Canadian Patents Database / Patent 2141485 Summary
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|(12) Patent Application:||(11) CA 2141485|
|(54) English Title:||TREATMENT OF WASTE PRINTED PAPERS WITH SURFACE ACTIVE POLYMERIC COMPOSITIONS FOR IMPROVED RECYCLABILITY|
|(54) French Title:||TRAITEMENT DE PAPIERS IMPRIMES USES A L'AIDE DE COMPOSITIONS POLYMERIQUES SURFACTIVES, POUR FACILITER LE RECYCLAGE|
- Bibliographic Data
- Representative Drawing
- Admin Status
- Owners on Record
|(51) International Patent Classification (IPC):||
|(72) Inventors :||
|(73) Owners :||
|(71) Applicants :|
|(74) Associate agent:|
|(22) Filed Date:||1995-01-31|
|(41) Open to Public Inspection:||1996-08-01|
|(30) Availability of licence:||N/A|
|(30) Language of filing:||English|
This invention relates to a treatment process of wastepaper for making printing
grade paper from newsprints and officewastes using surface active polymer composition
including a novel surface active terpolymer. In particular, the invention is concerned with a
process for removing ink from an aqueous pulp slurry by treating the pulp with a surface
active polymer composing of two to three comonomers in which at least one is a
hydrophobe and another is a hydrophil, having a glass transition temperature ranging from
about 105°C to about 170°C, alkali metal salts of the said surface active polymer and the
combination of the said surface active polymer with a fatty oil alkoxy derivative or fatty
The embodiments of the invention are in which an exclusive treatment of repulped
waste printed paper with surface active polymer compositions to improve recyclability, is
claimed and defined as follows:
1. A treated wastepaper composition useful for making printing grade paper
obtained by exposing printed waste paper repulped-slurry comprising of of offset, photocopy,
laser and inkjet printed papers contaminated with waster-based flexographic ink printed
papers in direct contact with a surface active polymer, the said surface active polymer being
an alkaline salt or an oil soluble organic material having a glass transition temperature in the
range 105°C to 170°C, characterized by being adsorbable to small ink particle surfaces,
and enhancing the receptivness of the said ink particles to other small inks, agglomerating
and then floating them out from an aqueous medium to enhance the brightness of the
2. The treatment of waste printed paper of claim 1 in which the wastepaper is a
mixture of newsprints and officewastes and, the surface active polymer is a copolymer or a
terpolymer having a glass transition temperature in the range 105°C to 170°C degrees
3. The treatment of claim 1 in which the copolymer or the terpolymer contains
at least one comonomer with an acid anhydride functionality.
4. The treatment of claim 2 in which mixtures of newsprints and officewaste
comprise offset and flexo-printed old newsprints (ONP) as well as xerographic, laserjet and
inkjet printed of officewastes.
5. The treatment of claim 3 in which a copolymer or a terpolymer containing
acid anhydride functionality is a styrene-2,5 furandione copolymer or a terpolymer of
styrene, 2,5 furandione and a third comonomer.
6. The treatment of claim 5 in which the third comonomer is an acid anhydride
other than 2,5 furandione.
7. The treatment of claim 6 in which the terpolymer is a styrene-2,5
furandione-2 dodecenyl succinic anhydride.
8. The process for preparing the terpolymer of claim 7 in which the 2-
dodecenyl succinic anhydride content is less than 20 mole percent by weight of the
9. The treatment in claim 1 in which the copolymer or the terpolymer is soluble
in an alkali.
10. The treatment of claim 1 in which the alkali salt of the copolymer or the
terpolymer is a sodium salt.
11. The treatment of claim 1 in which an aqueous solution of a metal chloride is
introduced together with the sodium salt of the coploymer or terpolymer.
12. The treatment of claim 11 in which the aqueous solution of the metal
chloride is calcium chloride.
13. The treatment of claim 1 in which the copolymer or terpolymer is soluble in
water insoluble oil.
14. The treatment of claim 13 in which the water insoluble oil is an ester.
15. The treatment of claim 14 in which the ester is dioctyl phthalate.
16. The treatment of claim 13 in which the oil solubilized copolymer or
terpolymer is incorporated into the said aqueous pulp slurry in the form of a water
17. The treatment of claim 16 in which a conventional frothing agent is added to
stabilize the froth during flotation.
TREATMENT OF WASTE PRiNTED PAPERS WITH SURFACE ACTIVE
POLYMERIC COMPOSITIONS FOR IMPROVED RECYCLABILITY
k5~r~ n~1 nf Ih~ ;ny.~ntinn
S Recycling of ~a,t"~d~ is a key to survival of pulp and paper industries. The
driving forces are limited by space for landfills, prevention of forests, and consumer
pressure and legislation for recycled content in paper products. To produce good quality
recycled paper requires, among other, the removal of ink from ~d~ a~ which is
commonly recogni~ed as ~a,t~,~d~J~l deinking. Various lenhno~ iPs are available for
10 doing this, which essentially consists of two steps: detaching in~k from fiber and separating
the suspended ink particles from the pulp slurry. For each step a variety of options are
open; ink dispersion is usually achieved in the repulping step by the addition of deinking
chemicals mostly in an alkaline medium, while ink separation is effected by screening,
washing or flotation.
