U.S. patent application number 11/556259 was filed with the patent office on 2008-05-08 for method and composition for improving fiber quality and process efficiency in mechanical pulping.
Invention is credited to Prasad Y. Duggirala, Sergey M. Shevchenko.
Application Number | 20080105392 11/556259 |
Document ID | / |
Family ID | 39367541 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080105392 |
Kind Code |
A1 |
Duggirala; Prasad Y. ; et
al. |
May 8, 2008 |
METHOD AND COMPOSITION FOR IMPROVING FIBER QUALITY AND PROCESS
EFFICIENCY IN MECHANICAL PULPING
Abstract
This invention provides a composition and method for improving a
mechanical pulping process by decreasing freeness and amount of
shives, providing energy and chemical savings, and enhancing
brightness and mechanical strength of a paper product made from a
pulp material in the process. The composition includes
formulations, such as surfactants, chelants, hydrotropes, reductive
and oxidative pulp modifiers, and pH-controlling chemicals. The
method includes selectively introducing these formulations to the
pulp material in the mechanical pulping process.
Inventors: |
Duggirala; Prasad Y.;
(Naperville, IL) ; Shevchenko; Sergey M.; (Aurora,
IL) |
Correspondence
Address: |
NALCO COMPANY
1601 W. DIEHL ROAD
NAPERVILLE
IL
60563-1198
US
|
Family ID: |
39367541 |
Appl. No.: |
11/556259 |
Filed: |
November 3, 2006 |
Current U.S.
Class: |
162/23 ; 162/72;
162/76; 162/77; 162/78; 162/80; 162/82; 162/90 |
Current CPC
Class: |
D21C 3/00 20130101; D21B
1/16 20130101 |
Class at
Publication: |
162/23 ; 162/77;
162/76; 162/72; 162/80; 162/82; 162/78; 162/90 |
International
Class: |
D21C 3/02 20060101
D21C003/02; D21B 1/02 20060101 D21B001/02; D21C 3/04 20060101
D21C003/04 |
Claims
1. A composition that improves a mechanical pulping process, said
composition comprising: (a) an effective amount of a surfactant
formulation having one or more surfactants; (b) an effective amount
of a chelant formulation having one or more chelants; (c) an
effective amount of a hydrotrope formulation having one or more
hydrotropes; (d) optionally an effective amount of a reductive pulp
modifier formulation having one or more reductive pulp modifiers,
or an effective amount of an oxidative pulp modifier formulation
having one or more oxidative pulp modifiers; and (e) optionally an
effective amount of one or more pH-controlling chemicals.
2. The composition of claim 1, including about 0.05 weight percent
to about 30 weight percent of the surfactant(s).
3. The composition of claim 1, wherein the surfactant formulation
includes one or more surfactants selected from the group consisting
of: non-ionic surfactants; alkyl alcohol alkoxylates; block polymer
alkyl alcohol alkoxylates; ethoxylated tridecyl alcohol;
ethoxylated propyloxylated hexadecanol; and combinations
thereof.
4. The composition of claim 1, including about 0.05 weight percent
to about 50 weight percent of the chelant(s).
5. The composition of claim 1, wherein the chelant formulation
includes one or more transitional metal chelants selected from the
group consisting of: aminocarboxylates; aminophosphonates;
polyphosphates; polyacrylates; organic phosphates; organic
phosphonates; phosphates; carboxylic acids; dithiocarbamates; and
combinations thereof.
6. The composition of claim 1, including about 0.05 weight percent
to about 50 weight percent of the hydrotrope(s).
7. The composition of claim 1, including an about one-to-one or
greater weight percent ratio of the hydrotrope to the chelant.
8. The composition of claim 1, including an about two-to-one or
greater weight percent ratio of the hydrotrope to the
surfactant.
9. The composition of claim 1, wherein the hydrotrope formulation
includes one or more hydrotropes selected from the group consisting
of: arylenesulfonates; carbohydrates having long-chain aliphatic
substituents; and combinations thereof.
10. The composition of claim 1, wherein the hydrotrope formulation
includes one or more hydrotropes selected from the group consisting
of: xylenesulfonate; cumenesulfonate; toluenesulfonate; and
combinations thereof.
11. The composition of claim 1, including about 0.01 to about 50
weight percent of the reductive pulp modifier(s).
12. The composition of claim 1, wherein the reductive pulp modifier
formulation includes one or more reductive pulp modifiers selected
from the group consisting of: water-soluble inorganic sulfites;
bisulfites; metabisulfites; substituted phosphines and tertiary
salts thereof; formamidinesulfinic acid and salts and derivatives
thereof; formaldehyde bisulfite adduct other aldehyde bisulfite
adducts; sulfoxylates; thiosulfates; dithionites; polythionates;
sulfinamides and ethers of sulfinic acid; sulfenamides and ethers
of sulfenic acid; sulfamides; phosphines; phosphonium salts;
phosphites; thiophosphites; and combinations thereof.
13. The composition of claim 1, including about 0.01 weight percent
to about 50 weight percent of the oxidative pulp modifier(s).
14. The composition of claim 1, wherein the oxidative pulp modifier
formulation includes one or more oxidative pulp modifiers selected
from the group consisting of: percarbonates; perborates; hydrogen
peroxide; activated hydrogen peroxide; organic peroxyacids and
salts thereof; dioxiranes; halogenamines; inorganic peroxides;
superoxides and peroxide-superoxides; inorganic peroxyacids and
salts thereof; peroxyhydrates; water-soluble organic peroxides;
nitrosodisulfonates; hypochlorites; hypobromites; chlorites;
chlorates; bromates; perchlorates; chlorine dioxide; chloroamines;
chloroamides; chlorosulfamides; bromoamines; bromoamides;
bromosulfamides; chlorosulfonic acid; bromosulfonic acid; chlorine;
and combinations thereof.
15. The composition of claim 1, including about 5 weight percent to
about 90 weight percent of the pH-controlling chemical.
16. The composition of claim 1, including one or more
pH-controlling chemicals selected from the group consisting of:
trisodium phosphate; sodium metaborate; ammonium carbonate; sodium
hydroxide; potassium hydroxide; lithium hydroxide;
tetramethylammonium hydroxide; magnesium hydroxide; magnesium
carbonate; sodium silicate; sodium carbonate; and combinations
thereof.
17. The composition of claim 1, wherein the composition decreases
freeness and amount of shives, provides energy and chemical
savings, and enhances brightness and mechanical strength of a paper
product made from a pulp material in the mechanical pulping
process.
18. A composition that improves a mechanical pulping process, said
composition comprising: (a) an effective amount of an alkyl alcohol
alkoxylate surfactant having formula
RO[(CH.sub.2CHCH.sub.3O).sub.X(CH.sub.2CH.sub.2O).sub.Y]M; wherein
R is C.sub.4 to C.sub.40 straight, branched, or ring alkyl, X is
from 1 to about 50, Y is from 0 to about 100, and M is H or an
alkali metal; (b) optionally an effective amount of a chelant
formulation having one or more chelants; (c) optionally an
effective amount of a hydrotrope formulation having one or more
hydrotropes; (d) optionally an effective amount of a reductive pulp
modifier formulation having one or more reductive pulp modifiers,
or an effective amount of an oxidative pulp modifier formulation
having one or more oxidative pulp modifiers; and (e) optionally an
effective amount of one or more pH-controlling chemicals.
19. The composition of claim 18, including about 0.05 weight
percent to about 99 weight percent of the alkyl alcohol alkoxylate
surfactant.
20. A method of improving a mechanical pulping process, said method
comprising: (a) contacting a pulp material with a surfactant
composition including an effective amount of an alkyl alcohol
alkoxylate surfactant having formula
RO[(CH.sub.2CHCH.sub.3O).sub.X(CH.sub.2CH.sub.2O).sub.Y]M; wherein
R is C.sub.4 to C.sub.40 straight, branched, or ring alkyl, X is
from 1 to about 50, Y is from 0 to about 100, and M is H or an
alkali metal; and (b) optionally introducing to the pulp material
separately from the surfactant composition, as part of the
surfactant composition, or with the surfactant composition but not
as part of the surfactant composition one or more formulations
selected from the group consisting of: one or more additional
surfactants; one or more chelants; one or more hydrotropes; one or
more reductive pulp modifiers; one or more oxidative pulp
modifiers; one or more pH-controlling chemicals; and combinations
thereof.
