CA2196177A1 - Process for the production of substantially homogenous mixtures - Google Patents

Abstract

In the proposed process for producing substantially homogenous mixtures of substances capable of reacting with one another, the substances in question are fed separately into a cold zone (2) and cooled to a point at which they are solid and non-reactive; they are then conveyed in finely divided form to a mixing zone (6) where they are mixed together, the temperature in the mixing zone (6) being maintained at a level below the softening temperature of the mixture contained therein.

Description

PROCESS FOR THE PRODUCTION OF
SUBSTANTIALLY HOMOGENOUS MIXTURES

This invention reiates to a process for producing sub-stantially homogeneous mixture~ of reactive subs~ances.
T~ che~.ical engineeri~g there are numerous processes for mixing together substances reactlve with one another in ~uch a way that they rea~t with one ~nother in a desired way. The great number of processes reflect the problem of producing mixtlres. It ls thus co~mon to work in diluting solvents which simultaneously serve to supply or remove energy, whereby all reacting components are present dissolved in the solvent or the reacting ~gents are unlted gradually, e.g.
drop by drop. Other mixlng techniq~e~ involve brin~ng to-ge~her two eduot streams in a reaction chamber, gradually dissol~ing or reactin~ a first componen~ ln a re~ing medium containing one or more further components or contr~lling re-act~ons by adding catalysts. It is common to use mechanical or other stlrring tools to achie~e a thoro~gh mixture of the reacting ~edi~m ne~essary for the reaction. Nevertheless it is still problematic ~o produce a highly homogeneous mixture of reacti~-e sub~tances which is optimal for the partl~ular p~rpose, in particular because the chemical reac~ions already start during the mixlng p~ocess, ~.e. before an optimal mix-ture of the component~ has ta~en place. This fre~uently de-tracts from the yield and puri~y o~ the products and results in increased costs for the produ~ts beca~e of low yield, elabora~e cleaning methods or complicate~ apparatus for pIO-ducing the mixtures.
one also comm~nly tries to optimize che~ical reaction5 by working .n large quantities of sol~ent to lnfluer.ce the mixing behavior of the ~eacting ~gents and thus the reactio~
course via the diluting effect. Large q~antitles of solvent requlre elabora~e recovery proce~ses, apart fro~ the fact ~0:31I35 E369116S~ ~2bbS6 ~2~2 6b+ 3HOd31N3~ J]I I I~On Ol~ 2T :2~ NYr-~2 - 2 - ~ ~96177 ~.at the qu~ntities of solvent must not on~y be supplied but also handled, separated, ~ieane~/reprocessed or eliminated.
In particular in the conve~sion of highly rea~ive sub-stances there can be un~e~irable consecutive reactions if ore does not s~c~eed in dis~ri~uting the reacti~ agents h~moge-neously. Such distribution i.s pr~blemat~c, howev~r, when o~e su~tance must be mixe~ into a second one, ~s is freque~tly ~one i~ the la~ with the help cf droppi~g funnels. At the place where ~he adde~ su~stance p~sses into ~he xeacting me-dlum a high concentration forms temporarily whi~h, in the ~ase of fast reactions, cannot be reduced using conventio~a].
mixers and stirrers f~st enough to a~oid merely pointwise con~e~sion with consecutive reactions.
The same holds for the pro~uctlon an~ ~urther processing of plas~ics when several reacting a~nts ~re present. Poin~-wise rëa~tion can lead to changed reaction con~ition~ a~ cer-tain points and thus i~fluence the nature, structure or dis-tri~ti~n of the products. This also hol~s for example for catalyzed reactions when the G~talyst is not distri~ute~ ho-mogeneously, Such inhomogeneities a~so occur for ex~mple ln the hardening of polyurethane foams whe~ for example mois-ture-hardening ~oams full-harden with the entrance vf atmo~-pheric humidity from the outside 40 the inslde, ~he se~ond component ~n 2~ fo~s is mixe~ in~omple~ely with the first c~mponent and therefore reacts only locally, or reactions take plaoe w1~h introduced water, on the one hand, and with ~n a~de~ agent, on the other, in the recycling of pr~poiymer resi~ues. Since the reactions take pl~ce in accordan~e w1th the a~ailability of the reacti~e substances, inhomog~ne-~ies ~oth impair th~ products and cause problems in carrying out recycling proce~ses, in particular ~ecause the 5i~ultaneous prese~ce of cans which are empty except for a small remain-der, partly ~ull cans or full ~ut useless C~5 can cause ~if-~f~erent qualities of prepolymers, different ~uanti~ies o~
hardeners an~, in the ç~se of cans that have becorne moist, also di$ferent quant~ ~ies of water to be brought into the b0:31I35 069~65:N~ ~ZbbS6 ~Z~2 6b+ 3HOd31N3~1 NN~W~3H:NO~ O~ Z~:ZI N~r-LZ

