WO1996003230A1

WO1996003230A1 - Process for preparing packages

Info

Publication number: WO1996003230A1
Application number: PCT/EP1994/002483
Authority: WO
Inventors: Mathias Pauls
Original assignee: Rathor Ag
Priority date: 1994-07-28
Filing date: 1994-07-28
Publication date: 1996-02-08
Also published as: EP0776245A1; AU7496194A; DE59504999D1; CA2196177A1; AU3381595A; WO1996003204A1; WO1996003231A1; AU3164695A; CA2196088A1

Abstract

A process for preparing packages containing reactive residues, especially pressurised cans (13) for producing polyurethane foams with propellants, in which the packages are placed in a cold region (2) and cooled until the residues in them solidify and are subsequently crushed in the cooled state, whereafter the crushed packages are separated into a fraction containing the reactive residues and a further fraction, the one containing the residues is taken to a mixing region (6) into which an agent which reacts with the residues is introduced, possibly with a catalyst, the temperature in the mixing region is kept below the softening temperature of the residues and reactive agent and the mixture of the fraction containing residues and the reactive agent and possibly a catalyst is taken into a reaction region (7), brought to a temperature favouring reaction and allowed to react.

Description

description

Process for preparing packaging

The invention relates to a process for the preparation of packaging containing reactive residues, in particular of pressure cans for the production of polyurethane foam with propellant gases. In the process, the packaging materials are obtained and the residues contained therein are converted into reusable products.

Residual packaging, such as occurs in large quantities, for example in the form of completely or partially emptied aerosol cans, is increasingly becoming a disposal problem. A deposit on landfills is prohibited for reasons of environmental protection, since the residues contained therein can get into the atmosphere, into the ground or into the groundwater and can cause considerable damage there. The same applies to combustion, which is often only incomplete, in particular in the case of chemical-technical products, and generates large amounts of pollutants which, if at all, can only be bound by expensive measures. In this respect, incineration leads to a significant reduction in the volume of waste, but does not necessarily lead to a solution to the environmental impact.

Particular problems arise when the residues contained in the packaging themselves are reactive and possibly also toxic products, as is the case, for example, with isocyanate-containing prepolymers for polyurethane foams. The same applies to other reactive plastic products, for example self-curing or curable mixtures for coatings, adhesive mixtures, etc. The problem is discussed in more detail below with the disposal of prepolymer-containing aerosol cans for the production of polyurethane foams, in this case only as an example is given.

Polyurethane foams have found widespread use in many fields. In particular in construction, they are widely used for sealing and insulating, as well as in other technical fields. As a rule, polyurethane foams are applied from aerosol cans that contain a polyurethane prepolymer together with the required blowing agent and any additives that may also be required. These aerosol cans are under pressure and cannot and must not be reused after use. On the other hand, they represent problem waste that is not accessible for normal disposal. In addition, aerosol cans from older production in particular regularly contain fluorinated chlorinated hydrocarbons, which should not be released into the atmosphere. More recent aerosol cans contain flammable propellants, such as propane, butane or dimethyl ether, which form explosive mixtures with air.

In the context of efforts to contain domestic and commercial waste, measures are increasingly being discussed and prescribed which compel manufacturers to take back the packaging of their products after use and to ensure that they are reused or disposed of themselves. Such measures have made it necessary to look for ways of economically treating such waste. In the treatment of withdrawn aerosol cans for polyurethane foam production there are a number of problems which complicate the economic reprocessing. For example, part of the cans taken back is under considerable pressure due to the propellant gas still remaining therein, which makes opening and combustion both a problem. Furthermore, the cans have a different filling state, from old cans with practically complete prepolymer filling, which can no longer be dispensed due to a blocked valve, to practically completely emptied cans with only the edges residual of prepolymer in uncrosslinked to crosslinked! Condition is enough.

So far, a number of processes for the preparation of packaging, including aerosol cans for the production of polyurethane foam, have become known. For example, it has been proposed to inject pressure cans via a lock system into a plant under intergas and to comminute them there. Furthermore, methods have become known for introducing aerosol cans into a plant, comminuting them there and extracting the ingredients with suitable solvents. In this process, both the packaging materials and the ingredients (prepolymer, propellant) are obtained.

