CA2061940A1 - Aluminum hydroxychloride as pitch control agent - Google Patents
Aluminum hydroxychloride as pitch control agentInfo
- Publication number
- CA2061940A1 CA2061940A1 CA 2061940 CA2061940A CA2061940A1 CA 2061940 A1 CA2061940 A1 CA 2061940A1 CA 2061940 CA2061940 CA 2061940 CA 2061940 A CA2061940 A CA 2061940A CA 2061940 A1 CA2061940 A1 CA 2061940A1
- Authority
- CA
- Canada
- Prior art keywords
- pulp
- paper
- percent
- aluminum hydroxychloride
- wood
- 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
- NNCOOIBIVIODKO-UHFFFAOYSA-N aluminum;hypochlorous acid Chemical compound [Al].ClO NNCOOIBIVIODKO-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 claims abstract description 74
- 230000008569 process Effects 0.000 claims abstract description 57
- 239000002023 wood Substances 0.000 claims abstract description 21
- 229920001131 Pulp (paper) Polymers 0.000 claims description 53
- 238000002156 mixing Methods 0.000 claims description 11
- 238000007670 refining Methods 0.000 claims description 5
- 230000000930 thermomechanical effect Effects 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 238000012545 processing Methods 0.000 abstract description 9
- 229910052782 aluminium Inorganic materials 0.000 abstract description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 5
- 239000011295 pitch Substances 0.000 description 40
- 239000000123 paper Substances 0.000 description 34
- 229940037003 alum Drugs 0.000 description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 22
- 239000000463 material Substances 0.000 description 18
- 239000000654 additive Substances 0.000 description 15
- 239000000523 sample Substances 0.000 description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 8
- 239000000835 fiber Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 239000003795 chemical substances by application Substances 0.000 description 7
- 239000008367 deionised water Substances 0.000 description 7
- 229910021641 deionized water Inorganic materials 0.000 description 7
- 230000000996 additive effect Effects 0.000 description 6
- 230000014759 maintenance of location Effects 0.000 description 6
- 239000011347 resin Chemical class 0.000 description 6
- 229920005989 resin Chemical class 0.000 description 6
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 5
- 235000011613 Pinus brutia Nutrition 0.000 description 5
- 241000018646 Pinus brutia Species 0.000 description 5
- 230000002378 acidificating effect Effects 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- -1 aluminum hydroxychlorides Chemical class 0.000 description 4
- 238000013459 approach Methods 0.000 description 4
- 238000004061 bleaching Methods 0.000 description 4
- 239000007844 bleaching agent Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000004537 pulping Methods 0.000 description 4
- 229910000029 sodium carbonate Inorganic materials 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 3
- 125000002091 cationic group Chemical group 0.000 description 3
- 238000010790 dilution Methods 0.000 description 3
- 239000012895 dilution Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000013055 pulp slurry Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-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
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229920013683 Celanese Polymers 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 235000011128 aluminium sulphate Nutrition 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 235000014113 dietary fatty acids Nutrition 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 238000011067 equilibration Methods 0.000 description 2
- 239000000194 fatty acid Substances 0.000 description 2
- 229930195729 fatty acid Natural products 0.000 description 2
- 150000004665 fatty acids Chemical class 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000002655 kraft paper Substances 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 238000010297 mechanical methods and process Methods 0.000 description 2
- 230000005226 mechanical processes and functions Effects 0.000 description 2
- 239000006259 organic additive Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- JVBXVOWTABLYPX-UHFFFAOYSA-L sodium dithionite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])=O JVBXVOWTABLYPX-UHFFFAOYSA-L 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate group Chemical group S(=O)(=O)([O-])[O-] QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 150000004684 trihydrates Chemical group 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- BHMLFPOTZYRDKA-IRXDYDNUSA-N (2s)-2-[(s)-(2-iodophenoxy)-phenylmethyl]morpholine Chemical compound IC1=CC=CC=C1O[C@@H](C=1C=CC=CC=1)[C@H]1OCCNC1 BHMLFPOTZYRDKA-IRXDYDNUSA-N 0.000 description 1
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 description 1
- 229910018626 Al(OH) Inorganic materials 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 description 1
- 201000011180 Dental Pulp Calcification Diseases 0.000 description 1
- 101100130497 Drosophila melanogaster Mical gene Proteins 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 101100345589 Mus musculus Mical1 gene Proteins 0.000 description 1
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 229910000329 aluminium sulfate Inorganic materials 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 229920006319 cationized starch Polymers 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012632 extractable Substances 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 239000000834 fixative Substances 0.000 description 1
- 235000011194 food seasoning agent Nutrition 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 229920000592 inorganic polymer Polymers 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- HDKLIZDXVUCLHQ-UHFFFAOYSA-N non-3-en-2-one Chemical compound CCCCCC=CC(C)=O HDKLIZDXVUCLHQ-UHFFFAOYSA-N 0.000 description 1
- 150000004689 octahydrates Chemical class 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000011146 organic particle Substances 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000011087 paperboard Substances 0.000 description 1
- QKFJKGMPGYROCL-UHFFFAOYSA-N phenyl isothiocyanate Chemical compound S=C=NC1=CC=CC=C1 QKFJKGMPGYROCL-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- 239000003352 sequestering agent Substances 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 230000003381 solubilizing effect Effects 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
Landscapes
- Paper (AREA)
Abstract
ABSTRACT
This invention comprises a process for treating wood based pulp with aluminum hydroxychloride to reduce or eliminate pitch problems associated with making and processing such pulp. Aluminum hydroxychloride having a basisity of at least 70 percent is added to wood based pulp in an amount of up to 5 percent by weight (based on the weight of ovendry pulp) at one or more points in the pulp and/or paper processes and at a system pH within the range of from about 3 to about 8. The use of this invention results in paper products which retain more of their brightness than pulp processed with other known aluminum containing products.
This invention comprises a process for treating wood based pulp with aluminum hydroxychloride to reduce or eliminate pitch problems associated with making and processing such pulp. Aluminum hydroxychloride having a basisity of at least 70 percent is added to wood based pulp in an amount of up to 5 percent by weight (based on the weight of ovendry pulp) at one or more points in the pulp and/or paper processes and at a system pH within the range of from about 3 to about 8. The use of this invention results in paper products which retain more of their brightness than pulp processed with other known aluminum containing products.
Description
206~9~0 AL~XIN~M ~YDROXYC~L4RIDE as PITC~ CON~RO~ AGEX$
BAC~GRO~ND OF ~E IN~2N~ION
The art of wood pulp processing and papermaking spans a variety of topics and chemistries. One of the concerns of pulp processors is pitch control. It has now been found that aluminum hydroxychloride, such as in the form of an aluminum hydroxychloride complex, can be used as an lo effective pitch control agent with less brightness loss of the pulp.
There are a number of definitions of pitch. Pitch is generally considered to be a mixture oS fatty acids, resin acids9 and unsaponifiable organic deposits of widely varying composition originating in the extractive fraction of wood. Pitch ~sometimes called resins or pitch resins) is a term used for the organic ~aterials that can be extracted from wood or wood pulp with an organic solvent such as ether. These hydrophobic extractables are usually dissolved or dispersed in the water phase of a pulp slurry;
however, under certain process conditions, these dispersions or solutions will destabilize and form pitch deposits. Pit~h deposits may contain more that just the naturally occurring resins, however. They may include a combination of (a) organic compounds (naturally occurring or produced by the digestion process, for examplQ, fatty and rosin acids and salts thereof, lignins and unsaponifiable materials); (b) insoluble mineral salts or " 20619~0 soaps (for example, calcium car~onate, calcium salts and fatty a~ids); and/or (c) organic and inorganic ~aterials present in papermaking additives tfor exa~ple, fatty acids or hydrocarbon oils found in many defoamers).
Some people classify pitch into two major types based on whether one i5 discussing naturally occurring pitch from virgin pulp (pitch) or pitch comprising additives from previous processing where these additives are found in pulp or paper which is being reprocessed (white pitch). White pitches may inc}ude lattices and/or organic polymers from coating compositions and organiC retaining material from preceding papermaking processes.
Pitch problems are both paper and pulp related. They are particularly evident in sulfite and groundwood (mechanical pulps) mills, where the solubilizing action ef the alkaline kraft proce5s is not present. Pitch problems manifest themselves in various ways, but the most common are dark, tacky, layered deposits on eguipment and sticky balls floating in pulp slurries. Pitch is a ma;or problem because it (l) agglomerates and also occludes other matter to form visible "dirt" in the final paper; (2~ plates out and collects on pulp and paper processing equipment such as screens, filters, refining equipment, pulp washers, and the paper machine: and (3) reduces pulp brightness and brightness stability. Once pitch becomes attached to the machine parts, the only way it can be r~moved is by scrubbing with organic solvents or special cleaning 20~1940 compounds. The down time associated with such procedures reduces the productivity of the plant.
~ he research in this area is made difficult because of the complex and reactive nature of this fraction of materials, because they often have been subjected to many chemical reactions during pulping and bleaching, and because the resin fraction is mixed with other wood components and materials added during the paper-making process. Additionally, changes in operating variables such as temperature, electrolyte content (for example, calcium and magnesium content) or pH can cause agglomeration and precipitation of pitch deposits.