21. The method of claim 20, wherein R is C.sub.8 to C.sub.22
straight, branched, or ring alkyl, X is from 1 to about 20, and Y
is from 1 to about 80.
22. The method of claim 20, including contacting the pulp material
with about 0.001 weight percent to about 5 weight percent of the
alkyl alcohol alkoxylate surfactant, based on oven-dry pulp.
23. The method of claim 20, including introducing to the pulp
material about 0.001 weight percent to about 5 weight percent of
the hydrotrope(s), based on oven-dry pulp.
24. The method of claim 20, including introducing to the pulp
material the hydrotrope formulation as part of the surfactant
composition if at least one other optional formulation is
introduced to the pulp material as part of the surfactant
composition.
25. The method of claim 20, including introducing to the pulp
material about 0.005 weight percent to about 5 weight percent of
the reductive pulp modifier(s), based on oven-dry pulp.
26. The method of claim 20, including introducing to the pulp
material about 0.01 weight percent to about 5 weight percent of the
oxidative pulp modifier(s), based on oven-dry pulp.
27. The method of claim 20, including introducing to the pulp
material about 0.05 weight percent to about 10 weight percent of
the ph-controlling chemical(s), based on oven-dry pulp.
28. The method of claim 20, wherein the pH-controlling chemical
includes an alkali and introducing the alkali to the pulp material
improves the mechanical strength of the paper product without
decreasing the brightness of the paper product.
29. The method of claim 20, including contacting the pulp material
with the surfactant composition and introducing to the pulp
material one or more of the formulation(s) at the same stage of the
mechanical pulping process.
30. The method of claim 20, including simultaneously or
sequentially contacting the pulp material with the composition and
introducing to the pulp material one or more of the
formulation(s).
31. The method of claim 20, wherein contacting the pulp material
either prior to refining or during refining.
32. The method of claim 20, wherein the mechanical pulping process
is selected from the group consisting of: stone ground wood;
pressurized ground wood; refiner mechanical pulp; pressurized
refiner mechanical pulp; thermo-refiner mechanical pulp;
thermo-mechanical pulp; thermo-chemi-mechanical pulp;
thermo-mechanical-chemi pulp; long fiber chemi-mechanical pulp; and
chemically treated long fiber.
33. The method of claim 20, wherein the pulp material is selected
from the group consisting of: wood chips; mechanical pulp; and
combinations thereof.
34. The method of claim 20, including improving the mechanical
pulping process by decreasing freeness and amount of shives,
providing energy and chemical savings, and enhancing brightness and
mechanical strength of a paper product made from the pulp material
in the mechanical pulping process.
Description
TECHNICAL FIELD
[0001] The invention relates generally to improving fiber quality
and process efficiency in thermomechanical and
chemi-thermomechanical pulping. More specifically, the invention
relates to using specialty chemical compositions including various
combinations of a surfactant, a chelant, and other compounds to
improve the mechanical properties and brightness of a paper product
produced from a pulp material manufactured in such a process. The
invention has particular relevance for decreasing freeness and
amount of shives, providing energy and chemical savings, and
enhancing brightness and mechanical strength of paper products.
BACKGROUND
[0002] Mechanical pulping is a common method to produce inexpensive
pulp without a significant loss of mass. Several technologies are
currently practiced in mechanical pulping to manufacture products,
such as stone ground wood (SGW), pressurized ground wood (PGW),
refiner mechanical pulp (RMP), pressurized RMP (PRMP), thermo-RMP
(TRMP), thermo-mechanical pulp (TMP), thermo-chemi-mechanical pulp
(TCMP), thermo-mechanical-chemi pulp (TMCP), long fiber
chemi-mechanical pulp (LFCMP), and chemically treated long fiber
(CTLF).
[0003] Though purely mechanical pulps have some advantages, such as
high opacity, high bulk, and good printing quality, they also have
inherent disadvantages, such as low mechanical strength and
susceptibility to yellowing. The yellowish color is due partly to
formation of chromophoric and leukochromophoric structures in the
production process as early as the first refining stage. The light
absorption coefficient changes significantly as woodchips are
converted into first-stage refined mechanical pulps. The greatest
changes occur at wavelengths below 400 nanometers. In the presence
of atmospheric oxygen, heat, and/or sunlight structures absorbing
light in this region give rise to colored structures. Metal
complexes and oxidation reactions may also play a role in creating
the increased light absorbency. Avoiding the formation of these
structures would result in mechanical pulps with increased
brightness and enhanced brightness stability.
[0004] Chelants and surfactants (sometimes referred to as surface
active agents) have historically had a place in pulp production.
Mechanical pulp production is affected by transitional metal ions
found in wood, which promote undesirable side reactions including
oxidative reactions that cause yellowing. Currently, commodity
chelants are used in mechanical pulping processes to immobilize
such metal ions. The role of chelants is generally to bind
transitional metal cations to prevent their catalytic activity in
decomposing bleaching chemicals, such as peroxide, hydrosulfite,
and the like. Surfactants have previously been employed in
papermaking to accelerate fiber swelling, and to soften and split
pulp.
[0005] The processes of bleaching and delignification of prepared
pulp, but not mechanical pulp manufacturing, have involved combined
use of surfactants and conventional chelants. For example, JP
05051889 A2 disclosed use of ethylenediaminetetraacetic acid
("EDTA") and diethylenetriamine pentaacetic acid ("DTPA") in oxygen
treatment of wood pulp (i.e., delignification). Similar
combinations used in ozone bleaching of chemical pulps have also
been reported (JP 08188976 A2). Combined use of polymeric chelants
and surface-active agents was proposed in JP 07138891 A2 for pulp
pretreatment before peroxide bleaching.
[0006] Chelant and surfactant combinations have been applied in
mechanical pulp production to improve the absorptive capacity of
thermomechanical pulp in the course of continuous production from
chips (SE 8002027). Pulp brightness, strength, and drainage
properties have also been improved by washing woodchips with liquor
containing chelants and surfactants between the impregnation and
refining stages of the paper production process (See U.S. Pat. No.
5,549,787 and FR 2042117).
[0007] Mechanical pulps typically have low strength. Chemical
treatment, such as alkalization, is sometimes used to increase
strength, at the expense of brightness. There thus exists a need
for economical methods of producing mechanical pulp materials
having increased mechanical strength and brightness. In particular,
it is desirable to develop a cost-efficient mechanical pulp with
improved mechanical strength without sulfonation. Preferably, such
a development would combine all components in a single composition.
Preserving these pulp properties has been difficult without
sacrificing printing properties and yield.
[0008] A successful approach to this problem would also be capable
of being tailored to the specific needs of individual mills and
conveniently added to the mill's current operation. Furthermore,
mechanical pulping mills strive to improve efficiency by conserving
energy and chemicals. Such improvements are related to the freeness
of pulp and amount of shives. Specialty chemicals may provide
improved liquor penetration and more efficient refining.
SUMMARY
[0009] Accordingly, the invention provides a composition that
decreases freeness and amount of shives, provides energy and
chemical savings, and enhances brightness and mechanical strength
of a paper product made from a pulp material in a mechanical
pulping process. The composition includes one or more surfactants,
one or more chelants, and one or more hydrotropes. The composition
optionally includes one or more reductive or oxidative pulp
modifiers and one or more pH-controlling chemicals.
[0010] In one aspect, the invention provides a composition that
improves a mechanical pulping process. The composition includes an
alkyl alcohol alkoxylate surfactant having formula
RO[(CH.sub.2CHCH.sub.3O).sub.X(CH.sub.2CH.sub.2O).sub.Y]M. R may be
a C.sub.4 to C.sub.40 straight, branched, or ring alkyl, X may be
from 0 to about 50, Y may be from 1 to about 100, and M may be H or
an alkali metal. In this aspect, the composition optionally
includes one or more chelants, one or more hydrotropes, one or more
reductive or oxidative pulp modifiers, and one or more
pH-controlling chemicals.