During recent years f~ rarhir printirlg has been developed beyond the printing of
paka~ing materials and is an option for newspaper printing. FI~ Y--~rqrhic inks are water
-based, providing printing and ~llVilUlllllC;ll~dl benefits, but their presence reduce deinking
quality by froth floîation and results in a more difficult effluent ~ cifi~ n from washing
devices. A very similar problem is ~u~u~ d for inkjet-printed officewastes. Sales of
inkjet printers are increasing rapidly due to more and more use of network computers,
electronic mail etc. Pulping of papers printed in Deskjet printer, utilizing a liquid ink
system, produces smaller particles than laser printers or rholo~ori~r5. In fact, on pulping,
the deskjet-printing inks which are essentially dyes dissolved in water and glycols, totally
disperse in aqueous repulping medium to produce a uniformly grey stock.
2s In practice segregation of wastepaper based on the type of printing is impossible. In
most cases, ~và,~L~,ud~ containing newsprints printed with offset and lithography are
cfm~ with flexo-printed newsprints. Similarly, officewastes containing toner based
printed papers are ~ r.l with inkjet-printed officewastes. Although successful
deinking technologies by froth flotation are available for offset and lithography printed
newsprints, a flexography or inkjet printed paper cull~;~lluilalion into other printed paper is
causing severe deinking problem for the reason mentioned above.
The present invention simplifies the deinking of flexo- and inkjet-printed papers
cr~n~ I wastepaper mixtures using repulping and froth flotation processes by treating
a repulped slurry in aqueous medium with a surface active polymer composition in
S presence or absence of a u~u~ h)llal surfactant to ~ " "~ small ink particles to a size
range suitable for flotation and finally removing those A~ d inks by creating air
bubbles under constant agitation from the said repulped slurry.
SllmmAI;y of Ihr i vPnlir~n
It has been discovered that improved recyclability of ~a~a~eli ~ with
flexography- and inkjet-printed papers is simply obtained by treating the w.. .~ pulp,
herein designated as repulped slurry, with a limited amount of a surface active polymer
compound or a mixture of said compounds. Subjecting printed ~va~ )d~15 ~
with paper printed by flPYrlgrArhir and inkjet processes to shear forces under alkaline
15 condition followed by treatment of this repulped secondary fiber slurry in an aqueous
medium with a surface active polymer compound or mixture of compounds having a glass
transition ~~ Jcla~Ul~ rAnging from 105 C to 170 C with or without a conventional
surfactant, effects separation of the ink particles in minimum time even at a ~ lalul~;
below 35 C. By surface active polymer compound is meant an organic polymer, more
20 specifically, a copolymer or terpolymer having at least one hydrophobic and one
hydrophillic monomers, the polymer being adsorbed by the ink particles thereby facilitates
repulsion of ink particles from fiber surface and agglomeration of the free irlks. The
polymeric i,i~LU~ Ulld:~ are specific ~ ".~ with the l~ydlu~ l);c part being styrene
and the hydrophillic part essentially contains an organic acid anhydride of the following
More particularly, this invention deals with styrene-acid anhydride copolymer or
terpolymer as a surface active polymer compound for treating repulped-secondary fiber.
Henceforth the term surface active polymer compound and surface active polymer
composition will be used illtv~ a~ ;ably to designate a single compound or a mixture of
u.~ By terpolymer is meant an organic polymer containing three different
monomer units in polymer chain and by treatment of repulped slurry is meant a process
5 which is adopted to incorporate the surface active polymeric ~:u-n~o~iLiull in an alkaline
medium to facilitate separation of inks from secondary fiber. The said polymericcr~mrr~ition is beleived to produce the ink separation effect by ;~gy,ll~ 1 i. .g ink particles,
perferably small ink particles of average particle size 10 microns and smaller by two
different ll~ l)c by charge neutralization of ink binder in an alkaline medium in
10 presence of an aqueous solution of metal halide or by ~Ir,~ ;LdLill~ them in a ~midly alkaline
medium as small solid particles followed by their ~ ",~ iorl with other ink particles of
similar size and preventing them from deposition on the pulp surface and, finally floating
them out with controlled air flow and agitation. Regardless of the correct exrl~n~ )n, it is
observed that the treatment of the pulp in alkaline medium with said surface active
15 polymeric Co~ u~iliull enhances the ~lomrrati~ n of small ink particles to the size range
of about 5 to 200 microns and then removes them from aqueous pulp slurry by froth
flotation, thereby completely or partially eliminates a pulp washing stage usually required to
remove small inks from repulped newsprints. It is in the aforesaid sense of being enhanced
~lonn.or~ion and reducing the residual small ink particles below S microns in removing
20 inks that deinking the secondary fiber is to be understood herein.
Perferred c~ mr- oiti~n~ of surface active polymer are those in which styrene and an
organic acid anhydride are essential chemical components in a copolymer, more
particularly, the acid anhydrides being 2,5 filr~n~ nr, 2- dodecenyl succinic anhydride
arld 2-methylene succinic anhydride.
