Method for treating residues resulting from the production of organic isocyanates

Abstract

The present invention relates to a method for treating residues resulting from the production of organic isocyanates by phosgenation of organic amines, the method comprising the step of mixing a first residue A and a second residue B to obtain a residue mixture, where residue A is obtained from the production of 1,5-pentane diisocyanate and residue B is obtained from the production of an isocyanate other than 1,5-pentane diisocyanate. The present invention further relates to the use of the first residue A resulting from the production of 1,5-pentane diisocyanate for stabilizing a second residue B resulting from the production of at least one organic isocyanate other than 1,5-pentane diisocyanate, and to the stabilized residue mixture.

Description

[Technical Field]

[0001] The present invention relates to a process for treating residues resulting from the production of organic isocyanates by phosgenation of organic amines. The present invention also relates to the use of residues resulting from the production of 1,5-pentane diisocyanate and to stabilized residue mixtures. [Background technology]

[0002] The industrial-scale production of isocyanates by reacting amines with phosgene is known and is described in detail in the literature (e.g., Ullmanns Encyclopedia der technischen Chemie, 4th edition, volume 13, pages 347-357, Verlag Chemie, GmbH, D-6940 Weinheim, 1977, or EP 1575908A1). The production of pure distilled diisocyanates in a distillation process usually produces by-product streams that must be disposed of as residue after removing as much free isocyanate as possible by distillation.

[0003] Such residues always carry reactive groups and therefore carry the risk of exothermic reactions leading to and including thermal runaway (i.e. exothermic chemical reactions and uncontrolled overheating of the technical equipment in which the residues are stored). To avoid this, studies are carried out on the thermal stability of the residues, with the aim of identifying the amount of heat released by the reaction and the so-called onset temperature (i.e. the temperature above which the reaction begins and energy is released). The residues can then only be stored for a specific time at a temperature that allows for a safety margin below the onset temperature.

[0004] Since it is advantageous to handle the residue in liquid form, and since the freezing point increases as the concentration of high-boiling by-products in the residue increases, the lower the onset temperature and the lower the temperature tolerance of the residue, the more dilution of the residue is required, so that either more valuable product remains in the residue or additional measures must be taken, such as adding a solvent.

[0005] To avoid unexpected reactions among the residues, it is typically desirable to treat different residues separately and not mix them. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] EP 1575908A1 [Non-patent literature]

[0007] [Non-Patent Document 1] Ullmanns Encyklopadie der technischen Chemie, 4th edition, volume 13, pages 347-357 [Non-patent document 2] Verlag Chemie, GmbH, D-6940 Weinheim, 1977 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention was therefore to provide a process which does not have the aforementioned drawbacks of the prior art and which allows improved handling of the residue mixtures resulting from the production of organic isocyanates. [Means for solving the problem]

[0009] This object is achieved according to the present invention by a process for treating residues resulting from the production of organic isocyanates by phosgenation of organic amines, the process comprising a mixing step of mixing a first residue A with a second residue B to obtain a residue mixture, wherein residue A is obtained from the production of 1,5-pentane diisocyanate and residue B is obtained from the production of an isocyanate other than 1,5-pentane diisocyanate.

[0010] Surprisingly, it has been found that mixing residues (preferably distillation residues) from the production of 1,5-pentane diisocyanate (hereinafter also referred to as pentamethylene diisocyanate or PDI) with other residues from the production of isocyanates other than pentamethylene diisocyanate does not increase the risk of an uncontrollable exothermic reaction, and in fact, in many cases, reduces the risk. This makes it possible to mix such residues without reducing the safety of the process, and therefore achieves technically favorable effects (for example, longer storage stability of the mixed residues or reduced equipment costs by saving additional residue storage tanks). DETAILED DESCRIPTION OF THE INVENTION

[0011] According to the present invention, the terms "comprising" or "containing" are preferably understood to mean "substantially consisting of", and particularly preferably to mean "consisting of". The further embodiments set out in the claims and in the description can be combined as desired, unless the context clearly indicates otherwise.

[0012] An "organic compound" or "organic radical" contains at least one unit containing a covalently bonded carbon-hydrogen bond.