[0011] In another aspect, the invention provides a method of
decreasing freeness and amount of shives, providing energy and
chemical savings, and enhancing brightness and mechanical strength
of a paper product made from a pulp material produced in a
mechanical pulping process. The method includes contacting the pulp
material with a surfactant composition including an alkyl alcohol
alkoxylate surfactant having formula
RO[(CH.sub.2CHCH.sub.3O).sub.X(CH.sub.2CH.sub.2O).sub.Y]M. R may be
from C.sub.4 to C.sub.40 straight, branched, or ring alkyl, X may
be from 1 to about 50, Y may be from 0 to about 100, and M may be H
or an alkali metal.
[0012] The method further includes optionally introducing to the
pulp material separately from the surfactant composition, as part
of the surfactant composition, or with the surfactant composition
but not as part of the surfactant composition one or more
additional formulations. These formulations include one or more
additional surfactants, one or more chelants, one or more
hydrotropes, one or more reductive pulp modifiers, one or more
oxidative pulp modifiers, one or more pH-controlling chemicals, and
combinations thereof.
[0013] It is an advantage of the invention to provide compositions
that decrease freeness and amount of shives, provide energy and
chemical savings, and enhance brightness and mechanical strength of
a paper product produced from a pulp material produced in a
mechanical pulping process.
[0014] A further advantage of the invention is to provide an
economical and efficient method of producing a high-quality paper
product via a mechanical pulping process.
[0015] It is another advantage of the invention to provide a
composition that helps prevent formation of chromophoric and
leukochromophoric structures in mechanical pulping processes thus
enhancing brightness and brightness stability of pulp
materials.
[0016] It is a further advantage of the invention to provide a
synergistic method of producing a paper product having resistance
to brightness loss and increased mechanical strength under energy
and chemical saving mechanical pulping process conditions.
[0017] Another advantage of the invention is to provide a method of
improving a mechanical pulping process by contacting a pulp
material with a surfactant composition and introducing to the pulp
material one or more formulations including a pH-controlling
chemical at the same stage of the mechanical pulping process;
wherein if the pH-controlling chemical is an alkali and is
introduced to the pulp material separately from the surfactant
composition, the alkali improves the mechanical strength of the
paper product without decreasing the brightness of the paper
product.
DETAILED DESCRIPTION
[0018] The following definitions are intended as guidelines and not
intended to limit the scope of the invention. The organization is
for convenience only and is not intended to limit any of the
definitions to any particular category.
[0019] "Alkyl alcohol" means a compound or mixture of compounds
having the formula ROH where R is a straight, branched, or ring
C.sub.4 to C.sub.40 alkyl group.
[0020] "Alkoxy" means an alkyl group attached to the parent
molecular moiety through an oxygen atom. Representative alkoxy
groups include methoxy, ethoxy, propoxy, butoxy, and the like.
Propoxy and ethoxy are preferred.
[0021] "Alkyl" means a monovalent group derived from a straight or
branched chain or ring saturated hydrocarbon by the removal of a
single hydrogen atom. The alkyl may be unsubstituted or substituted
with one or more groups selected from amino, alkoxy, hydroxy and
halogen. Representative alkyl groups include methyl, ethyl, n- and
iso-propyl, n-, sec-, iso- and tert-butyl, and the like.
[0022] "Hydroxide base" means hydroxide (OH) salts of alkaline and
alkaline earth metals, such as sodium, potassium, lithium,
magnesium, calcium, the like, and combinations thereof.
[0023] "Block polymer" means the polymer resulting from block
addition of more than one different type of monomer, such as
propylene oxide and ethylene oxide.
[0024] "Homo polymer" means the polymer resulting from the
polymerization of one type of monomer, such as propylene oxide or
ethylene oxide.
[0025] "Hetero polymer" means the polymer resulting from random
addition of more than one type of monomer, such as propylene oxide
and ethylene oxide.
[0026] "Formulation" as used herein includes one or more chemicals
in solid, powder, crystalline, or other form and/or a solution of
one or more chemicals in any suitable solvent in any appropriate
concentration.
[0027] "Oven-dry pulp" means a paper or pulp that has been dried in
an oven, contains practically no moisture, and has constant weight
within about 0.1 percent.
[0028] "pH-controlling chemical" means any suitable chemical or
compound that, when added to a solution, composition, and/or
formulation, is capable of adjusting pH, controlling pH, and/or
maintaining pH.
[0029] "Active solids" means percent of solid active components of
a material remaining after drying of a formulation. Inactive
admixtures (e.g., sodium chloride) are not considered an active
solid.
[0030] "CSF" means Canadian Standard Freeness as described in TAPPI
methods and measured in milliliters.
Chelant-Related Definitions
[0031] "Carboxylic acids" means organic compounds containing one or
more carboxylic group(s), --C(O)OH, preferably aminocarboxylic
acids containing a single C--N bond adjacent (vicinal) to the
C--CO.sub.2H bond, such as: [0032] i. EDTA
((HO.sub.2CCH.sub.2).sub.2NCH.sub.2CH.sub.2N(CH.sub.2CO.sub.2H).sub.2),
[0033] ii. DTPA
((HO.sub.2CCH.sub.2).sub.2NCH.sub.2CH.sub.2N(CH.sub.2CO.sub.2H)CH.sub.2CH-
.sub.2N(CH.sub.2CO.sub.2H).sub.2), the like, and alkaline and
alkaline earth metal salts thereof.
[0034] "DTPA" means diethylenetriamine pentaacetic acid.
[0035] "EDTA" means ethylenediaminetetraacetic acid.
[0036] "Dithiocarbamates" include monomeric dithiocarbamates,
polymeric dithiocarbamates, polydiallylamine dithiocarbamates,
2,4,6-trimercapto-1,3,5-triazine, disodium
ethylenebisdithiocarbamate, disodium dimethyldithiocarbamate, and
the like.
[0037] "Organic phosphates" means organic derivatives of
phosphorous acid, P(O)(OH).sub.3, containing single C--O--P bonds,
including triethanolamine tri(phosphate ester)
(N(CH.sub.2CH.sub.2OP(O)(OH).sub.2).sub.3), and the like.
[0038] "Organic phosphonates" means organic derivatives of
phosphonic acid, HP(O)(OH).sub.2, containing a single C--P bond,
such as HEDP (CH.sub.3C(OH)(P(O)(OH).sub.2),
1-hydroxy-1,3-propanediylbis-phosphonic acid
((HO).sub.2P(O)CH(OH)CH.sub.2CH.sub.2P(O)(OH).sub.2)); preferably
containing a single C--N bond adjacent (vicinal) to the C--P bond,
such as: [0039] i. DTMPA
((HO).sub.2P(O)CH.sub.2N[CH.sub.2CH.sub.2N(CH.sub.2P(O)(OH).sub.2).sub.2]-
.sub.2), [0040] ii. AMP (N(CH.sub.2P(O)(OH).sub.2).sub.3), [0041]
iii. PAPEMP
((HO).sub.2P(O)CH.sub.2).sub.2NCH(CH.sub.3)CH.sub.2(OCH.sub.2CH(CH-
.sub.3)).sub.2N(CH.sub.2).sub.6N(CH.sub.2P(O)(OH).sub.2).sub.2),
[0042] iv. HMDTMP
((HO).sub.2P(O)CH.sub.2).sub.2N(CH.sub.2).sub.6N(CH.sub.2P(O)(OH).sub.2).-
sub.2), [0043] v. HEBMP
(N(CH.sub.2P(O)(OH).sub.2).sub.2CH.sub.2CH.sub.2OH), and the
like.
Reductive Pulp Modifier-Related Definitions
[0044] "Sulfites" means dibasic metal salts of sulfurous acid,
H.sub.2SO.sub.3, including dibasic alkali and alkaline earth metal
salts such as sodium sulfite (Na.sub.2SO.sub.3), calcium sulfite
(CaSO.sub.3), and the like.