2,5 furandione copolymer is described in the Eur. Pat. No. 27, 274, the disclosure of
which is ill~vluulatrd herein by reference. Novel compounds of surface active polymer in
which the polymer being a mixture of a styrene-2,5 furandione copolymer and, a
terpolymer of styrene, 2,5 furandione and a third comorom~r are prepared by bulk
copOly~ aLiull of the particular l~y~lu~llùb~ employed with 10 to 40 mole percents 2,5
furandione and l to 20 mo~e percents of a third l,ULUUIIUIII~,I chosen from 2-dodecenyl
succinic anhydride, citraconic anhydride and 2-methylene succinic anhydride. This
preparation may typically be a~,u~u~ as follows.
S Two to four molar equivalents of styrene is heated with one to three molar
r~u~uiv_h,llL~ of 2,5 furandione at a t~ ,.aLul~; ranging from about 60 C to 90 C with a
catalytic amount of a free radical initiator such as laouryl peroxide, benzoyl peroxide in an
inert liquid medium such as toluene, benzene, xylene. These catalysts and diluent systems
and their amounts are well known and will not be described in detail. A typical
c.-nn~ nfr~til n of catalyst and a preferred diluent system of this invention are particularly
suitable for ink removal described in US Pat. No.3, 725, 360, the teachings of which are
il~UU~U~ ~,d herein by reference. The heating of styrene and 2,5 furandione is conùnued
for 10 to 60 minutes in oxygen free a~lllo6~JII.,.~ in order to initiate the reaction between
styrene and 2,5 succinic anhydride, as evidenced by a marginal increase in the viscosity of
15 solution, and then about 0.1 to 1.5 mole e~luiv~h,~i, of a third m~monr~mrr such as 2-
dodecenyl succinic anhydride is added. The reaction may be ddval~ vu~ly carried out at
slight pressure, for example, at about 5 pounds per square inch pressure in a glass
apparatus. The preferred ~IllfJ~ Ul~ during the third .~..". ,- - .l).. . addition is above 75 C.
Temperature below 75 C may be used, but the reaction is quite slow. After addition of a
third comonomer the reaction is continued for another l to 3 hours. When the required
extent of reaction is achieved, as determined by the viscosity of solution, the batch is then
stripped to remove liquid diluent, the product is recovered first by dissolving in sufficient
amount of acetone followed by ~l~Li~;td~ g it in water. The unique property of these
surface active polymers is that they are soluble in aLcali.
It should be noted that the said surface active polymer compositions with good ink
sl~el~m~r~fi~r~ and sufficient frothing character herein disclosed are obtainable only when 2-
dodecenyl succinic anhydride is added as a third comonomer during the reaction. No
addition of 2-dodecenyl succinic anhydride leads to products which are efficient in ink
agglomeration but do not possess sufficient frothing ability to remove most of the
a~ u~ a~d inks from aqueous pulp slurry. Such copolymers with a third Culllullulllr,l
other than 2-dodecenyl succinic anhydride or without any third cl~ml~nom~r are also suitable
for use as ink agglomerating agents in a-,~ol~dll~r to this invention are styrene-acid
anhydride copolymers or terpolymers.
The styrene-acid anhydride copûlymer is one having a styrene content at least about
50 mole percents, preferably from about 60 to 80 mole percents and a glass transition
b, u~ Lul~ in the range from about lûS C to about 170 C, preferably from about 110 C to
about 160 C. Preferred styrene-acid anhydride Cu,u~lyl~ and terpolymers are styrene-
citraconic anhydride copolymer, styrene-2,5 filrr~~i( 2 methylene succinic anhydride
terpolymer, styrene-2,5 furandione-citraconic anhydride terpolymer, styrene-2,5
furandione copolymer, the later being ,u~-liuul~ly preferred. The styrene-acid anhydride
copolymers and terpolymers other than those containing 2-dodecenyl succinic anhydride
can be prepared using techniques well known to the art. The preferred systems are
alternating and random copolymers as described by Moore in I.E.C. Prod. R.D. on page
315, V-25, 1986 and described as random copolymers on pages 359, 364 and 390, Trivedi
and Culbertson, Maleic anhydride, Plenum Press, New York, 1982. See also Czech CS.
Pat. No. 247, 037 for preparation of block copolymers.
More particularly this invention comprises the process to incorporate the said
surface active polymer ~ in a wastepaper repulped-slurry in an aqueous alkaline
20 medium in order to agglv-~ L~ free small inks, preferably small inks generated from
repulping of flexogarphic newsprints and inkjet-printed officewastes containing waste
printed paper mixtures and then separating the A~l~ml'rAl~d inks in the size range of about
5 to 200 microns from the pulp slurry by froth flotation.