- 3 - 2 1 q'6 1 7 7 pr~ess. ~his results fu~hermore in a batch-depen~ent qual-ity of the products.
A ~eed therefGre exists for a mixing p~ocess whi~h m~ke~
it p~ssible to mix chemi~al substances reactive with one ~n-other in sukstan~lally homogeneous fashion without a reaction occurring before the end of the mixing proce~s.
This proble~ is solved by a p~ocess o~ the abovemen-tioned type wherein the su~stan~es are introdu~ed into a coid zone separ~tely from one another ~nd ~oole~ until they exlst ln a solid and unreactive state, and th~n introd~Ged into the mixlng ~one in a finely dispersed state an~ ~ixed togethe~
there, the ~emperature in the mixing zone ~elng held below the softening temperature of the mixture o~tained therein.
T~e mixtures produced in the inventive process ~re sta-ble only at the particular low te~per~tures, so that upon temperature inc~ease a reaction oc~urs when a min~ m tem-perature necessary for ~arting the re~ction ls exceede~. It can generalLy ~e assumed that a slo~ reaction st~rts when the melting te~perature of one of the reactive subst~nces is re~ched. It is theref~re important tha~ the substances ~e held ~elow the pa~ticular softening temper~ture per se and in mixture.
The inventive process serves to mix ~t least two co~pO-nents together, but more th~n two components c~n ~lso be mixed together. one of the components can be a ca~alyst. In addltion it is possi~le dLrin~g pro~uction of these mixtures to admix a~ditives intended to be ~ontained in the re~ulting products, as well ~s solven~s which can be of importance fcr the course of the re~etion, for ~x~ple for temperature con-trol. At least one of the reactive substan~es ~s gener~liy ~
liq~id under normal conditio~s or at the rea~ti~ tempera~ure o~ exists in solution.
The in~entively obtained mixtures can ~e further pro~,-essed immedia~ely by being brought to a temperature bene~i-oial ~or r~action or ~eing introdu~ed into a re~ti~g medium, or they ~an ~e stored o~ transported in a cooled state. It i5 S0:31I3~ 069116S:Nt~ ~ZbbS6 S2~2 6b+ 3HOd31N3~1 NNtW21;~13H:NOn OW Zl :21 N~r-L2 _ ~ 4 ~ 2196177 also conceiva~le tc pa~kage such reactive mixtuxes suit~bly cr put them into ~ f~rm suita~le for an ~pplication a~d pre-serve them in a coole~ st~te so that for thelr use at a dif-ferent place they can ~.erely be t~ken out o~ ~ cold ~hest and used there. This can be done for exa~ple tn a chemical lab or plan~, or als~ by a wcrhman who for example brlngs ~ reactl~e mixture for producing ~ foam to a de~ired place and fo~s i' there by the ae~ic~n of temperature. A further possible ap~
cation i5 for example a ~,ixture of reactive substanses whi~h are stored unchanged side by side at low temperature but upon a tem~e~ture increase, for exa~ple above 0~C, cause a color re~ctio~ so that such a mixture can ~e ~sed as an in~icato~
for uninterrupted opera~ility of ~ cooling unit.
T~e inventive pro~ess is preferably performe~ at a tem-perature ~elow -60~~. It is especlally expedient to carry out the pr~e~s at the temperature of liq~id nitro~en. One ther.
expediently woxks in the absence o~ oxygen, which can als~ ~e r.ecessary at higher temper~tu~es and with oxygen-sensitive substances.
The substances reactive with one another a~e generally liquid. sub~tances or at leas~ one liquid subs~ance whiçh ~an serve as a solvent for one or more subs~ances. It is thus im-portant ~o bring this ii~id s~stance into ~ solid ~orm pre-~enting reaction, which is done in the ~old zone. One can naturally can also u~e substances in solution, in par~icular when ~he solvent is required for the l~teL reaction.
To brin~ the reactive su~stances used into ~h~ ~inely dispersed form necessary fo~ mixt~re one can use any desired crushing process. It is especially expedient to ~se spxay processes ln which th~ liqui~ substance or the s~bstance ln s~ution is atoml~e~ while ~ein~ cooled so that a small-sized powder ~rises. A further preferred possibillty ls to p~lver-ize in a mill, a ham~.er mill or the like the re~ctive su~-stan~e initially solidified in ~ ~rude for~. Furthermore it is possi~le to o~tain the ~ubstance in powde~ ~or~ vl~ a ~pray drylng process, the powder optionally first being 90:31I35 ~369~l65:NJ ~Z~bS6 ~2~2 6b+ 3HOd31N3i~1 NNdW~3H:NOn OW ~~:21 NJr-L2 cooled to the low ~emper~ure re~uired fo~ the mixlng proc-ess r The mixing zo~e use~ accordin~ to the invention is expe-die~tly a spray tower. A ~irst substance c~n be fed to this spray t~wer from above in the form of ~ small-si~ed powde.r, ~or exa~ple, and a second or further reactive su.bstanoes sprayed in while being cooled and solidlfied. To guarantee th~ low tempera~ure in the spray tower required by the ~roc-ess, lt can be necess~ry tG spray in liquid or gaseous nitro-gen ~or te~per~ture control, it being preferable to spr3y cold g~ eous ni~rogen into the lower ar~a of the spr~y tower and have the exit at th~ upper end in order to at~ain a swirling effe~t.
The inventi~e process is especi~lly suitzble for use ln recycli~ packings co~taining re~tive residues. Speci~l men-tion m~~t be m3de he~e of packing$ holding isocyanate-con-taininq pxepolymers for polyurethane ~oams. The inventive process will therefore be d~s~ri~ed in the follo~ing in terms of a recycling process for cartri~es holding prepolymers con~ainin~ iSooyanate groups for polyuretha~e foams.
Residue-containing p2ckings as occur for example i~
great quantities in the form of wholly or partly e~pty ca~-trid~es are increasingly bec~ming a disposal proble~. They ca~not be du~ped on disposal sites for reason~ of en~iron-~ental proteetlor~ since the residues eont~ine~ therein can pass into the a~mosphere, the soil or the grou~dwater ~nd lea~ to çonsldera~le damage there~ T~e s~me holds for b~rn-ing, whîch is ~requently incomplete in particular with chemi-~otechni~l p~oduc~s a~d produces great qu~ntities o~ pollut-ants ~hish can be ~ound only by elabor~te ~easure~ at al~. 3~rning thus leads to ~ great reduction in t~e vol~me of waste b~t does n~ necessa~ily solve the poll~tion problem.
Spec~l proble~s arise when the res-~ues çontaine~ in the paçkings are themselves reacti~e and possibly even toxic products, as is the ~ase for ex~mple with isoçyana~e-contair~-ing p~epolymers $or poly~rethane foams. T~e same holds for ~0:31I3S 06~6~:N~ ~2bbS6 ~2~2 6b+ ~HOd31N3~1 NN~W~d3H:NO~ O~ ~~:Z~ N~r-~Z