These known methods, some of which are quite efficient and are practiced, can be improved with regard to occupational safety, process management and efficiency. In particular, there are problems in a simple manner in which the residues contained in the packaging can be separated and passed on for suitable further use. Further problems arise from the fact that the packaging contains toxicologically unsafe substances as well as flammable solvents and propellant gases that can result in explosive gas mixtures after opening.

The invention is therefore based on the object of providing a method by which packaging, for example containers which contain polyurethane prepolymer, in particular for foam production, but also for adhesive purposes, is prepared together with solvents and / or propellant gases, and the valuable materials contained therein are obtained can be used without the uncontrolled release of ingredients which are harmful to health and the environment and without the process sequence being burdened by propellant gases released from the embal layers. The method is intended to meet the requirements for occupational safety and, in particular, to convert reactive residues still contained in the packaging into a form suitable for direct further processing.

According to the invention, this object is achieved with a method of the type mentioned at the outset, in which the packaging is introduced into a cold zone and cooled to such an extent that residues therein are solidified, the packaging is then comminuted in a cooled state, after which the comminuted packaging is placed in a the fraction containing the reactive residues and at least one further fraction are separated, the fraction containing residues is introduced into a mixing zone into which an agent reactive with the residues is introduced at the same time, optionally together with a catalyst, where the temperature in the mixing zone is kept below the softening temperature of the residues, such as the reactive agent, and the mixture thus obtained of the fraction containing residues and reactive agent and, if appropriate, catalyst analyzer is brought to a temperature sufficient for the reaction in a reaction zone and allowed to react completely.

With the method according to the invention it is possible to open and further process packaging in a completely harmless manner. In particular, it is achieved that the various materials contained in the packaging can be separated in a safe manner. The reactive residues, for example in the case of pressure cans for the production of polyurethane foam-containing prepolymers containing isocyanate and propellant gases, are treated in a manner which is safe from a safety point of view. Freezing the ingredients contained in the packaging does not result in an increase in pressure in the process or in undesirable reactions between reactive components. At the temperatures prevailing in the process, the presence of water is also harmless. The latter two points are important in the treatment of isocyanate-containing products if, for example, water is carried into the process due to damaged packaging. At the same time, reactive second components, for example glycols, contained in so-called ZK foams can be introduced into the process without problems. In this respect, the method according to the invention is suitable for treating both pressure cans for 1-component and 2-component foams as well as transitional forms between the two at the same time.

In the process according to the invention, the packs, for example pressure cans, are first introduced into a cold zone and cooled therein to such an extent that the residues therein, including those of low boiling point Solidify propellants. In general, temperatures of less than -80 ° C to -100 ° C are sufficient for this; However, it is expedient to work in liquid nitrogen as the cooling medium. In this case it is important that the process is carried out in the absence of oxygen in order to avoid the condensation of liquid oxygen, which could have a disadvantageous effect in later process steps.

The introduction into the cold zone is expediently carried out with a cellular wheel blow-through lock, with which the packaging to be introduced is introduced into a guide cage running in the cooling medium. In the cold zone, the packaging is then passed a sufficient distance through the cooling medium in order to achieve complete freezing.

After reaching the desired temperature, generally the temperature of liquid nitrogen, the packaging is led into the comminution zone, where it is comminuted in the cold state. The temperatures here should expediently be below -80 ^β C to -100 ^β C; if necessary, liquid nitrogen or cold gaseous nitrogen must be injected.

The comminution is expediently carried out in a hammer mill that works against a sieve. As a result, a shaking and flexing effect is achieved which - in addition to the comminution to a desired grain size - brings about a separation of the different materials: metal, paper, plastic and contents. It has surprisingly been found that the packaging materials - metal, paper and plastic - can be separated extraordinarily well from the ingredients - reactive residues and solvents / blowing agents in powder form. sen, the ingredients being obtained as a fine powder.

In a subsequent separation stage, the crushed packaging is separated into at least two fractions, one of which contains the reactive residues, including the propellant gas, in the solid state. A screen is expediently provided in this separation stage, expediently a vibrating screen through which the fine constituents, predominantly reactive residues and propellants, fall. Metal parts are separated using magnetic methods, larger plastic parts and scraps of paper are screened off on the vibrating screen.