[0013] The term "aliphatic" is defined herein to mean a saturated or unsaturated non-aromatic hydrocarbon group.

[0014] The term "araliphatic" is defined herein to mean a hydrocarbon radical consisting of both an aromatic hydrocarbon group and a saturated or unsaturated hydrocarbon group directly attached to the aromatic radical.

[0015] The terms "alicyclic" or "cycloaliphatic" are defined herein to mean optionally substituted carbocyclic or heterocyclic compounds or units that are not aromatic.

[0016] "At least one," as used herein, indicates one or more, e.g., 2, 3, 4, 5, 6, 7, 8, 9, or more. In reference to the components of the compounds described herein, this number does not indicate an absolute number of molecules, but rather indicates the nature of the component. Thus, for example, "at least one isocyanate different from pentamethylene diisocyanate" is understood to mean that there can be only one compound of this type or two or more different types of compounds of this type, without specifying the amount of each compound.

[0017] Numerical ranges expressed in the format "in / from x to y" are inclusive of the recited values. When more than one preferred numerical range is expressed in this format, it is understood that all ranges resulting from combining the various limits are also encompassed.

[0018] The process according to the present invention can be advantageously used, for example, in a manufacturing plant for producing organic isocyanates, when campaigns are carried out in which different organic isocyanates are produced, one of which is pentamethylene diisocyanate. In the production or purification of different organic isocyanates, a residue A and a second residue B may be produced at different times and may be mixed, for example, to achieve a desired effect (e.g., stabilization) in a residue storage tank. Therefore, it is not necessary to provide different residue storage means for each type of residue. Even if there is only one residue storage tank, it is not necessary to completely empty, much less clean, the tank when changing campaigns. Instead, a specific amount of the residue mixture can always be kept to allow for optimal concentration of each residue in the distillation and to benefit from stabilization by mixing with the 1,5-pentane diisocyanate-based residue.

[0019] Another opportunity arises when two production and / or distillation units for different organic isocyanates are located at the same site. In this case, residue A and residue B are produced simultaneously and can be subjected to a mixing step according to the process of the present invention. This step can be carried out in the piping where the residues are transferred to a collection and storage tank, a transport container, or an incineration plant, or in the residue storage tank. In the case of mixing in the piping, the residues can simply be mixed in the piping. The mixing of residue A and residue B is preferably improved using a static mixer or a dynamic mixing unit (e.g., one or more mixing pumps, dispensers, or agitated vessels). If mixing is carried out in the collection and storage tank, it preferably has dedicated inlet ports for each of the different residues, optionally equipped with dip tubes. Mixing is then carried out in the collection and storage tank using agitation means and / or a pump-operated circulation means (which can also be used to control the temperature of the residues). Mixing is preferably carried out in the collection and storage tank using agitation means.

[0020] Residue A is a liquid residue or suspension (preferably a liquid residue) obtained in the production of pentamethylene diisocyanate and containing not only PDI but also compounds formed based on PDI, for example, with a boiling point higher than that of PDI. These may include, for example, PDI oligomers, such as carbodiimides or trimers, ureas, urethanes, and even chlorinated compounds, such as carbamoyl chloride. Preferably, residue A is a liquid distillation residue obtained at the bottom of a column separating a mixture of PDI-containing substances from PDI. In this case, such residue A is also referred to as "from the production of pentamethylene diisocyanate."

[0021] Residue B is a liquid residue or suspension (preferably a liquid residue) obtained in the production of at least one isocyanate other than pentamethylene diisocyanate, and contains not only the at least one isocyanate but also, for example, compounds formed based on the at least one isocyanate and having a higher boiling point than the respective isocyanate. It is preferably a residue from the production of exactly one isocyanate other than PDI. Preferably, the at least one isocyanate other than PDI, in the production and / or purification process of which residue B is generated, is at least one aliphatic, cycloaliphatic, and / or araliphatic diisocyanate, particularly preferably at least one cycloaliphatic and / or araliphatic diisocyanate. More preferably, the at least one isocyanate other than PDI is hexamethylene diisocyanate, diisocyanatohexylmethane, isophorone diisocyanate (IPDI), bis(isocyanatomethyl)norbornane (NBDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, and / or xylylene diisocyanate, particularly preferably hexamethylene diisocyanate, diisocyanatohexylmethane, isophorone diisocyanate (IPDI), and / or xylylene diisocyanate, very particularly preferably IPDI and / or xylylene diisocyanate, most preferably IPDI and / or m-xylylene diisocyanate (hereinafter also referred to as XDI). In this case, such residue B is also referred to as "originating from the production of at least one isocyanate other than pentamethylene diisocyanate." Preferably, the at least one isocyanate different from PDI is exactly one isocyanate different from PDI and, optionally, its isomer, and therefore also the residue is based solely on this one isocyanate different from PDI and, optionally, its isomer.