~_ 6 other reactive plastic produ~ts, for example self-curiny or hardenable mixtures for çoa~ings, adhesi~e ~ixtures, et~.
Polyurethane fo~ms are commonly dlscharged fro~ car-tridges which contain a polyurethane prepol~mer ~o~ether ~lth required ~dditives. ~he~e cartri~ges ~annot be re~sed. On the other h~nd, they are problem waste which can~vt be disposed of in the normal way.
~ n accor~nce with eff~rts to limit househcld and indus-trial ~aste, measures are ~eing increasingly discusse~ and implemented to force manufacturers to take back their pxodu~.t packaging after use and en~ure ;~ reuse or dlsposal them-selves. Such meaqures ha~e made i~ ~ecessa~y to find w~ys of treating such waste eccnomica~ly. The treatment of returned c~rtridges for polyurethane foam production involves a number of problems which ~cmplicate e~onomic recycling. For example, some returned sartridges can be u~der pressure due to the penetration of moisture ~uring improper s~orage or treatment, which makes ~th openlng and bur~ing ~ problem. Fur~herm.ore ~he c~rtridges have different filli~g con~itions, ra~ging from.o~eraged cartrldges virtu~lly full of prepolymer which cannot be discharge~ d~e to a blocked valve, to ~irtually empty cartridges with only a remai~der o~ prepol~mer a~h~ring to the edges in ~n un~rossllnked to crosslinked state.
Up to now ~ number of processes have beco~e known for recycling packings, including aerosol cans for polyurethane foa~ productl.o~. For example it has been proposed to pass pressure cans via a slul~e system ~nto a plant u~der i~ert gas and crush ~he~ there. Furthe~, processes have be~o~e known for passing aero~ol cAns in~o a plant, crushlng them there an~ extracting the ingredients with ~itable ~lvents.
In these processes ~oth the packing ~aterial~ ~nd the ingre-dient~ ~prepolyme~, propellant~ are re~overed.
Howe~er these known processes, some of which are quite efficient and in use, are capa~le of being improve~ with re-gar~ to indu~trial safety, process control and quality cf the product~. It i~ proble~natic to separate the residue~3 ~on-20:31I35 069~6S:N~ ~Zb~S6 ~Z~2 6b+ 3HOd31N3dl NNY~dd3H:NOn I~ ~0:~ NYr-8Z

