Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD AND APPARAIUS FOR PRECONDITIONING LAMINA~l~u PAPER FOR RECYCLING
e invention relates to method and means for
conditioning corrugate paper kond preliminary to its separation
or delamination into its respective constituents for recycling.
It is now well known that significant economic advantages
may be gained from the recycling of paper waste, (including
corrugate) and if the waste to be recycled -- i.e. the "furnish"
-- is ccmprised of mixed papers, it is further known that such
econumic advantages may be enhanced, often to a considerable
extent, by sorting the various papers comprlsing the furnish
according to their respective qualitative categorles insofar
and to the extent it is feasible and possible to do so preliminary
to the actual recycling thereof.
This expedient avoids or minimizes admuxture of various
paper grades in any one recycling operation which would usually
relegate the recover~d product to a relatively inferior and,
hence, cheaper re-use. Conversely, pre-sorting of the paper
makes it possible for the better grades ~o be s~parated and
recycled separately from -the lesser grades and, hence, thereafter
used in suFerior and resultantly m~re valuable applications.
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Machinery for sorting waste papers is known and one such
machine is disclosed in U.S. Letters Patent No. 4,124,168 issued
to the Assignee of the present ~pplicant. Such machinery is,
however, most useful in the sorting of uncomplicated papers and
is largely ineffective in the sorting of lamunated papers of differing
qualities which may require to be delaminated prior to the actual
sorting operation.
; m e laminated paper product of present concern is corrugate
paper board, often simply termed "corrugate", which is used qui-te
io extensively, for example, in shipping boxes or containers.
In its ccmmonest form, corrugate cc~prises a core ply or
medium which is formed of stiff, crush-resistant, paper which is fluted
or rippled providing it with upper and lower crests and is
substantially receptive to water. This core ply is san~wiched between
15 plies of liner~oard or liners, so-called, of another paper grade,
normally less receptive to water and tightly bonded to the crests of
the core ply, usually by a starchy adhesive.
Recycling the corrugate in its original ccmposite or laminated
form and ~7ithout prior delamination would yield a product comprising
a mixture of the core ply material and the linerboard material;
such product being usually of relatively low value and useful only
in, so called, "low-end" applications. Conversely, separate recycling
o the liner board on the one hand and the core ply on the other,
after delamination of the board, will upgrade the potential uses
and, hence, the value of each of the recovered products;
conceivably, even imparting to the core ply, which is the
cheaper ccmponent, a greater value at times than that of the
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waste corrugate as a whole.
The separation of its constituents being thus shown to
be desirable, the corrugate is subjected to pre-conditioning
treatment to undermune, at least, the adhesive konds between its
several plies whereby to facilitate the ultimate rupture of the
bonds and, hence, the separation of the respective plies in
an ensuing sorting operation thus conducing to the subsequent
segregation of the paper grades from each other in the actual
recycling operation.
The only prior patent known to the Applicant having
specific relevance to the delamination of corrugate is that issued
to IANNAZZI - US 3,833,460 in the United States in which is
described a so-called "dry" technique; the present invention
being eontradistinctively describable as involving a "wet"
technique.
m eoretically, delamination of corrugate may be
acccmplished by soaking the board in a sùitable "solvent" --
e.g. water -- with or without additives an~, while possibly
effective to achieve delamination, indiscriminate soaking is not
commercially practicable or feasible for several reasons. For
example, it presents a problem in harvesting the respective
delaminated plies. The plies would be soaked through, hence,
less manageable for sorting purposes and, of course, prone to
disintegration and premature repulping before segregation; thus
defeating, at least partly, the purpose of the delamination and
pre-conditioning operations.
It should be emphasized that the w~rd "solvent" and its
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variations is used rather loosely herein for want of better
terminology to define a substance which is able to attack and weaken
or undermine adhesive which bind together the several laminae of
the corrugate whether or not by actually dissolving the adhesive.
