mmHg, 22% drainage performance enhancement was realized with addition of (polymer + bentonite).
Example 2
750 gram of 100% recycled linerboard pulp of which concentration is 0.62 % (i.e. 4.65 gram of solid in this furnish). Add 3.5 cc of polymer P or A (polymer solution concentration is 0.2 %). This is the same as adding 1.5 kg/ton polymer to furnish. Also add 2.5 kg/ton of bentonite (actual amount added is 1.875 gram).
Retention and Drainage test on 100% recycled fiber linerboard papermaking of which furnish condition is
Item Data
Paper Grade 180 g/m2
Furnish 100 % recycled Linerboard
PH 6.90
Ca++ 272 ppm
Concentration 0.62 %
Process Description Sequence
0 seconds Start shear stirring at 600 rpm
0-3 seconds Conditioning at 600 rpm 3-6 seconds Add polymer(1.5 kg/ton or 1500 ppm) at 800 rpm 6-9 seconds Add bentonite (2.5 kg/ton or 2500 ppm) at 1000 rpm 9-13 seconds Reaction at 800 rpm 13-18 seconds Conditioning at 1300 rpm 18-28 seconds *Draining with decreasing vacuum pressure.
Measure the vacuum pressure data (200 data per second) - Drainage
28 seconds **Stop draining. Measure the turbidity of filtrate. -
Retention
Drainage performance
Figure 2 shows drainage performance of (Polymer P + Bentonite) or (Polymer A + Bentonite) over blank. As an example, at vacuum pressure of 150 mmHg, it takes to complete the drain 992/200 = 4.96 seconds when polymer A or P is added with bentonite vs. 1470/200 = 7.35 seconds with no (polymer + bentonite) added. At vacuum pressure of 150 mmHg, 32.5% drainage performance enhancement was realized with addition of (polymer + bentonite).
Retention performance
Figure 3 shows retention performance in terms of turbidity reduction improvement (%).
When Polymer P (1 kg/ton) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 39.1% over Blank.
When Polymer P (1.5 kg/ton) + Bentonite (2.5 kg/ton) is used, turbidity reduction improvement (%) is 43.7% over Blank.
When Polymer A (1 kg/ton) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 41.3% over Blank.
When Polymer A (1.5 kg/ton) + Bentonite (2.5 kg/ton) is used, turbidity reduction improvement (%) is 42.5% over Blank.
Example 3
750 gram of bleached Kraft Pulp (90 %) and Broke (10 %) pulp of which concentration is 0.71 % (i.e. 5.325 gram of solid in this furnish). Add 2.7 cc of polymer P (polymer solution concentration is 0.2 %). This is the same as adding 1.0 kg/ton polymer to furnish. Also add 2.0 kg/ton of bentonite (actual amount added is 1.5 gram).
Retention and Drainage test on Bleached Kraft Pulp papermaking of which furnish condition is
Item Data
Paper Grade 130 g/m2
Furnish Bleached Kraft Pulp 90% +
Broke 10 %
PH 7.49
Concentration 0.71%
Process Sequence Description
0 seconds Start shear stirring at 600 rpm 0-3 seconds Conditioning at 600 rpm 3-6 seconds Add polymer(1 kg/ton or 1000 ppm) at 800 rpm
6-9 seconds Add bentonite (2 kg/ton or 2000 ppm) at 1000 rpm 9-13 seconds Reaction at 800 rpm 13-18 seconds Conditioning at 1300 rpm 18-28 seconds *Draining with decreasing vacuum pressure.
Measure the vacuum pressure data (200 data per second) - Drainage
28 seconds **Stop draining. Measure the turbidity of filtrate. -
Retention
Drainage performance
Figure 4 shows drainage performance of (Polymer P + Bentonite) over blank. As an example, at vacuum pressure of 100 mmHg, it takes to complete the drain 738/200 = 3.69 seconds when polymer P is added with bentonite vs. 956/200 = 4.78 seconds with no (polymer + bentonite) added. At vacuum pressure of 150 mmHg, 23% drainage performance enhancement was realized with addition of (polymer + bentonite).
Example 4
750 gram of bleached Kraft Pulp (90 %) and Broke (10 %) pulp of which concentration is 0.71% (i.e. 5.325 gram of solid in this furnish). Add 4.0 cc of polymer P (polymer solution concentration is 0.2%). This is the same as adding 1.5kg/ton polymer to furnish. Also add 2.5 kg/ton of bentonite (actual amount added is 1.875 gram).