A number of approaches have been tried either alone or in combination to reduce the presence of pitch and/or the problems associated with processing ~ulp and paper containing pitch. These approaches include seasoning wood, storing wood as chips, using kraft pulping methods rather than sulfite processes, controlling the types and amounts of wash aids and defoamers used in system processing, using a bleaching process, and using pitch absorbants such as talc and clay. Still other methods that have been tried include the a~dition of surfactants, chelating agents, crystal modifiers or dispersants, dispersants followed by fixatives, and controlling system parameters such as size of equipment.
In solving the problems associated with the presence of pitch in wood based pulp as it is being processed either as wood pulp and/or paper pulp one approach has been the 2~ 9~
use of a~uminum sul~ate, also callea alum or papermakers~
alum (Note that papermaker's alum is usually represented by the for.-ula Al2(SO~)3 14H20, whereas other types of alum may be represented with a different nu-~er of waters, for example Al2(SO4)3 18H20). Alum can be added to the mill system at many different times and locations. In a papermaking apparatus it may be added into the headbox at dosages ranging up to 4 percent on a dry fiber weight basis (4 percent equals 80 pounds of alum content per ton of dry fiber). ~n a wood pulp mill alu~ may be added at any place ~rom the pulpers, refiners and/or grinders through to the paper machine blend chest. Pulp mill applications can range in dosages up to 4 percent (80 pounds per ton) in the final dry fiber.
While it is not known exactly how alum works to reduce pitch in the pulping process, it is believed that alum fixes the pitch on the fibers of pulp. There are problems associated with the use of alum, however; these include the fact that the pitch particles are fixed to the pulp fibers, difficulties in handling and disposing of sulfate residues, and slime and deposit problems stemming from the use of sulfate-reducing bacteria. Additionally, loss of pulp brightness caused by the addition of alum is a major problem.
There have been several attempts to replace alum. One of these efforts has resulted in product(s) known as Gen+IonT~ (General Chemical Corporation), a proprietary polyaluminum hydroxychloride-based material having a 20~1940 cationic charge and designed for paper machines operating in the pH range of 6.0 to 7.5.
None of these approaches has resulted in a totally satisfactory solut-on to the problem of alum replacement.
There still remains a need for a product to replace alum as a pitch control agent, wherein the product can reduce or eliminate the pitch contaminants with less brightness losses. There also remains a need for a product to replace known aluminum containing products such as alum as a pitch control agent where the product can be used at acid pH's.
Thus, it is an object of this invention to provide a material to use as a substitute for known aluminum containing products as a pitch control agent in the processing of pulp which gives products that have less lS brightness losses. It is a further object of this invention to provide a material which i5 useful in the control of pitch and which can be used at acidic pH's.
~MMARY OF ~EE INVENTION
This invention comprises a process for treating wood based pulp with aluminum hydroxychloride to reduce or eliminate pitch problems associated with making and processing such pulp. Aluminum hydroxychloride having a basisity of at least 70 percent is added to wooc based pulp in an amount of up to S percent by weight (based on the weight of ovendrv pulp) at one or more points in the pu' and/or paper processes and at a system pH within t.;e ranse 20619~0 of from aDout 3 to about 8. The use of this invention results in paper products which retain more of their brightness (that is have less brightness reversion or less loss of brightness) than pulp processed with other known aluminum containing products such as alum.
DE~AILE3 DESCRIPTION OF T~E INVENTION
It has been found that aluminum hydroxychloride (Al2(OH)5Cl2) is useful in treating wood and/or paper pulp to reduce problems associated with the presence of pitch.
For purposes of this invention, this aluminum hydroxychoride is also called aluminum hydroxychloride complex (AHC), for example in its trihydrate form. The AHC
used in this invention must have a basici~y of at least 7-0 percent. A particular value for the basicity is from about 70 percent to about 90 percent; a more particular value is from about 80 percent to about 90 percent, and an even more particular value is from anout 80 percent to about 85 percent. The percent basicity of the AHC's used in this invention corresponds to the percentage of OH groups in the species Al(OH)43.
The processes of this invention may be used at pH's in the range of about 3 to about 8, especially in the range of about 4 to about 8, and ~ore particularly in the range of about 4.5 to about 8. In contrast to other aluminum hydroxychloride materials used as pitch control agents (such as Gen+IonT~ material), this invention may be 206~9~0 practiced at acidic pH's such as in the range of about 3 to about 6.
An example of an AHC which is useful in this invention is LocronT~ aluminum hydroxychloride complex. LocronT~ AHC
is an inorganic polymeric compound. Unlike other aluminum compounds, Locront~ AHC is believed to exist as a highly charged species, All~O4(OH)24(HzO) 12) ~7~ in solution. LocronT~
AHC may be supplied as a solid (LocronT~ S, a trihydrate form) or as a liquid (LocronT~ L, a solution of AHC
containing about 50 percent solids by weight) and is easy to handle and use. LocronT~ L is a clear, odorless and colorless material with a specific gravity of about 1.35 (at 20 degrees C) and a pH of about 3.6.
This invention may be used with all types of pulps.
These include 1) mechanical wood pulp, 2) alkaline process derived pulps and 3) paper pulp. Mechan~cal wood pulp is a pulp manufactured wholly or in part by a mechanical process, including stone-ground wood,. chemigroundwood and chip mechanical pulp. Uses include newsprint papers, specialty papers, tissue, toweling, paperboard and wallboard. Mechanical wood pulp is sometimes subdivided into three types:
a) thermomechanical pulp (TMP):
A high-yield pulp produced by a thermomechanical process in which wood particles are softened by pre-heating under pressure prior to a pressurized ~19~0 pri~ary refining stage. ~o~e that refining stages are frequently don~ as two or three ~tepsO~ TMP usually replaces or reduces the ch~mical pulp componen~ ~n newsprint or groundwood papers, b) refiner groundwood~ A variety of paper~
with substantial proportions of mechanical wood pulp processed in a reiner; and c) groundwood pulp: A mechanical wood pulp ~ :
produced by pressing a barked log against a pulpstone and reducing the wood to a mass of relat:ively short fibers.
.jj, Paper pulp is the pulp used as the starting material in papermaking. Paper pulp can contain virgin wood pulp and/or secondary stock. Secondary stock is a term for fibers which have previously been used i~ the papermaking process. The term includes paper stock reclaimed from a recycling of pre~iously used paper pulp products ~for example, newsp~pers) as well as wet or dry broke. It appears to be the general case that paper reclai~ed from a recycling o~ previously used paper is ~urned into pulp in separa.e mi'ls as recycled paper pulp to be us~ in secondary stocX. BroXe is paper being reprocessed ~or recycled from the paper making apparatus~ because it ~as 20~19~
not dried completely in the papermaking apparatus, was off specification, et cetera. Broke is repulped and can be mixed with virgin pulp to use in the headbox.
For a description of various types of pulps and methods for their preparation, see PU1D and p~per Manufaçture, Volume 2, Mechanical Pulping, Edited by Ray A.
Leask (third edition, 1987, prepared under Joint Textbook Committee of Paper Industry, Technical Association of the Pulp and Paper Industry (TAPPI) and Canadian Paper and Pulp Association, incorporated by reference herein. (See particularly Chapter VII).
For purposes of this invention wood based pulp is defined to mean wood pulp (both mechanical and alkaline process derived) and paper pulp. For purposes of the examples recited herein, thermomechanical pulps made from pine were used. ~
In practicing the processes of this invention, the aluminum hydroxychloride may be added to one or both of wood pulp and paper pulp at various points in the processing of these pulps. Wood pulp and paper pulp are manufactured and processed on a continuous basis and the AHC may be added at the beginning of a process or at one or more later stages when a pitch problem is observed. In the case of wood pulp, AHC may be added, for example, after the refining stage(s). For groundwood, AHC may be added, for example, in the grinder shower water. For TMP's and wood pulp processed in re~iner mills, AHC may be added, for example, at the discharge side of the latency chest. In a 20~1940 papermaking ~achine, AHC may be a~dea, for example, to t~e material in the headbox. It is preferred that AHC be added at the point in the particular process where a pitch problem is observed. Thus, treating the pulp means that the pulp is exposed to aluminum hydroxychloride in sufficient amount to reduce or eliminate problems caused by the presence of pitch.
In practicing the processes of this invention, aluminum hydroxychloride is added to the pulp at one or more points in the pulp or papermaking process as described above in an amount(s) such that the final aluminum hydroxychloride content of the pulp or paper is any amount up to 5 percent by weight, and more perferably any amount up to 2 percent by weight, based on the ovendry weight of pulp or paper. (It i5 to be noted that if the pulp is used to make paper, the terms pulp and paper are essentially the same.) Aluminum hydroxychloride may be added as a solid or in the form of a liquid, such as an aqueous solution to a pulp slurry. Dilution of the aluminum hydroxychloride in a solution, such as a water solution, before addition to ~he wood or paper pulp makes small dose application easier although it is not required. It will be appreciated by those skilled in the art that the concentrations of AHC in such liquids may vary and that one would add a quantity o~
a particular concentration of ~C which is appropriate to substantially reduce the degree of pitch problem observed.
