CA2418956A1 - Flotation deinking process - Google Patents
Flotation deinking process Download PDFInfo
- Publication number
- CA2418956A1 CA2418956A1 CA 2418956 CA2418956A CA2418956A1 CA 2418956 A1 CA2418956 A1 CA 2418956A1 CA 2418956 CA2418956 CA 2418956 CA 2418956 A CA2418956 A CA 2418956A CA 2418956 A1 CA2418956 A1 CA 2418956A1
- Authority
- CA
- Canada
- Prior art keywords
- deinking
- deinking agent
- cloud point
- flotation
- hydrophobic base
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000002761 deinking Substances 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims description 70
- 238000005188 flotation Methods 0.000 title claims description 54
- 230000008569 process Effects 0.000 title claims description 31
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 46
- 239000000835 fiber Substances 0.000 claims abstract description 29
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 28
- 229920000728 polyester Polymers 0.000 claims abstract description 27
- 239000000126 substance Substances 0.000 claims abstract description 24
- 239000002253 acid Substances 0.000 claims abstract description 22
- 239000007844 bleaching agent Substances 0.000 claims abstract description 19
- 150000008064 anhydrides Chemical class 0.000 claims abstract description 15
- 150000003839 salts Chemical class 0.000 claims abstract description 15
- 125000002947 alkylene group Chemical group 0.000 claims abstract description 14
- 238000006243 chemical reaction Methods 0.000 claims abstract description 14
- 230000003287 optical effect Effects 0.000 claims abstract description 12
- 150000001412 amines Chemical class 0.000 claims abstract description 7
- 239000000539 dimer Substances 0.000 claims abstract description 6
- 150000004665 fatty acids Chemical class 0.000 claims description 30
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 29
- 239000000194 fatty acid Substances 0.000 claims description 29
- 229930195729 fatty acid Natural products 0.000 claims description 29
- 239000010893 paper waste Substances 0.000 claims description 23
- 125000004432 carbon atom Chemical group C* 0.000 claims description 19
- 239000000123 paper Substances 0.000 claims description 18
- 229920001131 Pulp (paper) Polymers 0.000 claims description 16
- 239000013055 pulp slurry Substances 0.000 claims description 16
- 150000007513 acids Chemical class 0.000 claims description 8
- 229920000233 poly(alkylene oxides) Polymers 0.000 claims description 8
- 125000001142 dicarboxylic acid group Chemical group 0.000 claims description 7
- 125000004122 cyclic group Chemical group 0.000 claims description 6
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 5
- 125000001931 aliphatic group Chemical group 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 238000011068 loading method Methods 0.000 claims description 4
- 150000001298 alcohols Chemical class 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 229920000642 polymer Polymers 0.000 claims description 3
- 125000003342 alkenyl group Chemical group 0.000 claims description 2
- 125000000217 alkyl group Chemical group 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 2
- -1 sulphate anion Chemical class 0.000 claims description 2
- 229910021653 sulphate ion Inorganic materials 0.000 claims description 2
- 150000003627 tricarboxylic acid derivatives Chemical class 0.000 claims 7
- 125000006165 cyclic alkyl group Chemical group 0.000 claims 1
- 239000000976 ink Substances 0.000 abstract description 38
- 239000006260 foam Substances 0.000 abstract description 34
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 abstract description 8
- 150000003628 tricarboxylic acids Chemical class 0.000 abstract description 7
- 230000009467 reduction Effects 0.000 abstract description 6
- 239000002002 slurry Substances 0.000 abstract description 5
- 229920001515 polyalkylene glycol Polymers 0.000 abstract description 3
- 150000001991 dicarboxylic acids Chemical class 0.000 abstract description 2
- 239000000306 component Substances 0.000 abstract 1
- 239000000203 mixture Substances 0.000 description 25
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 21
- 239000002245 particle Substances 0.000 description 18
- 241000196324 Embryophyta Species 0.000 description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 14
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 12
- 150000001875 compounds Chemical class 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 238000004537 pulping Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 229960002163 hydrogen peroxide Drugs 0.000 description 6
- 239000000706 filtrate Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 4
- 239000004115 Sodium Silicate Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- OFPXSFXSNFPTHF-UHFFFAOYSA-N oxaprozin Chemical compound O1C(CCC(=O)O)=NC(C=2C=CC=CC=2)=C1C1=CC=CC=C1 OFPXSFXSNFPTHF-UHFFFAOYSA-N 0.000 description 4
- 239000000344 soap Substances 0.000 description 4
- 229910052911 sodium silicate Inorganic materials 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- 230000002411 adverse Effects 0.000 description 3
- 239000007900 aqueous suspension Substances 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000004061 bleaching Methods 0.000 description 3
- 125000002091 cationic group Chemical group 0.000 description 3
- 239000000084 colloidal system Substances 0.000 description 3
- 239000000356 contaminant Substances 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 238000009472 formulation Methods 0.000 description 3
- 239000010899 old newspaper Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- RYKIXDBAIYMFDV-UHFFFAOYSA-N 5-(7-carboxyheptyl)-2-hexylcyclohex-3-ene-1-carboxylic acid Chemical compound CCCCCCC1C=CC(CCCCCCCC(O)=O)CC1C(O)=O RYKIXDBAIYMFDV-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 2
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 description 2
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 229940037003 alum Drugs 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 238000009300 dissolved air flotation Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000011256 inorganic filler Substances 0.000 description 2
- 229910003475 inorganic filler Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229960003330 pentetic acid Drugs 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 239000003760 tallow Substances 0.000 description 2
- 230000032258 transport Effects 0.000 description 2
- QOVUSIZUVWPIAP-UHFFFAOYSA-N 2,6-bis(methoxycarbonyl)benzenesulfonic acid Chemical compound COC(=O)C1=CC=CC(C(=O)OC)=C1S(O)(=O)=O QOVUSIZUVWPIAP-UHFFFAOYSA-N 0.000 description 1
- 240000002791 Brassica napus Species 0.000 description 1
- 235000004977 Brassica sinapistrum Nutrition 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 102000016938 Catalase Human genes 0.000 description 1
- 108010053835 Catalase Proteins 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 244000060011 Cocos nucifera Species 0.000 description 1
- 235000013162 Cocos nucifera Nutrition 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 1
- 235000010469 Glycine max Nutrition 0.000 description 1
- 239000004831 Hot glue Substances 0.000 description 1
- 102000003992 Peroxidases Human genes 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229920006223 adhesive resin Polymers 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 229920006318 anionic polymer Polymers 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000003139 biocide Substances 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 230000009920 chelation Effects 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 235000012343 cottonseed oil Nutrition 0.000 description 1
- 239000013530 defoamer Substances 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- GRWZHXKQBITJKP-UHFFFAOYSA-L dithionite(2-) Chemical compound [O-]S(=O)S([O-])=O GRWZHXKQBITJKP-UHFFFAOYSA-L 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- HQQADJVZYDDRJT-UHFFFAOYSA-N ethene;prop-1-ene Chemical group C=C.CC=C HQQADJVZYDDRJT-UHFFFAOYSA-N 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 239000008233 hard water Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 125000001165 hydrophobic group Chemical group 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002736 nonionic surfactant Substances 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 235000019198 oils Nutrition 0.000 description 1
- 238000001935 peptisation Methods 0.000 description 1
- 108040007629 peroxidase activity proteins Proteins 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 125000001453 quaternary ammonium group Chemical group 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000007127 saponification reaction Methods 0.000 description 1
- 150000004671 saturated fatty acids Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 239000012453 solvate Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 150000001629 stilbenes Chemical class 0.000 description 1
- 230000002311 subsequent effect Effects 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate group Chemical group S(=O)(=O)([O-])[O-] QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 239000003784 tall oil Substances 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 238000004383 yellowing Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
- D21C5/02—Working-up waste paper
- D21C5/025—De-inking
- D21C5/027—Chemicals therefor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/64—Paper recycling
Landscapes
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Toxicology (AREA)
- Paper (AREA)
Abstract
The removal of inks from a pulp fiber slurry is accoplished by use of a combination of (1) a polyester obtained through reaction between di and/or tricarboxylic acids and/or anhydrides thereof and a polyalkylene glycol or one or more alkylene oxides, (2) a first deinking agent which is an alkoxylated hydrophobic base, e.g. an alcohol, amine, acid, dimer acid, salts thereof, or the like, and (3) a second deinking agent which is a second alkoxylated hydrophobic base having a cloud point about 2 to 20~ lower than the cloud point of the first deinking agent. Use of the three com-ponent combination allows an improved foam profile allowing longer continuous operation or one or more of a reduction in total chemical demand, optical bleach demand, and stickies.
Description
FLOTATION DEINKING PROCESS
Background of the Invention Around the world the use of the recycled fiber is now growing. A number of countries have already legislated that a certain part of the total paper production shall be constituted of recycled fiber. The methods which are used today for deinlcing are the flotation process and the washing process. The flotation process dominates and is the subject of the present invention.
The present invention is directed to the removal of inlcs from recycled paper products, i.e. de-inlcing. "Deinlcing" is the process of removing inlc and other con-taminants from waste paper and there are two main techniques in current use.
"Flotation deinlcing" entails forming an aqueous suspension of waste paper pulp fibers, inlc, and other non-cellulosic contaminants and then mixing air into the suspension. In the presence of certain additives, air bubbles selectively attach to ink particles and carry those particles to the surface of the aqueous suspension, thereby forming an ink rich froth. The froth is then removed leaving behind a relatively inlc-free fiber slurry.