Retention and Drainage test on Bleached Kraft Pulp papermaking of which furnish condition is
Item Data
Paper Grade 130 g/m
Furnish Bleached Kraft Pulp 90% +
Broke 10 %
PH 7.49
Concentration 0.71%
Process Description Sequence
0 seconds Start shear stirring at 600 rpm 0-3 seconds Conditioning at 600 rpm 3-6 seconds Add polymer (1.5 kg/ton or 1500ppm) at 800 rpm 6-9 seconds Add bentonite (2.5 kg/ton or 2500 ppm) at 1000 rpm 9-13 seconds Reaction at 800 rpm 13-18 seconds Conditioning at 1300 rpm 18-28 seconds *Draining with decreasing vacuum pressure.
Measure the vacuum pressure data (200 data per second) - Drainage
28 seconds **Stop draining. Measure the turbidity of filtrate. -
Retention
Drainage performance
Figure 5 shows drainage performance of (Polymer P + Bentonite) over blank. As an example, at vacuum pressure of 100 mmHg, it takes to complete the drain 647/200 = 3.235 seconds when polymer P is added with bentonite vs. 966/200 = 4.83 seconds with no (polymer + bentonite) added. At vacuum pressure of 150 mmHg, 33% drainage performance enhancement was realized with addition of (polymer + bentonite).
Retention performance
Figure 6 shows retention performance in terms of turbidity reduction improvement (%).
When Polymer P (1 kg/ton = 1000 ppm) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 82.3% over Blank
When Polymer P (1.5 kg/ton = 1500 ppm) + Bentonite (2.5 kg/ton) is used, turbidity reduction improvement (%) is 88.3% over Blank.
When Polymer T (1 kg/ton = 1000 ppm) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 82.3% over Blank.
When Polymer T (1.5 kg/ton = 1500 ppm) + Bentonite (2.5 kg/ton) is used, turbidity reduction improvement (%) is 86.4 % over Blank.
Example 5
750 gram of Bleached Kraft Pulp (88 %) + Broke (12 %) pulp of which concentration is 0.43 % (i.e. 3.225 gram of solid in this furnish). Add 0.8 cc of polymer R or Q (polymer solution concentration is 0.2 %). This is the same as adding 0.5 kg/ton polymer to furnish. Also add 2 kg/ton of bentonite (actual amount added is 1.5 gram).
Retention and Drainage test on Bleached Kraft Pulp papermaking of which furnish condition is
Item Data
Paper Grade 120 g/m 91^
Furnish Bleached Kraft Pulp (88 %)
+ Broke (12 %)
PH 5.50 Concentration 0.43 %
Process Description Sequence
0 seconds Start shear stirring at 600 rpm 0-3 seconds Conditioning at 600 rpm 3-6 seconds Add polymer (0.5 kg/ton or 500 ppm) at 800 rpm 6-9 seconds Add bentonite (2.0 kg/ton or 2000 ppm) at 1000 rpm 9-13 seconds Reaction at 800 rpm 13-18 seconds Conditioning at 1300 rpm 18-28 seconds *Draining with decreasing vacuum pressure.
Measure the vacuum pressure data (200 data per second) - Drainage
28 seconds **Stop draining. Measure the turbidity of filtrate. -
Retention
Drainage performance
Figure 7 shows drainage performance of (Polymer R or Q + Bentonite) over blank. As an example, at vacuum pressure of 50 mm Hg, it takes 565/200 = 2.825 seconds when Polymer Q is added with bentonite, and it takes to complete the drain 580/200 = 2.900 seconds when polymer R is added with bentonite, vs. 698/200 = 3.49 seconds with no (polymer + bentonite) added. At vacuum pressure of 50 mmHg, 15-20% drainage performance enhancement was realized with addition of (polymer + bentonite).
Retention performance
Figure 8 shows retention performance in terms of turbidity reduction improvement (%).
When Polymer Q (0.5 kg/ton = 500 ppm) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 80% over Blank.
When Polymer R (0.5 kg/ton = 500 ppm) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 80% over Blank.