The frozen constituents from reactive residues and propellant gases pass from the separation zone into a mixing zone, into which an agent reactive with the residues is introduced at the same time. Also in this mixing zone prevail Temperatu¬ ren of less than -80 ^β C to -100 ° C to the ge frozen state of the materials introduced to ensure and the injected reactive agent immediately to solidify to a fine powder. The result of this is that a uniform mixture of ingredients in powder form and reactive agent is formed, which, however, cannot react due to the prevailing temperature conditions. The temperatures in the mixing zone are in each case below the melting point of both the residues and the reactive agent.

A spray tower, into which the frozen ingredients fall from above, is expediently used as the mixing zone. The reactive agent is injected into this powder stream from side nozzles. sprayed, expediently together with cold gaseous nitrogen, in order to ensure the required low temperatures. Pre-cooling of the reactive eye is advisable, but the sprayability must remain guaranteed.

It may be appropriate to inject the reactive agent together with a catalyst which promotes the reaction with the reactive residues of the packaging. In the case of isocyanate-containing l'roμoIynioron ies nbor in nl ly moiIIPII is not required, since the isocyanana-containing mixtures already contain such catalysts.

The powdery mixture of ingredients and reactive agent and, if appropriate, catalyst is then passed into a reaction zone which, for example, consists of a conveyor belt moving continuously under the mixing zone. The powder collecting here is then brought to a temperature sufficient for the reaction Any solvents or propellant gases present evaporate on this occasion and are condensed at a suitable point, which is not a problem when using nitrogen as a refrigerant. In order to give the reaction product the desired shape, the conveyor belt can have lateral limitations To separate the reaction product from the conveyor belt, it is possible to provide separating agents, for example suitable coatings or release paper, and the heating in the reaction zone is expediently carried out using microwaves, which rapidly and directly heat the P Effect ulver material from the inside, so that there is a uniform degassing. Following the reaction zone, further processing and treatment zones can be provided, and finally a lock for discharging the fully reacted material.

As already mentioned, the method according to the invention is particularly suitable for processing residue-containing polyurethane foam pressure cans. In this case, the reactive agent is in particular a compound containing hydroxyl groups, for example water, ethylene glycol, propylene glycol, glycerol, oligomers and mixtures thereof and derivatives thereof. Ethylene glycol is preferred.

In the preparation of packaging for the production of polyurethane foams, it is advisable to convert the isocyanate-containing prepolymers themselves into foam materials in the process, which can be used, for example, for insulation and insulation purposes. Thus, with the method according to the invention, insulation boards can be produced continuously, the propellant gases contained in the powder produced in the mixing zone promoting foam formation. However, it is also easily possible to produce foils or to add additives, for example cellulose-containing materials. and then compress these mixtures into composite materials during or after the reaction. However, it is preferred to produce granules from reacted material, which is later processed.

The method according to the invention is explained in more detail by the accompanying figures. From this shows

1 schematically shows an embodiment of a system for carrying out the method according to the invention; FIG. 2 shows the entrance area of the system according to FIG. 1;

3 shows the conveying, comminuting and sorting part of the plant according to FIG. 1;

4 shows the mixing and reaction zone of the plant according to FIG. 1;

5 shows details of the feeding of the cellular wheel sluice;

6 shows details of the guidance of the transport system in plan view and

Fig. 7 the guide of Fig. 6 in cross section.

The illustration of an embodiment of the processing system according to the invention shown in the figure has an entrance lock 1, to which the pressure cans 13 to be treated are fed via a conveyor and sorting belt 11 (FIG. 5). The entrance lock is preferably designed as a cellular wheel blow-through lock, in the chambers 12 of which the cans 13 fall from above via a feed funnel 14 (FIG. 2). By rotating the cell wheel 1, the cans enter the lower region of the lock and are laterally ejected from the line 15 with the aid of gaseous nitrogen GAN. To facilitate this, the star feeder turns in a top _^ open, gas-tight container from which it can be aufschlagt be¬ in its lower region with a side un¬ ter pressurized gaseous nitrogen GAN, so that the pressure cell is befindli¬ che 13 can be ejected into a guide system 21 on the opposite side. The nitrogen supply via line 15 is preferably gaseous nitrogen from the Cold bath 2 ensured. It goes without saying that the rotational speed of the cellular wheel 1 and the pressure surges from the nitrogen line 15 for ejecting the pressure cans from the cellular wheel are coordinated with one another. For this purpose, the cellular wheel has a sensor marked with M.