[0045] "Bisulfites" means monobasic metal salts of sulfurous acid,
H.sub.2SO.sub.3, including alkali and alkaline earth metal
monobasic salts such as sodium bisulfite (NaHSO.sub.3), magnesium
bisulfite (Mg(HSO.sub.3).sub.2), and the like.
[0046] "Metabisulfites (Pyrosulfites)" means salts of pyrosulfurous
acid, H.sub.2S.sub.2O.sub.5, including sodium metabisulfite
(Na.sub.2S.sub.2O.sub.5), and the like.
[0047] "Sulfoxylates" means salts of sulfoxylic acid,
H.sub.2SO.sub.2, including zinc sulfoxylate (ZnSO.sub.2), and the
like.
[0048] "Thiosulfates" means salts of thiosulfurous acid,
H.sub.2S.sub.2O.sub.3, including potassium thiosulfate
(Na.sub.2S.sub.2O.sub.3), and the like.
[0049] "Polythionates" means salts of polythionic acid,
H.sub.2S.sub.nO.sub.6 (n is from 2 to 6), including sodium
trithionate (Na.sub.2S.sub.3O.sub.6), salts of dithionic acid,
H.sub.2S.sub.2O.sub.6, such as sodium dithionate
Na.sub.2S.sub.2O.sub.6, and the like.
[0050] "Dithionites (hydrosulfites)" means salts of dithionous
(hydrosulfinurous, hyposulfurous) acid, H.sub.2S.sub.2O.sub.4,
including sodium dithionite (hydrosulfite)
(Na.sub.2S.sub.2O.sub.4), magnesium dithionite (MgS.sub.2O.sub.4),
and the like.
[0051] "Formamidinesulfinic acid (FAS)" means a compound of formula
H.sub.2NC(.dbd.NH)SO.sub.2H and its salts and derivatives including
the sodium salt H.sub.2NC(.dbd.NH)SO.sub.2Na.
[0052] "Aldehyde bisulfite adducts" means compounds of formula
R.sub.1CH(OH)SO.sub.3H and metal salts thereof where R.sub.1 is
selected from alkyl, alkenyl, aryl and arylalkyl. Representative
aldehyde bisulfite adducts include formaldehyde bisulfite adduct
HOCH.sub.2SO.sub.3Na, and the like.
[0053] "Sulfinamides and ethers of sulfinic acid" means compounds
of formula R.sub.1--S(.dbd.O)--R.sub.2, where R.sub.1 is defined
above and R.sub.2 is selected from OR.sub.3 and NR.sub.4R.sub.5,
where R.sub.3-R.sub.5 are independently selected from selected from
alkyl, alkenyl, aryl and arylalkyl. Representative sulfinamides
include ethylsulfindimethylamide
(CH.sub.3CH.sub.2S(.dbd.O)N(CH.sub.3).sub.2), and the like.
[0054] "Sulfenamides and ethers of sulfenic acid" means compounds
of formula R.sub.1--S--R.sub.2, where R.sub.1 and R.sub.2 are
defined above. Representative sulfenamides include
ethylsulfendimethylamide (CH.sub.3CH.sub.2SN(CH.sub.3).sub.2), and
the like.
[0055] "Sulfamides" means compounds of formula
R.sub.1--C(.dbd.S)--NR.sub.4R.sub.5, where R.sub.1, R.sub.4 and
R.sub.5 are defined above. Representative sulfamides include
CH.sub.3CH.sub.2C(.dbd.S)N(CH.sub.3).sub.2, and the like.
[0056] "Phosphines" means derivatives of phosphine, PH.sub.3,
normally organic substituted phosphines of the formula
R.sub.6R.sub.7R.sub.8P where R.sub.6 to R.sub.8 are independently
selected from hydrogen, alkyl, alkenyl, aryl, arylalkyl (defined
below) and NR.sub.4R.sub.5 where R.sub.4 and R.sub.5 is defined
above. Representative phosphines include (HOCH.sub.2).sub.3P (THP),
and the like.
[0057] "Phosphites" means derivatives of phosphorous acid
P(OH).sub.3, including organic substituted phosphites of the
formula (R.sub.3O)(R.sub.4O)(R.sub.5O)P where R.sub.3-R.sub.5 are
defined above. Representative phosphites include
(CH.sub.3CH.sub.2O).sub.3P, and the like.
[0058] "Thiophosphites" means derivatives of phosphorothious acid
HSP(OH).sub.2, including organic substituted thiophosphites of
formula (R.sub.3O)(R.sub.4O)(R.sub.5S)P where R.sub.3 to R.sub.5
are defined above. Representative thiophosphites include
(CH.sub.3CH.sub.2O).sub.2(CH.sub.3CH.sub.2S)P, and the like.
[0059] "Phosphonium salts" means organic substituted phosphines of
the formula R.sub.1R.sub.3R.sub.4R.sub.5P.sup.+X.sup.-, where
R.sub.1 and R.sub.4 to R.sub.5 are as defined above and X is any
organic or inorganic anion. Representative phosphonium salts
include (HO.sub.2CCH.sub.2CH.sub.2).sub.3P.sup.+HCl.sup.-(THP),
[(HOCH.sub.2).sub.4P.sup.+].sub.2(SO.sub.4).sup.2-(BTHP), and the
like.
[0060] "Alkenyl" means a monovalent group derived from a straight
or branched hydrocarbon containing at least one carbon-carbon
double bond by the removal of a single hydrogen atom. The alkenyl
may be unsubstituted or substituted with one or more groups
selected from amino, alkoxy, hydroxyl, and halogen.
[0061] "Alkylene" means a divalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of two hydrogen
atoms, for example methylene, 1,2-ethylene, 1,1-ethylene,
1,3-propylene, 2,2-dimethylpropylene, and the like.
[0062] "Aryl" means aromatic carbocyclic radicals and heterocyclic
radicals having about 5 to about 14 ring atoms. The aryl may be
unsubstituted or substituted with one or more groups selected from
amino, alkoxy, hydroxy and halogen. Representative aryls include
phenyl, naphthyl, phenanthryl, anthracyl, pyridyl, furyl, pyrrolyl,
quinolyl, thienyl, thiazolyl, pyrimidyl, indolyl, and the like.
[0063] "Arylalkyl" means an aryl group attached to the parent
molecular moiety through an alkylene group. Representative
arylalkyl groups include benzyl, 2-phenylethyl, and the like.
Oxidative Pulp Modifier-Related Definitions
[0064] "Organic peroxyacid" means compounds of formula
R.sub.1C(O)O.sub.2H and metal salts thereof where R.sub.1 is
selected from alkyl, alkenyl, aryl and arylalkyl. Representative
organic peroxyacids include peroxybenzoic acid,
C.sub.6H.sub.5C(O)OOH, peracetic acid (PAA), CH.sub.3C(O)OOH,
performic acid, HC(O)OOH, perpropionic acid,
CH.sub.3CH.sub.2C(O)OOH, and the like.
[0065] "Inorganic peroxides" means monobasic (hydroperoxides) and
dibasic (peroxides) metal derivatives of hydrogen peroxide,
H.sub.2O.sub.2, including alkali and alkaline earth metal
derivatives such as sodium hydroperoxide (NaOOH), magnesium
peroxide (MgO.sub.2), and the like.
[0066] "Superoxides" means metal derivatives containing the group
of O.sub.2.sup.-, including alkali and alkaline earth metal
derivatives such as sodium superoxide (NaO.sub.2), and the
like.
[0067] "Peroxide-superoxides" means mixed alkali metal derivatives
of a formula 2MO.sub.2.M.sub.2O.sub.2, where M is an alkali or
alkaline earth metal, such as K.sub.2O.sub.3, and the like.
[0068] "Inorganic peroxy acids and salts thereof" means inorganic
acids containing a --O--O-- group, including peroxy monoacids
containing the group --OOH and peroxy diacids containing the group
--O--O--, and their metal salts, such as peroxymonosulfuric acid
(Caro's acid, (HO).sub.2SO.sub.2OOH), peroxydisulfuric acid
(HOSO.sub.2OOSO.sub.2OH), peroxymonophosphoric acid
H.sub.3PO.sub.5, sodium peroxymonocarbonate Na.sub.2CO.sub.4 and
peroxydicarbonate Na.sub.2C.sub.2O.sub.6, and the like.