Starch, for example, is a very common adhesive in corrugate and
while not truly soluble in water -- which is the preferred "solvent"
for starchy bonds -- it is certainly susceptible thereto and
capable of absorbing the water; beccning spongy and inclined
to lose its adhesive tenacity in consequence.
Reoognizing the desirability in many circumstances of
initiating delamination of the corrugate by soaking and so softening
the adhesive bonds uniting its plies, the invention seeks, broadly,
" to provide method and means for achieving this result without
seriously risking or conducing to wholesale premature repulping
of the corrugate.
t As a further and imFortant object, the invention seeks
to provide ~ethod and means for pre-conditio~ing corrugate for
recycling by controlled exposure thereof to a solvent capable of
attacking the adhesive b~nds to weaken them and thereby render
them su æeptible to other forces subsequently appIied to the
corrugate to complete the actual delamination thereof and, at the
same ti~e, to separate its respective plies from each other
for recycling.
More specifically, the invention seeks to provide
meth~d and means for ur.dermining the adhesive b~nds as aforesaid
by introducing the corrugate into a suitable solvent as herein
defined and by simMltaneously applying mechanical forces to the
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corrugate to procure maximum exposure of its adhesive bonds to the
solvent whereby to attack the bonds and effectively weaken them
before the paper ccmponents of the corrugate absorb too much of
the solvent and begin repulping.
m e invention achieves its foregoing objectives by the
provision of method and means for introducing the corrugate duly
cleaned and shredded (as hereinafter described) into fluid solvent --
for example, a water bath; shuffling the corrugate therein
promoting flushing of the solvent between its outer plies or liners
and otherwise conducing to exposure of the adhesive bonds to the
solvent; maintaining the shuffling of the corrugate for a brief
period of time sufficient in duration to enable the solvent to
reach, attack, soften and undermine said adhesive bonds but
insufficient to initiate active repulping of the corrugate;
withdrawing the corrugate from the bath aforesaid, draining it of
free solvent, before subjecting it virtually immediately thereafter
to stresses in sorting apparatus rupturing said softened konds and
separating the respective plies of the corrugate while at the same
time segregating or isolating them frcm each other for subsequent
re-cycling.
For a better understanding of the invention at this
juncture it is deemed useful to observe that the corrugate furnish
is usually provided in, so-called l'shredded" form, i.e. -- chopped-
up fragments rarely exceeding 100 sq. inches in plane dime,nsion and
with the corrugate core plies thereof usually crushed in consequence
of having be2n previously ccmpressed by a baling press into a
tightly cGmpacted bale; yielding fragments or shreds as aforesaid
of divers sizes, profiles and conditions when the bale is unkound.
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It is further noteworthy that, despite any cleaning
necessary for the rem~val contraries or the like entrained in the
furnish, the cvmponents of the corrugate may still remain somewhat
inpure in ccmparison to their original virginal state owing to
5 various "treatments" which the latter may have undergone in and
for its original use whereby it may have been loaded with relatively
irremovable contaminants such as coatings, adhesives, printing
materials and the like.
Moreover, while the invention has proven most effective
10 in enabling adequate separation of the several plies of the
oorrugate with mininal effort and with minimal premature repulping,
some incidental repulping is virtually inescapable which also tends
to degrade the recycled products in oomparison to their virginal state.
Finally, it should be noted that, while highly desirable, totally
"clean" delamination is not alway feasible for a variety of reasons
hich may stem from the composition of the respective plies; from
the specific adhesives used for their lamination; from coatings and
the like specifically applied to one or more of the plies, and so
forth.