20619~0 The levels of addition describeu for this invention are based on ovendry weight. Ovendry means containing practically no moisture. A paper or pulp is said to be ovendry when it has been dried in an oven at 105 ~ 3 degrees Centiqrade until its weight has become constant within about 0.1 percent. Ovendry is considered a more accurate term than airdry, because airdry can contain as much a 10 percent moisture.
A sample calculation to determine the amount of aluminum hydroxychloride which must be added to a wood pulp or paper pulp slurry to achieve a described aluminum hydroxychloride content may be made as follows. For a quantity of 250 tons of pulp with a 4 percent consistency, one would add at least 0.3 tons of alu~inum hydroxychloride to achieve an AHC content of about 3 percent. Two hundred fifty (250) tons (2000 pounds per ton) of a pulp stock having 4 percent consistency would mean the stock contained 10 tons of solids. (Note that the term consistency is generally defined to be the percentage by weight of airdry or ovendry fibrous material in a stock or stock suspension.
It is sometimes called density or concentration, and is used interchangeably with weight percent.) To obtain a loading of 3 ~percent aluminum hydroxychloride or. the ovendry product, one would need to add a_ least 0.3 tons (10 tons x .03) of aluminum hydroxychloride (mixed in whatever volume of water desired) to achieve the 3 percent loading.
20~ 9~
For purposes of the examples contained herein, the wood pulp was preconditioned to simulate conditions found in thermomechanical pulp mills. This ~equired heating the thermomechanical pulp stoc~ (pine) to about 71 degrees Centigrade and adjusting its consistency to about 3 percent by the addition of deionized water. The use of this highly basic alu~inum hydroxychloride (of which LocronT~ is one example) is believed to be suita~le for all pulp and paper raw material (also called wood based pulp herein) including, in particular, those systems which use a large percentage of recycled material or coating line waste.
While it is not known precisely how the invention works, it is believed that highly basic aluminum hydroxychlorides, such PS those with a minimum basicity of about 70%, act as a contaminant binder and~sizing agent for fine organic and inorganic particles such as resins, polymers from binders, pitc~es and white pitch.
It is believed that the high level of external cationic charge of the precipitation product neutralizes and/or binds anionically charged particles in such a ~ay with the pulp that they no longer burden the water system.
This precipitaqion product has an isoelectric point of about 8. This invention may be used in a pH range of from about 3 to about 8, and preferably in a range of from about 4 to about 8, and more particularly in a range of from about ~.5 to about 8. The acidic pH range ~here the invention may be used is from about 3 to 6. The pH a~
~hich the invention is utilized will depend on a varie~y o factors. For example, with bleaching materials such as V-BriteT~ bleach (from Hoechst Celanese Corporation) a pH in the acidic range of about 5.2 is generally preferr2d. IP
calcium carbonate is used as a filler, a neutral pH is preferred. The cationicity is stable and effective over a prolonged period of time, so that the highly basic aluminu~
hydroxychloride can be added even at the very beginning of the paper process without loss of activity over the course of time. In the paper process the high cationicity of the precipitation product stabilizes cationically charged organic additives such as retaining materials and cationized starch which are protected from being discharged and lost, and are thu~ preserved to the full extent of their effectiveness in stabilizing the system. The precipitation product surrounds organic ~polymers such as pitches and cationizes them so that they lose their adhesiveness. Since their external charges are now all about the same, the particles repel each other and are prevented from agglomerating.
For the practice of this invention it is contemplated that the usual and most convenient way of combining or mixing AHC and~pulp is by adding AHC (either in d~y form or as an aqueous solution) to the pulp. It is also within .he spirit anc scope of this invention to a d AHC and pulp to the process container or process system at about the same time or to add wood based pulp after the AHC is present in the con.ainer or process syste~.
206194~
~ t has also been found that additional benefits, especially in the acidic pH range, from the practice of this invention include reduction in the amount of fine fibers (those particles less than 1 m~ in size) and waste products or organic additives in the water system;
decreased need for cationic materials: increased machine capacity because of faster dewatering; better retent_on with a higher degree of filler retention, whether naturally anionically or cationically precharged; reduction or elimination of pH shift at concentrations of up to about 5 percent (by weight) (equal to about lO0 pounds per ton of ovendry pulp) aluminum hydroxychloride; prevention of gypsum forma'ion due to absence of aluminum sulfate; and reduction or elimination of defects resulting from formation of carbon dioxide present in other systems.
E~AMPLES
Eor purposes of these Examples, the pulp used was South American Pine thermomechanical pulp. As explained above, mechanical wood pulps are any wood pulp5 manufactured wholly or in part by a mechanical process;
stone groundwood, chemigroundwood, refiner ~echanical, and thermomechanical. The pulp used in this work was a mechanical pulp manufactured by a high yield thermomechanical process. The pulp was o~tained from a mill and required no further treatments other than diluting it to 3% consistency with the addition of deionize water and heating it to its normal mill te~erature of about 71 degrees Centigrade. A HunterLab D25-PC2 ~rightness Meter was used to measure brightness.
Unless otherwise noted, chemical abbreviations and symbols have their regular and customary meeting, 0 for oxygen, H for hydrogen, ml for milliliter, N for normal, C
for Centigrade, lb for pound(s), et cetera.
EgAMP~ES 1-~8 The general laboratory procedure used for Examples 1-48 was as follows. A 500 milliliter Erlenmeyer flask for each example was equipped with a stirrer and a constant temperature water bath i~itially set at a temperature of 71 degrees C. A pulp sample (15 grams, dry weight of thermomechanical pine pulp) was placed in, each of the 500 ml Erlenmeyer flasks and diluted with deionized water to a consistency of 3.25 percent (by weight) to facilitate mixing. The initial pH of the pulp samples in each of the flasks was 4.8. The pH was adjusted to about 5.2 using O.lN sodium carbonate. (A p~ of 5.2 was selected because it is believed to be within the optimal range of bleach response for this pulp, thus allowing for any effect on brightness by the other additives to be more readily observed.) The pulp samples were initially heated to 71 degrees C using a microwave oven (Whirlpool Model MW8650XR:
1.3 cubic feet; 700 watt) equipped with a temperature probe. The Erlenmeyer flasks containing the pulp were then -2061~40 sealed witn a rubber stopper and plao~d in the water bath to maintain the desired temperature prior to bleaching.
Additives to be added to each of the flasks were prepared.
These additives included solutions of each of the following: I,ocronTM S aluminum hydroxychloride complex (Hoechst AG), and reagent grade alum (octahydrate of alum;num sulfate Al2(50~)3 18H20) (Fisher Certified ACS).
The AHC additive was prepared as a 2 percent (weight/volume) solution of its respective non-water components. The alum was diluted until its specific gravity matched that of a 2 percent solution. (This dilution was 11 ml of the alum sample into 210 ml of deionized water). The additive indicated in Table I was then added with mixing to the particular flas~ in the amount shown in the table, and the flasks were resealed and placed back in the water bath for one hour. Af'er equilibrating in the water bath for one hour at 71 degrees C, the pulp samples were then deaerated by alternately pulling a vacuum (to about 0.9 bar pressure) using a standard laboratory vacuum pump followed by applying nitrogen at about 1.1 bar pressure. The deaeration/nitrogen addi~ion procedure was done three times on each sam ~ e. (The ceaeration/nitrogen addition procedures are believed to be necessary (at least in laboratory procedures) because the oxygen present in the pulp will decompose the sodium hydrosulfite. Bleach (-'-BriteT~ B, a proprietary blend of sodium hydrosulfite, sequestering agents and stabi:izers from Hoechst Celanese 206~0 Corp.) was added with agitation un~er an atmosphere of nitrogen (about 1.1 bar pressure) and the flask was resealed and placed in the water bath to allow for one hour retention at 71 degrees C. After this hour in the water bath, a 2.5 gram (dry weight) pulp sample was removed from each flask and diluted with deionized water to a consistency of about 0.5 percent. ~he pH of the resulting material (also called a furnish) was adjusted with sufficient O.lN sulfuric acid or O.lN sodium carbonate to get each sample to a pH of about 4.S + 0.1. A handsheet of 2.S grams and 15 cm diameter was formed on a Buchner funnel from the contents of each flasX using the method described in the Technical Association of the Pulp and Paper Industry (TAPPI~ Test Method T 218 om-83, incorporated by reference herein. Each handsheet was then air dried at ambient temperature (about 22 degrees C) and 50% relative humidity for approximately 16 hours.
Table I lists the amounts of additives used in each of the Examples. Since 15 grams of ovendry pulp were used for each example, the actual amount of additive can be calculated by multiplying the weight percent value in the Table times 15 and dividing by 100. Thus, Example 2 contained 15 x 0.385 . 100 grams of AHC; this equals .05775 or about .058 grams of AHC.
-`-` 20619~0 TAB~ I
,.
Example V-BriteTM LocronT~ Alum Number Bleach A~C(weight (weight (weightpercent) percent) percent) .
1 0.00 0.000 0.00 2 o.oo 0.385 o.oo 3 O.oo 0.770 o.oo 4 0.00 0.770 0.00 0.25 O.JOO 0.00 6 0.25 0.385 0.00 7 0.25 0.770 ~0.00 8 0.25 0.770 0.00 ~ 0.50 0.000 0.00 0.50 0.385 0.00 11 0.50 0.770 o. oa 12 O.5o 0.770 O.Oo 13 0.75 o.ooo o.oO
1 14 0.75 0.385 0.00 0.75 0.770 0.00 1 16 0.75 0.770 0.00 206~94~
.