A deinlcing process can be divided in three different steps; 1) disintegra-tion/dissolution of recycled fiber and release of the printing inlc from the fibers, 2) dispersing printing inlc in the water phase and 3) separation of the printing inlc.
These three steps are included in both the flotation process and the wash process.
The method which one uses depends on the requirements and conditions which are found where the activity is located. The flotation process generally has been found to remove the greatest amount of printing ink from a recycled fiber suspension and to be the most cost effective.
The first step of flotation deinking is to solvate/saturate the fiber and dis-engage the printing ink. When this is accomplished the particles must be modified so that they obtain suitable physical and chemical characteristics so that afterwards they can be lifted to the surface and removed with help of air bubbles.
Some parameters are important to be consider at the flotation, such as the size of the particle, airflow (particularly the air:stock ratio) in the flotation cell, the size of the air-bubbles, temperature, flotation time, pulp consistency (the concentration of the recycled fibers in the flotation cell), pH, the concentration of the chemicals as well as the degree of the hardness of the water.
The flotation process is carried out in such a manner that the recycled raw material of the fiber is passed through mechanical treatment in combination with associated chemicals. There are different methods depending upon the specific chemicals used, the concentration of those chemicals, and methods to process the raw material. The purpose of the mechanical treatment is that the paper be disintegrated into fibers that together with the chemicals result in an efficient removal of print inlc. However, a too strong mechanical influence can cause undesirable damage to the fibers as well as ink smearing and/or ink re-attachment due to fibers contacting one another.
Then comes filtering and dewatering, whereby the particle impurities are separated, followed by a purification step, generally by means of a vortex cleaner, where particles are separated. In a dispersing step the discharge of printing ink continues through mechanical treatment and chemical enhancement. Printing inlc and any remaining small particles are separated subsequently in the flotation step.
Different flotation techniques exist and in the more contemporary ones, one can float all small particles by pressurizing the flotation cell. Small impurities are separated through washing and to increase the brightness of the pulp, bleaching is performed through use of hydrogen peroxide, hydrosulfite, and the addition of conventional optical bleaches. Optical bleaches enhance the contrast between the inlc and the paper background causing the paper to look brighter and to enhance ink colors.
Flotation deinlcing processes are especially useful in removing hydrophobic inks with particle sizes larger than about 10 ~,m. The additives used in such pro-cesses are generally specialty surfactants or fatty acids which are intended to agglomerate the relatively finer ink particles to increase removal efficiency in the flotation stage. The presence of additives which over-disperse the ink particles rather than agglomerate them is considered detrimental to the effectiveness of the flotation stage.
Newspapers, magazines and other printed media have been recycled for many years. Recently the need to recycle paper has increased significantly and will likely continue to increase in the future in view of environmental concerns and legislative action. To reclaim fibers from printed material, a deinlcing process is required to remove the inlc and other contaminants. Deinlcing of waste paper has become increasingly more difficult because of changes in the printing techniques being used and the wide variety of printing inks. As a result a slurry of recycled waste paper contains a complex mixture of inks, resin binders, fillers, and the like, which must be removed.
The conventional industry chemical formulations for flotation deinlcing for many years have included a fatty acid or fatty acid soap. See, for example, U.S.
Patent Nos. 4,964,949 and 4,483,741. However, fatty acids and fatty acid soaps have a number of problems associated with them, e.g. high dosage rates (typically about 16 pounds/ton of waste paper but as high as 30 pounds/ton), relatively poor foam-ability thus causing the high dosage rates, and the general need for high levels of water hardness to achieve acceptable performance. The hard water often leads to handling problems as well as scale and deposit buildup in mill equipment.
More recently, non-ionic surfactants have been developed for use in deinking systems.
The use of various types of cationic materials in compositions for removal of inks from waste paper has been disclosed in several earlier patents. For example, polyoxyallcylene compounds containing amine or quaternary ammonium groups have been disclosed in such as US 4,483,741, US 4,605,773, JP 59 137587, DE 3,928,599, DE 4,007,598, and DE 4,007,597. Similar formulations which are claimed to be effective specifically for deinlcing of paper printed with flexographic inks have been disclosed in DE 4,007,596, WO 90 05806 and EP
478505. Surfactants such as the ones described in the preceding patents may be regarded as materials in which a single substance contains both non-ionic and cationic moieties. None of these prior art compositions, however, have been found capable of adequately removing the very fine hydrophilic inlcs in a flotation deinking stage or a combined flotation and wash deinking system.
US 5,736,622 discloses a synthetic collector which consists of a polyester based on a polyalkylene glycol and a di or tricarboxylic acid. The patent goes on to improve on such a deinking agent by adding into the polymerization mixture a saturated fatty acid with 12-18 carbon atoms, and controlling the molecular weight to be between 3,000 and 10,000.
While a polyester has been found to be helpful in improving brightness and ink removal efficiency, the performance has not been found to be sustainable under continuous real world mill operations due to adverse changes in the foam profile, i.e. the foam begins to build with time and will not collapse at the desired rate to effi-ciently remove the inlc. Further, the extended foam lifetime has been found to result in rejects backup which results in float cell leveling and overflow/surging problems. The addition of conventional defoamers, e.g.
silica/silicone and ethylene oxide/-propylene oxide surfactants and the lilce, have not corrected the problem. Rather they have been found to persist in the system and penalize generation of the desired de-inking foam profile. Ink re-attachment has been observed with use of the defoamers.
Accordingly, it is an object of the present invention to provide a method of deinking printed media whereby improved foam control allows enhanced continuous running conditions, i.e. without loss of brightness and/or inlc removal efficiency over time.
It is a further object of the invention to remove the inks while minimizing the total chemical demand of the process.
Background of the Invention Around the world the use of the recycled fiber is now growing. A number of countries have already legislated that a certain part of the total paper production shall be constituted of recycled fiber. The methods which are used today for deinlcing are the flotation process and the washing process. The flotation process dominates and is the subject of the present invention.
The present invention is directed to the removal of inlcs from recycled paper products, i.e. de-inlcing. "Deinlcing" is the process of removing inlc and other con-taminants from waste paper and there are two main techniques in current use.
"Flotation deinlcing" entails forming an aqueous suspension of waste paper pulp fibers, inlc, and other non-cellulosic contaminants and then mixing air into the suspension. In the presence of certain additives, air bubbles selectively attach to ink particles and carry those particles to the surface of the aqueous suspension, thereby forming an ink rich froth. The froth is then removed leaving behind a relatively inlc-free fiber slurry.
A deinlcing process can be divided in three different steps; 1) disintegra-tion/dissolution of recycled fiber and release of the printing inlc from the fibers, 2) dispersing printing inlc in the water phase and 3) separation of the printing inlc.
These three steps are included in both the flotation process and the wash process.
The method which one uses depends on the requirements and conditions which are found where the activity is located. The flotation process generally has been found to remove the greatest amount of printing ink from a recycled fiber suspension and to be the most cost effective.
The first step of flotation deinking is to solvate/saturate the fiber and dis-engage the printing ink. When this is accomplished the particles must be modified so that they obtain suitable physical and chemical characteristics so that afterwards they can be lifted to the surface and removed with help of air bubbles.
Some parameters are important to be consider at the flotation, such as the size of the particle, airflow (particularly the air:stock ratio) in the flotation cell, the size of the air-bubbles, temperature, flotation time, pulp consistency (the concentration of the recycled fibers in the flotation cell), pH, the concentration of the chemicals as well as the degree of the hardness of the water.
The flotation process is carried out in such a manner that the recycled raw material of the fiber is passed through mechanical treatment in combination with associated chemicals. There are different methods depending upon the specific chemicals used, the concentration of those chemicals, and methods to process the raw material. The purpose of the mechanical treatment is that the paper be disintegrated into fibers that together with the chemicals result in an efficient removal of print inlc. However, a too strong mechanical influence can cause undesirable damage to the fibers as well as ink smearing and/or ink re-attachment due to fibers contacting one another.
Then comes filtering and dewatering, whereby the particle impurities are separated, followed by a purification step, generally by means of a vortex cleaner, where particles are separated. In a dispersing step the discharge of printing ink continues through mechanical treatment and chemical enhancement. Printing inlc and any remaining small particles are separated subsequently in the flotation step.
Different flotation techniques exist and in the more contemporary ones, one can float all small particles by pressurizing the flotation cell. Small impurities are separated through washing and to increase the brightness of the pulp, bleaching is performed through use of hydrogen peroxide, hydrosulfite, and the addition of conventional optical bleaches. Optical bleaches enhance the contrast between the inlc and the paper background causing the paper to look brighter and to enhance ink colors.
Flotation deinlcing processes are especially useful in removing hydrophobic inks with particle sizes larger than about 10 ~,m. The additives used in such pro-cesses are generally specialty surfactants or fatty acids which are intended to agglomerate the relatively finer ink particles to increase removal efficiency in the flotation stage. The presence of additives which over-disperse the ink particles rather than agglomerate them is considered detrimental to the effectiveness of the flotation stage.
