Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD OF PROCESSING PACKAGING
~his lnvention relates to a process for recycling pack-
l~gs conLaining rea~tive resldues, ln pa~ticular cartridges
for pro~ucln~ p~iyurethane fodm. In the process the packing
~ateria;s are reco~ered and the resid~es contai~ed therein
con~erted into reusable products.
~ esidue-~ontaining packings as occur for ex~ple ir.
great ~uantitles in the form of wholly or partly empty car-
tridges ~re increasing~y be~oming a di~posal problem. They
cannot be dumped on disposal sites fo reasons of environ-
ment~l protection since the residues containe~ therein can
p~ss into the atmosphere, the s~il or the groundwater and
lead to conside~ble damage there. The same holds for burn-
lng, which is frequently incomplete in particular with chemi-
cotechnical products and produces great quantities o~ pollut-
an s which can be bound only ~y elaborate measures, if at
all. ~urning thus leads to a great reduction ~ the volu~e of
waste but does not necessarily so}ve the pollution problem.
Special problems ar.se when the residues ~ontai~ed ln
the pack;ngs are ~hemselves reactive ~nd possibly ever. toxic
products, as is tbe case for example with is~cyana~e-~ontaln-
ing prepolymers for poly~rethane f~ams. The same holds for
othex reactive plastic products, ror example self-c~r;ng c-
hardenable mixtures for coatings, adhesive mixt~res, etc. Ir.
tne fol~owing the probiem will be dis~ussed in rela~lon to
the disposal of prep~lymer-containing cartridges for pro~c-
ing poly~rethane foams, this case being given on].y as an ex-
ample.
Polyurethane foams ha~e become widely used in many
fiel~s. They are commonLy used partic-~larly in the ~onstru~-
tion lndustry ~or sealing and ins~llating, ~s well as in cther
technical fields. Polyurethane ~oams are commcnly dlscharg~d
~rom cartridges containing a polyurethane prepolymer together
with req~ired additives. The3e ~artridges cannot be reused.
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On the other han~, they are problem ~aste which cannot be
disposed of in the nor~al way.
In accordance wlth effor~s to limit househol~ and indus-
trial waste, measures are ~eing increasingly discussed an~
imple~ented to force manuf~cturers ~o take ~ack their produc~
packag~ng after use and ensure its r~use or disposal them-
selves. Such measures have made it necess~ry to find ways of
~reating suçh waste econo~ically. The treat~ent of returned
cartridges for polyurethane fo~m pro~uction involves a nu~be
of pro~lems which ~o~npli~ate econlomic recyclln~. For exa.np~e,
some returned cartridges can ~e under pressure due t~ the
penetration of ~oleture during improper storage or t~eatme~,
which makes both openin~ and ~urning a proble~. Fu~therm~re
the cartri~ges have different fiiling co~dltio~s, ranging
from over~ed cart~idges ~irtually full of prepolyme~ which
can~ot 4e dischar~ed ~ue to a blocked ~alve, to ~irtually
empty Gartridges with only a remainder of prepolymer adheriny
to the e~ges in a~ uncrosslinked to crosslin~ed state.
~ p to now a number of proçesses have become ~own for
recycling pa~ki~gs, includin~ aerosol ca~ for polyurethane
foa~ pro~uc~ion. For example it has been proposed to pass
pressure çans via a sluice system into a plant unde~ inert
gas and crush them there. Furthe~, processes ha~e become
known for passing aerosol cans into a plant, crushing them
there and ext~actin~ the ingredients with sui~able solvents.
In ~hese proce~ses both the packing materials and the ingre-
dients (prepolymer, propell~n~ ~re recovered.
~ owever these known processes, some of which are guite
efficient and in use, are capable of ~eing i~proved with re-
gard to industriai safety, process con~ol and effi~ien~y. It
is problema~ic to separate the residues cont~ined in the
packings in slmple fashion and direct the~, to suitable reuse.
Further proble~s arise fro~ the fact that the packings -on-
tain toxi~ologic~lly unsafe substa~ces as well as combustible
solven~s ~hich çan yield explosive gas mixtures after open-
in~. ~n particular these process~s are designed fo~ recyclin~
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pr~pellan~-containing aerosol cans, however, which limi~s
their appii~a~ility for pressureless cartridges.