The treatment of waste printed paper is preceeded by an alkaline repulping step.Repulping of secondary fiber may be effected using any conventional process and
apparatus. Typically waste paper is subjected to m~ hAnirAI shearing in a so called high
uu--~i~L~ ,y laboratory pulper. The function of a pulper in waste paper recycling operations
is to defiber the paper and detach ink particles from fibers. The pulper produces a high
uu~ ,y pulp slurry herein designated as "repulped slurry", when waste printed paper is
agitated with a high speed rotor in an aqueous alkaline medium. The consistency of
repulped slurry typically varies from about 5 to 20 percent and usually from about 7 to 13
percents by weight of paper fiber basis dry weight of waste printed paper relative to the
total weight of the slurry. The pH of the aqueous alkaline medium ranges from about 7.5
5 to about 11.5, more frequently the pH is maintained in the vicinity of about 8.0 to 10.5.
Repulping chemicals may be added to the pulper. The reason for adding chemica~s to the
pulper is to assist in the easy release of the u~ld~ ~lc materials such as ink and sticikes,
from waste paper and to make these uad~ abl~ materials accessible for separation by
conventional deinking processes such as screening, flotation and washing. The principal
10 repulping chemicals used in this invention are: sodium hydroxide, sodium silicate,
chelating agent and hydrogen peroxide. A typical repulping chemical ~bll,~bsi~iu~. contains
1.0 to 4.0 percent sodium silicate, 0.5 to 2.0 percent hydrogen peroxide, 0.1 to 0.25
percent chelant such as dic~ , .; "~-pentaacetic acid (DTPA), sodium hydroxide as
required to adjust the pH from 7.5 to 11.5. In some cases dilute hydrochloric acid is also
15 used for pH adjustment depending on the resulting pH of the pulp slurry after addition of
all pulping chemicals except sodium hydroxide. The L~ a~ul~ of the pulper is held in the
range of about 25 C to 60 C. A t. ., .1,., ..1 1 1, ~ above 60 C may be used with an ullde~ildble
loss in mechanical shear during the repulping process. The time of repulping may be from
about 10 to 30 minutes. Usually, a repulping time of about 15 to 25 minutes is
In most cases, the repulped slurry contains free ink particles ranging from about 0.1
micron to about 200 microns or more. It has been discovered that the treatment of a diluted
repulped slurry with a surface active polymer composition surprisingly improved the
ml rr11ion of small ink particles ranging frûm about 0.1 micron to about 10 microns. A
25 subsequent flotation of the aforesaid treated slurry in a conventional flotation cell has
readily removed the inks from aqueous slurry. Since the invention process is particularly
applicable to waste printed paper c-.ni: ' with papers printed with fl~Yrl~r~rhir and
inkjet processes, such ink removal process may also be applied for flotation deinking of
flexo- or inkjet-printed wastepapers alone.
Flotation of the repulped flber may be effected using any conventional process and
apparatus. Typically repulped slurry from pulper is treated in a flotation cell under
controlled agitation and air flow. The choise of an agitator, an agitator speed and an air
flow rate are well known art and will not be discussed here in detail. The pulp consistency
5 in the flotation cell may be varied from about 0.2 percerlt to about 1.2 percent of dry pulp in
relation to the total weight of slurry. More preferred pulp ~:UII~;:/t~,ll.,y is from about 0.3
percent to about 0.8 percent by weight. Treating the low ~;u~i~L~O y pulp with an aqueous
medium containing a surface active polymer ~o~ ,osiLiu.. may be cu., .~ ly effected in a
flotation cell by simply adding the surface active polymer composition to the repulped
10 slurry. The pH of the fiber slurry may range from about 7.5 to about 10.5. More
preferred pH range is from about 8.0 to about 9.5. The pH can be adjusted by addition of
an acid or a base as required.
All alkali soluble cu~ol~.~.c.s and terpolymers herein described as surface active
polymer compunds may be hl.,ul~JoldL~(l in the flotation cell as their alkali metal salts more
15 preferably as their sodium salts. In their anionic form, an aqueous solution of metal
chloride is also added to the pulp slurry together with the surface active polymer
romro~i~ion. Generally, calcium chloride, potassium chloride and ~ chloride are
used as met~l chlorides but calcium chloride dihydrate is preferred.
The amount of the said surface active polymer composition used typically ranges
zo from about 0.3 percent to about 2.5 percent and usually about 0.5 percent to about 2.0
percent on dry basis weight of waste printed paper in repulped slurry. The amount of metal
chloride is usually about the same as the said surface active polymer cu~ùsiLiull~
Another suitable method to introduce the said surface active polymer compositions
which are insoluble in aqueous alkaline solution having a pH less than 10.5, in an aqueous
25 pUlp slurry in a flotation cell is in the form of a water-based dispersion. A water-based
dispersion of a surface active polymer composition may be prepared by first dissolving the
solid polymer in a water insoluble organic solvent in a ~.UllC.,ll~ Liull range of about 3
percent to about 8 percent by weight of the solvent and then dispersing this polymeric
solution in water. The organic solvents which are suitable for this application are esters and
ethers, more particularly phthalate and adipate type esters such as dioctyl phthalate, dibutyl
adipate. The water is the domimant phase in the aqueous dispersion of the said polymeric
solution. Preferred ratio is 40 parts of polymerlc solution to 60 parts of water by weight.