The cans pass from the cell wheel via a guide 21 into the cold bath 2, which is filled with liquid nitrogen. The guide 21 expediently consists of an elongated basket construction which is open on all sides and which enables the unhindered entry of liquid nitrogen and exit of gaseous nitrogen. Details of the guide 21 and the transport device 23 for transporting the pressure sockets 13 are described in more detail below in connection with FIGS. 4 and 5.

On their way through the cold bath 2, which is fed with fresh liquid nitrogen LIN via line 24 depending on the level and has a measuring sensor LIC for level control, the pressure cans 13 are cooled to the bath temperature. The cage structure of the guide 21 ensures the free access of the refrigerant and the rapid removal of the gaseous nitrogen generated. Gaseous nitrogen is drawn off from the bath area via line 16 with the aid of a fan 17. The length of the guide 21 and the Transport¬ speed are adjusted so that the Druck¬ cans 13 also at complete rest panel to a sufficiently low temperature of at least - 80 ^β C to -100 C ^β are cooled.

The pressure sockets 13 are transported in the guide 21 with the aid of the transport device 23, which expediently consists of a conveyor belt 25 which is guided in a circle and has transport gates protruding therefrom. beln 26, which engage from above in the guide 21 and push the cans 13 guided in front of it. Transport rollers 27 ensure precise guidance of the transport forks 26. The forks 26 are arranged on the conveyor belt 25 at intervals which are matched to the size of the pressure cans 13 to be transported. A measuring station M is used to monitor the transport speed and to coordinate it with the feed speed of the pressure cans 13.

After passing through the cooling bath 2, the pressure cans 13 pass from the guide 21 into the conveying device 3 (FIG. 3) in the form of a revolving conveyor belt 31 which has transport segments which are matched to the size of the cans 13. The conveying device 3 is preferably designed as a steep conveyor which receives the pressure cans 13 in the segments formed by transport forks 33 arranged at regular intervals and releases them overhead into the comminution device 4. The conveyor belt is guided over rollers 32 provided with a measuring station M for monitoring and controlling the conveying speed.

The crushing device 4 consists of a shredder or preferably a hammer mill 41. The hammer mill 41 preferably works against a sieve in order to ensure a certain grain size of the crushed material. At the same time, the sieve 42 has a flexing effect, which has a positive effect on the separation of the contents, which are embrittled by the cold, from the metal of the jacket and existing plastic parts of the valve. It is understood that for the Aufrechererhaltung er¬ ford variable low temperatures of -80 ° C to - 100 C ^β refrigerant, preferably liquid nitrogen LIN may be added via line 43 when the temperature control TK reports an impermissible temperature increase. The working speed is controlled and controlled via the sensor M. Gaseous nitrogen is discharged via the line 44 and recycled or blown off via a valve 45.

The comminuted material passes from the comminution 4 into the sorting device 5. This initially consists of a vibrating sieve 51, on which the coarse and the fine parts are separated. Coarse particles are mainly the comminuted sheets of the compressed gas container, which are shaken off on the inclined sieve 51 and are discharged from the process via a lock, not shown.

Powdery ingredients and fine fractions of the pressure can body and the valve mechanism pass through the vibrating screen 51 onto a first magnetic separator 52, which separates the remaining iron and aluminum components from plastic particles and ingredients. Magnetic components are first separated on the first magnetic separator 52 and placed on a first conveyor belt 53, which also receives the metal and plastic parts shaken off the screen 51. A second conveyor belt 54 receives plastics, ingredients and non-magnetic metal parts, which are separated into metallic and non-metallic components via a second magnetic separator 55 coupled to the conveyor belt. The metallic components get on the first conveyor belt 53, the non-metallic components are fed directly into the spray tower 6. Cold gaseous nitrogen can be supplied via line 56 if the temperature control TIC reports an impermissible temperature increase. Measuring sensors M check the speed of all moving parts of the separation system 5.

It goes without saying that a temperature of at most -80 ° C. to -100 ° C. is guaranteed in the comminution system as well as in the sorting device by corresponding supply lines for refrigerants, preferably nitrogen in gaseous or liquid form .