The inventlon is therefvre based o~ the problem ~f pxo-
vidir.g a process ~or recycling packings, ~or example con~a.n-
ers holding polyurethane prepolymers in particular for foam
prod~ction but also for adhesive purpcsesr together with sol-
vents, and recovering the useful materials contained therein
without releasing u~he~lthy and pollutive ln~redient~ in un-
contr~lled fashion and withou~ the course of the pro~es~ ~e-
ing burdened by reactive components released from the Pack-
ing3. The proces~ shQui~ ~ee~ the re~uirement~ for industrial
s~fet~ and i.n particular con~ert reacti~e resid~es ~til~ con-
tained in ~he packings int~ a form suitable for direct fu~-
ther proc~ssin~,
This proble~ is solve~ according to the in~ention by a
process of ~he ~bo~e~en~ioned type wherein the packings are
introduced into a cold zone and ~ooled until resldues con-
~ined therein solidify, the packings are then crushed in the
cooled state, the crushed pacXings ~re divided in~o ~ frac-
ti~n containing ~he reactive residues and a~ least one fur-
ther fraction, the residue-containlng fr~tion is intro~uce~
into a mixing zone intc which an agent rea~tive ~ith the
residues is simult~neously introduced, optionally together
~it~ a catalyst, the temper~ture in the mixing zone being
held below the softenln~ temperatu~e of ~he residues and the
reactive agent, and the resulting mixture of resi~ue-cont~in-
ing f~action and reactive a~ent and optio~ally ~ta].ys~ is
brought to a temperature s~fficient for reaC~iOn ~d rea~ted
in a reaction zo~e.
The inventive process makes i~ pos$ible to open and
proceqs p~ckings in ~ fully sa~e way. In particular lt per-
mits ~he v~rious materials contained in the pa~ki~gs to be
separ~ted safely. The re~ctivç residues, for exa~ple isocy-
anate-cont~lning prepolymers in ~artridges for pro~ucing
poly~reth~ne foam, ~re treate~ in a safe ~nner. Due to the
freezing of the ingredient~ contained in the pa~kings there
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is neithe~ a reaction-i~du~e~ pxessure increase in the pro~-
ess no~ u~desirable reaction be~wee~ reacti~e componen~s. A~
the temperatures prevailing in the prOCess ~he presenee of
water is also harmless. The ~wo latter points are of impo~-
tan~e in tre~ting isocya~ate-~on~aining products when for ex-
ample damaged packings carry wate~ into ~he pr~ce~s. At the
same time, re~ctive second çompo~ents ~ontained in ~o-calLed
2C fD~s, for example glycol~, carboxylic aci~S or water, can
be easily intro~uced into the process. The inventl~e process
is thus suitable for treating bo.th cartridges for lC and ~¢
foams and transltional forms b~tween the two simultaneously.
In the inven~ive pro~ess the pdckings, for example car-
tridges, are fi~st introd~ce~ int~ a ~ld zone and c~oled
thereln until the residues ~ontained therein, includin~ any
low-boiling sol~ents therein, solidify. ~emperatures lowe~
than -~0~C to -1~0~C are generally suffiçient ~or this pur-
pose, but one expediently works in llquid nitro~en as a cool-
ing mediu~. In ~his ca~e it is import~t th~t the process be
performed in the absence of oxygen to avoid condensation of
llquid o~ygen which çould have an a~verse effect in later
process steps.
The packings are expediently introduce~ into the cold
~one using a celiular wheel pneumatic sluice which introduces
the p~cking lnto ~ g~ide cage extending in the coolin~ ~e-
dium. ~n the ~old zone the p~cki~ ls then g~i~ed a suffl-
cient distance through the cooling ~edi~m to ob~ain complete
freezing.
When the desire~ temperature is reached, gener~lly the
temper~t~re of liquid nitrogen, the packings are guided intc
the c~ushing zone where they are ~ru~he~ in the col~ s~a~e.
The temperatures here should expediently be under -80~C to
-100~~; it might ~e necessary to spray in liquid nit~ogen or
cold gaseous nitrogen.
Cr~shinq lS exped~ently ~one in ~ hammer ~ill working
~g~inst a sifter. This ~hiev~s a shaking an~ fulllng effect
which not only crushes to a ~esire~ particle size bu~ also
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separates the various materials: metal, paper, plastic and
ingre~i~nts. It has surprisingly turned out that the pa~king
m~terials (metal, paper and plastic) can thereby be separ~ted
extremely weli from the in~redlents ~reac'i~e resid~es an~
s~lvents/a~itivés in powder form), the ingredients being ob-
tained as fine powde~.