Newspapers, magazines and other printed media have been recycled for many years. Recently the need to recycle paper has increased significantly and will likely continue to increase in the future in view of environmental concerns and legislative action. To reclaim fibers from printed material, a deinlcing process is required to remove the inlc and other contaminants. Deinlcing of waste paper has become increasingly more difficult because of changes in the printing techniques being used and the wide variety of printing inks. As a result a slurry of recycled waste paper contains a complex mixture of inks, resin binders, fillers, and the like, which must be removed.
The conventional industry chemical formulations for flotation deinlcing for many years have included a fatty acid or fatty acid soap. See, for example, U.S.
Patent Nos. 4,964,949 and 4,483,741. However, fatty acids and fatty acid soaps have a number of problems associated with them, e.g. high dosage rates (typically about 16 pounds/ton of waste paper but as high as 30 pounds/ton), relatively poor foam-ability thus causing the high dosage rates, and the general need for high levels of water hardness to achieve acceptable performance. The hard water often leads to handling problems as well as scale and deposit buildup in mill equipment.
More recently, non-ionic surfactants have been developed for use in deinking systems.
The use of various types of cationic materials in compositions for removal of inks from waste paper has been disclosed in several earlier patents. For example, polyoxyallcylene compounds containing amine or quaternary ammonium groups have been disclosed in such as US 4,483,741, US 4,605,773, JP 59 137587, DE 3,928,599, DE 4,007,598, and DE 4,007,597. Similar formulations which are claimed to be effective specifically for deinlcing of paper printed with flexographic inks have been disclosed in DE 4,007,596, WO 90 05806 and EP
478505. Surfactants such as the ones described in the preceding patents may be regarded as materials in which a single substance contains both non-ionic and cationic moieties. None of these prior art compositions, however, have been found capable of adequately removing the very fine hydrophilic inlcs in a flotation deinking stage or a combined flotation and wash deinking system.
US 5,736,622 discloses a synthetic collector which consists of a polyester based on a polyalkylene glycol and a di or tricarboxylic acid. The patent goes on to improve on such a deinking agent by adding into the polymerization mixture a saturated fatty acid with 12-18 carbon atoms, and controlling the molecular weight to be between 3,000 and 10,000.
While a polyester has been found to be helpful in improving brightness and ink removal efficiency, the performance has not been found to be sustainable under continuous real world mill operations due to adverse changes in the foam profile, i.e. the foam begins to build with time and will not collapse at the desired rate to effi-ciently remove the inlc. Further, the extended foam lifetime has been found to result in rejects backup which results in float cell leveling and overflow/surging problems. The addition of conventional defoamers, e.g.
silica/silicone and ethylene oxide/-propylene oxide surfactants and the lilce, have not corrected the problem. Rather they have been found to persist in the system and penalize generation of the desired de-inking foam profile. Ink re-attachment has been observed with use of the defoamers.
Accordingly, it is an object of the present invention to provide a method of deinking printed media whereby improved foam control allows enhanced continuous running conditions, i.e. without loss of brightness and/or inlc removal efficiency over time.
It is a further object of the invention to remove the inks while minimizing the total chemical demand of the process.
It is a still further object of the invention to reduce optical bleach demand.
It is a still further object of the invention to reduce the amount of sticlcies in a paper pulp.
These and still further objects will be apparent from the ensuing description of the present invention.
Summary of the Invention The present invention is directed to a deinking method which is useful in re-moving inks from recycled printed media in a flotation deinlcing system or combined flotation/wash deinlcing system. The flotation deinlcing method generally entails adding to an aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between di and/or tricarboxylic acids and/or anhydrides thereof and a polyallcylene oxide or an alkylene oxide, (2) a first deinlcing agent which is an allcoxylated hydrophobic base, e.g. an alcohol, amine, acid, dimer acid, salts thereof, or the like, and (3) a second deinking agent which is an allcoxylated hydrophobic base and which has a cloud point about 2 to 20°, preferably about 4-18°, lower than the cloud point of the first deinlcing agent.
The deinking method of the present invention effectively and efficiently removes ink in a flotation process or in the flotation stage of a combined flotation/wash process.
By using this combination of materials at appropriate levels and in the appropriate sequence, improved release of the inlcs from the waste paper fibers can be accomplished without over-dispersing the inlcs while simultaneously initiating agglomeration of the fine ink particles and then completing the .
agglomeration to a sufficient extent that the ink particles coalesce and are of sufficient size to be effectively and efficiently removed in the froth of conventional flotation deinking equipment.
Brief Description of the Fi ure Figure 1 is a graph of foam life in minutes vs. plant hours running showing the foam profiles of the samples of Example 1.
Detailed Description of the Invention More particularly, the present invention entails adding to an aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di-and/or tri-carboxylic acid and/or anhydride thereof with an allcylene oxide or a poly-allcylene oxide, (2) a first deinking agent which is an allcoxylated hydrophobic base, e.g. an alcohol, amine, acid, dimer acid, salts thereof, or the lilce, and (3) a second deinlcing agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20°, preferably 4 to 18°, lower than the cloud point of the first deinking agent. The combination may further contain a fatty acid or salt thereof.
The polyesters for use herein may be obtained through reaction of (a) a hydro-phobe, i.e. a dicarboxylic acid, a tricarboxylic acid, an anhydride of a dicarboxylic acid, an anhydride of a tricarboxylic acid, and combinations thereof with (b) a hydrophile, i.e. polyalkylene glycol or an alkylene oxide in an alkoxylation reaction. The hydrophobic acids/anhydrides may be either aliphatic or aromatic. Preferably for better foam control ring structures are used. Such acids and anhydrides are well known and commercially available from numerous sources.
A particularly preferred class Iof cyclic aliphatic di-acids are of the formula:
HOOC-A-(CH2)X-COOH
wherein A is a cyclic aliphatic group having 6 to 10 carbon atoms and x is an integer from 0 to about 15. While the acid groups may be ortho, meta or para, they are pre-ferably ortho or para. Optionally, the ring is further substituted with one or more hydrophobic groups, such as a straight or branched chain alkyl group having about 3 to 18, preferably about 4 to 12, carbon atoms.
Still further optionally a portion of the cyclic di- and/or tri-carboxylic acid and/or anhydride is substituted by sulphate or other anions. Increased anionicity has been found to enhance the removal of stickies.
Suitable allcylene oxides have 2 to 4 carbon atoms, preferably 2 to 3, and most preferably 2. While mixtures of alkylene oxides may be used, no benefit from so doing has been observed. If a hydrophilic polyalkylene oxide polymer is used, it is prepared from the same allcylene oxides.
The polyester generally has a hydrophobe loading of about 35 to 55 wt %, a hydrophile loading of about 35 to 55 wt %, and a terminal carboxyl content of about 5 to 15 wt %. Preferably, the polyester has a molecular weight in the range of about 2,500 to 5,000 daltons, though higher or lower molecular weight polymers may be used in specific circumstances depending upon the specific composition of the materials being deinked.
The first deinking agent is an alkoxylated hydrophobic base. Suitable hydro-phobic bases include any compounds which are hydrophobic and which can be alkox-ylated by reaction with an alkylene oxide. Examples of such compounds include alcohols, amines, acids, dimer acids, and salts thereof. Most commonly an alcohol or an acid will be used. Generally the hydrophobe compound will contain about 12 to 60 carbon atoms, preferably about 12 to 30 carbon atoms, and most preferably about 14 to 20 carbon atoms. Suitable allcylene oxides have 2 to 4 carbon atoms, preferably 2 or 3. Generally a mixture of two allcylene oxides will be used, either jointly or sequentially to form a bloclc or a random configuration.
The second deinlcing agent, like the first, is an allcoxylated hydrophobic base, but it has a cloud point of about 2 to 20°C below the cloud point of the first deinlcing agent. Preferably the cloud point is about 4 to 18° below that of the first deinlcing agent. Suitable hydrophobic bases include any compounds which are hydrophobic and which can be allcoxylated by reaction with an alkylene oxide.
Examples of such compounds include alcohols, amines, acids, dimer acids, and _ g _ salts thereof. Most commonly an alcohol or an acid will be used. Generally the hydrophobe compound will contain about 12 to 60 carbon atoms, preferably about 12 to 30 carbon atoms, and most preferably about 14 to 20 carbon atoms.
Suitable alkylene oxides have 2 to 4 carbon atoms, preferably 2 or 3. Generally a mixture of two allcylene oxides will be used, either jointly or sequentially to form a block or a random configuration.
Table 1 identifies some allcoxylated hydrophobic bases suitable for use as either the first or second deinlcing agent, depending upon the specific cloud point of the alkoxylated base. The cloud point is determined in a water solution between 0 and 100°C by heating a solution of the sample being analyzed until the solution clouds, then cooling until the solution clears. The temperature at which the solution clears is the cloud point.
Table 1 Deinking Moles Cloud Point, Agent HYdrophobe Moles Moles AdditionC
EO PO EO
1 C18 alcohol21 6 random 72 2 C18 alcohol6 21 6 block 62-64 3 Tallow 54 18 random 63 4 C18 alcohol63 28 random 62 Stearic 19.5 8 random 55-62 acid 6 C18 alcohol51 39 random 52 7 C18 alcohol10 20 10 block 48-50 8 Stearic 19.5 8 random 48-50 acid 9 C 18 alcohol45 45 random 44 C18 alcohol10 15 10 block 35 Generally the polyester, the first deinking agent, and the second deinking agent are used in as low amounts as will produce the desired deinking effect.