_ 7 tained in the packin~s in simple fashion and obtain hom.ogene-ous product~ for suita~le re~se.
The lnventive process makes it possikle ~o process reac-tive residues of packings in a ~ully safe way. The re~çtive ~esid~es, for example isocyanate-contai~ing prepoLymers lrl ~artridges for producing polyurethane ~oam, are tLe~ted i~ a ~afe manner. Due to the free~ing of the reactive ~u~tances or residues there is neither a reaction-i~duced pressure in-crease in the process nor un~esirable reaction between reac-tlve components. At ~he temperatures prevailing i~ the pro~-ess the presence of water is also h~rmless. The two latter points ~re of importance in treating iso~yana~e-containing products when for ex~mple da~ged packi~s c~rry water into the process. At the same ti~e, reactive se~on~ co~ponen~s contained in ~o-called 2~ ~oams, for ex~mple glycols, c~rbox-ylic acids or water, can be easily introduce~ into the pro~-ess. The in~entive pxooess i~ thus s~ita~le for treating bo~h cartridges for lC and 2¢ fo~ms and transitional forms ~etween the two simultaneously, and for converting the reactive resi-dues inta hlgh-quality an~ homo~eneous prod~ts.
In the i~ventive process packings, for example c~r-tridges, are first introduced into a cold zone and coole~
therein until the reactive residue~ therein, including ~ny low-boillng solvents therein, soli~ify. Temperatures lower th~n -80~C to -100~C ~re ge~er~lly sufflcient for this pur-pose, but one expediently works in liquid ni~rogen as a cool-ing medium. In this case it i~ import.ant that the process ~e performed in the a~se~ce o~ oxygen to ~voî~ condensati~n o~
~iquid oxygen which coul~ ha~e an adverse effe~t in later process steps.
When ~he ~esired temperature is reached, generaIly the tempexature of liquid nitrogen, the packings are crushed in the cold state. The temperatures here should expedien'ly ~e under -80~C to -lOO~C; it might be ~ece~sary to spray in liq-uid ~itrogen cr cold ga~eous nltrogen.

~0:31I3S 069~16S:N~ ~ZbbS6 ~2~Z 6~+ 3HOd31N3~ N~ 311:NO~ ~O:~l N~r-8Z

21 96~ 77 _ - 8 - .

Crushing is expediently done in a ha~mer mill working against a si~ter. This achie~es a shaking ~nd fulling effect which not only crushes to a desire~ particle slze but also separates the various materials: metal, pape~, plastic and i~gredie~ts. It has ~rprisingly turned Cut that t~e p~cki~
materlals (metal, paper and p~astic~ can thereby be sepa~ated extremely well from the ingre~ients ~rea~ti~e residues and solvents/additives in pow~er form~, the i~gredient~ bein~ ob-tained as fine powder.
In a subsequen~ ~eparating step.the ~rushed paGking~ are divided into at least two fractions, one of whish contai~,s ~he reactive residues inclu~ing propellant in a soli~ state.
This separating step expediently uses a slfter, prefera~ly a rl~dle sifter, t~rough which the flne componen~ mainly re-active resi~ues and solvent) fall. Me~al part~ are ~eparated with magnetic metho~s, la~ge plastlc par~s and scraps of p~
per sie~ed out on the riddle sifter.
The frozen ingredients from reactive substa~ces and ~ol-ven~ pass fro~ t~e separatlng zone into ~ ~ixlng zone in which an agent reactlve w~th the resid~es i~ simultaneollsly i~troduced as a f~rther reactive substance. ~emperat~res lower than -80~C to -100~C also prevail in this mixin~ ~one to ensure the frozen ~tate of the introduced materials and solldify the spr~yed-in reactive agent imm~diately in~o a ~ine powder. This permits for~ation of a unifarm mixture of ingredients ln powder for~ ~nd rea~tive agent, whieh ~nnot react ~ue to the pre~ailing temper~ture conditions. The tem-peratures in the mixin~ zone are 1n any ca3e below the melt-ing point of both the residues and reactive ~ent ~nd the ~ixt~e.
A spray tower is expe~iently u~e~ as a ~ixing zone, the frozen in~redients falling in from ~ove. The reacti~e agent is sprayed into this powder stream from lateral noz21es, preferably together with cold qa~eous nitr~en to ensure the necess~y low ~emperatures. It i~ expedient to precool the reactive agent but it must remain sprayab~e.