In a subsequent sepAr~ting step the crushed packin~s are
~ivide~ into at ie~st two fractio~s, one of which contair.s
the re~ctive resid~es includlng pro~ellant ln a solid ~a~.e.
This separ~ing step expedientiy u~es a sifter, prefera~ly a
riddie sifter, thro~lgh whlch the fine components ~mainly re-
actlve residues and solvent~ fall. Metal pa~ts ar~ separate~
with ~agnetlc methods, large plastic parts and scr~ps of pa-
pe~ sieved out on the riddle sifter.
The frc~en ingredient~ from reactive ~esidues and sol-
vent pass ~rom the separating zone intc a mixing zone into
which an agent rea~tive with the residues is simultaneously
introduGed. Temperatures l~wer ~han -~0~~ to -100~C also pre-
vail in this mixing ~one to ens~re the frozen st~te of the
i~troduced materials and solidify the spr~yed-in reactive
age~t ~ne~iately int~ a fine pow~er. This permit~ fox~ation
of a uniform ~ixture of ingredients ir powdex form an.d reac-
ti~e agent, ~hi~h cannot ~eaçt due to the prevailing tempera-
ture con~ltions. ~he temperatures in ~he mlxing zone are ir.
any ~a~e below ~he melting point of both the residues ~n~ the
reactive agent.
A ~pray ~ower i~ expe~iently used a~ ~ mixing ~one, the
fro~en ingredients falling in fro~ above. The rea~t.ive agent
is sp~ayed into this pow~e~ st~eam from lateral nozzles,
preferably together with ~old g~seo~s nitrogen to ensure the
necessa~y low temperatures. It is expe.~ient to precool the
re~ctive agent ~ut i~ must remain sprayable.
It can ~e expedient to spray in the reactive age~t ~o-
gether wi~h a catalyst which promotes the ~eaction with the
reactive re~idues ~f the packinss. This is gener~lly u~neces-
s~ry with isocyanate-çontaining prepoly~er~, however, since
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the isocyanate-containing mixtures alrea~y ccntain such ca~a-
lysts.
The powdery mix~ure of ingredients a~ reactive agerlt
and optionally catalyst is ~hen ~ulded lnto a re~ctrion ~one
which ~onsists for example of a conveyer bel~ movlng continu-
ously under the mixin~ zone. ~he po~er colle~ting h~re is
then ~rought ~o a temperature suffieient for re~ctio~ in or-
der to react. Any solvents contained evaporate at this point
~nd are co~densed out at a suitable place, which i~ no prob-
lem when nitr~en is used ~s a cooli~g medium. ~o give the
rea~tion product the desired fo~m .he con~eyer belt can have
lateral li~its. For separ~ting the reaction product ~rom the
conveyer bel~ it is possible to pro~ide parting means, for
example suita~le coatings or release paper. The he~t.ing in
the reaction zone is expediently done with microwaves, which
cause fast direct heating of the powder ~a~erial from the i~-
slde to the outside s~ that uniform degassing occurs.
Following the re~ction zone one can provide further
processing and treatin~ zcnes as well as a flnal sl~ice for
passing out the reacted ma~erial,
As mentioned ~ove, the inventive process is especially
suitable for xecyciing resi~ue-contai~ing polyurethane fo~m
~artridges. In this case the reactive agent is in particular
a hydroxy co~pound, for example water, ethylene glycol, pro-
pyle~e glycol, glycerol, oligomers and mixtures thereof ~s
well as ~e~ivatives thereof. Ethylene glyco~, water and poly-
ether alcohols are preferre~, where~y ln any case ~t least
two reactive hydro~en atoms should ~e present. Polycarboxylic
aci~a c~n like~ise be uced. Espec~ally sultable polye~her ~1-
cohols are ~he so-c~lled Jeffamines (tr~demark).
In recycling ~ackings for producin~ polyurethane foams
it is advantageous to con~ert the isocy~na~e-cont~i~ing p~e-
polymers in the process i~self i~to foam materials whiGh can
be u~ed for example for insulati~g purposes. The inventive
process can thus c~ntinuously produce insulation boards,
whereby the propel'ants contained in t~e powder p~oduced in
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the mlxing zone promote foam formation. It is also rea~ily
possi~e to pro~uce foils or to admix additi~es, for example
cellulose~containing materials, an~ then press these mixtllres
into ~omposite mate~ials during or ~fter reac~ion. ~owever it
is preferable to produce gran~les fxom ~e~cted material which
are further processed later.