~ 1.00 0.000 0.00-18 1.00 0.385 0.00 19 1.00 0.770 0.00 I _ 1.00 0.770 0.00 21 1.25 0.000 0.00 22 1.25 0.385 .
23 1.25 0.770 0.00 24 1.25 0.770 0.00 0.00 0.000 0.00 . I
26 0.00 0.000 0.50 27 0.00 0,000 ~ 1.00 28 0. 00 0. 000 1. 00 ..
29 0.25 0.000 0.00 . .. _ .... _ 0.25 0.000 0.50 131 0 . 25 0. 000 1 . 00 _ . 0 . 25 0 . 000 1 .
33 0.50 0.000 0.00 34 0.50 0.000 0.50 __ _ ~
0.50 0.000 1.00 36 0 . 50 0. 000 1 . 00 206194~
_ 0.75 0.000 0.00 38 0.75 0.000 0.50 39 0.75 0.000 1.00 _ .
0.75 0.000 l.Oo .
41 1.0~ 0.000 O.00 _ _ 1.00 0.000 0.50 44 1.00 0.000 1.00 ..
1.25 0.000 0.00 __ 1.25 0.000 0.50 47 1.25 0.000 1.00 . .
48 1.25 O.Ooo 1.00 Example 43 is not reported. Flask broke.
EZA~P~E8 1~A-48A
Examples lA through 48A were done to evaluate t~e brightness of the handsheets prepared in Examples 1-~8.
For these examples, the handsheet made from Example 1 was evaluated as Example lA, and so on. Each of the handshee~s made in Examples 1-48 was evaluated for briahtness by usin7 the procedure described in the Technical Association of the Pulp and Paper Incustry (TAPPI), Method I 452 o~.-87, ~06ts~a incorporated by reference herein and ~he Hunter apparatus listed above.
The data for these examples is found in Table II.
TA~LE Il I - ..... _ . - ,_, ¦Example pH After Value Change in Effect~2 ¦Number Retention Measured Brightness by TAPPI (Gain) Method ~ _ ¦ lA 5.1 52.7 0.0 na I
2A 4.5 51.3 -1.4 -1.4 I
l 3A 4.2 49.8 -2.9 -2.9 ,~
l 4A 5.5 50.4 -2.3 -2.3 ._ , l 5A 5.3 57.0 4.3 na . _ 6A 4.5 56.6 3.9 ¦ -o.~
.... .... .... _ _ _ , _ 4.5 56.2 3.5 -0.8 l 8A 5.5 55.2 2.5 -1.8 . __ . _ I
l 9A ~ 5.4 60.1 7.4 na l .. _ . , lOA 4.9 60.2 7.5 0.1 l ._ _ .
11~ 4.6 58.7 6.0 12A 5.7 58.1 5.4 -2.0 I
13A ¦ 5.7 61.9 9.2 na 20~1940 ... . .. . .. .
14A 5.0 61.1 ~ 8.4 15A 4.9 58.6 5~9 -~ .3 . I
l 16A 5.8 60.0 7.3 -1.9 _ _ .. .... _ l 17A 5.8 63.3 10.6 na ¦ 18A S.1 62.0 9.3 -1.3 ._ ...... ~ . ...... _.__ ._ ._ l9A 5.1 60.8 8.1 -2.5 ..... _ ._ .. _ 20A 5.5 60.6 _. - 1.4 2 lA 5.9 63.6 10.9 na 22A 5.3 60.5 7. a -3.1 ¦ 23A 5.2 61.9 9.2 -1.7 .
l 24A 6.8 61.0 8.3 -2.6 ...____ l 25A 5.1 52.7 0.0 na ...... _ _ . .
l 26A 3.5 49.6 -3.1 -3.1 I
¦ 27A 3.2 47.6 - 5.1 -5.1 l .
¦ 28A 5.4 48.8 -3.9 -3.9 I _ . ... . . .. .
¦ 29A 5.3 57.0 4.3 n e ¦ 30A ~ 3.5 52.9 0.2 -4.1 ¦ 31A 3.2 52.2 - 0.5 - 4.8 ¦ 32A 5.5 52.7 0.0 -4.3 I ._ 33A 5.4 60.1 7.4 ¦ na 20~1940 _ _ . _ ~ ~
34A 3.654.8¦ 2.1 -5.3 , _ ~ , . ._ 35A 3.353.8 1.1 -6~3 _ _ 1 36A 5.656.3 3.6 -3.8 l l ._ ¦ 37A 5.761.9 9.2 ~a l I . .. _ .
¦ 38A 3.7 56.9 4.2 -5.0 l I
¦ 39A 3.3 S4.4 1.7 -7.5 ¦ 40A 5.7 57.7 5.0 -4.2 4lA 5.8 63.3 10.6 na . . .. I
42A 3.9 57.8 5.1 -5.5 10 ¦ 44A 3.3 54.4 1.7 -8.9 .
l 45A 5.9 63.6 10.9 na . ~
46A 4.2 58.0 5.3 -5.6 47A 3.5 55.5 2.8 -8.1 48A S.9 58.7 6.0 -4.9 _ _ 20~'~9l~
lna means not applicable.
2This column provides data calculate~ by taking t}.e difference in the Change in Brightness column minus its corresponding untreated sample or blank for each set of experiments. For example, comparing Locronr~ AHC treated E~ample 22 to the alum treated Example 46 tboth of which were bleached at 1.25 percent V-BriteT~ bleach and treated with the corresponding pitch control products at equivalent aluminum ion concentration) shows that the ~ocronl~ AHC
treated Example 22 lost 3.1 points of brightness (10.9-7.8), while the alum treated sample lost 5.6 points of brightness (10.9-5.3). Thus, the LocronT~ AHC treated example yielded less brightness loss. Note: 0.385 percent LocronT~ A~C addition is equal to about o.5 percent alum addition, and 0.77 percent LocronT~ AHC addition is equal to about 1.0 percent alum addition on an equivalent aluminum ion basis.
E2~HP~E~ ~9-5O
COMPARAIIVE EXAMPTT'S
2~
Examples 49-55 were run to compare the brightness retention of handsheets made with Gen+IonT~ material to handsheets made in accordance with this invention using aluminum hydroxychloride. These materials were added on an equivalent aluminum ion basis.
Oven dried unbleached pine stock (210 grams) (weight basis as determined by drying in an oven at 105 degrees C
until weight equilibration was reached) prepared according 2~9~
to the method of Example 1 was placed in a 10 Liter buc~et and dilutGd with ~eic.nize3 ~ater to a con3istency of about 3 percent. The p~ of the re~ultins ~ateria; was then adjusted to about 5.2 by adding sufficient amounts of dilute (O.lN) sodium carbonate. After adjusting the pH to about 5.2, the sample was divided into 7 equal portions each containing approximately 30 grams of ovendry stock.
Each of the samples weighed about lOG0 grams. Each of the 7 samples was placed in a water bath maintained at about 71 degrees C until the temperature of the sample had equilibrated to the bath temperature (about 30 minutes).
Dilutions of the additives to be added to the samples were prepared as follows: Additive LL was made by mixing 20 grams of aluminum hydroxychloride complex ~LocronT~ S) with 500 ml of deionized water. ~dditive G3 w~s made by mixin~
20.0 grams of Gen+IonT~ 9023C with 500 ml of deionized water. Additive G6 was ~ade by mixing 20.0 grams of Gen+IonT~ 9026C with 500 ml of deionized water. After equilibration of the samples, the additives listed in Table III were added as indicated. Note that weight percen~ of Al~3 added can be calculated for each example by dividing the value liste~d in the last column by 20.
,~,; _, . . . .. . .
T~
. .. _ ~. ~
Example Sample ~dditive Amount of ~mount of Number Number Additive Al+3 added Added (~1) (lb./ton of stocX) 49 1 LL 5.8 1.4 2 L~ 11.8 2.88 51 _ 3 _ G3 15.2 1.~4 52 _ 4 G3 30.4 2.88 53 5 G6 13.1 1.44 54 6 G6 26.2 2.88 7 . NoneNone None All of the samples were then returned to the constant temperature bath (retention bath) at 71 degrees C and kept in the bath for about one hour. After the hour in the retention bath, the pH of each sample was ~easured and then adjusted to a pH of about 4.5 by adding up to 1 milliliter of O.lN ~zSO~ or O.lN sodium carbonate. Two handshee~s were made with the contents of each sample flask using the procedure described in the Technical Assoc-ation of the Pulp and Paper Industry, Method T 452 om-83, incorporated by reference herein. The brightness of each of the handsheets mad~ was measured using a Hunter D25-PC2 Brishtness Meter, and using the procedure described in the Technical Association of the Pulp and Paper Indust~ , Method T 452 om-87, incorporated by reference herein. Four measurements were taken for each han~sheet. The average of the four values is recorded in Table IV. For ea-h example 20~19~0 the aver-~e of Sheet A and Sheet B and the value for Effect (see the first sentence of note 2 under Table II) are recorded in Table V; note that the value for the blank (Example 55) is 62.0- Table ~ shows thaS the ~amples 'reat~d with AHC retair,ed ~.ore of their brightness.