The powdery ingredients and plastic parts reaching the spray tower 6 (FIG. 4), which have a temperature of at most -80 ° C. to -100 ° C., so that propellant gases contained therein are also present in a solid state with reaction medium sprayed in via spray line 6 in the upper region of spray tower 6 and optionally catalyst. The reaction medium, preferably ethylene glycol, is in the liquid state in the storage tank 62, the catalyst in the storage tank 63. Dosing stations are assigned to both tanks.

Reaction medium from the container 62 and catalyst from the container 63 are injected via the line 61 into the spray tower 6 in a metered ratio to the reactive constituents, it being possible for a precooling section to be provided in the course of the supply line 61 in order to divide the materials onto a cool to acceptable temperature (above the melting point). However, the spray material solidifies within the spray tower, even at the temperatures of less than -80 ° C to -100 ° C. To maintain the temperature in the spray tower, it is therefore advisable to introduce additional cooling medium, for example liquid nitrogen LIN via line 64 or gaseous nitrogen via line 65, if the temperature control TIC reports a need. It is It is expedient to inject the cooling medium in the lower regions of the spray tower in order to ensure an additional swirling and mixing of reactive compound, catalyst and reactive can content through the cold nitrogen rising in the spray tower 6.

The mixture of reactive can content, reactive compound and catalyst in powder form reaches the reaction space 7 from the spray tower 6. A reaction belt 71 is arranged inside the reaction space 7, which takes up the falling material from the spray tower 6 and into the actual one Reaction zone 72 leads where the reaction is induced by heat. For this purpose, heating elements 73 are arranged above the conveyor belt 71, which use microwave or infrared rays to heat the reaction material on the conveyor belt 71 to a temperature sufficient for the reaction, for example room temperature or above.

In order for the reaction material 74, e.g. H. the mixture of reactive can contents, reactive compound and catalyst to prevent the conveyor belt 71, it may be appropriate to cover the conveyor belt with a separating film 75 which is unwound from a roll 76a and wound onto a second roll 76b. The release film can be used several times if necessary.

The reaction material reacts on the conveyor belt 71 to the respectively desired product. At the same time, blowing agent and adsorbent nitrogen of the refrigerant still contained in the mixture from the spray tower are released and sucked off via line 77 and fed to a blowing agent separation (not shown) and extraction. The blowing agent escapes from the reac- tion material 74 causes a partial foaming of the reaction material, which is not undesirable for certain uses.

At the end of the conveyor belt 71 there is a scraper 78 with which the reacted reaction material is released from the conveyor belt or the separating film and discharged from the process via the product lock 8 and discharged via a conveyor belt 81. Nitrogen lines 81 and 82 regulate the supply of protective gas in the lock area, nitrogen being expediently used as the protective gas, but this need not be cooled. Further nitrogen lines 83 and 84 in the area of the entry and exit of the separating film 75 prevent the entry of oxygen into the system in this area. The use of cooling nitrogen is not necessary here either.

It goes without saying that the method according to the invention is carried out in a cold and heat insulated system. In particular, the entry of oxygen must also be prevented in order to prevent liquid oxygen from condensing into the cooling bath 2. It is advantageous for the gas guidance that the entire process is carried out into the spray tower 6 at temperatures at which propellant gases are present in a solid state. This allows propellant gases to be drawn off centrally via the suction line 77 in the reaction chamber 7 and for extraction feed. The fully reacted / hardened polyurethane material, which exits the process from the product lock 8, can be used as granules for any further use. For example, the use for insulating materials and in composite materials comes into question. 5 shows details of the lock system at the entrance to the method, the cellular wheel blow-through lock being rotated by 90 ° in relation to the illustration in FIGS. 1 and 2.

The pressurized cans intended for the process with the polyurethane prepolymer residues 13 are introduced into the cells 12 of the cellular wheel blow-through lock 1 via the conveyor and sorting belt 11. A feed hopper 14, under which the lock rotates away, ensures the precise insertion of the nozzles 13.

The conveyor and sorting belt 11 expediently has ribs or forks 15 which separate the cans 13 transported on the conveyor belt from one another. In this way, at a given conveying speed, the cycle of dispensing the cans can be matched precisely to the transport speed of the rotary valve 1 and the transport cycle in the guide 21 of the cooling bath 2. The specification of a cycle also allows the cans 13 to be brought out of the sluice 1 with the aid of pressurized nitrogen through the line 15 (FIG. 2).