The inventi~e process is especially suita~le for ~ecy-
cling pressureless polyurethane foam cartridges whi~h are
empt.ed on site using a s~i~a~le pistol and then retllrned to
the m~nufacturer for recycling, These ca~tri~ges, which are
used both for lC and fo~ ~C foams, ~re pressureless ~urlng
storage and generally contain no expa~ding or fo~ming agent.
I~ an lmprovement in fo~ing beha~ior is necessary and this
improvement cannot be achieved by using w~ter a~ the se~ond
compo~en$, low-boiling sol~ents c~n be present, for example
pentane, w~lch are liquid ~t nor~al temperature but e~ap4rate
with the seco~d ~omponent at the reaction temperatures of the
prepolymer and produce arl expandin~ effect. The inventive
process can likewise ~e used for ae~osol cans for polyure-
thane foam production if an effective ~ep~tion ~f propel-
lant is e~sured in the are~ of the reacti.on zone. The proces~
is thus fuhdamentally suitable for packings whlch also con-
tain expanding agents and achieve ~n expanding a~d~or foaming
effect, optionally in acoorda~ce with temperature.
The inventi~e proce~s will ~e explaine~ more closely ~y
the enclose~ drawings, in which
Fiq. 1 shows sçhematically an embodiment of ~ plan~ f-~r
carrylng out the inventive pro~es~;
Fig. 2 shows the entrance area of the plant according to
Fi~. l;
Fig. 3 shows the conveying, crushing and sor~ing part of
the plant a~cording to Fig. l;
Fi~. 4 shows the mixing and reaction z~nes of the plant
a~cordi~g to Fig. 1:
Fig. 5 ~hows details of the feed by the cellular wheel
slui~ei
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Fig. 6 sho~s details of the transport system gulde in a
horizont~l projection, an~
Fi~. 7 shows the guide of Fig. 6 in ~ross section.
The view of an embodiment of the nventive recyçli~g
plant sho~n in Figure 1 has entry sluice 1 which is fed car-
trldges 13 to ~e treated via ~onveyor and sorting belt 11
~Fig. 5). The entry sluice is preferably formed as a cellular
wheel pneumatiç sl~ice into chambers l~ of which ~artri~ges
13 fall from a~ove via fee~ hopper l~ ~Fig. 2). Rotation of
celluiar wheel 1 causes the cartridges ~o pass into the l~wer
are~ of the s1uice and be ejected l~ter~lly with the he'p of
gaseous nitrogen G~N from pipe lS. To make this possible ~he
cel~ular wheel rotate.~ in a gas~ight con~alner ~pen at t~e
top which ~an ~e sub~ected to pressurized ~seo~s ni~roge~
~AN from one side ln its lower ~rea ~o that c~rtridge 13
therein can be eje~ed o~ the opposite side into guide system
21. The nitrogen supply via pipe 15 ~.~ preferably ensured
with gaseous nitrogen from co~d bath ~. O~viously the ~ota-
tional speed of cellular wheel 1 ~nd the pressure surges f~om
nitrogen pipe 15 ror ejecti~g the cartridges f~om the cellu-
lar wheel are mutually coordinate~. The cellul~r wheel has
for this purpo~e a measuring sensor ~rke~ M.
From the cellul~r wheel the ca~tridges p~s via guide 21
lnto cold ~ath 2 filled with liquid nitro~en. ~uide 21 expe-
dien~ly consists o~ an elo~g~te b~sket construction open on
all sides which per~its unhindered a~mission of liquid nltro-
gen and es~ape of gaseous ~i~rogen. ~etails of guide 21 and
tr~nsport de~ic~ ~3 for transporti~g çartridge~ 1~ will be
described more closely below in c~nnection with Flgs. ~ and
5.
On their w~y through col~ bath 2, ~hi~h is s~pplied with
fresh li~id nitro~en LIN in accord~nce wi~h level via. pipe
24 and has measuring sensor LIC for checking level, car-
~ri~es 13 are coaled to the bath tempe~ature. The ca~e
s'ructure of guide ~1 ensures free ad~ission of cooling me-
~ium an~ quick discharge of prod~ced gaseous nitroge~. Gase-
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ous nitrogen is re~ove~ fro~ the ~a~h a~ea via pipe 1~ wi~h
the help of ventilat~r 17. The len~th of guide Z1 and the
transpor~ speed are ~d~usted so th~t cartridges 13 are cooled
to a surflclerLtly low temper~ture of at lea~t -80~C to -100~~
even when comple~ely fille~ h re~ainder.