60:31I35 069~165:N~ ~2bbS6 ~2~2 6~+ 3HOd31N3~1 NN~W~3H:NOh OW bl:2~ N~r-L2 It c~n ~e expedient to spray in the reactive agent to-ge~her with a catalyst ~hich promotes the reaction with the reacti~e residues of the packings. This is generally unneces-~ary wl~h lsocyanate-containi~ prepolymers, however, when the iso~yana~e-containing mixtures alxea~y contain such cata-lysts.
The ~old powdery mixture of ingredients an~ re~ctive agent and optionally cat~lyst is then guided into ~ reaction zone ~hich ~onsist~ for exa~ple of ~ conveyer ~elt mo~
continuously unde~ the mixing ~one. ~he powder collecti~
here is then brought to a temperature suffiçient for reaction in or~er ~o react. Any sol~ents contained evapor~te at this p~int a~d are condenced out. at a suita~le place, which is no pro~lem when nit~ogen is used as a ~ooling mediu~. To ~ive the reaction pro~Gt the desired form the conveyer ~elt can ha~e ~ ateral lilnits . For separating the reaction product fron~
the conveyer belt it is possible ~o provide parting means, for example suitable coatings or release paper. The hea~in~
in the reaction zone ls expediently done with ml~rowa~es, which ~ause f~st ~ire~t he~ting of the powder material from the inside to the outsi~e so th~t u~iform degassing a~d heat-ing occur.
Fo~lowing the reac~ion zone one can provide further processing and treating zones as well as a final sluice for passing out the reacted material.
~ s ~entioned above, the inventive pro~ess lS especially suitable for recycling residue-containing poly~rethanç foam cartridges. In this ea~e the reactive agent is in particular a hydroxy co~pound, for example wa~er, ethylene ~ly~ol, pro-pylene gly~ol, gly~erol, oligomers and mixtures thereo~ as well as ~eriv~tives thereof. Ethylene qlycol, water ~nd poly-ether alcohols are prefer~ed, whereby irl any ~i~se ~t least ~wo re~ctive hydrogen atoms should be present. Polycarboxylic ~cids can likewise be used. ~specially suit~le polyether al-coho~s are the so-called ~effami~es ~trademark).

31I35 0691~6S:Ntl ~2bbS6 ~Z~2 6b+ 3HOd311'!3~ n~ W~1~131 l:NO~ OW S~ :2~ N~r-~2 - lo - 2 1 96 1 77 In recycling pa~kings for producinq polyurethane fo~ms it is ~dvantage~us to ~onvert the isocy~nate-cont~ining pre-polymers in the pro~ess itsel~ into foam ~aterials which can be ~sed for example for lnsulatin~ purposes. The i~entive process can thus co~tinuously produc~ lnsulation boards, ~hereby the propellants contained in the powder prcduced in the mixin~ ~cne promote fo~m formation. It is also readily possi~le to produce foils or to admix additives, for example cellulose-containing materlals, and then press these miXt~re5 into composi~e materials durln~ or afte~ reaction. However lt 1S preferable to produ~e granules from ~ea~ted ~aterial which are further processed later.
The ln~entive process ca~ be us~d in particular for re-cycling pressureless polyurethane foa~ car~ridge~ which are emptied on site ~sing ~ suit~bl~ pistol and then retu~ne~ to the manu~actu~er for recycling. These c~rtridge~, which are u~ed both for lC and ~or 2~ fo~ms, are pres~rele~s du~ing sto~ge and ~enerally contain no exp~ndin~ or ~oamin~ agen~.
If an improvement in foaming behavior is necessary an~ thls improvement cannot be ~Ghieve~ by using wa~er as the ~econd component, low-boili~g sol~ents can be present, for ex~ple pentane, which are liq~id at normal temperature, solid a.t the temper~ture of li~uid nitro~en, but evaporate with the second co~p~nent at the reaction temper~tures of the pxepolyme~ an~
prod~ce an expanding effeçt. The inventive process c~n like-~ise be used for aeroscl ~ans for polyu.~ethane foam produc-tion if an effective separation of propellant is ensured ~ur-ing the later reaction. The process is thus fund~entally ap-plicable for rec~clin~ packlngs which contain not only reac-tive subs~ances b~t also expandin~ ~gents ~nd achieve an ex-panding and/or foaming effect, optionally in ac~crdanGe with te~perature.
The inventive proeess will be expl~ined ~ore closely by ~e enclosed drawings, in which Fig. 1 schematically shows ~ plant for ~e~yeli~g pa~k-ings~