A selected emkodiment of the invention exemplary of its
elements, p~rts and principles will now be described with reference
to the accomFanying drawings wherein:
Fig. 1 - is an isometric view of a fragment or shred
of a common form of corrugate;
Fig. 2 - a schematic, side elevational view of apparatus
according to the in~ention;
Fig. 3 - a section along the line III-III of Fig. 2;
Fig. 4 - a longitudinal section of the apparatus of
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Fig. 2 along the line IV-IV of Fig. 3;
Fig. 5 - a longitudinal sectional view in schematic form
of apparatus alternative to that shown in
Fig's 2, 3 and 4 of the drawing;
Fig. 6 - a view corresponding to Fig. 4 with a drainage
attachment;
Fig. 7 -- a longitudin21 sectional view in schematic form
of apparatus alternative to that shown in
Fig. S;
Fig. 8 - shows in graphic form the amount of water pick
up and the ease of separation of corrugate as a
function of time, and
Fig. 9 - shows the effects of various operating
parameters on the time of easy separation of
corrugate, also in graphic form.
It need scarcely be pointed out that the drawings are
presented in schematic form in the interest of clarity and for the
sake of better ccmprehension of the inventive concepts as
distinguished from the manner in which the illustrated apparatus
20 would be engineered for industrial or ccnmercial purposes.
In the following description of the invention method and
apparatus aspects thereof have been intermingled for better
; c~mprehension whereby the method will sometimes be ob~ious from
- the de æription of the apparatus which will, in turn, be sometines
better apparent from the de æribed method.
Keeping in mind the wide variations therein which are not
only possible bu-t reasonably commcn, the corrugate C selected for the
purpose of this description is visualized as the simple, familiar,
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variety in which the core ply 2 is ccmmonly formed of semi-chemical
fibres and is laminated to linerboard skins or liners 4-4 of
unbleached kraft fibre by a starchy, wateî-susceptible adhesive
forming bonds 6 at which the liners 4-4 contact and are secured to
the crests 6' of the corrugations 8.
In the normal, uncrushed state of the corrugate C, its
corrugations 8 provide flutes or channels lO through which ~onds 6
can readily be reached by fluid in which it is immersed. Ccmm~nly,
however, the corrugations 8 will be crushed in the h~ling of the
furnish and, while that may well restrict access to the bonds 6, the
general disruption of the corrugate C, which is also a conccmmitant
of baling, will tend to increase its exposure or receptivity to the
solvent and thus compensate to a greater or lesser degree for the
constrictions resulting from the collapse of the channels lO.
It having already been explained that the core ply 2 is
more readily saturable than the liners 4-4, the invention seeks
to concentrate ujpon maximum wetting of the bonds 6 within the least
time whereby to minimize soaking of th~ liners 4-4 and, hence, so to
retard the repulping thereof.
Thus, the invention visualizes the introduction of pre-
cleaned corrugate C, in its shredded form, into a solvent fluid
to be more particularly described and of shuffling the corrugate in
the solvent to flex it, tilt it, reorient it, tumble it and
general~y move it around not only to expose new areas thereof to the
solvent, but also to gain maxlmum accessability of the adhesive bonds
6 thereto.
i Gne convenient and very simple expedient for carrying out
- this step is to provide the solvent in an elongated, axially
, :
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horizontal container such as a tank, shown for example in Fig. 2 and
other views of the drawings. A tank as aforesaid may be constituted
by the tu~ular, rotatable, drum 20 shown in Fig. 2 and other views,
which is provided with bulkheads 22-22 at its ends; there being
5 central apertures 24-26 in the blllkheads 22-22 for the introduction
and removal of corrugate C into and out of drum 20.
Said drum 20 is intende to provide an enviror~ent in
which the corrugate C may be conveniently bathed in the solvent
fluid whose nature and character depend necesQ~rily on and are
10 most appropriate to the specific adhesive used in the lamination
of the particular corrugate C under treatment.
As previously stated, comnon starch is a very popular
adhesive used for this purpose and is also susceptible to an aqueous
solvent which tends to soften it and diminish its adhesive
15 tenacity. As is well known, the effects of such aqueous solvent
on the starch may, of course, be enhanced under certain conditions
by the admixture therewith of a wetting agent such as, for example,
urea or poly alkoxylated aLkyl phenol available on the market under
the trademark TRIl~N X-100.