Cartridges 13 ~re transported in guide 21 with the help
of transport device 23 expediently consis~i~g of circula~ing
transport ~elt 25 with protrudin~ transp~rt forks 26 w~ich
engage in guide 21 from above and push cartridges 13 gui~ed
therein ahead of themselves~ Transport rolls 27 ensure pre-
clse gui~ance o~ t~anspo~t forks 26. Fork~ 26 are disposed ~n
transport belt 25 at inte~vals coor~in~ted with the size of
çartri.dges 13 to be tr~nsported. Measuring unit M serves to
monitor ~he tr~nsport speed and its co~rdina~ion with the
feed rate of cartrldges ~3.
After running through co~d bath ~ cartridges 13 pass Ol~t
of ~ e 21 into conveying devlce 3 (Fig. 3~ in the form of
circulating conveyer belt 31 having transport segments coor-
~ina~ed wi~h the size of cartri~ges 13~ ~onveying de~ice 3 is
preferably formed as a ste~ conveyor whi~h ~eceives car-
tridges 13 in the se~ments ~ormed by transport fork~ 33 dis-
posed at regular inter~als and releases ~he~ o~erhe~d into
crushing de~lce 4. The conveyer belt is guided vi~ rolls 32
provlded with ~easuri~g uni~ M fo~ monitoring a~d controll3.ng
the co~veying speed.
Crushing device 4 ~onsi~ts of a shredder or prefçra~].y
hammer mill 41. Ham~er ~ill 41 prefer~bly wo~ks against a
sifter to guarantee a ~ertain particle si~e of ~he ~rushed
m~terial. Sifter 42 simultaneously pro~uces a fulling effect
which promotes separation of the insredients embri~tled by
the cold from the container ma~erial. Obvio~sly one c~n add
cooling me~i~m, p~e~erably liqui~ nltro~en ~IN, Vid pipe ~3
for ~alntaining the necess~ry low tempe~atures of -~0~C to
-100~C if temperat~re check T~ indicates an inadmissible ri.se
in temperature. The working spee~ ls checked and controlled
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vi~ measuring sensor M. Gageous ~i~rogen is remove~ via pipe
44 and recycled or blown off via valve 45.
From crushing ~evice 4 '~e cr~she~ ~a~erial passe~ into
sorting deviee 5. This consists flrst of riddle sif~.er 51 on
which coarse parts ~,re separ~ted from fine parts. Coarse
parts are ~ainly the crushe~ materials o~ the container ~hi~h
are shaken cff orl inçlined sifter S1 ~nd discharged frc~r~ the
~xocess via a sluice not shown.
Powdery i~gredients and fine p~rts of the ~ont~iner pass
through riddle sifter 51 onto first magnetic separator 52
which sep~r~tes r~m2ining iro~ and alu~inum components fr~m
plastic p~r~icles an~ ingredients. On first ~agneti~ s~p~r~-
tor 5~ magnetic components are first separated ~nd fed to
~irst transport ~elt 53 whlch. also receives ~he metal ~r.d
plasti~ parts shaken off by slf~er Sl. Second transpor~ belt
54 recei~e~ plastics, i~gredlents and nonmagnetic metal
p~rts, ~hich are dlvi~ed into metallic ~nd nonmetallic frac-
tion~ via second magnet1~ separator S5 couple~ with the
transport belt. The metallic fractions p~s~ onto firs~ trans-
port belt 53, the nonmetallic are guided dire~tly lnto spray
~o~er 6. Cold ~aseous nitrogen ca~ be supplied vla pipe 56 if
~emper~ture check TI~ ~ndicates an inadmissl~le rise ~n tem-
perature. Measuring sensors M check the working speed of all
moving parts of separating system 5. If the ~rtridges con-
sist entirely of nonme~llic materials the ~agnetic separ~-
tors can natu~ally be ~ispensed with.
Obviously a temperature of no more than -80~C to -10~~C
is e~sured both in the crus~ing plant and in the s~rting ~e-
vice by suitable feeding pipes for ~o~ling medium, preferably
ni.trogen in gaseous or li~id form.