[0069] "Peroxyhydrates" are inorganic salts containing hydrogen
peroxide of crystallization, such as sodium metasilicate
peroxyhydrate Na.sub.2SiO.sub.3.H.sub.2O.sub.2.H.sub.2O, and sodium
borate peroxyhydrate NaBO.sub.2.H.sub.2O.sub.2.3H.sub.2O, and the
like.
[0070] "Organic peroxides" are any organic chemicals containing a
--O-- group, including organic peroxyacids as defined herein,
dioxiranes such as dimethyldioxyrane (CH.sub.3).sub.2CO.sub.2, and
the like.
[0071] "Nitrosodisulfonates" are alkali and alkaline earth metal
salts of nitrosodisulfonic acid such as potassium
nitrosodisulfonate (Fremy's salt) (KSO.sub.3).sub.2NO, and the
like.
[0072] "Hypochlorites", "chlorites", "chlorates" and
"perchlorates", are water-soluble metal salts of hypochlorous HOCl,
chlorous HOClO, chloric HOClO.sub.2 and perchloric HOClO.sub.3
acids, respectively, such as sodium hypochlorite, NaOCl, and the
like.
[0073] "Hypobromites" and "bromites" are water soluble salts of
hypobromous acid, HOBr, and bromic acid, HBrO.sub.3, respectively,
including sodium hypobromite, NaOBr, and the like.
[0074] "Chloroamines" and "bromoamines" are ammonium derivatives of
the formulae NH.sub.xHal.sub.y, where Hal is Cl or Br, or
alkylamine derivatives NR.sub.1R.sub.2Hal.sub.x, where R.sub.1 and
R.sub.2 are defined above and x and y are independently 1 to 3. In
aqueous solution, chloramines and bromoamines may be present as the
corresponding ammonium salts.
[0075] "Chloroamides" and "bromoamides" are amide derivatives
containing --C(O)N(R.sub.1).sub.pH.sub.qHal.sub.r groups where Hal
is defined above, p and q are independently 0 to 1 and r is 1 to 2,
such as product compositions formed in a mixture of sodium
hypochlorite NaClO and urea H.sub.2NCONH.sub.2 or sodium
hypochlorite NaClO and 5,5-dimethylhydantoin, and the like.
[0076] "Chlorosulfamides" and "bromosulfamides" are amide
derivatives containing --SO.sub.2N(R.sub.1).sub.pH.sub.qHal.sub.r,
where R.sub.1, Hal, p, q and r are defined above, such as the
product composition formed in a mixture of sodium hypochlorite,
NaClO, and sulfamide, H.sub.2NSO.sub.2NH.sub.2, and the like.
[0077] "Chlorosulfonic acid" is a chemical of the formula
ClSO.sub.3H.
[0078] "Activated oxidizing agent" means an oxidizing agent used in
combination with one or more activators. In some embodiments, the
oxidizing agent is activated hydrogen peroxide.
Surfactant Preparation
[0079] The alkyl alcohol alkoxylates of this invention have the
formula RO[(CH.sub.2CHCH.sub.3O).sub.X(CH.sub.2CH.sub.2O).sub.Y]M.
R may be from C.sub.4 to C.sub.40 straight, branched, or ring
alkyl, X may be from 1 to about 50, Y may be from 0 to about 100,
and M may be hydrogen or an alkali metal. It is contemplated that
the structure of the alkyl alcohol alkoxylate may be a block
polymer, a hetero polymer, a homo polymer, or combinations thereof.
In one preferred embodiment, X is from 1 to 20, Y is from 20 to 80,
and M is hydrogen. In a preferred embodiment, M is hydrogen. In
another preferred embodiment, M is potassium. In alternative
preferred embodiments, R is a C.sub.8 to C.sub.22 alkyl or a
C.sub.16 alkyl. In a further embodiment, X is from 1 to 20. In
another embodiment, Y is from 20 to 80.
[0080] They are typically prepared by heating a C.sub.4 to C.sub.40
alkyl alcohol, or mixture of C.sub.4 to C.sub.40 alkyl alcohols
(sometimes referred to herein as ROH) with propylene oxide and/or
ethylene oxide in the presence of hydroxide base. The ethylene
oxide and propylene oxide may be added in random or block fashion,
resulting in either a hetero polymer or a block polymer,
respectively. The reaction is preferably conducted at a temperature
of about 150.degree. C. in a pressure vessel at a pressure of about
50 psi to about 75 psi. The alkoxylate product may either be left
in salt form or neutralized with acid.
[0081] Random addition of ethylene oxide and propylene oxide
involves simultaneous addition of both components to the alcohol,
such that the rate of addition is controlled by their relative
amounts and reaction rates. In the case of random addition, it
should be appreciated that the above formula is not a structural
formula. Rather, it is a representation of molar amounts, X and Y,
of ethylene oxide and propylene oxide added to the alcohol.
[0082] In block addition, either the ethylene oxide or the
propylene oxide is added first to the alcohol and allowed to react.
The other component is then added to the alcohol and allowed to
react. In this case, the above formula is representative of the
structure of the alkoxylated alcohol, except that the
(C.sub.2H.sub.4O).sub.X and (C.sub.3H.sub.6O).sub.Y groups may be
reversed, depending on the order of propylene oxide or ethylene
oxide addition. The resulting polymer is a highly water-soluble
solid.
Composition
[0083] In a preferred aspect, the composition of the invention is
an alkyl alcohol alkoxylate surfactant having formula
RO[(CH.sub.2CHCH.sub.3O).sub.X(CH.sub.2CH.sub.2O).sub.Y]M; wherein
R is C.sub.4 to C.sub.40 straight, branched, or ring alkyl, X is
from 1 to about 50, Y is from 0 to about 100, and M is H or an
alkali metal, as explained in more detail above. In this
embodiment, the composition optionally includes one or more
chelants, one or more hydrotropees, one or more reductive or
oxidative pulp modifiers, and one or more pH-controlling chemicals
(each explained in more detail herein).
[0084] The composition of the invention, in one embodiment,
includes an effective amount of a surfactant formulation having one
or more surfactants. The role of the surfactants is to improve
penetration of liquid or steam into the woodchips thus facilitating
homogenization in the mechanical pulping process. It is
contemplated that a variety of surfactants may be used in
accordance with the invention. Representative surfactants include
non-ionic surfactants, alkyl alcohol alkoxylates (as above); block,
homo, and hetero polymer alkyl alcohol alkoxylates; ethoxylated
tridecyl alcohol; ethoxylated propyloxylated hexadecanol; the like;
and combinations thereof. The surfactant formulation typically has
from about 0.05 weight percent to about 30 weight percent of one or
more surfactants. In a preferred embodiment, the composition has
from about 1 weight percent to about 10 weight percent of one or
more surfactants.
[0085] In another preferred embodiment, the composition includes
surfactant alone and has from about 0.05 weight percent to about 99
weight percent of one or more surfactants. Preferably, such a
surfactant only composition has from about 5 weight percent to
about 30 weight percent of one or more surfactants. In a more
preferred embodiment, the surfactant only composition has from
about 10 weight percent to about 20 weight percent of one or more
surfactants.
[0086] In a preferred aspect, the composition also includes an
effective amount of a chelant formulation having one or more
chelants. As stated above, the presence of metal ions, such as
transitional metal ions, promote undesirable side reactions
including oxidative reactions and complex formation with lignin
that cause yellowing. Chelants efficiently immobilize these ions to
prevent such undesirable side reactions. Effective chelants include
transitional metal chelants, such as aminocarboxylates,
aminophosphonates, polyphosphates, polyacrylates, organic
phosphates, organic phosphonates, phosphates, carboxylic acids, the
like, and combinations thereof. Preferred chelants include
carboxylic acid, phosphonates, DTPA and salts thereof, EDTA and
salts thereof, and 1)TMPA and salts thereof. Typically, about 0.05
weight percent to about 50 weight percent chelant is sufficient.