The polyester is generally used in an amount of about 0.05 to about 0.5 wt % based on the total weight of fiber present, preferably about 0.075 to about 0.25 wt %.
The two deinking agents are used in a ratio of about 1:10 to about 10:1 and in a total amount of about 0.001 to 0.3 wt % based on the total weight of fiber present.
The specific amounts to be used for optimum performance will vary depending upon many factors including the equipment being used and the specific recycle composition. Thus they must be determined by routine trial and error testing.
While a fatty acid or salt thereof of the formula RCOO-M, wherein R is a linear, branched, or cyclic allcyl or alkenyl group having about 7 to about 48 carbon atoms and M is hydrogen or a counterion such as Na, I~, Ca, NH4, or NHx(CHaCH20H)y wherein x and y are each integers from 0 to 4 and total 4, may be added along with the polyester and the two allcoxylated deinking agents, so doing is not preferred due to the problems caused by use/compatibility of such compounds. When used, however, for economic reasons the fatty acid or salt thereof are most commonly used in the form of mixtures of such materials having about 12 to 48 carbon atoms and derived from natural oils such as marine, rapeseed, tallow, tall oil, soy, cottonseed, coconut, and the like. The fatty acid functions primarily to agglom-erate inlc particles. The fatty acid or the salt there-of may be present in an amount from about 0.05 to 1.5 wt % based upon the weight of the waste paper, more preferably from about 0.1 to 0.5 wt %, and most preferably from about 0.2 to 0.5 wt %. The fatty acid or salt may be added either to an aqueous pulp slurry at the pulping stage or to the pulp slurry prior to its introduction to the flotation stage.
The deinlcing procedure of the present invention entails the use of a flotation stage to remove inks, including very fine hydrophilic inks (flexographic inlcs) 1 from printed media, particularly some waste newspapers wherein up to 100% of the ink may be flexographic.
Generally, the process comprises a pulping step wherein printed waste paper, sometimes in combination with virgin wood pulp, is treated in an alkaline medium with water in a reactor having an agitation system. The aqueous suspension so form-ed contains pulp fiber, inks, coatings, inorganic fillers, and the like, in an amount of from about 3 to 18 wt % and is maintained at a pH of about 7.5 to 11. Typical chemicals used in the pulper have conventionally included such as NaOH and hydro-gen peroxide. Sodium silicate, a metal chelating agent such as diethylenetriamine-pentaacetic acid (DTPA), and.
calcium chloride have also been added to the pulper and/or flotation to maintain water hardness to ensure calcium soap formation. It is a particular benefit of the present invention that the total chemical demand of the pulping process can be reduced by the more efficient removal of the ink which permits use of less severe conditions and/or less chemicals.
As indicated the sodium hydroxide adjusts the pH to be alkaline to aid inlc release, swell cellulose fibers, wet the fibers, and disperse the released ink, fillers, etc. It also neutralizes chemical components such as fatty acids and provides the desired pH for subsequent bleaching and the flotation steps. How-ever, the downside is increased fiber yellowing (a pronounced effect at pH >
9.5 which requires correction by the addition of bleaching agents), saponification of organics (the binders and adhesives in the recycled paper products) which results in sticlcies and machine deposits and release/formation of colloidal material via alkaline peptization which can adversely effect the efficiency of the foam to effectively transport the released ink during the flotation. Also the released organics and colloids contami-nate the water circuits which in turn increases the BOD/COD (biological oxygen demand/chemical oxygen demand) and the demand for water treatment chemical clean-up before discharge or reuse.
Hydrogen peroxide is typically used as a bleaching agent and in the pulper to offset the adverse effects of excessive sodium hydroxide. Other conventional bleach-ing agents, e.g. sodium hyposulfite, and optical bleaches such as sulfonated stilbenes, may be used.
Sodium silicate is used to provide system buffering and metal chelation.
It is used to avoid pH shocks which could result in deposits, and as a wetting or anti-corrosion agent, bleaching agent stabilizer and a source of alkalinity for. pH
It is a still further object of the invention to reduce the amount of sticlcies in a paper pulp.
These and still further objects will be apparent from the ensuing description of the present invention.
Summary of the Invention The present invention is directed to a deinking method which is useful in re-moving inks from recycled printed media in a flotation deinlcing system or combined flotation/wash deinlcing system. The flotation deinlcing method generally entails adding to an aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between di and/or tricarboxylic acids and/or anhydrides thereof and a polyallcylene oxide or an alkylene oxide, (2) a first deinlcing agent which is an allcoxylated hydrophobic base, e.g. an alcohol, amine, acid, dimer acid, salts thereof, or the like, and (3) a second deinking agent which is an allcoxylated hydrophobic base and which has a cloud point about 2 to 20°, preferably about 4-18°, lower than the cloud point of the first deinlcing agent.
The deinking method of the present invention effectively and efficiently removes ink in a flotation process or in the flotation stage of a combined flotation/wash process.
By using this combination of materials at appropriate levels and in the appropriate sequence, improved release of the inlcs from the waste paper fibers can be accomplished without over-dispersing the inlcs while simultaneously initiating agglomeration of the fine ink particles and then completing the .
agglomeration to a sufficient extent that the ink particles coalesce and are of sufficient size to be effectively and efficiently removed in the froth of conventional flotation deinking equipment.
Brief Description of the Fi ure Figure 1 is a graph of foam life in minutes vs. plant hours running showing the foam profiles of the samples of Example 1.
Detailed Description of the Invention More particularly, the present invention entails adding to an aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di-and/or tri-carboxylic acid and/or anhydride thereof with an allcylene oxide or a poly-allcylene oxide, (2) a first deinking agent which is an allcoxylated hydrophobic base, e.g. an alcohol, amine, acid, dimer acid, salts thereof, or the lilce, and (3) a second deinlcing agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20°, preferably 4 to 18°, lower than the cloud point of the first deinking agent. The combination may further contain a fatty acid or salt thereof.
The polyesters for use herein may be obtained through reaction of (a) a hydro-phobe, i.e. a dicarboxylic acid, a tricarboxylic acid, an anhydride of a dicarboxylic acid, an anhydride of a tricarboxylic acid, and combinations thereof with (b) a hydrophile, i.e. polyalkylene glycol or an alkylene oxide in an alkoxylation reaction. The hydrophobic acids/anhydrides may be either aliphatic or aromatic. Preferably for better foam control ring structures are used. Such acids and anhydrides are well known and commercially available from numerous sources.
A particularly preferred class Iof cyclic aliphatic di-acids are of the formula:
HOOC-A-(CH2)X-COOH
wherein A is a cyclic aliphatic group having 6 to 10 carbon atoms and x is an integer from 0 to about 15. While the acid groups may be ortho, meta or para, they are pre-ferably ortho or para. Optionally, the ring is further substituted with one or more hydrophobic groups, such as a straight or branched chain alkyl group having about 3 to 18, preferably about 4 to 12, carbon atoms.
Still further optionally a portion of the cyclic di- and/or tri-carboxylic acid and/or anhydride is substituted by sulphate or other anions. Increased anionicity has been found to enhance the removal of stickies.
Suitable allcylene oxides have 2 to 4 carbon atoms, preferably 2 to 3, and most preferably 2. While mixtures of alkylene oxides may be used, no benefit from so doing has been observed. If a hydrophilic polyalkylene oxide polymer is used, it is prepared from the same allcylene oxides.
The polyester generally has a hydrophobe loading of about 35 to 55 wt %, a hydrophile loading of about 35 to 55 wt %, and a terminal carboxyl content of about 5 to 15 wt %. Preferably, the polyester has a molecular weight in the range of about 2,500 to 5,000 daltons, though higher or lower molecular weight polymers may be used in specific circumstances depending upon the specific composition of the materials being deinked.
The first deinking agent is an alkoxylated hydrophobic base. Suitable hydro-phobic bases include any compounds which are hydrophobic and which can be alkox-ylated by reaction with an alkylene oxide. Examples of such compounds include alcohols, amines, acids, dimer acids, and salts thereof. Most commonly an alcohol or an acid will be used. Generally the hydrophobe compound will contain about 12 to 60 carbon atoms, preferably about 12 to 30 carbon atoms, and most preferably about 14 to 20 carbon atoms. Suitable allcylene oxides have 2 to 4 carbon atoms, preferably 2 or 3. Generally a mixture of two allcylene oxides will be used, either jointly or sequentially to form a bloclc or a random configuration.
The second deinlcing agent, like the first, is an allcoxylated hydrophobic base, but it has a cloud point of about 2 to 20°C below the cloud point of the first deinlcing agent. Preferably the cloud point is about 4 to 18° below that of the first deinlcing agent. Suitable hydrophobic bases include any compounds which are hydrophobic and which can be allcoxylated by reaction with an alkylene oxide.
Examples of such compounds include alcohols, amines, acids, dimer acids, and _ g _ salts thereof. Most commonly an alcohol or an acid will be used. Generally the hydrophobe compound will contain about 12 to 60 carbon atoms, preferably about 12 to 30 carbon atoms, and most preferably about 14 to 20 carbon atoms.
Suitable alkylene oxides have 2 to 4 carbon atoms, preferably 2 or 3. Generally a mixture of two allcylene oxides will be used, either jointly or sequentially to form a block or a random configuration.