Water based dispersion may be suitably made by stirring the mixture at high speed with a
5 propeller in presence of a small amount of a dispersant. A sodium salt of benzene napthyl
sulfonate in the c--n~PntrAti-)n range of about 0.05 to 0.1 percent of dispersion may be used
as a dispersant. It should be noted that the use of this water based dispersion is limited to
an aqueous pulp slurry having pH less than about 10.5.
Because removing the ink particles as much as possible is most desirable in the
15 deinking of repulped secondary fibers, an important feature of secondary pulp recycling is
agglomeration of small ink particles having particle size below S microns. In general,
water-based dispersion of surface active polymer composition may be employed forAFel~m~-rAtine small inks in practicing the present invention. The water-based dispersion is
believed to produce the aforesaid effect by ~Jlr~ dLill~ the dispersed surface active
15 polymer as solid particles of small sizes on their introduction to an aqueous pulp slurry
having pH about 10 or less and once precipitates promoting AeelomrrAf ion of free small ink
The introduction of a surface active polymer composition in the form of a water-based dispersion in flotation cell improves deinking for repulped secondary fiber, more
20 preferably for repulped fiber containing xerography, laser printed papers and old
newsprints (ONP). The function of a water insoluble solvent is beleived to be the swelling
of ink-fiber interface of fused large ink particles and breaking them to small particles
suitable for ~ &1~ ion and flotation. The amount of water-based dispersion typically
ranges from about 0.1 percent to about 2.0 percent by weight of surface active polymer
25 c~mr~it;--n based on dry basis weight of pulp in aqueous slurry.
Of course, the aqueous slurry in flotation cell may contain other additives
commonly used in flotation deinking operation. Examples of such are chelating agents,
frothers, conventional deinking agents, defomers etc. Nonionic or anionic deinking agents
may be employed together with water-based dispersion in the practice of this invention.
Because of the low foaming nature of these solid surface active polymeric particles in pulp
slurry, usually a frothing agent is used to float out the ;le~l.,ll,r,,.lr,l ink particles from
aqueous medium. Examples of satisfactory frothing agents include those materialsdescribed as 'polyalkylene oxide block ~V~JOIy~ ' on pages 300-371, Schick, Nonionic
5 Sllrf~ Marcel Dekker, rnc., New York, 1966. See also JP. Pat. No. 05, 51 887.
Conventional fatty acid soaps and other nonionic surfactants may also be used as frothing
Using surfactant to provide sufficient foaming ability is a well known art and
surfactant compositions of secondary fiber recyclates provide a wide selection from which
10 to choose a frothing agent for practicing the present invention. Usually the amount of
frothing agents is small and typically ranges from about 0.01 percent to about 0.1 percent
by weight based on dry pulp for nonionic type frothing agents and ranges from about 0.1
percent to about 0.5 percent by weight on dry pulp for fatty acid soap type frothers. A
chelating agent may be introduced in the pulp slurry imm, ,' 'y after flotation process.
15 The amount of chelating agent may range from about 0.1 percent to about 2.0 percent of the
dry basis weight of pulp.
The alkaline salts and the water-based ~licrt rcinnc of surface active polymericcomposition disclosed in this invention may be used for deinking of waste papers printed
by li~llv~laL)II~, offset, flexography processes and office wastes processed by xerography,
20 laserjet and deskjet printers. More preferentially, alkaline metal salts of said surface active
polymer compositions may be used to deink waste printed papers ~, ~ with
significant amount of flexo and inkjet printed papers and the water- based dispersions can
be more suitably used for mixture of officewastes and old newsprints (ONP) including
flexo printed newsprints. The vrrl~ w a ~t~ in this invention include xerography, laser and
25 inkjet printed papers.
Description of ~h, prefered r ~ ,n. 1; ., ..., 1 ~
As illustrative of deinked waste printed-paper ~omrnciti~n comprising of both
newsprints and vrrl- -,wa ,l~, wa~t~Ja~ with two separate, v.ll~,o~iLiolls were repulped in
f~ 4 3 ~
a laboratory high ~UIIDi~Ltll~,y pulper. About 920 grams of waste printed papers were torn
into about 3- inch squares and charged in a laboratory pulper containing appropriate amount
of warm water to adjust the required ~:UII~i~t~ y. The repulping was carried out in alkaline
medium of pH 10.5 by adding 2.0 percent sodium silicate, 3.0 percent hydrogen peroxide,
S 0.1 percent chelant-.li~Lllyl~ .;,lrL)- .,~ ;r acid and sodium hydroxide in required
quantity to adjust the pH. In these cllll~ù:iilllclll~ and u ,llbu~:lilll~,.l~a hereafter, all weights
and concentrations are based on weight percent of dry basis weight of paper unless
otherwise specified. The repulping was carried out by mixing the ,UIIILIUCi~iUll in the pulrer
for about 20 minutes with a rotor speed of about 1500 revolutions per minute. The
lû l~ lulc of the pulp slurry was about 45 C. These two repulped ~r/mrnci~ nC before
treatment with surface active polymer ~UIIILIUsiLiUII of styrene-acid anhydride copolymer or
terpolymer in a flotation cell are designated as 'H-l and H-2 Repulped Stocks' as in given
H-1 and H-2 REPULPED STOCKS
Repulped stock H-1 H-2
OLD NEWSPRINT (wt.%) (wt.%)
Flexographic 30 30
Offset 70 40
HP-laserjet NIL 10
HP-deskjet NIL 10
Photocopy NIL 10
The 'w~l~L~ used in these examples of repulped stocks are old newsprints
25 printed by offset and water-based flf-Yr,~r~rhir processes. The Orrl~ cs used in these
examples were 21.6 cm x 27.9 cm sheets printed on one side with uniform alfabetic text
generated by HP-laserjet and HP-deskjet printers. The laserjet printed text was
photocopied on one side of a white paper of same size using SAVIN 7500 copier
employing a toner. The pulp ~u~ if c in the repulped stocks were 8 percent and 13
percent for H-l and H-2 repulped stocks l~ ,ly.