Preferably the chelant is present from about 1 weight percent to
about 30 weight percent. Most preferably, the composition includes
from about 5 weight percent to about 20 weight percent of one or
more chelants.
[0087] In one aspect, the composition includes an effective amount
of a hydrotrope formulation having one or more hydrotropes.
Contemplated hydrotropes include arylenesulfonates, such as
xylenesulfonate, cumenesulfonate, and toluenesulfonate and
carbohydrates having long-chain aliphatic substituents, such as
Glucopon.RTM. (available from Fitz Chem Corp. in Itasca, IL) and
Glucopon.RTM.-like compounds. An example of a Glucopon compound is
Glucopon 425N, D-glucose, decyl ethers, octyl ethers, oligomeric
D-glucopyranoside, C.sub.10 to C.sub.16 alkyloligomeric (available
from Cognis Corporation in Hoboken, N.J.).
[0088] It is further contemplated that the hydrotrope formulation
may include any combination of these and similar compounds. In an
embodiment, the composition has from about 0.05 weight percent to
about 50 weight percent of one or more hydrotropes. Preferably, the
composition includes from about 0.05 weight percent to about 50
weight percent of the hydrotrope(s). In another preferred
embodiment, the composition has from about 5 weight percent to
about 30 weight percent hydrotrope. The most preferred hydrotrope
content of the composition is from about 10 weight percent to about
20 weight percent.
[0089] In one embodiment that contains the hydrotrope formulation,
the weight percent ratio of hydrotrope to chelant is typically
about one-to-one or greater. In another embodiment, the weight
percent ratio of hydrotrope to surfactant is typically about
two-to-one or greater.
[0090] The presence of one or more hydrotropes in the composition
acts to increase the aqueous solubility of certain slightly soluble
compounds. Generally, all the individual components of the
invention are soluble in water; however, certain combinations, such
as a nonionic surfactant with other, more polar components, may
require a wetting agent, such as a hydrotrope to provide
compatibility of the composition in a single formulation. In an
embodiment where the composition is applied as a single mixture,
rather than as separate components, operational and performance
advantages are observed.
[0091] A preferred embodiment includes using one or more non-ionic
surfactants, which are typically not compatible with chelants. For
example, if the composition includes ethoxylated, propoxylated
hexadecanol (a preferred surfactant) and pentasodium DTPA (a
preferred chelant), the non-polar surfactant component
precipitates. Incorporating a hydrotrope in the correct ratio (as
explained below) maintains solubility of the non-ionic components
and thus ensures stability of the composition.
[0092] A synergistic effect is observed with the addition of a
reductive pulp modifier to the composition. Such reductive pulp
modifiers include those compounds that are capable of transforming
functional groups in bleached pulp from a higher oxidation category
to a lower oxidation category. Representative reductive pulp
modifiers include water-soluble inorganic sulfites, bisulfites,
metabisulfites, substituted phosphines and tertiary salts thereof,
formamidinesulfinic acid and salts and derivatives thereof,
formaldehyde bisulfite adduct other aldehyde bisulfite adducts,
sulfoxylates, thiosulfates, dithionites, polythionates,
sulfinamides and ethers of sulfinic acid, sulfenamides and ethers
of sulfenic acid, sulfamides, phosphines, phosphonium salts,
phosphites, thiophosphites, the like, and combinations thereof.
Preferred reductive pulp modifiers include sodium sulfite,
bisulfite, and metabisulfite.
[0093] The effective amount of reductive pulp modifier added to the
pulp material is the amount that enhances the brightness and
resistance to thermal yellowing in the mechanical pulping of wood
that brings increased brightness of the pulp material or paper
product compared to untreated pulp material or paper product.
Typically, about 0.01 to about 50 weight percent of one or more
reductive pulp modifiers is effective. A more preferred amount is
from about 5 weight percent to about 30 weight percent. The most
preferred range is from about 10 weight percent to about 20 weight
percent.
[0094] In another aspect, the composition includes addition of an
effective amount of one or more oxidative pulp modifiers. Oxidative
pulp modifiers include those chemical substances capable of
transforming functional groups in pulp material from a lower
oxidation category to a higher oxidation category. Benefits of this
transformation include increased brightness and resistance to
thermal yellowing in the mechanical pulping of wood that brings
higher brightness of the pulp material or paper product compared to
untreated pulp material or paper product. Effective amounts of one
or more oxidative pulp modifiers are contemplated to be in the
range of about 0.01 weight percent to about 50 weight percent.
Preferably, one or more oxidative pulp modifiers are present from
about 1 weight percent to 20 weight percent. Most preferably, the
composition includes about 5 weight percent to about 15 weight
percent of one or more oxidative pulp modifiers.
[0095] Representative oxidative pulp modifiers include
percarbonates, perborates, hydrogen peroxide, activated hydrogen
peroxide, organic peroxyacids and salts thereof dioxiranes,
halogenamines, inorganic peroxides, superoxides and
peroxide-superoxides, inorganic peroxyacids and salts thereof,
peroxyhydrates, water-soluble organic peroxides,
nitrosodisulfonates, hypochlorites, hypobromites, chlorites,
chlorates, bromates, perchlorates, chlorine dioxide, chloroamines,
chloroamides, chlorosulfamides, bromoamines, bromoamides,
bromosulfamides, chlorosulfonic acid, bromosulfonic acid, chlorine,
the like, and combinations thereof.
[0096] The oxidative pulp modifier may be used in combination with
one or more "activators." The activators include compositions that
enhance the effect of the oxidizing agent through catalysis of the
oxidation reaction, change in pH, or both. Representative
activators include, but are not limited to phosphoric acid;
monosodium phosphate; monosodium sulfate; monosodium carbonate;
TEMPO (2,2,6,6-tetramethylpiperydidnyoloxyl); 4-hydroxy-TEMPO;
ammonium molybdate; tetraacetylethylenediamine (TAED); and
pH-changing chemicals affecting oxidation rates, such as acetic
acid.
[0097] The presence of alkali (a representative pH-controlling
chemical) typically strengthens the paper product at the expense of
decreasing its brightness. In one embodiment, the invention
includes use of alkali or other pH-controlling chemicals. The
composition and method of the invention have the benefit of
enabling use of such alkali or pH-controlling chemicals to increase
mechanical strength of the paper product without reducing its
brightness. Representative pH-controlling chemicals include
trisodium phosphate, sodium metaborate, ammonium carbonate, sodium
hydroxide, potassium hydroxide, lithium hydroxide,
tetramethylammonium hydroxide, ammonium hydroxide, magnesium
hydroxide, magnesium carbonate, sodium silicate, sodium carbonate,
the like, and combinations thereof. Typically, in an embodiment,
the composition includes about 5 weight percent to about 90 weight
percent of the pH-controlling chemical. A more preferred range of
one or more pH-controlling chemicals in the composition is from
about 20 weight percent to about 50 weight percent.
[0098] It should be appreciated that the composition may include
other organic and inorganic compounds, for example, salts,
solvents, and/or wetting agents as needed in certain applications.
Any other such compounds may be included without varying from the
scope of the invention.
Method of Application
[0099] The composition may be applied onto wood chips or pulp
material to prepare the material for mechanical pulping (e.g., in a
chip silo, conveyer belt, or atmospheric steaming bean) or during
mechanical pulping (e.g., grinding, refining). The components can
be applied separately at different stages of the process. For
example, a surfactant may be contacted with the wood chips on the
conveyor belt and a reductive pulp modifier may be introduced to
the pulp material during refining. The preferred way to implement
the method of the invention is in a single formulation before or
during the mechanical pulping process.
[0100] It should be appreciated that the composition may be applied
by any means available, such as spraying on wood chip stock, mixing
with the liquor (i.e., dilution water), applying with steam (e.g.,
in a refiner via steam tubes), the like, and combinations thereof.
The precise location where the composition of the invention is
applied, either as a single formulation or in separate components,
depends on the specific equipment involved, the exact process
conditions being used and the like. In some cases, the composition
may be added at one or more locations for optimal
effectiveness.