~AB~ IV
Sheet Number Br.aht~ess .
Example Sample Sheet Average Number Number of 4 _ _ _ Readlngs = = = 6 2 B 61.0 52 4 A 58.8 52 4 B 58.8 53 5 A S9.2 53 5 B 59.3 54 6 A 58.0 54 B 58.0 7 A 62.0 7 B 62.2 lSheet lost.
~ ~,~. ~,~ ~ ~ ~ ~ ~ ~ _ 2 0~6 1.9 4 0 V
Esriqhrne ;s " __ _ ~ _ Example Number Average of Sheets Æffect I .
49 62.0 - 0.1 l I
61.1 - 1.0 l I _ I
~ 5~ 7 54 58.0 - 4.1 . I
. 55 62.1 Blank l _ _
BAC~GRO~ND OF ~E IN~2N~ION
The art of wood pulp processing and papermaking spans a variety of topics and chemistries. One of the concerns of pulp processors is pitch control. It has now been found that aluminum hydroxychloride, such as in the form of an aluminum hydroxychloride complex, can be used as an lo effective pitch control agent with less brightness loss of the pulp.
There are a number of definitions of pitch. Pitch is generally considered to be a mixture oS fatty acids, resin acids9 and unsaponifiable organic deposits of widely varying composition originating in the extractive fraction of wood. Pitch ~sometimes called resins or pitch resins) is a term used for the organic ~aterials that can be extracted from wood or wood pulp with an organic solvent such as ether. These hydrophobic extractables are usually dissolved or dispersed in the water phase of a pulp slurry;
however, under certain process conditions, these dispersions or solutions will destabilize and form pitch deposits. Pit~h deposits may contain more that just the naturally occurring resins, however. They may include a combination of (a) organic compounds (naturally occurring or produced by the digestion process, for examplQ, fatty and rosin acids and salts thereof, lignins and unsaponifiable materials); (b) insoluble mineral salts or " 20619~0 soaps (for example, calcium car~onate, calcium salts and fatty a~ids); and/or (c) organic and inorganic ~aterials present in papermaking additives tfor exa~ple, fatty acids or hydrocarbon oils found in many defoamers).
Some people classify pitch into two major types based on whether one i5 discussing naturally occurring pitch from virgin pulp (pitch) or pitch comprising additives from previous processing where these additives are found in pulp or paper which is being reprocessed (white pitch). White pitches may inc}ude lattices and/or organic polymers from coating compositions and organiC retaining material from preceding papermaking processes.
Pitch problems are both paper and pulp related. They are particularly evident in sulfite and groundwood (mechanical pulps) mills, where the solubilizing action ef the alkaline kraft proce5s is not present. Pitch problems manifest themselves in various ways, but the most common are dark, tacky, layered deposits on eguipment and sticky balls floating in pulp slurries. Pitch is a ma;or problem because it (l) agglomerates and also occludes other matter to form visible "dirt" in the final paper; (2~ plates out and collects on pulp and paper processing equipment such as screens, filters, refining equipment, pulp washers, and the paper machine: and (3) reduces pulp brightness and brightness stability. Once pitch becomes attached to the machine parts, the only way it can be r~moved is by scrubbing with organic solvents or special cleaning 20~1940 compounds. The down time associated with such procedures reduces the productivity of the plant.
~ he research in this area is made difficult because of the complex and reactive nature of this fraction of materials, because they often have been subjected to many chemical reactions during pulping and bleaching, and because the resin fraction is mixed with other wood components and materials added during the paper-making process. Additionally, changes in operating variables such as temperature, electrolyte content (for example, calcium and magnesium content) or pH can cause agglomeration and precipitation of pitch deposits.
A number of approaches have been tried either alone or in combination to reduce the presence of pitch and/or the problems associated with processing ~ulp and paper containing pitch. These approaches include seasoning wood, storing wood as chips, using kraft pulping methods rather than sulfite processes, controlling the types and amounts of wash aids and defoamers used in system processing, using a bleaching process, and using pitch absorbants such as talc and clay. Still other methods that have been tried include the a~dition of surfactants, chelating agents, crystal modifiers or dispersants, dispersants followed by fixatives, and controlling system parameters such as size of equipment.
In solving the problems associated with the presence of pitch in wood based pulp as it is being processed either as wood pulp and/or paper pulp one approach has been the 2~ 9~
use of a~uminum sul~ate, also callea alum or papermakers~
alum (Note that papermaker's alum is usually represented by the for.-ula Al2(SO~)3 14H20, whereas other types of alum may be represented with a different nu-~er of waters, for example Al2(SO4)3 18H20). Alum can be added to the mill system at many different times and locations. In a papermaking apparatus it may be added into the headbox at dosages ranging up to 4 percent on a dry fiber weight basis (4 percent equals 80 pounds of alum content per ton of dry fiber). ~n a wood pulp mill alu~ may be added at any place ~rom the pulpers, refiners and/or grinders through to the paper machine blend chest. Pulp mill applications can range in dosages up to 4 percent (80 pounds per ton) in the final dry fiber.
While it is not known exactly how alum works to reduce pitch in the pulping process, it is believed that alum fixes the pitch on the fibers of pulp. There are problems associated with the use of alum, however; these include the fact that the pitch particles are fixed to the pulp fibers, difficulties in handling and disposing of sulfate residues, and slime and deposit problems stemming from the use of sulfate-reducing bacteria. Additionally, loss of pulp brightness caused by the addition of alum is a major problem.
There have been several attempts to replace alum. One of these efforts has resulted in product(s) known as Gen+IonT~ (General Chemical Corporation), a proprietary polyaluminum hydroxychloride-based material having a 20~1940 cationic charge and designed for paper machines operating in the pH range of 6.0 to 7.5.
None of these approaches has resulted in a totally satisfactory solut-on to the problem of alum replacement.
There still remains a need for a product to replace alum as a pitch control agent, wherein the product can reduce or eliminate the pitch contaminants with less brightness losses. There also remains a need for a product to replace known aluminum containing products such as alum as a pitch control agent where the product can be used at acid pH's.
Thus, it is an object of this invention to provide a material to use as a substitute for known aluminum containing products as a pitch control agent in the processing of pulp which gives products that have less lS brightness losses. It is a further object of this invention to provide a material which i5 useful in the control of pitch and which can be used at acidic pH's.
~MMARY OF ~EE INVENTION
This invention comprises a process for treating wood based pulp with aluminum hydroxychloride to reduce or eliminate pitch problems associated with making and processing such pulp. Aluminum hydroxychloride having a basisity of at least 70 percent is added to wooc based pulp in an amount of up to S percent by weight (based on the weight of ovendrv pulp) at one or more points in the pu' and/or paper processes and at a system pH within t.;e ranse 20619~0 of from aDout 3 to about 8. The use of this invention results in paper products which retain more of their brightness (that is have less brightness reversion or less loss of brightness) than pulp processed with other known aluminum containing products such as alum.
DE~AILE3 DESCRIPTION OF T~E INVENTION
It has been found that aluminum hydroxychloride (Al2(OH)5Cl2) is useful in treating wood and/or paper pulp to reduce problems associated with the presence of pitch.
For purposes of this invention, this aluminum hydroxychoride is also called aluminum hydroxychloride complex (AHC), for example in its trihydrate form. The AHC
used in this invention must have a basici~y of at least 7-0 percent. A particular value for the basicity is from about 70 percent to about 90 percent; a more particular value is from about 80 percent to about 90 percent, and an even more particular value is from anout 80 percent to about 85 percent. The percent basicity of the AHC's used in this invention corresponds to the percentage of OH groups in the species Al(OH)43.
The processes of this invention may be used at pH's in the range of about 3 to about 8, especially in the range of about 4 to about 8, and ~ore particularly in the range of about 4.5 to about 8. In contrast to other aluminum hydroxychloride materials used as pitch control agents (such as Gen+IonT~ material), this invention may be 206~9~0 practiced at acidic pH's such as in the range of about 3 to about 6.
An example of an AHC which is useful in this invention is LocronT~ aluminum hydroxychloride complex. LocronT~ AHC
is an inorganic polymeric compound. Unlike other aluminum compounds, Locront~ AHC is believed to exist as a highly charged species, All~O4(OH)24(HzO) 12) ~7~ in solution. LocronT~
AHC may be supplied as a solid (LocronT~ S, a trihydrate form) or as a liquid (LocronT~ L, a solution of AHC
containing about 50 percent solids by weight) and is easy to handle and use. LocronT~ L is a clear, odorless and colorless material with a specific gravity of about 1.35 (at 20 degrees C) and a pH of about 3.6.
This invention may be used with all types of pulps.
These include 1) mechanical wood pulp, 2) alkaline process derived pulps and 3) paper pulp. Mechan~cal wood pulp is a pulp manufactured wholly or in part by a mechanical process, including stone-ground wood,. chemigroundwood and chip mechanical pulp. Uses include newsprint papers, specialty papers, tissue, toweling, paperboard and wallboard. Mechanical wood pulp is sometimes subdivided into three types:
a) thermomechanical pulp (TMP):
A high-yield pulp produced by a thermomechanical process in which wood particles are softened by pre-heating under pressure prior to a pressurized ~19~0 pri~ary refining stage. ~o~e that refining stages are frequently don~ as two or three ~tepsO~ TMP usually replaces or reduces the ch~mical pulp componen~ ~n newsprint or groundwood papers, b) refiner groundwood~ A variety of paper~
with substantial proportions of mechanical wood pulp processed in a reiner; and c) groundwood pulp: A mechanical wood pulp ~ :
produced by pressing a barked log against a pulpstone and reducing the wood to a mass of relat:ively short fibers.