The H-l and H-2 repulped stocks are made into handsheets by passing through a
Handsheet mæhine according to TAPPI test method T-272-om-92 and through a Buchner
funnel according to TAPPI method T-218-om-92. These two methods were used to justify
the effect of small ink particles on deinking. It is already understood that TAPPI method T-
218-om-92 is more suitable for brightness ~ lL of stocks containing large ~mountof small ink particles wherein a filter paper of 2.5 microns pore size was used in the present
invention to make hqn;ChPPts On the other hand, the handsheets making in accordance
with TAPPI method T-272-om-92 was performed using a 140 mesh screen. The
handsheets made according to Tappi methods T-2 1 8-om-92 and T-272-om-92 from control
repulped stock H-l had average hriehrnPccps of 39-40% ISO and 42-43% ISO
15 ~ u~,Li~ly determined in accordance with the Technical ~ssociation of Pulp and Paper
Industry (TAPPI) method T-217. The H-2 repulped control handsheets made according to
Tappi test method T-272-om-92 had an average brightness of 54% ISO ~PtPrrninPd in
accordance with TAPPI method T-217 and an average ink particles surface area of 0.0174
meter square per meter square of paper as ffPtPrrninP~ by an image analy~er 'Ultimage
20 version 2.1' coupled with an optical I.i.lvs~uL/e, Carl Zeiss, Germany and determined on
handsheets with 60 grams per meter square basis weight.
This example illustrates the preparation of styrene-2,5 furandione- 2, dodecenylanhydride terpolymer ~Ulll~U~iLiUII followed by deinking of repu,'ped stocks H- 1 and H-2 as
described in Example I with this prepared sur~ace active polymer ~ mrr~cifi~-n in accordance
with one r:l . ,1.~.1; " ,. . f of the treatment of this invention.
One hundred and four parts Of ~rr~ ir ^~^'y I molar equivalent of a commercial
grade freshly distilled styrene, was charged in a flask equipped with a stirring system.
About 1600 milliliters of benzene and thirty seven parts of commercial grade 2,5-
furandione was added in the flask and the total charge was heated at 60 C for 10 minutes to
dissolve all 2,5-furandione. Then about 0.85 part by weight of freshly crystallized benzoyl
5 peroxide was added to the flask in an oxygen free atmosphere and a positive pressure of
about S pounds per square inch was m:~irt~inrd in the flask. The t~ Lulti of themixture was raised to about 75 C and held for about I hour until the reaction between
styrene and 2,5-furandione started as evident by an increase in the turbidity of the solution.
Twenty parts of appoximately 0.1 molar equivalent of a commercial grade 2-dodecenyl
LO succinic anhydride was added to the mixture. Reaction was carried out for another 90
minutes ~ the mixture L~ Lul~; in the range of 75 to 80 C. The batch was
then cooled to 60 C, benzene was stripped off and polymer was ~..,.,;~iL~L~d from acetone
solution by adding water. The aforesaid ~yllLll~,SiL~,.I product, a mixture of terpolymer of
styrene-~,5 furandione-2 dodecenyl succinic anhydride having a glass transition
15 t~ Lul~ of about 137 C and a copolymer of styrene-2,5 furandione having glasstransition temperature of about 160 C, herein designated as 'terpolymer composition' was
used to deink repulped stocks H-l and H-2 . The sodium salt of this terpolymer
Cu~ u~;Liull was made by dissolving the product in aqueous sodium hydroxide solution.
A number of flotation ~I...i,,,..,l~ were made using varying consistency of
20 repulped slurries H-l and H-2 (1). The treatment of varing weight percent of prepared
sodium salt of terpolymer ~ull~l~osiLiul~ (2) with repulped slurries was made in a laboratory
open-Top Leeds cell type flotation cell. With minor differences, the treatment procedure
used in each experiment was as follows.