1~ :31I35 la69~6s:Nld ~2tbS6 ~2~2 6~+ 3HO~lN3~il NNbW~;~3H:NOn OW Sl :Z~ N~r-L2 Fig. 2 ~hows the entry area of the plant according to Flg. 1;
Fig. 3 shows the co~veying, crushing and sorti~g p2rt of the plant ac~or~ing to Fig. 1; an~
F~g. 4 shows the mixing ~nd reaction zones of the p;~nt according to Fig. 1.
The view ~f a recycli~g plant for cartridges having re-active re~i~ues as showh i~ Fi.gure ~ has entry sluice 1 which ~s fed cartri~ges 13 ~o be tre~ted. The entry sluice is pref-erably for~ed as a cell~l~r wheel pneu~atic s~uice into c~am-~er~ 12 of which cartridges 13 ~a11 from ab~e via fee~ hop-per 14 IFig. 2). Rotation of ceLlular wheei 1 c~ses the car-tridge~ ~o pass into the lower area of the sluice and be e~ected laterally with the help of gaseous ~itroyen GA~ from pipe 15. To ~ake this possible the cellul~r wheel rotates in a gas~1ght cont~iner open ~t ~hè top which ~n be subjecte~
to pre~urized gaseous ni~rogen GAN .rom one si~e 1~ its lower area so that cartridge 13 therein can be ej~cte~ on the opposi~e side into guide system 21. The ~itrogen supply ~ia pipe 15 is p~eferably ensured with gaseous nitrogen from cold b~th 2. Ok~iously the rotational speed of cellular wheel 1 and the pressure ~urges from ~itrogen pipe 15 for ejectin~
the cartridges frum the cellul~r wheel are mutually c~ordi-nated. The cellular wheei has for this p~rpose a me~suring sensor marXed M.
From the cellular wheel the cartridges pass ~i~ guide 21 into cald bath 2 filled with li~uid nitrogen. ~ui~e 21 expe-~iently consists of an elongate basket construction open on ~11 sides which permit~ unhindered admisslon o~ liquid nitro-gen and es~pe of gaseous ni~rogen.
On their way through cold bath 2, which is supplied with fresh liquid nit~ogen LrN in accordance wi~h level via pipe 24 an~ has meas~ring ~ensor LIC for checki~ le~el, c~r-trid~es 13 are cooled to the bath temperature. The cage structure of guide 21 ensures free ~dmisslon of cooling ~e-dlum ~n~ quick di~charge of produced g~seous nitrogen. Gase-2~:31I35 069~65:N~ ~Zbb~6 ~2~2 6~+ 3HOd31N3~1 NN~wdd3H:Non OW 5~:2~ N~r-~z -12- 21~6177 ous nitrogen is removed from the b~h area via pipe 16 wlth the help of ventilator 17. The leng~h of guicle ~1 and the transport s~eed are adjuste~ ~o that cartrid~es 13 are cooled to ~ sufficiently low temperature of at least -~0~C to -100~~
even when completely filled with remainder.
C~rtridges 13 are transported in guide 2~ with the help of tra~sport device 23 expediently consisting of çirculating txan~port belt 2S wi~h protruding transport forks 26 which engage in guide 21 from a~ove and push cartri~ges 13 guide~
therein ahea~ of themsel~es. Transport rolls ~7 ensure pre~
cise guidance of transport forks 26. Forks Z~ are ~isposed ~n tra~.sport belt 25 at intervals coordinated with the si2e of ca~tridges 13 to be transported. Me~suring uni~ M serves to mon1tor tne transport speed and its coordination with th~
feed rate of cartridges 13.
~ fter running through ~old ~h 2 c~rtr1dges 13 pass o~t of guide 21 into conveying device 3 ~Fig. 3) in the form of circulating conveyer belt 31 ha~ing transport segments ~oor-dinated with ~he size of cartri~ges 13. Con~eying ~evi~e 3 is preferably formed as a steep conveyor whiçh receives çar-tridges 13 ln the segments forme~ by transport forks 33 dis-posed a~ regular intervals and releacos them overhea~ into crushing device 4. The conveyer belt is gui~ed ~ia rolls 32 provided with measuring uni~ M for monitorlng and contr~lling the conveylng speed.
~ rushing device 4 consists of a shredder or preferably ha~mer mill 41. ~ammer mill 41 prefe~ably work~ ~gainst a sifter to guarantee a cer~ain particle size of the crushed ~aterial. Sifter q2 simulta~eously produces a fuilin~ effec~
whi~h promotes separativn of the in~redients embrittled by the cold ~rom the ~ont~iner ~aterial. Obviously one can a~d ~ooling medi~m, preferably liquid nitro~en ~IN, via pipe 43 for maint~lning the necess~ry low te~perature~ of -80~C to -100~C if ~emperature check T~ indicates an inadmissible rise in temperat~re. The working speed is ~hecked and contro~led ~T :31I3S 069~6S:Ntl ~2b~56 ~2~2 6b+ 3HOd31N3~1 ~JN~ 131 I:NOf'l OW Y~ :2~ N~r-~z '21 96 1 77 vla measurin~ senso~ ~. Gaseous ni~rogen is removed via pipe 4~ and recycled or bl~wn off via valve 4S.
From çrushing devlce 4 the crushed ~aterial passes into sorting device 5. This consist~ first of rid~le sifter 51 on which coarse parts are separate~ from fine parts. Co~rse pa~ts are mainiy the crushed materials of the contalner which are shaken off on lnclined sifte~ 51 and disch~ged f~om the process via a sluice not shown.
Powdery ingredients and flne parts Gf the contai~er p~ss thro~gh riddle sifter 51 onto first ma~neti~ separator 52 whiçh separates re~aining iron 2nd aluminum compone~ts from plastic particles and ingre~ients~ On first magnetic separa-tor 52 ~gnetic components are first separated and fed to fi~st transport bel~ S3 whl~h also receives the met~l ~nd plastic parts shaken off by sifter 51. Second transpo~t ~elt 54 receives plastics, ingredients and nor.magnetic metal parts, which are divided int~ metallic and nonmetallic frac-tions via second magnetic separator ~5 c~upled with the transport ~elt. The met~llic fra~tions pass onto ~ir~t trans-port belt 5~, the non~etallic are guided dire~tly into spray tc~er 6. Cold gaseous nitro~en can ~e sup~lie~ via pipe 56 if temperature check TIC indlçates an in~dmissi~le rise in te~-perature. Measuring sensors M çheck the working speed of all moving parts of $eparat.ing syste~ 5. If the cartridges con-sist entirely of no~metalli~ ma~erials the magnetic separa-tors can n~tur~lly be dispensed with.
Obviou~ly a te~per~ture of no more than -80~C to -100~C
is ensured both in the crushing plan~ and in the sortln~ de-vic~ by suit~ble feeding pipes for cooling medium, preferably nitrogen in gaseous or liquid form.
The pow~ery ingre~ients and plastic parts passing into spray tower 6 (Fig. 4~ and having a te~perature of no more than -ao~s to -100~G so th~t solvents ~ontained therein are ~lso present in ~ soli~ state, ~re mixed with ~e~cting ~edium and option~lly catalyst spraye~ i~to the upper a~ea of spray tower 6 via ~eed ~1~ The r~ctin~ mediu~, preferably eth~lene b~:31I35 0691165:,W ~2~S6 ~2~2 6~+ 3HOd31N3~1 NN~W~d3H:NOn OW 91:21 N~r-~2 ~_ - 14 - 2196177 glycol, is located in the li~uid state in supply ~ank 62, ~he catalyst in supply tank 63. Both tanks ha~e meterin~ units coorc~inated therewith.
Reacting medium from tank ~2 ~n~ c~t~lyst ~ro~ tank 63 are sprayed into spray tower 6 ~i~ pipe 61 in dosed relati Qn to the reactive ingredients, whe~eby a precooling stretch can be p~oYide~ in the ~ourse cf feeding pipe 61 for cooling the m~teri~ls to a beneficial ~empe~ature ~ove melting point).
The spray material solidifies upon entering or withirl the s~y tower itself at the temperatures of less than -80~C to -100~C pre~ailing there. For maintainin~ ~he temper~ture in the spray towe~ it is therefore expedient to lntroduce cool-ing medium addltionally, for example ~iquid nitrogen LIN vla pipe 64 or gaseous nitrogen via pipe 65, if te~perat~re check TI~ indlcates ~ need there~or~ It ls expedie~t ~o ~pray the cooling mediu~ into the lower areas of the spray tower to e~l-sure additional swirling and mlxt~re of reactive compound, catalyst and reactive can content by cold nitroge~ risi~g i~
~pray tower ~.
From spray tower 6 the mixture of reactive cartridge content, reactive co~p~un~ an~ catalyst passes in powder form into roac~ion space 7. ~ithin rea~tion spa~e 7 there i~ ~eac-t~o~ belt 71 for recei~inq the falling material fro~ ~pxay tower 6 and guiding it into actual reaction zone 72 wne~e the reactio~ is indu~e~ ~y heat. For this puxpose heat elements 73 a~e dispos~d above conveyer belt 71 for heati~ ~h~ reac-tlO~ ~aterial on conveyer belt 71 with microw~ves or infr~red rays to ~ tempera~ure s~fficient for reaction, for ex~mple ~oom temperatu~e or therea~ove.
To prevent reactisn ~aterial 74, i.e. the mix~re of re-acti~e cartridge content, reactive compcun~ and catalyst, fro~ ~tiGking to conveyer belt 71 it may be expedien~ to cover the conveyer belt with sepa~ating foi~ 75 whi~h is wo~d of~ roll 76a and onto se~o~d roll 7~b. The separatJ.ng foil is optionally reusable.