Thus, in the present ern~odiment, the solvent fluid S
contained in drum 20 between its bulkheads 22-22 consists of water
(with or without additives) which is replenishable fram time to time
when required as at 28 through an aperture a~oresaid in one of the
bulJsheads 22 or into fill chute 30, if preferred.
It should be re~nphasized at this juncture, that the
effectiveness of the present process is depex~dent upon several factors
to a greater or lesser degree according to the specific corrugate C
being pre-corditioned.
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1~us, not only shculd the solvent S utilized be that most
appropriate to the adhesive used in the lamunation of the corrugaté
C but, in addition, the temperature thereof may also be varied
according to prevailing conditions as may be the exposure of the
corrugate C thereto -- i.e. its residence time in the solvent.
Other factors may also be relevant e.g. the shred size;
the vigor of the shuffling, a~d so forth. However, these parameters
are not quite as important as the solvent, its temperature, and the
residence time.
In the present example, fill chute 30 is disposed to
em~ty into drum 20 through aperture 24 in one of the ~ulkheads 22;
this being the entry point for the shredded corrugate C into drum 20;
the exit point thereof being the discharge aperture 26 in the
opposite bulkhead 22.
The residence time of the corrugate C is that spent in its
transit frcm its point of entry to the point of its exit frcm drum 20
and recourse may, of course, be had to various expedients for
advancing the corrugate C between these two points.
For example, the residence time may be governed by the rate
at which the corrugate C is introduced into drum 20 as well as the
rate of rotation of the latter as will appear.
As will be apparent from Fig. 6 corrugate C fed rapidly
into drum 20 tends to pile up adjacent aperture 24 where it is
first dropped by fill chute 30. However, the pile uP understandably
ten~s to level off as drum 20 is rotated whereby several other
beneficial results are collaterally achieved.
That is to say, rotation of the drum 20 w;ll tend to
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carry and lift the lOwermost layers of corrugate C out of the fluid
solvent bath at the bottom of drum 20 and drop them again on top of
the pile thereby making room for the upper strata of the pile to be
acco~odated and ~mersed in the solvent substantially as s~own in
5 Fig. 3.
Likewise, the rotation will shuffle and reorient the
corrugate shreds exposing new surfaces thereof to the solvent and
will move then about to promote flushing of the solvent S through
the channels 10 of core ply 2. Thus, in general, the rotation of
drum 20 will have the effect of shuffling the corrugate C contained
th~rein to impart to it a variety of movements such as flexing,
tilting, tNmbling, up-setting and so forth causing the solvent to
flush back and forth in channels 10 and thereb~ maximi~e its access
to the a & esive bonds 6.
m e shuffling of corrugate C as well as its advancement
within drum 20 may also be enhanced or achieved entirely by lengthwise
disposition of spaced apart fins or vanes 32 on its interior walls 34
so as to be co-rotatable therewith. As will be obvious, corrugate C
in drum 20 will be periodically lifted by the rotating vanes 32 a~d
dropped back thus const~ntly shuffling and re-shuffling it. Moreover,
a somewhat diagonal or spiral inclination of vanes 32 on drum walls 34
in an appropriate orientation will co-incidentally procure the
required advancement of corrugate C while it is being shuffled as-
aforesaid (not illustrated).
Accordingly, all corrugate C introduced into rotating drum 20
will ultimately be duly immersed in the solvent fluid S contained
therein as and while it is being advanced frcm the point of its
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entry to the point of its exit from drum 20.
The rotation of drum 20 will therefore be seen to serve as
an effective expedient not only for enhancing exposure of corrugate C
to the solvent fluid S but also for procuring its advance between the
two points aforesaid~ ~Iowever, while quite effective for these
purposes a rotatable drum is not the only expedi nt available for
shuffling the corrugate C and advancing it in a bath of solvent fluid S.