Table 1 identifies some allcoxylated hydrophobic bases suitable for use as either the first or second deinlcing agent, depending upon the specific cloud point of the alkoxylated base. The cloud point is determined in a water solution between 0 and 100°C by heating a solution of the sample being analyzed until the solution clouds, then cooling until the solution clears. The temperature at which the solution clears is the cloud point.
Table 1 Deinking Moles Cloud Point, Agent HYdrophobe Moles Moles AdditionC
EO PO EO
1 C18 alcohol21 6 random 72 2 C18 alcohol6 21 6 block 62-64 3 Tallow 54 18 random 63 4 C18 alcohol63 28 random 62 Stearic 19.5 8 random 55-62 acid 6 C18 alcohol51 39 random 52 7 C18 alcohol10 20 10 block 48-50 8 Stearic 19.5 8 random 48-50 acid 9 C 18 alcohol45 45 random 44 C18 alcohol10 15 10 block 35 Generally the polyester, the first deinking agent, and the second deinking agent are used in as low amounts as will produce the desired deinking effect.
The polyester is generally used in an amount of about 0.05 to about 0.5 wt % based on the total weight of fiber present, preferably about 0.075 to about 0.25 wt %.
The two deinking agents are used in a ratio of about 1:10 to about 10:1 and in a total amount of about 0.001 to 0.3 wt % based on the total weight of fiber present.
The specific amounts to be used for optimum performance will vary depending upon many factors including the equipment being used and the specific recycle composition. Thus they must be determined by routine trial and error testing.
While a fatty acid or salt thereof of the formula RCOO-M, wherein R is a linear, branched, or cyclic allcyl or alkenyl group having about 7 to about 48 carbon atoms and M is hydrogen or a counterion such as Na, I~, Ca, NH4, or NHx(CHaCH20H)y wherein x and y are each integers from 0 to 4 and total 4, may be added along with the polyester and the two allcoxylated deinking agents, so doing is not preferred due to the problems caused by use/compatibility of such compounds. When used, however, for economic reasons the fatty acid or salt thereof are most commonly used in the form of mixtures of such materials having about 12 to 48 carbon atoms and derived from natural oils such as marine, rapeseed, tallow, tall oil, soy, cottonseed, coconut, and the like. The fatty acid functions primarily to agglom-erate inlc particles. The fatty acid or the salt there-of may be present in an amount from about 0.05 to 1.5 wt % based upon the weight of the waste paper, more preferably from about 0.1 to 0.5 wt %, and most preferably from about 0.2 to 0.5 wt %. The fatty acid or salt may be added either to an aqueous pulp slurry at the pulping stage or to the pulp slurry prior to its introduction to the flotation stage.
The deinlcing procedure of the present invention entails the use of a flotation stage to remove inks, including very fine hydrophilic inks (flexographic inlcs) 1 from printed media, particularly some waste newspapers wherein up to 100% of the ink may be flexographic.
Generally, the process comprises a pulping step wherein printed waste paper, sometimes in combination with virgin wood pulp, is treated in an alkaline medium with water in a reactor having an agitation system. The aqueous suspension so form-ed contains pulp fiber, inks, coatings, inorganic fillers, and the like, in an amount of from about 3 to 18 wt % and is maintained at a pH of about 7.5 to 11. Typical chemicals used in the pulper have conventionally included such as NaOH and hydro-gen peroxide. Sodium silicate, a metal chelating agent such as diethylenetriamine-pentaacetic acid (DTPA), and.
calcium chloride have also been added to the pulper and/or flotation to maintain water hardness to ensure calcium soap formation. It is a particular benefit of the present invention that the total chemical demand of the pulping process can be reduced by the more efficient removal of the ink which permits use of less severe conditions and/or less chemicals.
As indicated the sodium hydroxide adjusts the pH to be alkaline to aid inlc release, swell cellulose fibers, wet the fibers, and disperse the released ink, fillers, etc. It also neutralizes chemical components such as fatty acids and provides the desired pH for subsequent bleaching and the flotation steps. How-ever, the downside is increased fiber yellowing (a pronounced effect at pH >
9.5 which requires correction by the addition of bleaching agents), saponification of organics (the binders and adhesives in the recycled paper products) which results in sticlcies and machine deposits and release/formation of colloidal material via alkaline peptization which can adversely effect the efficiency of the foam to effectively transport the released ink during the flotation. Also the released organics and colloids contami-nate the water circuits which in turn increases the BOD/COD (biological oxygen demand/chemical oxygen demand) and the demand for water treatment chemical clean-up before discharge or reuse.
Hydrogen peroxide is typically used as a bleaching agent and in the pulper to offset the adverse effects of excessive sodium hydroxide. Other conventional bleach-ing agents, e.g. sodium hyposulfite, and optical bleaches such as sulfonated stilbenes, may be used.
Sodium silicate is used to provide system buffering and metal chelation.
It is used to avoid pH shocks which could result in deposits, and as a wetting or anti-corrosion agent, bleaching agent stabilizer and a source of alkalinity for. pH
control. The downside of using the silicate include its strong dispersive action and colloid generation which result in variable foam flotation profiles which can negatively impact ink removal.
These downside effects are reduced in the present invention by operating at low sodium hydroxide levels thereby avoiding the need for the hydrogen peroxide and silicate during pulping. Also, the need for biocides to prevent enzyme (peroxidase and catalase) loss of the hydrogen peroxide is eliminated during final bleaching. Furthermore, the associated additives for deposit/scale control are negated since the use of fatty acids can be minimized or avoided and no additional calcium is needed to ensure calcium soap formation and organics/colloid interference to the process is minimized.
According to the process of this invention, the three components can be added directly to the pulper during the pulping stage, preferably near the beginning thereof, or to the flotation cell prior to flotation. The components can be added individually or they may be pre-mixed. Mill conditions will determine the most suitable condi-tions.
After the slurry exits the pulper, it is diluted to about 1 wt % solids. If a fatty acid or salt thereof is used, it may be added. Alternatively, the fatty acid component may be added partially during the pulping operation and partially upon entry to flotation. Thereafter, air is introduced into the flotation equipment to cause vigor-ous mixing of the diluted pulp slurry and to ensure foam generation for inlc trans-port/removal from the system.
As a result of the addition of the combination of (1) the polyester, (2) the first alkoxylated deinking agent, and (3) the second lower cloud point deinlcing agent, the ink particles are released from the recycled printed media and agglomerated into larger particles. The air bubbles then attach to the agglomerated ink particles and carry the agglomerated particles to the surface of the flotation equipment and form a foam thereon. This ink-rich foam is removed from the surface in any of the conventional manners well known in the art of deinking. A particular benefit of the present invention is the character of the foam which is produced. The foam has high ink carrying capability that upon leaving the flotation cell collapses in a regular and controlled manner so that the resulting inlcy liquid can be easily removed and sent to waste treatment for final disposal.
Following the flotation deinlcing procedure, the pulp slurry is thickened to about 6 to 12 wt % solids and washed using conventional equipment readily available and in widespread commercial use. The filtrate from the washing is typically treated in a dissolved air flotation (DAF) clarifies to remove inlcs, fill-ers, fiber fines, and other suspended solids so that the filtrate water can be recycled for use in a sub-sequent deinking procedure. Commonly, cationic, nonionic and/or anionic polymers are added to the filtrate prior to or in the dissolved air flotation clarifies so that the suspended solids will be agglomerated and/or flocculated and removed.
Many modifications and variations of the basic deinking procedure explained herein have been proposed and/or are in commercial use and the method of the pres-ent invention may be applied to those procedures. The simple system explained herein is used for illustration purposes only and is not meant to be in limitation of the scope of this invention. The pulping process may be carried out either in a continuous way or batchwise,~ with excellent results with any type of printed media including newspaper, magazines, printed cardboard and colored printed media. The recycled paper is fed to the process so that it is present in an amount of about 10 to 100 wt % of the fiber undergoing pulping. The equipment used in this process is conventional equipment which is readily available and in widespread use.
The use of the deinking components of the present invention has several advantages when compared to the conventional prior art. Compared to conventional deinlcing methods, a significant reduction in total chemical demand is realized when using this method. The ink removal rate is often also increased over conventional flotation methods, resulting in either increased production rates without sacrifice of product quality. Most importantly, the foam profile is such that extended continuous operations result.
While most preferably no fatty acid is used in the present process, there will be situation when a small amount is desirable. The dosage rate of the fatty acid component of the composition can be substantially reduced from the 1 to 2 wt % for a conventional process to below about 0.2 wt %, preferably below about 0.1 wt %, based on the total weight of fiber for the present invention. The none or lower amount significantly reduces the potential for scale and deposit problems normally associated with fatty acid components of deinking formulations both in the deinlcing equipment itself and at the subsequent paper machine. Expensive downtime for equipment clean-up is minimized and a higher quality final paper product can be produced.
Environmental concerns are causing paper mills to continually seelc to reduce the amount of fresh water used. This means that increasing amounts of mill water must be reused. It is an advantage of the present invention that not only is the clarity of the filtrates produced in washing stages following the flotation deinking stage improved but also the subsequent drainage rate because of an increased removal of both inorganic fillers, e.g. calcium carbonate and titanium dioxide, and fiber fines which are in the waste paper pulp slurry being treated. In view of improved filtrate clarity, the amount of flocculants required for water clarification and subsequent reuse is reduced. In view of increased drainage rate, plant through-put can be increased.