[0101] In one embodiment, the composition of the invention is
directly fed into the refiner at the mechanical pulping stage. In
an embodiment, the method includes contacting the pulp material
with about 0.001 weight percent to about 5 weight percent of the
alkyl alcohol alkoxylate surfactant (as explained in more detail
above), based on oven-dry pulp. More preferably, the surfactant
level is from about 0.003 weight percent to about 0.2 weight
percent, based on oven-dry pulp. The most preferred surfactant
level is from about 0.005 weight percent to 0.1 weight percent
based on oven-dry pulp.
[0102] In another embodiment, the method includes introducing to
the pulp material about 0.005 weight percent to about 5 weight
percent of one or more reductive pulp modifiers (as explained in
more detail above), based on oven-dry pulp. Preferably, the
reductive pulp modifier is added from about 0.01 weight percent to
about 0.5 weight percent, based on oven-dry pulp. Most preferably,
one or more reductive pulp modifiers are added from about 0.02
weight percent to about 0.1 weight percent, based on oven-dry
pulp.
[0103] In one embodiment, the method includes introducing to the
pulp material about 0.01 weight percent to about 5 weight percent
of one or more oxidative pulp modifiers, based on oven-dry pulp. A
preferred level of the oxidative pulp modifier is from about 0.01
weight percent to about 0.5 weight percent, based on oven-dry pulp.
A most preferred dosage of one or more oxidative pulp modifiers
from about 0.02 weight percent to about 0.1 weight percent, based
on oven-dry pulp.
[0104] One or more chemicals to control or adjust pH are needed in
certain embodiments. The level of pH-controlling chemical may vary
depending upon the pH requirements or pH of the system. These
embodiments include introducing to the pulp material (as stated,
either separately or mixed with one or more other components of the
composition) from about 0.05 weight percent to about 10 weight
percent of one or more pH-controlling chemicals, based on oven-dry
pulp. In one embodiment, the pH-controlling chemicals are
introduced from about 0.1 weight percent to about 2 weight percent,
based on oven-dry pulp. In a preferred embodiment, the
pH-controlling chemicals are used from about 0.4 weight percent to
about 1 weight percent, based on oven-dry pulp.
EXAMPLES
[0105] The foregoing may be better understood by reference to the
following examples, which are intended to illustrate methods for
carrying out the invention and are not intended to limit the scope
of the invention.
[0106] Compositions used in the following examples are listed
below. All percentages are in weight percent, unless indicated
otherwise. [0107] i. Composition A: about 14.5% chelant, about
17.5% hydrotrope, and about 3% surfactant. [0108] ii. Composition
A1: about 0.15% chelant and about 0.15% Composition A. [0109] iii.
Composition B: about 5.4% chelant, about 15.2% hydrotrope, about
1.3% surfactant, and about 16.2% reductive pulp modifier. [0110]
iv. Composition B1: about 0.3% Composition A and about 0.2%
reductive pulp modifier. [0111] v. Composition C: about 0.3%
Composition A, about 0.2% reductive pulp modifier, and about 2%
pH-controlling chemical. [0112] vi. Composition C1: about 0.3%
Composition A, about 0.2% reductive pulp modifier, and about 1%
trisodium phosphate (Na.sub.3PO.sub.4). [0113] vii. Composition C2:
about 0.3% Composition A, about 0.2% reductive pulp modifier, and
about 0.5% pH-controlling chemical. [0114] viii. Composition D:
about 0.5% Composition B and about 0.5% NaOH. [0115] ix.
Composition E: about 0.3% Composition A, about 0.2% reductive pulp
modifier, and about 0.5% pH-controlling chemical. [0116] x.
Composition F: about 0.3% Composition A, about 0.2% reductive pulp
modifier, and about 1% sodium metaborate (NaBO.sub.2). [0117] xi.
Composition C: about 0.5% Composition A and about 1% oxidative pulp
modifier. [0118] xii. Composition H: about 0.5% Composition A and
about 1% oxidative pulp modifier. [0119] xiii. Composition I: about
0.3% Composition A, about 0.2% reductive pulp modifier, about 0.25%
alkali, and about 0.25% pH-controlling chemical. [0120] xiv.
Composition J: about 0.3% Composition A, about 0.2% reductive pulp
modifier, and about 0.5% pH-controlling chemical. [0121] xv.
Composition K: about 16% surfactant. [0122] xvi. Composition L:
about 24% pH-controlling chemical, about 2% chelant and about 9.5%
reductive pulp modifier. [0123] xvii. Composition M: about 0.1%
Composition L and about 0.5% sodium hydroxide. [0124] xviii.
Composition N: about 24% pH-controlling chemical, about 2% chelant,
and about 9.5% sodium sulfite. [0125] xix. Composition O: about
0.5% Composition N and about 0.5% sodium hydroxide.
[0126] For the below examples, the pulp materials and process
conditions were chosen based on freeness so that the treatments
would not reduce the freeness to values lower than 200 ml CSF. Pulp
material was typically mixed with the composition and may be heated
and cooked in a digester at between about 120.degree. C. and about
150.degree. C. Alternative methods of heating include preheating in
a microwave at about 80.degree. C., heating with infrared energy,
or by heating using any suitable means. The digested pulp may
subsequently be refined in a PFI mill running from about 2,000 RPM
to about 20,000 RPM, depending on the setting.
[0127] The treated pulp was diluted with deionized water to 5
percent consistency and then dewatered to 20 percent consistency.
The dewatered pulp was bleached at 20 percent consistency at
70.degree. C. for about 1 hour with from 2.5 to 3 weight percent
H.sub.2O.sub.2, about 2 weight percent NaOH, and optionally about
1.13 weight percent sodium silicate. Handsheets were made using a
Buchner funnel (5 gram o.d. pulp, O15 cm, pressed and air-dried)
and/or a Noble&Wood handsheet mold (8 in.sup.2, 60 Wm.sup.2).
Brightness was measured using Elrepho and Technodyne instruments
(ISO Brightness--R457). All percentages are weight percent of the
product to o.d. pulp.
Example I
[0128] TMP: GWD-rejects, cooked and digested for 20 min at
150.degree. C. in a microwave, PFI mill 20,000 RPM (reduced-force
beating), bleached with 2.5% H.sub.2O.sub.2. Brightness
measurements are shown in Table I below.
TABLE-US-00001 TABLE I Sample Treatement Brightness Control 68.37
Composition B 73.11
Example II
[0129] CTMP: GWD-rejects, 1.8% sodium sulfite added to the pulp,
cooked and digested for 20 min at 150.degree. C. in microwave, PFI
mill 20,000 RPM (reduced-force beating), initial pH 8.1, bleached
with 2.5% H.sub.2O.sub.2. Freeness (CSF, ml) and brightness
measurements are shown in Table II. FiberBrite.RTM. 03PO054
("FB03") is a pulp brightness enhancer available from Nalco
Company.RTM. in Naperville, Ill.
TABLE-US-00002 TABLE II Sample Treatment Freeness Brightness
Control: no chelant* 645 71.57 Control: 0.2% FB03* 76.67 0.15%
DTPA, no chelant* 650 74.85 0.15% DTPA, 0.2% FB03* 77.33 0.15%
Composition A1, no chelant* 565 68.98 0.15% Composition A1, 0.2%
FB03* 72.90 Composition A1, no chelant* 545 74.96 Composition A1,
0.2% FB03* 77.51 *at the bleaching stage
Example III
[0130] CTMP: TMP-accepts, 0.5% NaOH and 1% Na.sub.2SO.sub.3 added
to the pulp material, cooked and digested for 15 min at 120.degree.
C.; PFI mill 1,000 RPM, bleached with 2.5% H.sub.2O.sub.2.
Brightness data are shown in Table III.
TABLE-US-00003 TABLE III Sample Treatment Brightness Control 53.6
0.25% Composition A 55.4 0.5% Composition A 55.3
Example IV
[0131] CTMP: TMP-accepts, 0.5% NaOH and 1% Na.sub.2SO.sub.3 added
to the pulp material, cooked and digested for 15 min at 120.degree.
C., PFI mill at 2,000 RPM, bleached with 2.5% H.sub.2O.sub.2.