That is to say, equivalent purposes may ~e served by the relay
system illustrated schematically in Fig. 5 of the drawing which is
shown as comprising a non-rotatable tank 120 for a pool P of solvent a~d
a train of ccmmunicating paddle wheels 40 installed therein to extend
between fill chute 130 and the point of exit 126 from tank 120. In
a manner which will be quite obvious, the entering corrugate C is
received by the first paddle wheel 40 in the train and is relayed
by it to the next and so on until it reaches exit point 126. In
this embodiment, the paddles 42 of each said paddle wheel are
carried through an arcuate path which lies partly in the pcol P
contained in tank 120 where~y said corrugate C is not only constantly
re-shuffled but is, from time to time immersed and re-immersed in
the solvent as it is being received and relayed as aforesaid.
m e structures illustrated and described disclose various
expedients whereby corrugate C nay be shuffled and advanced in a bath
of solvent in order to provide access of the solvent to he bonds 6
joining the liners 4-4 to the core plies 2 of shreds of corrugate C
and to control the residence time; it being appreciated that the
residence is also variable according to the distance to be traversed
by the corrugate between its points of entry a~d exit as well as by
the speed of the specific advancing nechanisms.
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Usually, any free solvent S or most of it remaining
trappe in channels 10 of core ply 2 will be drained therefrom
in the course of such incidental stirring as the corrugate C may
receive in its removal from the solvent S and its transfer to
delaminating and sorting apparatus. However, positive drainage may
be achieved by subjecting the corrugate C to a mechanical draining
treatment such as rotating cage 50 which is shown in schematic section
in Fig. 6 of the drawing in receiving relation to drum 20.
Said cage 50 may or may not be equipped with vanes 132
CorresFonding to vanes 32 in drum 20; the cage being broken in Fig. 6
with the respective portions thereof shown as vaned and unvaned.
; Cage 50 may be rotated to shuffle the corrugate C delivered
thereto by the soaking apparatus; the free solvent being drained
therefrom during such shuffling while the corrugate ves in
cage 50 from the discharge end of drum 20 to the output end 52 of cage 50.
An alternate expedient for drainage is represented by the
bucket chain trans~ort 60 mounting scoops 62 and positioned at the
exit end of tank 120 to scoop corrugate C from the last paddle
wheel 40 in the train and to carry it uF~ardly out of the fluid solvent
S to a point outboard of tank 120 and there to drop it; the fluid
solvent S entrained in the corrugate C being allowed to drain back
through the bucket chain transport 60 either into t~nk 120 or into
sump 64 w~lere it may be collected and re-circulated.
The dredging device 70 in tank 220 (Fig. 7) may, in
appropriate circumstances, substitute for the paddle wheel train
of Fig. 5 being similarly equipped with paddles 72 to which corrugate
C is delivered by fill chute 230 and by which it is then pushed through
fluid solvent S both in tank 220 to the exit end 226.
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Although perhaps not as vigorous as the rotating drum 20 or
the relay system of Fig. 5, the bucket chain transport 60 in Fig!s 5
and 7 and dred9e device 70 in Fig. 7 will nevertheless stir the
corrugate C in its transit through and out of tanks 120 and 220 to
a degree more or less sufficient to achieve the objects of the
invention depending on various factors such as the average size of
the corrugate shreds.
Mbtor M shown in Fig. 2 drives wheels W which.rotate drum 20
and may also ~ower the mobile structures of Fig's 5 and'7. Either
said ~otor M or the transmissions (not shown) normally and conventionally
associated therewith or may be regulatable to govern the speed of the
equipment and so to control the residence time of the corrugate C in
; solvent S.
Certain operating parameters relating to the conditioning
of corrugate were investigate'd under model conditions using the
following test procedure: -
Single wall corrugate ~oard ~basis weight 42-26-42) adhered with
a starch base adhesive was cut into strips 150 mm perpendicular to
flute channels by 15 mm. The strips were immersed in the conditioning
29 solvent for a given time and delaminated on an INSTR~N Tester within
1-1/2 min. of re~overy from the solvent.