As can be seen from FIG. 5, the blow-through sluice 1 opens at its lower end (opposite the feed hopper 14) into the guide 21 into which the pressure sockets slide and with the help of the pressure surge from the line 15 in the direction of the transport device 23 are expelled.

6 and 7 show details of the guide 21 and the transport device 23 for transporting the pressure sockets 13 within the guide 21.

The guide 21 has an overall elongated, cage-like or basket-like structure. The leadership essentially consists of parallel guide rails 22 which leave enough space for the entry of liquid nitrogen and the exit of evaporated nitrogen. The guide rails 22 are held together on the outside by fixing rings 27 such that the relative position to one another is fixed. The fixing rings encompass the entire guide 21 with the exception of the upper end, where the space between two guide rails 22 remains free, so that a transport fork 26 or the like can engage from above and push the cans 13 located in the guide 21 through the guide. The result is an elongated cage made of rails 22 guided in parallel and encircling fixing rings 27, which in the upper region leaves a free space for the movement of the transport fork 26 over its entire length. The size of the cage is matched to the size of the pressure cans and is selected so that the cans cannot become jammed when they are passed through. In the illustration, the can 13 is transported with the bottom first in the direction of the arrow, the fork 26 comprises the valve region 18.

The transport forks 26 are located on a conveyor belt 25 which, via a correspondingly arranged system of transport rollers 27, conveys the cans through the guide 21 to the conveyor belt 31, where they fall out of the guide 21 and from the transport elements 32 of the conveyor belt 31 be included. From the end of the guide 21, the conveyor belt 25 is moved back over the bath 2 in the direction of the rotary valve 1, where the gates Bails 26 engage in the guide 21 again at a designated location and transport the pressure cans located in the guide through the bath 2. It goes without saying that the entire guide 21 runs in the area of the actual cooling section in the cooling bath 2 in such a way that liquid nitrogen is washed around the cans on all sides.

Claims

Expectations

1. A process for the preparation of packaging containing reactive residues, in particular pressure cans for the production of polyurethane foams with propellant gases, characterized in that the packaging is introduced into a cold zone and cooled to such an extent that residues contained therein solidify , the packagings are then comminuted in a cooled state, after which the comminuted packagings are separated into a fraction containing the reactive residues and at least one further fraction, the fraction containing reactive residues is introduced into a mixing zone, into which a zone containing the Residues of reactive agent, if appropriate, is introduced together with a catalyst, the temperature in the mixing zone being kept below the softening temperature of the residues, such as that of the reactive agent, and the mixture of reactive reagent thus obtained The fraction containing the k state and thus the reactive agent and optionally the catalyst are brought into a reaction zone to a temperature which is sufficient for the reaction and allowed to react completely.

2. The method according to claim 1, characterized in that it is carried out at a temperature <-80 ° C.

3. The method according to claim 2, characterized in that the method is carried out in the absence of oxygen.

4. The method according to claim 3, characterized in that the packaging is passed through a bath with liquid nitrogen.

5. The method according to any one of the preceding claims, characterized in that the packaging is introduced into a cooling section with the aid of a cellular wheel blow-through lock.

6. The method according to any one of the preceding claims, characterized in that the packaging is crushed at a temperature <- 80 ° C with a hammer mechanism working against a sieve.

7. The method according to any one of the preceding claims, characterized in that the reactive residues contained in the packaging are pulverized during comminution.

8. The method according to any one of the preceding claims, characterized in that the mixing zone is a spray tower.

9. The method according to claim 8, characterized in that the reactive agent is sprayed into the powder passing the spray tower from reactive residues.

10. The method according to claim 8 or 9, characterized gekenn¬ characterized in that gaseous or liquid cold nitrogen is injected for temperature control in the spray tower.

11. The method according to any one of the preceding claims, characterized in that the reaction zone is heated with microwaves.

12. The method according to any one of the preceding claims, characterized in that evaporating propellant gases are separated by condensation in the reaction zone.

13. The method according to any one of the preceding claims, characterized in that in the packaging contained reactive residues are prepolymers containing isocyanate groups for the production of polyurethane foam.

14. The method according to claim 13, characterized in that the reactive agent is a hydroxy group-containing compound.

15. The method according to claim 14, characterized in that the hydroxy group-containing compound is ethylene glycol.

16. The method according to any one of the preceding claims, characterized in that additives are added in the mixing and / or reaction zone.