The advantages of the deinking composition of the present invention as com-pared with conventional deinking compositions are further illustrated in the follow-ing Examples in which all parts and percents are by weight unless otherwise specified. All filter pads for brightness were made using alum as specified in TAPPI Test Method T 218 om-83. Where necessary the pulp samples were first diluted to 1 wt % solids (equivalent to a 3 gram air-dried sheet) with tap water, 2 ml of 10% alum solution added to each sample, and the slurry then thickened on a Buchner funnel using Ahlstrom grade 631-25 filter paper. The filter pads were air dried before taking brightness measurements. All brightness data was obtained using an ACS Spectrosensor II spectrophotometer and reported as TAPPI 452 brightness. The brightness data represents the percent of light at wavelength 452 manometers which is reflected off the filter pad and recorded by the spectrophotometer.
Example 1 A mixture of 35% MAG (old magazines), 65% ONP (old newspapers) were shredded dry and combined. The mixture was added to a plant pulper along with water (120°F) and the each of the four different deinking/flotation deinlcing chemical systems specified in Table 2. The pulps had a consistency of about 12-14 %.
The polyester was the 1:1 molar reaction product of 5(6)-carboxy-4-hexyl-2-cyclohexene-1-octanoic acid with polyethylene glycol (mw 1450). "Deinlc agent 1" was a block ethoxylated and propoxylated C-18 alcohol having a cloud point of 48-50°C. "Deink agent 2" was a random ethoxylated and propoxylated C-alcohol having a cloud point of 42-44°C. The fatty acid was predominantly C-18.
In Table 2, "A" is a prior art conventional fatty acid only foaming system used in the plant. "B" is a prior conventional fatty acid/alkoxylated hydrophobe blend deinlcing system used in the plant. "C" is a blend of an aromatic polyester and a single alkoxylated hydrophobe deinlcing system. "Example 1" is a composition of the present invention utilizing the 3 component deinlcing system applied under plant conditions.
The bleach demand for samples "A" and "B" was 0.4 wt % in each of the pulper and the tower. The bleach demand for samples "C" and Example 1 was 0 in the pulper and 0.6 wt % in the tower Table 2 Chemical Regimes - % on Dry Fiber Test Fatty Poly-Deink Deink BiocideBleach SampleAcid SilicateesterAgent Agent NaOH (ppm) Demand 1 2 pulper tower A 0.45 1.8 --- --- --- 0.35 20 0.40 0.42 B 0.12 1.8 --- 0.05 --- 0.34 20 0.40 0.60 C --- --- 0.0250.09 --- 0.20 --- --- 0.60 1 --- --- 0.0250.06 0.03 0.20 --- --- 0.60 The deinlcing performance of the 4 deinking compositions was evaluated and the results are shown in Table 3. After each of the four combinations of chemicals, water and waste paper was pulped for 15-20 minutes, test samples were taken. The samples were diluted to 1 % using additional water and deinlcing performance deter-mined. Filter pads were made for measuring the brightness of the deinked pulp at this point. The balance of the pulp slurry was then passed into the plant's normal flotation cell. The foam that collected on the surface was allowed to flow over a weir and the foam characteristics determined. Another filter pad was made for measuring the brightness of the deinlced pulp after flotation.
Table 3 Deinlcin~ Performance Float Float Cell Finals Feed Accepts Sample BRT ERIC BRT ERIC Gain pH BRT ERIC
A 44 850 54.8 280 10.8 9.4 59 150-200 B 43 896 54.4 <200 11.4 9.2 60 150-200 C 44 920 52.7 <180 8.7 8.2 59 150-200 I 43 1100 52.0 <200 9.0 8.2 59 I50-200 "BRT" = brightness "ERIC" = estimated residual ink count Figure 1 provides the Foam Profiles of extended continuous plant runs using the four systems. The Foam Profiles graphs foam life (in minutes) vs.
plant running time (in hours).
As shown in Figure l, Samples A and B (conventional fatty acid deinlcing with sodium salt of stearic acid) exhibited a typical wide operating band of foam life ranging from about 1.5 to 3.5 minutes. Sample A had a foam density p of 0.15-0.2 g/cc and a low foam half life of 1.5 minutes. Sample B had a foam density p of 0.2-0.3 g/cc, which indicates a higher inlc content than Sample A, and a foam half life of 2.5-3.5 minutes.
Sample C produced a foam which continued to increase and did not collapse on a regular basis. Sample C had a higher foam density p of 0.25-0.35 g/cc which indicates a still higher inlc carrying capability than Samples A and B, but in view of the foam not collapsing, the system is not useful in the absence of a defoamer, the use of which causes the aforementioned problems.
Sample 1 (invention) exhibited a quite narrow operating band with foam life ranging from 2.5 to 3.5 minutes. Sample 1 had a high foam density p of 0.2-0.3 g/cc, which indicates good a high ink content. The half life of the foam was less than 2 minutes. The three component deinking composition produced an excellent foam profile while simultaneously allowing a reduction in the sodium hydroxide/silicate requirement from 2.25 wt % to 0.2 wt %.
Example 2 The procedure of Example 1 was repeated at a plant processing mixed office waste paper at a rate of 265 tons per day (TPD). This actual mill data resulted from on-line 24-hr processing at this Iow yield plant (about 50%).
With mixed office waste feed, the focus is on quality. The trial covered three of the 10 grades of paper produced at the plant.
"DIA-3" was a bloclc ethoxylated and propoxylated C-18 alcohol having a cloud point of 62°C. "DIA-4" was a random ethoxylated and propoxylated alcohol having a cloud point of 44°C. The polyester was the 1:l molar reaction product of 5(6)-carboxy-4-hexyl-2-cyclohexene-1-octanoic acid with polyethylene glycol (mw 1450). The fatty acid was predominantly C-18.
The various compositions evaluated and the resulting performances are given in Table 4 in which "Dirt" is the residual inlc count in ppm, "SPEC
Count"
is the residual count of other materials such as plastics, hot melt adhesive resins, binders etc., and "Bleach optical" is the optical bleach demand as a percentage of the plant's normal bleach demand.
These downside effects are reduced in the present invention by operating at low sodium hydroxide levels thereby avoiding the need for the hydrogen peroxide and silicate during pulping. Also, the need for biocides to prevent enzyme (peroxidase and catalase) loss of the hydrogen peroxide is eliminated during final bleaching. Furthermore, the associated additives for deposit/scale control are negated since the use of fatty acids can be minimized or avoided and no additional calcium is needed to ensure calcium soap formation and organics/colloid interference to the process is minimized.
According to the process of this invention, the three components can be added directly to the pulper during the pulping stage, preferably near the beginning thereof, or to the flotation cell prior to flotation. The components can be added individually or they may be pre-mixed. Mill conditions will determine the most suitable condi-tions.
After the slurry exits the pulper, it is diluted to about 1 wt % solids. If a fatty acid or salt thereof is used, it may be added. Alternatively, the fatty acid component may be added partially during the pulping operation and partially upon entry to flotation. Thereafter, air is introduced into the flotation equipment to cause vigor-ous mixing of the diluted pulp slurry and to ensure foam generation for inlc trans-port/removal from the system.
As a result of the addition of the combination of (1) the polyester, (2) the first alkoxylated deinking agent, and (3) the second lower cloud point deinlcing agent, the ink particles are released from the recycled printed media and agglomerated into larger particles. The air bubbles then attach to the agglomerated ink particles and carry the agglomerated particles to the surface of the flotation equipment and form a foam thereon. This ink-rich foam is removed from the surface in any of the conventional manners well known in the art of deinking. A particular benefit of the present invention is the character of the foam which is produced. The foam has high ink carrying capability that upon leaving the flotation cell collapses in a regular and controlled manner so that the resulting inlcy liquid can be easily removed and sent to waste treatment for final disposal.
Following the flotation deinlcing procedure, the pulp slurry is thickened to about 6 to 12 wt % solids and washed using conventional equipment readily available and in widespread commercial use. The filtrate from the washing is typically treated in a dissolved air flotation (DAF) clarifies to remove inlcs, fill-ers, fiber fines, and other suspended solids so that the filtrate water can be recycled for use in a sub-sequent deinking procedure. Commonly, cationic, nonionic and/or anionic polymers are added to the filtrate prior to or in the dissolved air flotation clarifies so that the suspended solids will be agglomerated and/or flocculated and removed.
Many modifications and variations of the basic deinking procedure explained herein have been proposed and/or are in commercial use and the method of the pres-ent invention may be applied to those procedures. The simple system explained herein is used for illustration purposes only and is not meant to be in limitation of the scope of this invention. The pulping process may be carried out either in a continuous way or batchwise,~ with excellent results with any type of printed media including newspaper, magazines, printed cardboard and colored printed media. The recycled paper is fed to the process so that it is present in an amount of about 10 to 100 wt % of the fiber undergoing pulping. The equipment used in this process is conventional equipment which is readily available and in widespread use.
The use of the deinking components of the present invention has several advantages when compared to the conventional prior art. Compared to conventional deinlcing methods, a significant reduction in total chemical demand is realized when using this method. The ink removal rate is often also increased over conventional flotation methods, resulting in either increased production rates without sacrifice of product quality. Most importantly, the foam profile is such that extended continuous operations result.