.jj, Paper pulp is the pulp used as the starting material in papermaking. Paper pulp can contain virgin wood pulp and/or secondary stock. Secondary stock is a term for fibers which have previously been used i~ the papermaking process. The term includes paper stock reclaimed from a recycling of pre~iously used paper pulp products ~for example, newsp~pers) as well as wet or dry broke. It appears to be the general case that paper reclai~ed from a recycling o~ previously used paper is ~urned into pulp in separa.e mi'ls as recycled paper pulp to be us~ in secondary stocX. BroXe is paper being reprocessed ~or recycled from the paper making apparatus~ because it ~as 20~19~
not dried completely in the papermaking apparatus, was off specification, et cetera. Broke is repulped and can be mixed with virgin pulp to use in the headbox.
For a description of various types of pulps and methods for their preparation, see PU1D and p~per Manufaçture, Volume 2, Mechanical Pulping, Edited by Ray A.
Leask (third edition, 1987, prepared under Joint Textbook Committee of Paper Industry, Technical Association of the Pulp and Paper Industry (TAPPI) and Canadian Paper and Pulp Association, incorporated by reference herein. (See particularly Chapter VII).
For purposes of this invention wood based pulp is defined to mean wood pulp (both mechanical and alkaline process derived) and paper pulp. For purposes of the examples recited herein, thermomechanical pulps made from pine were used. ~
In practicing the processes of this invention, the aluminum hydroxychloride may be added to one or both of wood pulp and paper pulp at various points in the processing of these pulps. Wood pulp and paper pulp are manufactured and processed on a continuous basis and the AHC may be added at the beginning of a process or at one or more later stages when a pitch problem is observed. In the case of wood pulp, AHC may be added, for example, after the refining stage(s). For groundwood, AHC may be added, for example, in the grinder shower water. For TMP's and wood pulp processed in re~iner mills, AHC may be added, for example, at the discharge side of the latency chest. In a 20~1940 papermaking ~achine, AHC may be a~dea, for example, to t~e material in the headbox. It is preferred that AHC be added at the point in the particular process where a pitch problem is observed. Thus, treating the pulp means that the pulp is exposed to aluminum hydroxychloride in sufficient amount to reduce or eliminate problems caused by the presence of pitch.
In practicing the processes of this invention, aluminum hydroxychloride is added to the pulp at one or more points in the pulp or papermaking process as described above in an amount(s) such that the final aluminum hydroxychloride content of the pulp or paper is any amount up to 5 percent by weight, and more perferably any amount up to 2 percent by weight, based on the ovendry weight of pulp or paper. (It i5 to be noted that if the pulp is used to make paper, the terms pulp and paper are essentially the same.) Aluminum hydroxychloride may be added as a solid or in the form of a liquid, such as an aqueous solution to a pulp slurry. Dilution of the aluminum hydroxychloride in a solution, such as a water solution, before addition to ~he wood or paper pulp makes small dose application easier although it is not required. It will be appreciated by those skilled in the art that the concentrations of AHC in such liquids may vary and that one would add a quantity o~
a particular concentration of ~C which is appropriate to substantially reduce the degree of pitch problem observed.
20619~0 The levels of addition describeu for this invention are based on ovendry weight. Ovendry means containing practically no moisture. A paper or pulp is said to be ovendry when it has been dried in an oven at 105 ~ 3 degrees Centiqrade until its weight has become constant within about 0.1 percent. Ovendry is considered a more accurate term than airdry, because airdry can contain as much a 10 percent moisture.
A sample calculation to determine the amount of aluminum hydroxychloride which must be added to a wood pulp or paper pulp slurry to achieve a described aluminum hydroxychloride content may be made as follows. For a quantity of 250 tons of pulp with a 4 percent consistency, one would add at least 0.3 tons of alu~inum hydroxychloride to achieve an AHC content of about 3 percent. Two hundred fifty (250) tons (2000 pounds per ton) of a pulp stock having 4 percent consistency would mean the stock contained 10 tons of solids. (Note that the term consistency is generally defined to be the percentage by weight of airdry or ovendry fibrous material in a stock or stock suspension.
It is sometimes called density or concentration, and is used interchangeably with weight percent.) To obtain a loading of 3 ~percent aluminum hydroxychloride or. the ovendry product, one would need to add a_ least 0.3 tons (10 tons x .03) of aluminum hydroxychloride (mixed in whatever volume of water desired) to achieve the 3 percent loading.
20~ 9~
For purposes of the examples contained herein, the wood pulp was preconditioned to simulate conditions found in thermomechanical pulp mills. This ~equired heating the thermomechanical pulp stoc~ (pine) to about 71 degrees Centigrade and adjusting its consistency to about 3 percent by the addition of deionized water. The use of this highly basic alu~inum hydroxychloride (of which LocronT~ is one example) is believed to be suita~le for all pulp and paper raw material (also called wood based pulp herein) including, in particular, those systems which use a large percentage of recycled material or coating line waste.
While it is not known precisely how the invention works, it is believed that highly basic aluminum hydroxychlorides, such PS those with a minimum basicity of about 70%, act as a contaminant binder and~sizing agent for fine organic and inorganic particles such as resins, polymers from binders, pitc~es and white pitch.
It is believed that the high level of external cationic charge of the precipitation product neutralizes and/or binds anionically charged particles in such a ~ay with the pulp that they no longer burden the water system.
This precipitaqion product has an isoelectric point of about 8. This invention may be used in a pH range of from about 3 to about 8, and preferably in a range of from about 4 to about 8, and more particularly in a range of from about ~.5 to about 8. The acidic pH range ~here the invention may be used is from about 3 to 6. The pH a~
~hich the invention is utilized will depend on a varie~y o factors. For example, with bleaching materials such as V-BriteT~ bleach (from Hoechst Celanese Corporation) a pH in the acidic range of about 5.2 is generally preferr2d. IP
calcium carbonate is used as a filler, a neutral pH is preferred. The cationicity is stable and effective over a prolonged period of time, so that the highly basic aluminu~
hydroxychloride can be added even at the very beginning of the paper process without loss of activity over the course of time. In the paper process the high cationicity of the precipitation product stabilizes cationically charged organic additives such as retaining materials and cationized starch which are protected from being discharged and lost, and are thu~ preserved to the full extent of their effectiveness in stabilizing the system. The precipitation product surrounds organic ~polymers such as pitches and cationizes them so that they lose their adhesiveness. Since their external charges are now all about the same, the particles repel each other and are prevented from agglomerating.
For the practice of this invention it is contemplated that the usual and most convenient way of combining or mixing AHC and~pulp is by adding AHC (either in d~y form or as an aqueous solution) to the pulp. It is also within .he spirit anc scope of this invention to a d AHC and pulp to the process container or process system at about the same time or to add wood based pulp after the AHC is present in the con.ainer or process syste~.
206194~
~ t has also been found that additional benefits, especially in the acidic pH range, from the practice of this invention include reduction in the amount of fine fibers (those particles less than 1 m~ in size) and waste products or organic additives in the water system;
decreased need for cationic materials: increased machine capacity because of faster dewatering; better retent_on with a higher degree of filler retention, whether naturally anionically or cationically precharged; reduction or elimination of pH shift at concentrations of up to about 5 percent (by weight) (equal to about lO0 pounds per ton of ovendry pulp) aluminum hydroxychloride; prevention of gypsum forma'ion due to absence of aluminum sulfate; and reduction or elimination of defects resulting from formation of carbon dioxide present in other systems.
E~AMPLES
Eor purposes of these Examples, the pulp used was South American Pine thermomechanical pulp. As explained above, mechanical wood pulps are any wood pulp5 manufactured wholly or in part by a mechanical process;
stone groundwood, chemigroundwood, refiner ~echanical, and thermomechanical. The pulp used in this work was a mechanical pulp manufactured by a high yield thermomechanical process. The pulp was o~tained from a mill and required no further treatments other than diluting it to 3% consistency with the addition of deionize water and heating it to its normal mill te~erature of about 71 degrees Centigrade. A HunterLab D25-PC2 ~rightness Meter was used to measure brightness.
Unless otherwise noted, chemical abbreviations and symbols have their regular and customary meeting, 0 for oxygen, H for hydrogen, ml for milliliter, N for normal, C
for Centigrade, lb for pound(s), et cetera.