5~:31I35 069~165:W ~2~bS6 ~2~2 6b+ 3HOd31N32~1 I'r~1.';121~1311:NOfl Ol~l ~1:2~ Ntlr-L2 OI1 conveyer belt 71 the reaction material reacts into the partlcLlar product ~esired. At the sarne tim.e sol~rer~ts and adsorpti~rely bound coolin~ medium nit.rogen still cont~ined in the mixture from the spr~y tower are released ~nd sucke~ o~f via pipe 77 and ~irected to separation and sol~ent recovery (not shown). In the presen~e, or upon forma.tion, of a ~o~min~
agent, such as pentane or CO2, the es~pe from reaction mate-ri~l 74 causes par~ial foaming of the reac~lon materi~l, which is not undesirable for certain purposes.
A~ the end of c~nveyer belt 7l there is scraper 18 f~r deta.ching the reacted reacti~n materi~l from the conveyer ~elt or separ~ting foil, lt heing passed ~ut of the pr~ces~
via product sluice 8 and taken ~way via ~onveyer belt Bl. Ni-~rogen pipes 81 a~d 82 regulate ~he protec~ive ~as s~pply in the sluice area, the protective gas used 4eing expe~ie~tly nitrogen, which need not be cooled. Further nitrogen pi.pes 83 a~ 84 in the area of the entran~e a~d exlt of separating foil 75 preve~t oxygen from en~ering the system in t~is area.
It is also unne~ess~ry to use cool nitroge~ here.
Obviously the lnve~tive proces~ is ~erforme~ in ~ ~ol~-and heat-insulate~ plant. In particul~r the entrance of oxy-gen must also be prevented in order to prevent liq~id cxygen from condensing into cold bath 2. It is of ~v~ntage for the ~as distribution to perfor~ the entire pr~cess in~ludi~g ~pray to~e~ 6 ~t temper~tures at which solvent ~nd foaming agent exist in a solid state. This p~rmits them ~o ~e removed centrally ~ia suction pipe 77 in reactlon space ~ an~ di-re~e~ to re~overy, The reacted~ured polyurethane material emergin~ from the pro~ess i~ pro~uct sluice e san be dlrected to any desire~ fu~ther use in ~he form of gr~r.~les. Posslble uses are for example for insulating materials and in compos-ite mater~als.