Varying repulped slurry .~ . .,. ;..5 from about 0.3 to 1.0 percent by weight of2s dry pulp was made by diluting the stock H-l and H-2 as described in Example I by adding
required amount of warm water with constant stirring and then adjusting the pH of the
diluted pulp slurry to a given pH (3). The pH of pulp slurry was varied from about 8.0 to
about 10Ø Varying amounts of the said terpolymer composition were added in the form
of a sodium salt to provide from 0.1 to 2.0 percent by weight of terpolymer composition
based on dry pulp together with an aqueous solution of calcium chloride of about equal
amount to terpolymer connr~iti~-n by weight of calcium chloride. The temperature of the
slurry was adjusted from about 30 C to about 60 C (5). This pulp slurry containing the
said terpolymer ~Ulll,uo~iLiull was then treated by mixing at high speed of about 1200
5 revolutions per minute for about I to S minutes (4). This treatment period is designated
herein as 'conditioning period'.
Air was introduced in the flotation cell to remove agglomerated inks after
c~n~iiti- nin~ of repulped slurry. The air flow rate was about 3000 milliliters per minute.
Flotation was carried out for about 10 rrlinutes and then air flow was stopped. About 0.3
lû percent of chelant-di~ yl~ ilia ~ ,-pentaacetic acid by weight of dry pulp was added to
the flotation cell and slurry was agitated for another one minute. The pH of the resulting
deinked pulp slurry was then adjusted tû 8.5 and slurry is made into handsheets by passing
through a Handsheet machine according to TAPPI test method T-272-om-92 and through a
Buchner furmel according to TAPPI method T-218-om-92 as described in Example 1. The
15 brightness of the handsheets were determined in accordance with the TAPPI method and
residual ink surface area was determined by image analysis mentioned in Example I. The
Table I ~-".. - ;, s the results of seven t 'I" ' ;1ll' 'Il` It is evident that a brightness gain of
about 8 points is achieved.
This example, illustrates treatment of repulped stocks H- I and H-2 of Example I in
~C~,OIdall~,~ with another ~ l,U-lilllc llL of this invention, using a surface active polymer
c.~mr.~ .n having a glass transition ~~ a~ulc; of about 162 C comprises of sodium
25 salt of styrene-2,5 furandione copolymer prepared by so' lhili7in~ 50 parts of the said
copolymer in 1200 milliliters of 0.5 molal sodium hydroxide. The g~ hili7~ion was
carried out under constant stirring for 3 hours at about 45 C. Treatment of repulped stocks
and then flotation of ~lf)nnrr~t---1 inks were carried out in a similar fâshion as described in
Example II, except that a sodium salt of styrene-2,5 furandione copolymer was used for
pulp treatment instead of a terpolymer composition. ~arying amounts of sodium salt of
styrene-2,5 furandione copolymer together with an aqueous solution of calcium chloride of
about equal amount of the copolymer ~ l by weight of calcium chloride was added
in the pulp slurry in flotation cell. The % ISO brightness and ink surface area of deinked
5 pulp are given in Table 11. A marked illl~)lU ~ ;IIL in % ISO brightness and a decrease in
the ink surface area is evident aher treatment.
As illust}ative of another ~ .I.bo.lilll.,.lL, a surface active polymer composition
containing an anionic frothing agent was prepared by heating 50 parts by weight of styrene-
2,5 furandione copolymer having glass transition ttlll~ Lu~ of about 128 C with 10 parts
of by weight of sodium oleate in 1200 milliliters of 0.5 molar sodium hydroxide solution
under constant stirring. The mixing was carried out for about 3 hours at a ~ ldLul :i of
15 about 45C. Six series of ~ ,.lL~ were made using this alkaline solution of surface
active polymer Culll~o~iLiOI~ for treating the repulped stocks H- I and H-2 of Example I with
varying pulp UUll~; ,t~ and then flotating out the agglomerated inks from the slurry by
repeating the procedure of Example 11. The amount of the aforesaid alkaline solution of
surface active polymer ~ulll~u~iliol~ added to the repulped stocks contained 1.6 weight
20 percent by weight of styrene-2,5 furandione copolymer on dry basis weight of pulp in the
slurry. An aqueous solution of calcium chloride containing 2.0 percent by weight of
calcium chloride on dry basis weight of pulp in the slurry was also added to the pulp slurry
before c~n~ in~ period. The pH of the slurry was adjusted to about 8.5 in each
experiment and the pulp slurry L~ Lul~ was about 45 C for all exr~ rim~ n~ A flotation
2s time of about 10 minutes was used for all r~ Handsheets made from deinked
pulps aher flotation of treated repulped stocks H-l and H-2 had brightness values and ink
surface areas as shown in Table Ill.
The data shows that the treated repulped-secondary fiber has improved brightnesseven with a smaller concentration of styrene-2,5 furandione copolymer in a short
..... ~1;1;.",;"t~ time.