EgAMP~ES 1-~8 The general laboratory procedure used for Examples 1-48 was as follows. A 500 milliliter Erlenmeyer flask for each example was equipped with a stirrer and a constant temperature water bath i~itially set at a temperature of 71 degrees C. A pulp sample (15 grams, dry weight of thermomechanical pine pulp) was placed in, each of the 500 ml Erlenmeyer flasks and diluted with deionized water to a consistency of 3.25 percent (by weight) to facilitate mixing. The initial pH of the pulp samples in each of the flasks was 4.8. The pH was adjusted to about 5.2 using O.lN sodium carbonate. (A p~ of 5.2 was selected because it is believed to be within the optimal range of bleach response for this pulp, thus allowing for any effect on brightness by the other additives to be more readily observed.) The pulp samples were initially heated to 71 degrees C using a microwave oven (Whirlpool Model MW8650XR:
1.3 cubic feet; 700 watt) equipped with a temperature probe. The Erlenmeyer flasks containing the pulp were then -2061~40 sealed witn a rubber stopper and plao~d in the water bath to maintain the desired temperature prior to bleaching.
Additives to be added to each of the flasks were prepared.
These additives included solutions of each of the following: I,ocronTM S aluminum hydroxychloride complex (Hoechst AG), and reagent grade alum (octahydrate of alum;num sulfate Al2(50~)3 18H20) (Fisher Certified ACS).
The AHC additive was prepared as a 2 percent (weight/volume) solution of its respective non-water components. The alum was diluted until its specific gravity matched that of a 2 percent solution. (This dilution was 11 ml of the alum sample into 210 ml of deionized water). The additive indicated in Table I was then added with mixing to the particular flas~ in the amount shown in the table, and the flasks were resealed and placed back in the water bath for one hour. Af'er equilibrating in the water bath for one hour at 71 degrees C, the pulp samples were then deaerated by alternately pulling a vacuum (to about 0.9 bar pressure) using a standard laboratory vacuum pump followed by applying nitrogen at about 1.1 bar pressure. The deaeration/nitrogen addi~ion procedure was done three times on each sam ~ e. (The ceaeration/nitrogen addition procedures are believed to be necessary (at least in laboratory procedures) because the oxygen present in the pulp will decompose the sodium hydrosulfite. Bleach (-'-BriteT~ B, a proprietary blend of sodium hydrosulfite, sequestering agents and stabi:izers from Hoechst Celanese 206~0 Corp.) was added with agitation un~er an atmosphere of nitrogen (about 1.1 bar pressure) and the flask was resealed and placed in the water bath to allow for one hour retention at 71 degrees C. After this hour in the water bath, a 2.5 gram (dry weight) pulp sample was removed from each flask and diluted with deionized water to a consistency of about 0.5 percent. ~he pH of the resulting material (also called a furnish) was adjusted with sufficient O.lN sulfuric acid or O.lN sodium carbonate to get each sample to a pH of about 4.S + 0.1. A handsheet of 2.S grams and 15 cm diameter was formed on a Buchner funnel from the contents of each flasX using the method described in the Technical Association of the Pulp and Paper Industry (TAPPI~ Test Method T 218 om-83, incorporated by reference herein. Each handsheet was then air dried at ambient temperature (about 22 degrees C) and 50% relative humidity for approximately 16 hours.
Table I lists the amounts of additives used in each of the Examples. Since 15 grams of ovendry pulp were used for each example, the actual amount of additive can be calculated by multiplying the weight percent value in the Table times 15 and dividing by 100. Thus, Example 2 contained 15 x 0.385 . 100 grams of AHC; this equals .05775 or about .058 grams of AHC.
-`-` 20619~0 TAB~ I
,.
Example V-BriteTM LocronT~ Alum Number Bleach A~C(weight (weight (weightpercent) percent) percent) .
1 0.00 0.000 0.00 2 o.oo 0.385 o.oo 3 O.oo 0.770 o.oo 4 0.00 0.770 0.00 0.25 O.JOO 0.00 6 0.25 0.385 0.00 7 0.25 0.770 ~0.00 8 0.25 0.770 0.00 ~ 0.50 0.000 0.00 0.50 0.385 0.00 11 0.50 0.770 o. oa 12 O.5o 0.770 O.Oo 13 0.75 o.ooo o.oO
1 14 0.75 0.385 0.00 0.75 0.770 0.00 1 16 0.75 0.770 0.00 206~94~
.
~ 1.00 0.000 0.00-18 1.00 0.385 0.00 19 1.00 0.770 0.00 I _ 1.00 0.770 0.00 21 1.25 0.000 0.00 22 1.25 0.385 .
23 1.25 0.770 0.00 24 1.25 0.770 0.00 0.00 0.000 0.00 . I
26 0.00 0.000 0.50 27 0.00 0,000 ~ 1.00 28 0. 00 0. 000 1. 00 ..
29 0.25 0.000 0.00 . .. _ .... _ 0.25 0.000 0.50 131 0 . 25 0. 000 1 . 00 _ . 0 . 25 0 . 000 1 .
33 0.50 0.000 0.00 34 0.50 0.000 0.50 __ _ ~
0.50 0.000 1.00 36 0 . 50 0. 000 1 . 00 206194~
_ 0.75 0.000 0.00 38 0.75 0.000 0.50 39 0.75 0.000 1.00 _ .
0.75 0.000 l.Oo .
41 1.0~ 0.000 O.00 _ _ 1.00 0.000 0.50 44 1.00 0.000 1.00 ..
1.25 0.000 0.00 __ 1.25 0.000 0.50 47 1.25 0.000 1.00 . .
48 1.25 O.Ooo 1.00 Example 43 is not reported. Flask broke.
EZA~P~E8 1~A-48A
Examples lA through 48A were done to evaluate t~e brightness of the handsheets prepared in Examples 1-~8.
For these examples, the handsheet made from Example 1 was evaluated as Example lA, and so on. Each of the handshee~s made in Examples 1-48 was evaluated for briahtness by usin7 the procedure described in the Technical Association of the Pulp and Paper Incustry (TAPPI), Method I 452 o~.-87, ~06ts~a incorporated by reference herein and ~he Hunter apparatus listed above.
The data for these examples is found in Table II.
TA~LE Il I - ..... _ . - ,_, ¦Example pH After Value Change in Effect~2 ¦Number Retention Measured Brightness by TAPPI (Gain) Method ~ _ ¦ lA 5.1 52.7 0.0 na I
2A 4.5 51.3 -1.4 -1.4 I
l 3A 4.2 49.8 -2.9 -2.9 ,~
l 4A 5.5 50.4 -2.3 -2.3 ._ , l 5A 5.3 57.0 4.3 na . _ 6A 4.5 56.6 3.9 ¦ -o.~
.... .... .... _ _ _ , _ 4.5 56.2 3.5 -0.8 l 8A 5.5 55.2 2.5 -1.8 . __ . _ I
l 9A ~ 5.4 60.1 7.4 na l .. _ . , lOA 4.9 60.2 7.5 0.1 l ._ _ .
11~ 4.6 58.7 6.0 12A 5.7 58.1 5.4 -2.0 I
13A ¦ 5.7 61.9 9.2 na 20~1940 ... . .. . .. .
14A 5.0 61.1 ~ 8.4 15A 4.9 58.6 5~9 -~ .3 . I
l 16A 5.8 60.0 7.3 -1.9 _ _ .. .... _ l 17A 5.8 63.3 10.6 na ¦ 18A S.1 62.0 9.3 -1.3 ._ ...... ~ . ...... _.__ ._ ._ l9A 5.1 60.8 8.1 -2.5 ..... _ ._ .. _ 20A 5.5 60.6 _. - 1.4 2 lA 5.9 63.6 10.9 na 22A 5.3 60.5 7. a -3.1 ¦ 23A 5.2 61.9 9.2 -1.7 .
l 24A 6.8 61.0 8.3 -2.6 ...____ l 25A 5.1 52.7 0.0 na ...... _ _ . .
l 26A 3.5 49.6 -3.1 -3.1 I
¦ 27A 3.2 47.6 - 5.1 -5.1 l .
¦ 28A 5.4 48.8 -3.9 -3.9 I _ . ... . . .. .
¦ 29A 5.3 57.0 4.3 n e ¦ 30A ~ 3.5 52.9 0.2 -4.1 ¦ 31A 3.2 52.2 - 0.5 - 4.8 ¦ 32A 5.5 52.7 0.0 -4.3 I ._ 33A 5.4 60.1 7.4 ¦ na 20~1940 _ _ . _ ~ ~
34A 3.654.8¦ 2.1 -5.3 , _ ~ , . ._ 35A 3.353.8 1.1 -6~3 _ _ 1 36A 5.656.3 3.6 -3.8 l l ._ ¦ 37A 5.761.9 9.2 ~a l I . .. _ .
¦ 38A 3.7 56.9 4.2 -5.0 l I
¦ 39A 3.3 S4.4 1.7 -7.5 ¦ 40A 5.7 57.7 5.0 -4.2 4lA 5.8 63.3 10.6 na . . .. I
42A 3.9 57.8 5.1 -5.5 10 ¦ 44A 3.3 54.4 1.7 -8.9 .
l 45A 5.9 63.6 10.9 na . ~
46A 4.2 58.0 5.3 -5.6 47A 3.5 55.5 2.8 -8.1 48A S.9 58.7 6.0 -4.9 _ _ 20~'~9l~
lna means not applicable.