While most preferably no fatty acid is used in the present process, there will be situation when a small amount is desirable. The dosage rate of the fatty acid component of the composition can be substantially reduced from the 1 to 2 wt % for a conventional process to below about 0.2 wt %, preferably below about 0.1 wt %, based on the total weight of fiber for the present invention. The none or lower amount significantly reduces the potential for scale and deposit problems normally associated with fatty acid components of deinking formulations both in the deinlcing equipment itself and at the subsequent paper machine. Expensive downtime for equipment clean-up is minimized and a higher quality final paper product can be produced.
Environmental concerns are causing paper mills to continually seelc to reduce the amount of fresh water used. This means that increasing amounts of mill water must be reused. It is an advantage of the present invention that not only is the clarity of the filtrates produced in washing stages following the flotation deinking stage improved but also the subsequent drainage rate because of an increased removal of both inorganic fillers, e.g. calcium carbonate and titanium dioxide, and fiber fines which are in the waste paper pulp slurry being treated. In view of improved filtrate clarity, the amount of flocculants required for water clarification and subsequent reuse is reduced. In view of increased drainage rate, plant through-put can be increased.
The advantages of the deinking composition of the present invention as com-pared with conventional deinking compositions are further illustrated in the follow-ing Examples in which all parts and percents are by weight unless otherwise specified. All filter pads for brightness were made using alum as specified in TAPPI Test Method T 218 om-83. Where necessary the pulp samples were first diluted to 1 wt % solids (equivalent to a 3 gram air-dried sheet) with tap water, 2 ml of 10% alum solution added to each sample, and the slurry then thickened on a Buchner funnel using Ahlstrom grade 631-25 filter paper. The filter pads were air dried before taking brightness measurements. All brightness data was obtained using an ACS Spectrosensor II spectrophotometer and reported as TAPPI 452 brightness. The brightness data represents the percent of light at wavelength 452 manometers which is reflected off the filter pad and recorded by the spectrophotometer.
Example 1 A mixture of 35% MAG (old magazines), 65% ONP (old newspapers) were shredded dry and combined. The mixture was added to a plant pulper along with water (120°F) and the each of the four different deinking/flotation deinlcing chemical systems specified in Table 2. The pulps had a consistency of about 12-14 %.
The polyester was the 1:1 molar reaction product of 5(6)-carboxy-4-hexyl-2-cyclohexene-1-octanoic acid with polyethylene glycol (mw 1450). "Deinlc agent 1" was a block ethoxylated and propoxylated C-18 alcohol having a cloud point of 48-50°C. "Deink agent 2" was a random ethoxylated and propoxylated C-alcohol having a cloud point of 42-44°C. The fatty acid was predominantly C-18.
In Table 2, "A" is a prior art conventional fatty acid only foaming system used in the plant. "B" is a prior conventional fatty acid/alkoxylated hydrophobe blend deinlcing system used in the plant. "C" is a blend of an aromatic polyester and a single alkoxylated hydrophobe deinlcing system. "Example 1" is a composition of the present invention utilizing the 3 component deinlcing system applied under plant conditions.
The bleach demand for samples "A" and "B" was 0.4 wt % in each of the pulper and the tower. The bleach demand for samples "C" and Example 1 was 0 in the pulper and 0.6 wt % in the tower Table 2 Chemical Regimes - % on Dry Fiber Test Fatty Poly-Deink Deink BiocideBleach SampleAcid SilicateesterAgent Agent NaOH (ppm) Demand 1 2 pulper tower A 0.45 1.8 --- --- --- 0.35 20 0.40 0.42 B 0.12 1.8 --- 0.05 --- 0.34 20 0.40 0.60 C --- --- 0.0250.09 --- 0.20 --- --- 0.60 1 --- --- 0.0250.06 0.03 0.20 --- --- 0.60 The deinlcing performance of the 4 deinking compositions was evaluated and the results are shown in Table 3. After each of the four combinations of chemicals, water and waste paper was pulped for 15-20 minutes, test samples were taken. The samples were diluted to 1 % using additional water and deinlcing performance deter-mined. Filter pads were made for measuring the brightness of the deinked pulp at this point. The balance of the pulp slurry was then passed into the plant's normal flotation cell. The foam that collected on the surface was allowed to flow over a weir and the foam characteristics determined. Another filter pad was made for measuring the brightness of the deinlced pulp after flotation.
Table 3 Deinlcin~ Performance Float Float Cell Finals Feed Accepts Sample BRT ERIC BRT ERIC Gain pH BRT ERIC
A 44 850 54.8 280 10.8 9.4 59 150-200 B 43 896 54.4 <200 11.4 9.2 60 150-200 C 44 920 52.7 <180 8.7 8.2 59 150-200 I 43 1100 52.0 <200 9.0 8.2 59 I50-200 "BRT" = brightness "ERIC" = estimated residual ink count Figure 1 provides the Foam Profiles of extended continuous plant runs using the four systems. The Foam Profiles graphs foam life (in minutes) vs.
plant running time (in hours).
As shown in Figure l, Samples A and B (conventional fatty acid deinlcing with sodium salt of stearic acid) exhibited a typical wide operating band of foam life ranging from about 1.5 to 3.5 minutes. Sample A had a foam density p of 0.15-0.2 g/cc and a low foam half life of 1.5 minutes. Sample B had a foam density p of 0.2-0.3 g/cc, which indicates a higher inlc content than Sample A, and a foam half life of 2.5-3.5 minutes.
Sample C produced a foam which continued to increase and did not collapse on a regular basis. Sample C had a higher foam density p of 0.25-0.35 g/cc which indicates a still higher inlc carrying capability than Samples A and B, but in view of the foam not collapsing, the system is not useful in the absence of a defoamer, the use of which causes the aforementioned problems.
Sample 1 (invention) exhibited a quite narrow operating band with foam life ranging from 2.5 to 3.5 minutes. Sample 1 had a high foam density p of 0.2-0.3 g/cc, which indicates good a high ink content. The half life of the foam was less than 2 minutes. The three component deinking composition produced an excellent foam profile while simultaneously allowing a reduction in the sodium hydroxide/silicate requirement from 2.25 wt % to 0.2 wt %.
Example 2 The procedure of Example 1 was repeated at a plant processing mixed office waste paper at a rate of 265 tons per day (TPD). This actual mill data resulted from on-line 24-hr processing at this Iow yield plant (about 50%).
With mixed office waste feed, the focus is on quality. The trial covered three of the 10 grades of paper produced at the plant.
"DIA-3" was a bloclc ethoxylated and propoxylated C-18 alcohol having a cloud point of 62°C. "DIA-4" was a random ethoxylated and propoxylated alcohol having a cloud point of 44°C. The polyester was the 1:l molar reaction product of 5(6)-carboxy-4-hexyl-2-cyclohexene-1-octanoic acid with polyethylene glycol (mw 1450). The fatty acid was predominantly C-18.
The various compositions evaluated and the resulting performances are given in Table 4 in which "Dirt" is the residual inlc count in ppm, "SPEC
Count"
is the residual count of other materials such as plastics, hot melt adhesive resins, binders etc., and "Bleach optical" is the optical bleach demand as a percentage of the plant's normal bleach demand.
Table 4 Chemical Performance Regime %
on dry fiber Fatty DIA-3 DIA-4 Poly- Dirt SPEC BleachComments Acid 62 44 ester (ppm) Count Optical 0.90 0.12 --- --- 6-8 800-1200 100.0 Control Reduced bleach 0.45 0.12 0.03 0.100 4-6 < 600 64.0 10 day run 0.90 0.12 0.03 --- 6-8 800-1000 100.0 Reduced bleach 0.30 0.12 0.03 0.100 6-8 700-800 67.0 42 day run Reduced bleach 0.30 0.12 0.03 0.075 6-8 600-800 80.0 4 day run Reduced bleach 0.30 0.12 0.03 0.040 > 10 800-1000 90.0 4 day run -The results demonstrate the overall reduced chemical demand for a three component system as well as a substantial reduction in the optical bleach demand.
The fatty acid demand was reduced by 50% and the optical bleach demand by 30-36%. Annualized savings from the reduced optical bleach demand for just the three of 10 paper grades manufactured at the plant is estimated at more that $300,000.
Example 3 The procedure of Example 1 was repeated on a mixed office waste furnish while varying the composition of the polyester resin. The first was as disclosed in Example l, the second contained 1.9 wt % of the sodium salt of dimethylsulfo-isophthalate, and the third contained 5 wt % of the same salt. When the polyesters were used in a three component deinking system, the level of sticlcies found in the deinked product was reduced as the amount of the anionic salt increases.
Example 4 The procedure of Example 1 was repeated at a deinked marlcet pulp operation processing a 70:30 ratio of old newspaper:magazines. The plant was typically operating with 0.44 % fatty acid and 0.06 % of DIA-3 to produce paper having a brightness of 60-62 with an ERIC spread of 130-180, of which the maj ority was 13 0-160.