Example 6
750 gram of ONP 100 % furnish of which concentration is 0.28 % (i.e. 2.10 gram of solid in this furnish). Add 1.1 cc of polymer K or A (polymer solution concentration is 0.2 %). This is the same as adding 1.0 kg/ton polymer to furnish. Also add 2.0 kg/ton of bentonite (actual amount added is 1.5 gram).
Retention and Drainage test on 100% recycled newsprint papermaking of which furnish condition is
Item Data
Paper Grade 46 g/m
Furnish ONP 100 %
PH 7.05
Concentration 0.28 %
Process Description
Sequence
0 seconds Start shear stirring at 600 rpm
0-3 seconds Conditioning at 600 rpm
3-6 seconds Add polymer (1.0 kg/ton or 1000 ppm) at 800 rpm
6-9 seconds Add bentonite (2.0 kg/ton or 2000 ppm) at 1000 rpm 9-13 seconds Reaction at 800 rpm 13-18 seconds Conditioning at 1300 rpm 18-28 seconds *Draining with decreasing vacuum pressure.
Measure the vacuum pressure data (200 data per second) ~ Drainage
28 seconds **Stop draining. Measure the turbidity of filtrate. -
Retention
Drainage performance
Figure 9 shows drainage performance of (Polymer A or K + Bentonite) over blank. As an example, at vacuum pressure of 212 mm Hg, it takes to complete the drain 1642/200 = 8.21 seconds when polymer A is added with bentonite, and it takes 1799/200 = 8.99 seconds when polymer K is added with bentonite, vs. 2224/200 = 11.12 seconds with no (polymer + bentonite) added. At vacuum pressure of 212 mmHg, 20-26% drainage performance enhancement was realized with addition of (polymer + bentonite).
Example 7
750 gram of ONP 100 % furnish of which concentration is 0.28 % (i.e. 2.10 gram of solid in this furnish). Add 1.6 cc of polymer K or A (polymer solution concentration is 0.2 %). This is the same as adding 1.5 kg/ton polymer to furnish. Also add 2.5 kg/ton of bentonite (actual amount added is 1.875 gram).
Retention and Drainage test on 100% recycled newsprint papermaking of which furnish condition is
Item Data
Paper Grade 46 g/m
Furnish ONP 100 %
PH 7.05
Concentration 0.28 %
Process Description Sequence
0 seconds Start shear stirring at 600 rpm 0-3 seconds Conditioning at 600 rpm 3-6 seconds Add polymer (1.5 kg/ton or 1500 ppm) at 800 rpm 6-9 seconds Add bentonite (2.5 kg/ton or 2500 ppm) at 1000 rpm 9-13 seconds Reaction at 800 rpm 13-18 seconds Conditioning at 1300 rpm 18-28 seconds *Draining with decreasing vacuum pressure.
Measure the vacuum pressure data (200 data per second) -- Drainage
28 seconds **Stop draining. Measure the turbidity of filtrate. -
Retention
Drainage performance
Figure 10 shows drainage performance of (Polymer A or K + Bentonite) over blank. As an example, at vacuum pressure of 212 mm Hg, it takes to complete drain 1462/200 = 7.31 seconds when polymer A is added with bentonite, and it takes 1493/200 = 7.465 seconds when polymer K is added with bentonite, vs. 2235/200 = 11.17 seconds with no (polymer + bentonite) added. At vacuum
pressure of 212 mmHg, 33-34% drainage performance enhancement was realized with addition of (polymer + bentonite).
Retention performance
Figure 11 shows retention performance in terms of turbidity reduction improvement (%).
When Polymer A (1 kg/ton) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 37.1 % over Blank
When Polymer A (1.5 kg/ton) + Bentonite (2.5 kg/ton) is used, turbidity reduction improvement (%) is 48.2 % over Blank.
When Polymer K (1 kg/ton) + Bentonite (2 kg/ton) is used, turbidity reduction improvement (%) is 38.8 % over Blank.
When Polymer K (1.5 kg/ton) + Bentonite (2.5 kg/ton) is used, turbidity reduction improvement (%) is 40.7 % over Blank.
While the present invention is described above in connection with preferred or illustrative embodiments, these embodiments are not intended to be exhaustive or limiting of the invention. Instead, the invention is intended to cover all alternatives, modifications and equivalents included within its scope, as defined by the claims.