2This column provides data calculate~ by taking t}.e difference in the Change in Brightness column minus its corresponding untreated sample or blank for each set of experiments. For example, comparing Locronr~ AHC treated E~ample 22 to the alum treated Example 46 tboth of which were bleached at 1.25 percent V-BriteT~ bleach and treated with the corresponding pitch control products at equivalent aluminum ion concentration) shows that the ~ocronl~ AHC
treated Example 22 lost 3.1 points of brightness (10.9-7.8), while the alum treated sample lost 5.6 points of brightness (10.9-5.3). Thus, the LocronT~ AHC treated example yielded less brightness loss. Note: 0.385 percent LocronT~ A~C addition is equal to about o.5 percent alum addition, and 0.77 percent LocronT~ AHC addition is equal to about 1.0 percent alum addition on an equivalent aluminum ion basis.
E2~HP~E~ ~9-5O
COMPARAIIVE EXAMPTT'S
2~
Examples 49-55 were run to compare the brightness retention of handsheets made with Gen+IonT~ material to handsheets made in accordance with this invention using aluminum hydroxychloride. These materials were added on an equivalent aluminum ion basis.
Oven dried unbleached pine stock (210 grams) (weight basis as determined by drying in an oven at 105 degrees C
until weight equilibration was reached) prepared according 2~9~
to the method of Example 1 was placed in a 10 Liter buc~et and dilutGd with ~eic.nize3 ~ater to a con3istency of about 3 percent. The p~ of the re~ultins ~ateria; was then adjusted to about 5.2 by adding sufficient amounts of dilute (O.lN) sodium carbonate. After adjusting the pH to about 5.2, the sample was divided into 7 equal portions each containing approximately 30 grams of ovendry stock.
Each of the samples weighed about lOG0 grams. Each of the 7 samples was placed in a water bath maintained at about 71 degrees C until the temperature of the sample had equilibrated to the bath temperature (about 30 minutes).
Dilutions of the additives to be added to the samples were prepared as follows: Additive LL was made by mixing 20 grams of aluminum hydroxychloride complex ~LocronT~ S) with 500 ml of deionized water. ~dditive G3 w~s made by mixin~
20.0 grams of Gen+IonT~ 9023C with 500 ml of deionized water. Additive G6 was ~ade by mixing 20.0 grams of Gen+IonT~ 9026C with 500 ml of deionized water. After equilibration of the samples, the additives listed in Table III were added as indicated. Note that weight percen~ of Al~3 added can be calculated for each example by dividing the value liste~d in the last column by 20.
,~,; _, . . . .. . .
T~
. .. _ ~. ~
Example Sample ~dditive Amount of ~mount of Number Number Additive Al+3 added Added (~1) (lb./ton of stocX) 49 1 LL 5.8 1.4 2 L~ 11.8 2.88 51 _ 3 _ G3 15.2 1.~4 52 _ 4 G3 30.4 2.88 53 5 G6 13.1 1.44 54 6 G6 26.2 2.88 7 . NoneNone None All of the samples were then returned to the constant temperature bath (retention bath) at 71 degrees C and kept in the bath for about one hour. After the hour in the retention bath, the pH of each sample was ~easured and then adjusted to a pH of about 4.5 by adding up to 1 milliliter of O.lN ~zSO~ or O.lN sodium carbonate. Two handshee~s were made with the contents of each sample flask using the procedure described in the Technical Assoc-ation of the Pulp and Paper Industry, Method T 452 om-83, incorporated by reference herein. The brightness of each of the handsheets mad~ was measured using a Hunter D25-PC2 Brishtness Meter, and using the procedure described in the Technical Association of the Pulp and Paper Indust~ , Method T 452 om-87, incorporated by reference herein. Four measurements were taken for each han~sheet. The average of the four values is recorded in Table IV. For ea-h example 20~19~0 the aver-~e of Sheet A and Sheet B and the value for Effect (see the first sentence of note 2 under Table II) are recorded in Table V; note that the value for the blank (Example 55) is 62.0- Table ~ shows thaS the ~amples 'reat~d with AHC retair,ed ~.ore of their brightness.
~AB~ IV
Sheet Number Br.aht~ess .
Example Sample Sheet Average Number Number of 4 _ _ _ Readlngs = = = 6 2 B 61.0 52 4 A 58.8 52 4 B 58.8 53 5 A S9.2 53 5 B 59.3 54 6 A 58.0 54 B 58.0 7 A 62.0 7 B 62.2 lSheet lost.
~ ~,~. ~,~ ~ ~ ~ ~ ~ ~ _ 2 0~6 1.9 4 0 V
Esriqhrne ;s " __ _ ~ _ Example Number Average of Sheets Æffect I .
49 62.0 - 0.1 l I
61.1 - 1.0 l I _ I
~ 5~ 7 54 58.0 - 4.1 . I
. 55 62.1 Blank l _ _
Claims (24)
1. A process for treating wood based pulp to reduce the problems associated with pitch, wherein said process comprises mixing aluminum hydroxychloride having a basicity of at least 70 percent with said pulp in an amount sufficient to form pulp or paper containing up to 5 percent by weight of aluminum hydroxychloride based on an ovendry weight of said pulp or said paper, and wherein said process is performed at a pH selected from a range of from about 3 to about 8.
2. A process as claimed in Claim 1, wherein said aluminum hydroxychloride is in the form of an aqueous solution.
3. A process as claimed in Claim 1 wherein said pH is in a range from about 4 to about 8.
4. A process as claimed in Claim 3 wherein said pH is in a range from about 4.5 to about 8.
5. A process as claimed in Claim 1 wherein said pH is in the range from about 3 to about 6.
6. A process 25 claimed in Claim 1, wherein said wood based pulp is wood pulp.
7. A process as claimed in Claim 6, wherein said wood pulp is thermomechanical wood pulp.
8. A process as claimed in Claim 6, wherein said wood pulp is refiner groundwood.
9. A process as claimed in Claim 6, wherein said wood pulp is groundwood pulp.
10. A process as claimed in Claim 6 wherein said mixing is done after refining stage(s) of said pulp.
11. A process as claimed in Claim 6 wherein said pH is in the range from about 3 to about 6.
12. A process as claimed in Claim 1 wherein said wood based pulp is paper pulp.
13. A process as claimed in Claim 1 or Claim 12, wherein said mixing is done at a headbox of a papermaking apparatus.
14. A process as claimed in Claim 1, wherein said amount of aluminum hydroxychloride in said pulp or said paper is an amount up to 2 percent.
15. A process as claimed in claim 12 wherein said pH is in a range from about 3 to about 6.
16. A process for producing paper having reduced loss of brightness, wherein said process comprises mixing aluminum hydroxychloride having a basicity of at least 70 percent with at least one of wood pulp or paper pulp used in forming said paper in an amount sufficient to form a paper containing up to 5 percent by weight of aluminum hydroxychloride based on an ovendry weight of said paper, and wherein said process is performed at a pH selected in a range from about 3 to about 8.
17. A process as claimed in Claim 16, wherein the pH is in a range of from about 4 to about 8.
18. A process as claimed in Claim 17, wherein the pH is in a range from about 4.5 to about 8.
19. A process is claimed in claim 16, wherein the pH is in a range from about 3 to about 6.
20. A process as claimed in Claim 16, wherein the process comprises mixing wood pulp and aluminum hydroxychloride.
21. A process as claimed in Claim 16, wherein the process comprises mixing paper pulp and aluminum hydroxychloride.
22. A process as claimed in Claim 20, wherein said amount of aluminum hydroxychloride is an amount up to 2 percent by weight.
23. A process as claimed in Claim 21, wherein said amount of aluminum hydroxychloride is an amount up to 2 percent by weight.
24. Paper made by any of the processes claimed in any one of Claims 16, 17, 18, 19, 20, 21, 22 or 23.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US66252591A | 1991-02-28 | 1991-02-28 | |
US07/662,525 | 1991-02-28 |
Publications (1)
Publication Number | Publication Date |
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CA2061940A1 true CA2061940A1 (en) | 1992-08-29 |
Family
ID=24658074
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA 2061940 Abandoned CA2061940A1 (en) | 1991-02-28 | 1992-02-27 | Aluminum hydroxychloride as pitch control agent |
Country Status (5)
Country | Link |
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JP (1) | JPH04333686A (en) |
BR (1) | BR9200600A (en) |
CA (1) | CA2061940A1 (en) |
FI (1) | FI920881A (en) |
MX (1) | MX9200849A (en) |
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GB2375992A (en) | 2001-06-01 | 2002-12-04 | Ilford Imaging Uk Ltd | Recording method |
KR100597949B1 (en) * | 2005-12-31 | 2006-07-13 | 뜨인돌건설산업 주식회사 | Cutting device for road |
JP6216957B2 (en) * | 2015-03-13 | 2017-10-25 | 株式会社片山化学工業研究所 | Pitch control agent for papermaking process and pitch failure prevention method |
-
1992
- 1992-02-24 BR BR929200600A patent/BR9200600A/en not_active Application Discontinuation
- 1992-02-27 MX MX9200849A patent/MX9200849A/en unknown
- 1992-02-27 CA CA 2061940 patent/CA2061940A1/en not_active Abandoned
- 1992-02-27 FI FI920881A patent/FI920881A/en not_active Application Discontinuation
- 1992-02-28 JP JP4284692A patent/JPH04333686A/en active Pending
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FI920881A (en) | 1992-08-29 |
BR9200600A (en) | 1992-10-27 |
JPH04333686A (en) | 1992-11-20 |
MX9200849A (en) | 1992-10-01 |
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