Using a deinlcing combination of 0.31 % fatty acid, 0.05 % of DIA-3 having a cloud point of 62-64°, 0.01 % of DIA-4 having a cloud point of 44°, and 0.05 of the polyester, the brightness values exceeded 62 with a 30% reduction in hydrogen peroxide and ERIC values being tightened to 110-130. This improved performance was obtained with a 30% reduction in fatty acid usage while sodium hydroxide and silicate were kept at plant levels.
on dry fiber Fatty DIA-3 DIA-4 Poly- Dirt SPEC BleachComments Acid 62 44 ester (ppm) Count Optical 0.90 0.12 --- --- 6-8 800-1200 100.0 Control Reduced bleach 0.45 0.12 0.03 0.100 4-6 < 600 64.0 10 day run 0.90 0.12 0.03 --- 6-8 800-1000 100.0 Reduced bleach 0.30 0.12 0.03 0.100 6-8 700-800 67.0 42 day run Reduced bleach 0.30 0.12 0.03 0.075 6-8 600-800 80.0 4 day run Reduced bleach 0.30 0.12 0.03 0.040 > 10 800-1000 90.0 4 day run -The results demonstrate the overall reduced chemical demand for a three component system as well as a substantial reduction in the optical bleach demand.
The fatty acid demand was reduced by 50% and the optical bleach demand by 30-36%. Annualized savings from the reduced optical bleach demand for just the three of 10 paper grades manufactured at the plant is estimated at more that $300,000.
Example 3 The procedure of Example 1 was repeated on a mixed office waste furnish while varying the composition of the polyester resin. The first was as disclosed in Example l, the second contained 1.9 wt % of the sodium salt of dimethylsulfo-isophthalate, and the third contained 5 wt % of the same salt. When the polyesters were used in a three component deinking system, the level of sticlcies found in the deinked product was reduced as the amount of the anionic salt increases.
Example 4 The procedure of Example 1 was repeated at a deinked marlcet pulp operation processing a 70:30 ratio of old newspaper:magazines. The plant was typically operating with 0.44 % fatty acid and 0.06 % of DIA-3 to produce paper having a brightness of 60-62 with an ERIC spread of 130-180, of which the maj ority was 13 0-160.
Using a deinlcing combination of 0.31 % fatty acid, 0.05 % of DIA-3 having a cloud point of 62-64°, 0.01 % of DIA-4 having a cloud point of 44°, and 0.05 of the polyester, the brightness values exceeded 62 with a 30% reduction in hydrogen peroxide and ERIC values being tightened to 110-130. This improved performance was obtained with a 30% reduction in fatty acid usage while sodium hydroxide and silicate were kept at plant levels.
Claims (16)
1. A method of performing flotation deinking which is characterized by adding to an aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di or tricarboxylic acid or anhydride thereof with a polyalkylene oxide or with an alkylene oxide, (2) a first deinking agent which is an alkoxylated hydrophobic base and (3) a second deinking agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20°
lower than the cloud point of the first deinking agent.
lower than the cloud point of the first deinking agent.
2. A method of reducing the total chemical demand of a flotation deinking process which is characterized by adding to an aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di or tricarboxylic acid or anhydride thereof with a polyalkylene oxide or with an alkylene oxide, (2) a first deinking agent which is an alkoxylated hydrophobic base and (3) a second deinking agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20° lower than the cloud point of the first deinking agent.
3. A method of increasing the ink removal rate of a flotation deinking process which is characterized by adding to an aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di or tricarboxylic acid or anhydride thereof with a polyalkylene oxide or with an alkylene oxide, (2) a first deinking agent which is an alkoxylated hydrophobic base and (3) a second deinking agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20° lower than the cloud point of the first deinking agent.
4. A method of increasing the production rate of a paper mill which processes an aqueous waste paper pulp through a flotation deinking process which is characterized by adding to the aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di or tricarboxylic acid or anhydride thereof with a polyalkylene oxide or with an alkylene oxide, (2) a first deinking agent which is an alkoxylated hydrophobic base and (3) a second deinking agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20° lower than the cloud point of the first deinking agent.
5. A method of reducing optical bleach demand for producing paper from a waste paper pulp slurry which is subjected to flotation deinking which is characterized by adding to the aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di or tricarboxylic acid or anhydride thereof with a polyalkylene oxide or with an alkylene oxide, (2) a first deinking agent which is an alkoxylated hydrophobic base and (3) a second deinking agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20° lower than the cloud point of the first deinking agent.
6. A method of reducing the stickies content resulting from an aqueous waste paper pulp slurry which is processed by a flotation deinking process which includes a fatty acid, which is characterized by adding to the aqueous waste paper pulp slurry each of (1) a polyester obtained through reaction between a di or tricarboxylic acid or anhydride thereof with a polyalkylene oxide or with an alkylene oxide, (2) a first deinking agent which is an alkoxylated hydrophobic base and (3) a second deinking agent which is an alkoxylated hydrophobic base and which has a cloud point about 2 to 20° lower than the cloud point of the first deinking agent.
7. The method of Claims 1-6 characterized in that the polyester is prepared from a cyclic aliphatic di-acid of the formula:
HOOC-A-(CH2)x -COOH
wherein A is a cyclic aliphatic group having 6 to 10 carbon atoms and x is an integer from 0 to about 15.
HOOC-A-(CH2)x -COOH
wherein A is a cyclic aliphatic group having 6 to 10 carbon atoms and x is an integer from 0 to about 15.
8. The method of Claim 7 characterized in that the COOH groups are ortho or para to each other.
9. The method of Claim 7 characterized in that the cyclic aliphatic group is further substituted with one or more straight or branched chain alkyl groups having about 3 to 18 carbon atoms.
10. The method of Claim 7 characterized in that a portion of the cyclic di- and/or tri-carboxylic acid and/or anhydride is substituted by a sulphate anion.
11. The method of Claim 7 characterized in that the polyester is prepared by reaction with a polyalkylene oxide polymer which was prepared from an alkylene oxide having 2 to 4 carbon atoms.
12. The method of Claim 7 characterized in that the polyester has a hydro-phobe loading of about 35 to 55 wt %, a hydrophile loading of about 35 to 55 wt %, and a terminal carboxyl content of about 5 to 15 wt %.
13. The method of Claims 1-6 characterized in that the hydrophobic bases of the first and second deinking agents are each independently selected from alcohols, amines, acids, dimer acids, and salts thereof containing about 12 to carbon atoms.
14. The method of Claims 1-6 characterized in that the polyester is used in an amount of about 0.05 to about 0.5 wt % based on the total weight of fiber present, and the two deinking agents are used in a weight ratio of about 1:10 to about 10:1 and in a total amount of about 0.001 to 0.3 wt % based on the total weight of fiber present.
15. The method of Claims 1-6 characterized in that the flotation deinking is performed in the further presence of a fatty acid or salt thereof of the formula RCOO-M, wherein R is a linear, branched, or cyclic alkyl or alkenyl group having about 7 to about 48 carbon atoms and M is hydrogen or a counterion selected from the group consisting of Na, K, Ca, NH4, or NHx(CH2CH2OH)y wherein x and y are each integers from 0 to 4 and total 4.
16. The method of Claim 15 characterized in that the amount of the fatty acid or the salt thereof is from about 0.2 to 0.5 wt %.
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US60/223,414 | 2000-08-07 | ||
PCT/US2001/041584 WO2002012618A2 (en) | 2000-08-07 | 2001-08-07 | Flotation deinking process |
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EP2386681A1 (en) | 2010-05-14 | 2011-11-16 | Universitat Politècnica de Catalunya | Process for recycling waste paper, product obtained there from and its uses |
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JP3081120B2 (en) * | 1994-04-08 | 2000-08-28 | 花王株式会社 | Deinking agent |
US5560806A (en) * | 1994-04-22 | 1996-10-01 | Ppg Industries, Inc. | Process for deinking electrostatic printed paper using a combination of non-ionic surfactants |
JP2992194B2 (en) * | 1994-05-10 | 1999-12-20 | 花王株式会社 | High temperature deinking method |
US5718801A (en) * | 1994-08-11 | 1998-02-17 | Ppg Industries, Inc. | Method for controlling froth and reducing stickies in the flotation process for deinking waste paper using a froth moderating agent |
CA2199745A1 (en) * | 1994-09-12 | 1996-03-21 | David A. Longhini | Deinking composition and method for deinking waste paper |
US5660683A (en) * | 1995-05-02 | 1997-08-26 | Betzdearborn Inc. | Process for deinking waste paper using a mixture of thiol ethoxylate and alcohol alkoxylates |
US5712233A (en) * | 1996-01-22 | 1998-01-27 | Witco Corporation | Alkoxylate surfactant compositions and the use thereof in paper deinking |
SE9600730D0 (en) * | 1996-02-27 | 1996-02-27 | Bim Kemi Ab | Method of mass production |
JP3313046B2 (en) * | 1997-04-21 | 2002-08-12 | 花王株式会社 | Deinking method |
-
2001
- 2001-08-07 US US09/923,595 patent/US6544383B2/en not_active Expired - Fee Related
- 2001-08-07 WO PCT/US2001/041584 patent/WO2002012618A2/en active Application Filing
- 2001-08-07 JP JP2002517890A patent/JP4233867B2/en not_active Expired - Fee Related
- 2001-08-07 EP EP01971357A patent/EP1309754A2/en not_active Withdrawn
- 2001-08-07 CA CA 2418956 patent/CA2418956A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
WO2002012618A2 (en) | 2002-02-14 |
US20020066880A1 (en) | 2002-06-06 |
EP1309754A2 (en) | 2003-05-14 |
US6544383B2 (en) | 2003-04-08 |
JP4233867B2 (en) | 2009-03-04 |
WO2002012618A3 (en) | 2002-06-06 |
JP2005520057A (en) | 2005-07-07 |
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