The resistance to delamination was measured as an average force
required to rupture the ~ond between the crests of the medium and
linerboard. Each value represents testing of at least five strips
and 8-10 readings per strip. Moisture content of strips was
determined im~ediately after testing by oven drying.
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"Control" conditions are defined as employing as the conditioning
solvent water at 20 C with no additive thereto.
Values for the resistance to delamination of corrugate
under various treatment oonditions are shown in Figure 8. With
reference thereto, curve 1 shows the variation of the resistance
to delamination as a function of time under control treatment
conditions At zero time, the resistance to delamination
considerably exceeds the strength of the individual laminae
comprising the corrugate, and tearing of the laminae takes place.
"Easy delamination" is considered to occur when the resistance
drops to an arbitrary value of 60 grams in the above described
test procedure, as conditioned corrugate will normally be suh~ect
to a force of at least this magnitude in subsequent fi~re classifying
apparatus. Under control conditions of treatmient, easy
delamination occurs after some 50 seconds of immersion (Point A).
The moisture content of the conditioned corrugate is
shown in Figure 9. Under standard conditions it may be seen that
the moisture content increases mode~ately rapidly over the time
period at about which easy delamination is reached (Cul^ve 1, Point A').
Although not shown in the acccmpanying data, it will be appreciated
that the wet strength of the individual laminae decreases both
as the water content thereof increases and also as a function of
time. Under control conditions it is found that the wet strength
of the laminae may approach zero, as evidenced by the disintegration
of the l~ mnae, after about 5 minutes immersion. There is then
a differential bet~7een the time required for "easy delamination"
and that which disintegration of the corrugate laminae OCCUL-S.
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In practise this differential may be increased by
removing the corrugate from the treatment bath prior to the time
at which easy delamination occurs. Solvent entrauned with the
corrugate continues to attack the adhesive bond between the
laminae and reduce the resistance to delamination. Part of the
entrained solvent will drain from the corrugate by the described
means provided for this purpose. : A portion thereof will be imbiked
into the corrugate to increase the moisture content thereof and
thus to decrease the wet strength thereof. However, whilst the
resistance to delamination is quickly reduced to below the easy
; delamination value, the quantity of solvent available for imbibition
may generally be controlled so as to be less than that which will
co~pletely saturate the laminae and lead to their disintegration.
m e time differential may also be affected by the
te~perature of operation of the conditioning ~ath and the solvent
; employed. In Figures 8 and 9 values obtained where the temperature
of operation is reduced to 10C are shown as curve 2. Predictably,
the time for easy delamination was increased, a value o 1.3
minutes being obtained (Point B).~Flg. 9). Surprisingly, the moisture
content of the corrugate at the time for easy separation (Point B')
(Fig. 8) was significantly less than that which obtains for the control,
pointing to an increased time differential. It may also be remarked
that it is advantageous to reduce the amount of solvent passing
into the fibre classifying apparatus with which the instant
~5 conditioning apparatus will generally be employed.
The control con~itions were ~urther varied by using as
-' solvent water containing 0.004% by volume of a non-ionic surfactant
356
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(Triton X-100, trademark for a poly alkoxylated alkyl phenol), whilst
maintaining the temperature of the bath at 20 C. The values obtained
are shown in Figures 8 and 9 in curve 3. m e time for easy
separation was reduced, (Point C~ in ccmparison to the control.
Whilst the rate of moisture pick up of the corrugate essentially
duplicated that found for the control, the m3isture content of the
corrugate at easy separation time (Point C') was significantly
lower than that for the control, again pointing to an increased
time differential.
The foregoing being the best form of the invention -
presently known to the inventors, it is by no means inconcei~able
that means other than those specifically enumerated may be
resorted for carrying out the inventive concepts described without
departing frcm the true scope of the invention as defined in the
following claims.