~ he pow~ery ingredie~ts and pla~tic parts passing in~o
spray tower 6 ~Fig. 4) and havin~ a te~pera~ure of no more
than -80~C to -100~C sO that sol~ents contalned therein are
also present in a solid s~a~e, a~e mixed with rea~ting me~ium
and optionally cata.lyst sprayed into the upper area of spr~y
tower 6 via feed ~1. The rea~:tin~ rnedium, preferzl~ly ethylene
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_
glyo~l, is located in the liqui~ state in supply tank 62, the
catalyst in supply t~nk 63. ~oth t~nks have mete~ing unit.Y
coordin~ted therewith.
Reacting medium from tank 62 and catalyst fro~ tank 63
are sprayed into spray tower 6 via pipe 61 in dosed relation
to the reaçtive in~xedients, whereby a precovling stretch can
be provided in the course o~ feeding pipe ~1 ~or cooling the
materials to a bene~icial temperature ~above melting p~int).
However, the sp~ay material soli~ifie~ wit~lin the spray tower
itsel~ at the temper~tures of less than -80~~ to -100~C pre-
vailing there. For maintaining the temperature in the spray
towe~ it is therefore expedient to introduce çooling me~ium
a~itionally, ~or ex~mple l~qui~ nitrogen LIN ~la pipe ~4 or
gaseous nitroqen via pipe 65, if temper~ture ~heck TIC in~i-
oates a ~eed therefor. It is expedient to spray the coolir~
medium into the lower ~reas of the spray tower to en~ure ad-
dj.t~onal swirlins and mixt~re of re~ctive compound, cat~lyst
and reacti~e ca~ content by cold n~trOgen ~ising in spxay
tower 6.
Fro~ spr~y tower 6 the mixt~re of reactive cartridge
content, rea~tive compo~r.d and catalyst p~sses in pow~er form
into reaction space 7. Wlthin reaction space 7 there is reac-
~ion belt 71 for ~eçeivin~ the falling material from spr~y
~ower 6 and guiding it lnto actual rea~tion zone 72 where the
reaction is induced by heat. For this pu~pose heat elements
73 ar~ disposed abo~e conveyer ~elt 71 for heating the reac-
~ion material on ~onveyer belt 71 with microwaves or infr~re~
~ays to a temperatu~e sufficient fo~ reaction, for example
room te~perature or thereabove.
To prevent reactlon materlal 74, i.e. the mixture of re-
a~tlve cartridge ~ontent, re~ctive compound and cataly~t,
from sticking to conveyer belt 71 it may ~e expedient to
~over the conveyer bel~ with separating foil 75 whlch is
wound off roll 76a an~ onto second roll 76b. The separating
~oll lS optionally reusa~le~
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0~ conveyer ~elt 71 the reaction ma~eri~l reacts into
the partic~lar produ~t desired. ~t the sa~e time solvent~ ancl
adsorptively boun~ cooling medium nitrogen sti.il con~alned in
the mixture fro~ the spray tower are released ~nd suoke~ off
via pipe 77 a~d dlrected to sep~ration a~ solvent recovery
~ot shown~. ln the presence, or upon formation, of a f~aming
agen~, suGh as pentane or CO2, the esc~pe from re~ction mat~-
ri~l 74 causes parti~l foa~in~ of the rea~tion material,
which is n~t un~esirable for certain p~rposes.
A~ ~he end of conveyer belt 71 there is scraper 73 for
detaching the reacted r~action m~terial ~rom the convPyer
belt or separating foil, it being p~sse~ out o~ the process
via pro~uct sluice 8 ~d taken away ~ia conveyer ~elt ~1. Ni-
trogen pipes ~1 and 82 regul~te t~e protective ga~ ~upply ir
the sluice ~re~, ~he prote~ti~e gas used belng expediently
nitrogen, which need not be ~ooled. Further nitroge~ pipes ~3
and ~4 in the are~ of the entrance and exit of separatil~g
foil 75 prevent oxy~en from enterin~ the systèm in this area.
I~ is also unnecessary to use cool nitrogen here.