9~:31I35 0691~6S:N~ ~ZbbS6 ~2~2 6b+ IHOd31N3~ I]ll:NOf'l OW ~1:21 N~L-L2

Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS.

1. A process for producing substantially homogeneous mixtures of reactive substances, characterized in that the substances are introduced into a cold zone separately from one another and cooled until they exist in a solid and unreactive state, and then introduced into a mixing zone in a finely distributed state and mixed together there, the temperature in the mixing zone being held below the softening temperature of the thus obtained mixture.

2. The process of claim 1, characterized in that it is performed at a temperature < -80°C.

3. The process of claim 2, characterized in that it is performed at the temperature of liquid nitrogen in the absence of oxygen.

4. The process of any of claims 1 to 3, characterized in that at least one of the substances is present as a liquid.

5. The process of any of claims 1 to 4, characterized in that at least one of the substances is present dissolved in a solvent.

6. The process of claim 4 or 5, characterized in that at least one of the substances is cooled and solidified while being sprayed.

7. The process of any of the above claims, characterized in that at least one of the substances is pulverized mechanically at a temperature < -80°C.

8. The process of any of the above claims, characterized in that the mixing zone is a spray tower.

9. The process of claim 8, characterized in that one of the reactive substances is sprayed into the spray tower while being cooled and solidified, one or more further substances passing through the spray tower in a finely distributed state.

10. The process of claim 8 or 9, characterized in that gaseous or liquid cold nitrogen is sprayed into the spray tower, preferably in its lower area, for temperature control.

11. The process of any of the above claims, characterized in that the mixing zone is followed by a reaction zone in which the substantially homogeneous mixture of substances reactive with one another is brought to a temperature sufficient for reaction and reacted.

12. The process of any of the above claims, characterized in that it is applied for recycling reactive residues contained in packings.

13. The process of claim 12, characterized in that the reactive residues are prepolymers containing isocyanate groups for polyurethane foam production.

14. The process of claim 13, characterized in that the prepolymers containing isocyanate groups are mixed with a hydroxy compound.

15. The process of claim 14, characterized in that the hydroxy compound is water, ethylene glycol or a polyether alcohol,

16. The process of any of claims 12 to 15, characterized in that additives are added in the mixing and/or reaction zones.

17. The process of any of claims 12 to 16, characterized in that the reaction zone is heated with microwaves.