S In still another e~l~b()~ a surface active polymer composition containing anonionic frothing agent was prepared by heating 100 parts of styrene-2,5 furandione
copolymer having a glass transition L~ Lul~ of about 128 C with 2.5 parts of DI 600
(product of Kao Corp.) in 1200 milliliters of I molal sodium hydroxide solution under
constant stirring. The mixing was carried out for about 3 hours at a ~ Lul~ of about
10 55C. Four runs were made using this alkaline solution of surface active polymer
composition for treating the repulped stocks H-l and H-2 of Example I and then flotating
the agglomerated inks by repeating the procedure of Example II. The amount of the
aforesaid alkaline solution of surface active polymer composition added to the repulped
stocks contained 1.6 weight percent by weight of styrene-2,5 furandione copolymer on dry
15 basis weight of pulp in the slurry. An aqueous solution of calcium chloride containing 2.0
percent by weight of calcium chloride on dry basis weight of waste printed paper in pulp
slurry was also added to the flotation cell before 1 . .,,.l;l;. .,,;,,~ period. The pH of the slurry
was adjusted to about 8.5 in each experiment and the pulp slurry t~ UIC; was about
45C for all ~l1rl;1". .,1~ A flotation time of about 10 minutes was used in each set of
20 ~ run. ~ chPPtC made from deinked pulps after flotation of treated repulped
stocks H-l and H-2 had brightness values and ink surface areas as shown in Table IV. A
recycled fiber with ISO brightness of about 54% had been obtained for newsprints~. - ' with about 30% by weight of flexo-printed newspaper.
2s EX~MPT,~, VI
The following illustrate ~,IIlb~ Li.ll~ of the invention in which a surface active
polymer, styrene-2,5 furandione copolymer having a glass transition temperature 147 C
had been treated with the repulped stocks H-2 as in Example I in a flotation cell in the form
of a water-based dispersion.
The water-based dispersion of the aforesaid copolymer was prepared by dissolving80 parts of the copolymer in 1000 rnilliliters of dioctyl phthalate. The dissolution had been
carried out at about 60 C under constant stirring for about 6 hours. Fourty parts of this
S polymer solution was then dispersed in 60 parts of water by high speed mixing of the
composition with a propeller. About 0.01 part of sodium salt of dOdeCyll~f-7f .If ~ r(lilii,
acid by 100 parts of the copolymer was added as a dispersant.
Treatment of the repulped H-2 stock as described in Example I had been carried out
in a flotation cell by adding a Yarying amount of the said water-based dispersion at about
10 60 C to the repulped slurry with a varying pulp ~Ullsi~Lt.l~y and then mixing the slurry for
about 15 minutes. About 1.0 percent by weight of sodium oleate by weight of dry pulp and
about same amount of calcium chloride in the form of an aqueous solution had been added
to the pulp slurry. The pH of the repulped slurry was adjusted to about 8.5 and the slurry
was c~ for about 2 minutes and then flotation of the agglomerated ink particles
15 were carried out in the same fashion as described in Example 11. Results of the brightness
values of the handsheets made from deinked pnlp and the ink surface areas on thehAnrl~hfets are summarized in Table V. The present treatment process, which by
:UllI,UaldliV~ evaluation with other standard treatment process known to the prior art, serve
to prove the superiority of our novel pulp treatment process. Thus, in a separate treatment
2û process a ~u..~.lLiullal ink collector system known to the prior art, comprises of about l
percent by weight of sodium oleate and I percent by weight of calcium chloride in the form
of an aqueous solution, had been used to treat repuled stock H-2 in a similar fashion as
described above without any addition of a water-based dispersion of styrene-2,5 furandione
copolymer. The resulting brightness value and ink particle surface area of this standard
2s treatment process is also given in Table V for c ~ " ~ only and is outside the teachings
of the present invention.
In Table V, data illustrates clearly the relative superiority of our novel treatment
process of repulped slurry with water-based dispersion of ester solution of styrene-2,5
furandione copolymer with regard to its improved brightness and decreased surface area of
the ink particles. All treatment processes involving water-based dispersion. namely.
i"~ nos. ~1 and ~2, are in accordance with present invention are herein defined
All of these treatment processes, it will be noted, are acceptable when measured
S against the standards described in Example I and experiment no. E3 of l~xample V.
Although the invention has been illustrated by typical examples, it is not limited
thereto. Changes and m-~rlifi~ :~til-nc of the examples, of the invention herein chosen for the
purposes of disc~osure can be made which do not constitute departure from the spirit and
scope of the invention.
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|Forecasted Issue Date||Unavailable|
|(41) Open to Public Inspection||1996-08-01|
|Abandonment Date||Reason||Reinstatement Date|
|1998-02-02||FAILURE TO PAY APPLICATION MAINTENANCE FEE||1998-04-20|
|1998-10-19||R30(2) - Failure to Respond|
|1999-02-01||FAILURE TO PAY APPLICATION MAINTENANCE FEE||1999-03-09|
|Fee Type||Anniversary Year||Due Date||Amount Paid||Paid Date|
|Maintenance Fee - Application - New Act||2||1997-01-31||$50.00||1997-01-23|
|Reinstatement: Failure to Pay Application Maintenance Fees||$200.00||1998-04-20|
|Maintenance Fee - Application - New Act||3||1998-02-02||$50.00||1998-04-20|
|Reinstatement: Failure to Pay Application Maintenance Fees||$200.00||1999-03-09|
|Maintenance Fee - Application - New Act||4||1999-02-01||$50.00||1999-03-09|
|Current Owners on Record|
|SAIN, MOHINI M.|
|Past Owners on Record|