O~viously the inventive pro~ess is perfo~med in a cold-
and heat-insulate~ plant. In particular the entranGe ~f oxy-
gen m~st also be prevented in order ~o prevent li~uid oxygen
from ~ondensi~g into cold ba~h 2. It is of adva~tage for the
gas distribution to perform the entire process i~cludin~
spr~y tower ~ a~ temperatures at which solve~t and foaming
agent exist in a solid state. This permit~ them to be remo~ed
centrally vla suction pipe 77 in reaction space 7 and di-
rected to recovery. ~he reacted~ure~ polyurethane materia]
emerging f~om the process in product sluice 8 can ~e ~irected
to any deslred f~rther u~e in the form of granules Possib]e
uses are for example ~or insul~ting materials and in compos-
ite materials.
Flg. 5 shows details of the sluice system at the ~ntry
o$ the process, the cellu~ar wheel pneumati~ slui~e bei~g re-
tated ~0~ relative to the view of Fi~s. 1 and 2.
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- 13 -
Car~ridges 13 wlth polyurethane prepolymer residues i~-
tended for the proçess are int~uced vi~ co~veyor and sort-
irg belt ll to ~e~l~ 12 of cellula~ wheel pneumatic sluice 1.
Feed hopper 14, under which the slulce rotates ~way, ens~res
accurate introduction ~f c~rtrid~es 13.
Conveyor and sorting belt 11 expediently has ribs or
forks 15 for separating cartridges i~ transported o~ ~he con-
veyer belt from one ~nother. One can thus exaçtly coor~ina~
the cysle of cartridge rele~se with the transport speed of
cellul~r wheel sluiee 1 and the transport cycle in g~lde ~1
of cold bath 2 at ~ given G~nveyin~ speed. ~he fixing of a
cycle further allows c~rtridges 13 to be discharged ~ro~
sluice 1 in precisely timed fashion with the help of pressu~-
i~ed ni~rogen through pipe 15 (Fig. 2j.
As e~ident from Fig. 5, pne~ma~c sl~ice 1 opens at its
lower end ~opposit~ feed hopper 14) in~o g~i~e 21 into whi~h
the car~ridges slide, being ejeçted toward tra~sport dev1~e
23 with the help of the pressure surge from pipe 15.
Figs. 6 and 7 show details of guide 21 and tr~sport de-
vice 23 for transpor~in~ c~rtridges 13 within gulde 21.
Gui~e 21 has ~ltogethe~ an elongate, cage- or basketlike
structure. Th~ guide consists s~bstantially of parallel ~uide
rails Z2 which leave enough room there~etween for the a~mis-
sion z~ liquid nitrogen ~nd the es~ape of evaporated nltro-
gen. ~ulde rails 22 ~re held together ~y fixing ~ings ~7 on
the outside such that their relative positlor. to ~ne other is
fixed. The fixin~ rings encompass entire guide 21 with the
ex~eption of the ~pper end, where the space hetween two guide
rails 22 remains free so that tran~port fork 2~ or the like
~an engage from above and push c~rtri~ges 13 lo~ated i~ ~ui~e
21 through the gui~e. This re~lts ln the picture o~ an elon-
gate cage comprisi~g parallel rails 22 ~n~ encompa~sing fix-
ing ring~ 27 which leaves a free space over i~s entire leng~h
in the up~er are~ for motio~ of transpor~ foxk 2~. The size
of the c~e is ~oordinated with ~he size of the cartrldges
and selected so that the cartridges cannot ~ilt when ~ei~g
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- 14 -
g~ided thro~gh. In the ~rawi~g cartridge 13 ls transporte~ ln
the ~i~ection of the arrow with the botto~ fir.st and fork 2
embraces fitting 18.
Transport fo~ks 2~ are located on ~r~nsport ~elt 25
which transports the cartridges ~hrough ~uide ~l via a suita-
bly dispose~ system of transport roll~ ~7 to con~eyer belt
31, where they ~ll out Or guide 21 an~ are recel~ed by
transport ~lements 32 of conv~yer belt 31. Fro~ the end of
~uide 21 transport belt 25 is moved ~ack above bath 2 toward
cellular wheel sluice 1, where forks 26 again eng~ge ln guide
21 a~ the intende~ place an~ transport the cartridges located
in the guide through b~th Z. Ob~iously e~tire gui~e 21 ex-
tends in the area of the a~t~al coollng stretch in cold ~ath
2 in such a way tha~ ~he car~ridges are washed by liq~id ni-
trogen on all sides.
9~:31I35 069116S:N~ ~2b~56 ~2~2 6~+ 3HOd31N3~1 NNbWd~3H:NOh OW ~~:21 N~r-L2