Brightness, burst index (kPam.sup.2/g), and tensile index (Nm/g)
are shown in Table IV. This example illustrates minimized
brightness loss at the mechanical pulping stage in presence of
alkali that was used to improve mechanical properties of handsheets
made of bleached pulp.
TABLE-US-00004 TABLE IV Sample Treatment Brightness Burst index
Tensile index Control 57.8 0.80 22.3 0.5% Composition D 57.6 0.97
24.6
Example V
[0132] TMP: TMP-accepts, cooked and digested for 15 min at
120.degree. C., PFI mill at 6000 RPM, bleached with 4%
H.sub.2O.sub.2. Original pH (pH-A), pH after PFI mill (pH-B),
brightness measurements, burst index (kPam.sup.2/g), and tensile
index (Nm/g) are shown in Table V. Unbleached pulp had a brightness
of 50.09.
TABLE-US-00005 TABLE V Tensile Sample Treatment pH-A pH-B
Brightness Burst index index Control 4.2 4.3 53.3 1.02 24
Composition B1 5.0 4.4 57.87 1.16 27 Composition C 7.0 6.9 59.98
1.42 27 Composition F 8.2 7.1 55.28 1.32 29
Example VI
[0133] TMP: GWD-rejects, cooked and digested for 15 min at
120.degree. C., PFI milled at 20,000 RPM, bleached with 2.5%
H.sub.2O.sub.2. Original pH (pH-A), pH after PFI mill (pH-B),
brightness measurements, burst index (kPam.sup.2/g), and tensile
index (Nm/g) are shown in Table VI. Moderate alkaline buffering
combined with other components of the composition led to marked
improvements in brightness and mechanical integrity. Such buffering
is possible with trisodium phosphate or sodium metaborate that are
potential alternatives to standard alkalization with sodium
hydroxide. Sodium hydroxide provides higher strength, but more
moderate buffering provides higher brightness. Alkalization
normally negatively affects brightness, and the proposed
compositions compensate for this deficiency.
TABLE-US-00006 TABLE VI Tensile Sample Treatment pH-A pH-B
Brightness Burst index index Control 6.4 5.8 71.30 1.16 25
Composition D 11.1 6.2 75.02 1.42 32 Composition C1 9.2 6.9 75.91
1.25 28 Composition F 9.5 6.7 74.21 1.31 29
Example VII
[0134] TMP: TMP-accepts, cooked and digested for 15 min at
120.degree. C., PFI mill at 6,000 RPM, bleached with 4%
H.sub.2O.sub.2. Original pH (pH-A), pH after PFI mill (pH-B),
brightness measurements, burst index (kPam.sup.2/g), and tensile
index (Nm/g) are shown in Table VII. As can be seen, trisodium
phosphate is affecting strength only at high concentrations.
Metaborate is more efficient at the same dose. The data also show
that combined application of the new chemistry with
oxidants-alkaline buffers such as perborate and especially
percarbonate provides significant improvement.
TABLE-US-00007 TABLE VII Tensile Sample Treatment pH-A pH-B
Brightness Burst index index Control 4.3 4.12 53.43 1.02 25
Composition C2 6.42 5.66 56.26 0.94 25 Composition C1 6.62 6.51
56.41 1.25 24 Composition F 8.02 7.09 55.65 1.40 28 Composition G
7.53 7.78 60.7 1.16 27 Composition H 7.21 6.75 56.19 1.25 26
Example VIII
[0135] TMP: GWD-rejects, cooked and digested for 15 min at
120.degree. C., PFI mill at 10,000 RPM, bleached with 3%
H.sub.2O.sub.2, 1.13% sodium silicate added to the pulp.
Comparative brightness measurements, burst index (kPam.sup.2/g),
and tensile index (Nm/g) are shown in Table VIII.
TABLE-US-00008 TABLE VIII Brightness Brightness Whiteness Whiteness
Burst Tensile Sample Treatment drum dried air dried drum dried air
dried index index Composition B 78.42 81.67 52.71 57.81 0.72 28.2
Composition I 77.31 81.79 51.49 57.93 0.95 28.1 Composition J 78.32
81.11 51.89 56.89 0.94 28.1 Composition E 77.34 80.92 49.57 56.22
0.87 30.5
Example IX
[0136] TMP: GWD-rejects, cooked and digested for 15 min at
120.degree. C., PFI mill at 4,000 RPM, pulp material dosed with PAA
and H.sub.2O.sub.2 dosed as actives and Composition B as product,
bleached at 70.degree. C. for 1 hour with 3% H.sub.2O.sub.2 and 2%
NaOH. Table IX shows unbleached and bleached brightness and tensile
index (Nm/g).
TABLE-US-00009 TABLE IX Brightness Brightness Tensile Sample
Treatment unbleached bleached Index Control 63.23 73.4 19.36 0.5%
NaOH 60.62 71.7 23.72 0.5% NaOH 66.24 77.0 23.41 0.05% DTPA 0.02%
FB03 0.2% H.sub.2O.sub.2 0.25% NaOH 66.45 77.5 23.11 0.25%
Na.sub.2CO.sub.3 0.05% DTPA 0.02% FB03 0.2% H.sub.2O.sub.2 0.5%
NaOH 65.84 78.8 25.8 0.05% DTPA 0.02% FB03 0.2% peracetic acid 0.5%
NaOH 63.54 77.8 27.41 0.5% Composition B
Example X
[0137] TMP: GWD-rejects, cooked and digested for 5 min at
120.degree. C., PFI mill at 4,000 RPM, pulp material dosed with PAA
and H.sub.2O.sub.2 as actives and Composition B as product,
bleached at 70.degree. C. for 1 hour with 3% H.sub.2O.sub.2 and 2%
NaOH. Table X shows bleached brightness and tensile index
(Nm/g).
TABLE-US-00010 TABLE X Brightness Sample Treatment bleached Tensile
Index Control 77.05 20.34 0.25% NaOH 76.77 23.36 0.085%
Mg(OH).sub.2 77.78 21.56 0.25% NaOH 76.81 23.46 0.085% Mg(OH).sub.2
0.25% NaOH 78.12 22.96 0.25% Composition B 0.25% NaOH 77.64 23.36
0.085% Mg(OH).sub.2 0.25% Composition B 0.25% NaOH 77.85 23.36
0.085% Mg(OH).sub.2 0.25% Composition A 0.25% NaOH 76.97 23.22
0.025% FB03
Example XI
[0138] Prototype product for CTMP applications (Composition A) was
evaluated. The composition was applied at a rate of 6 lb/ton o.d.
wood chips. The composition was applied at the refining stage, and
its effect was followed during the multi-stage refining-bleaching
process. The evaluation demonstrated a possibility of caustic
removal at the refining stage without any negative effect on paper
strength, freeness, shives, or energy consumption. Composition A
also produced improvement in brightness and higher efficiency in
the first stage bleaching and lesser peroxide consumption in the
second stage bleaching. When Composition A was applied at the
impregnation refining stage, cutting peroxide by 14 kg/ton at the
second stage, bleaching did not negatively affect brightness, which
was even higher than under normal conditions. Application of the
composition at the refining stage provided 10 percent energy
savings that, when the same energy was applied, resulted in a 10
percent productivity increase.
Example XII
[0139] The goal of this trial was to reduce the specific energy
required thereby increasing production rate. Prototype products
from TMP applications (Compositions B, K, and M) were evaluated.
Composition K was applied at the rate of 1 lb/ton (0.45 weight
percent) and sodium hydroxide at 0.5 weight percent to o.d. wood at
the refiner stage. Freeness reduction was observed with each
prototype ranging from 4 percent (8 ml drop) to 9.7 percent (20 ml
drop). Brightness of unbleached pulp increased with Composition B
by 1.0 point and 1.2 points (at 2 lb/ton dose). The gain in
brightness of bleached pulp, which was not directly measured, was
expected to be greater than that observed in the unbleached pulp.
Breaking length, tensile strength, and tensile energy absorption
("TSA") all improved, with TEA increasing up to 24 percent.
[0140] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope of the invention and without diminishing its intended
advantages. It is therefore intended that such changes and
modifications be covered by the appended claims.
* * * * *