[0022] Both the production process, i.e. the synthesis itself and the purification process, are encompassed in the present invention by the production of isocyanates, so that in this case the term "production of isocyanates" does not only relate to the production itself, but rather also to residues resulting from the production of isocyanates, which may have been produced by distillation as well.

[0023] In a further embodiment of the process according to the invention, residue A and / or residue B, preferably residue A and residue B, are distillation residues.

[0024] In a preferred embodiment, residue B originates from the production of exactly one aliphatic, cycloaliphatic or araliphatic diisocyanate other than 1,5-pentane diisocyanate, preferably from the production of exactly one araliphatic or cycloaliphatic diisocyanate. Particularly preferably, residue B originates from the production of hexamethylene diisocyanate, diisocyanatohexylmethane, IPDI, bis(isocyanatomethyl)norbornane (NBDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane or xylylene diisocyanate, very particularly preferably from the production of IPDI or xylylene diisocyanate, most preferably from the production of IPDI or XDI.

[0025] To maximize the yield of valuable products and thus maximize the economic viability of the production process, it is desirable for residue A and / or residue B to contain as little of the corresponding valuable product as possible. However, an excessively low residual content of monomeric isocyanate can result in a severe viscosity increase, including solidification of the residue, so in practice, a compromise must always be reached. The residue, upon removal from isocyanate production, typically contains approximately 5% to 85% by weight, preferably 10% to 60% by weight, particularly preferably 15% to 50% by weight, and very particularly preferably 20% to 40% by weight of monomeric isocyanate. The temperature can, in principle, be selected as desired. A higher temperature of the residue helps to keep the viscosity low and, therefore, the pumpability. However, a drawback to increasing the temperature is that the components of the isocyanate residue can undergo exothermic reactions with each other or with themselves. Temperatures in the range from 15° C. to 180° C., preferably in the range from 40° C. to 150° C., particularly preferably in the range from 60° C. to 110° C., have proven to be an advantageous compromise.

[0026] Therefore, it is also preferred that the temperature in the mixing step is at least periodically, preferably continuously, in the range of 15°C to 180°C, preferably in the range of 40°C to 150°C, particularly preferably in the range of 60°C to 110°C.

[0027] To reduce temperature and concentration fluctuations, at least one residue mixture obtained through the mixing step is preferably stored in at least one residue container, where the mixing step can be carried out in a separate mixing device upstream of the residue container or, preferably, in the residue container itself. The amount of residue mixture present in the residue container buffers fluctuations in the incoming residue flow.

[0028] The above considerations regarding the preferred temperature in the mixing step also apply to the storage of at least one residue mixture obtained in the mixing step. The temperature during storage is therefore at least periodically, preferably continuously, within the range of 15°C to 180°C, preferably within the range of 40°C to 150°C, particularly preferably within the range of 60°C to 110°C. It is particularly important to observe temperature limits during long-term storage of the resulting residue mixture, since the possibility of harmful effects such as solidification or exothermic decomposition of the residue increases with increasing storage time. When storing residues, it is advantageous to limit the residence time of the residue in the storage container. The residence time is preferably at most 28 days, particularly preferably at most 7 days, very particularly preferably at most 2 days, and most preferably at most 1 day. The calculated residence time, obtained by dividing the available volume by the volumetric flow rate of the residue stream through the residue container, is important. If the inflow and / or outflow of the residue occurs discontinuously or at a non-constant volumetric flow rate, the time-averaged value of the volumetric flow rate may be used.

[0029] Storage in residue containers can lead to the deposition of residue components on the walls of the residue container. This risk is particularly high in the area of ​​the heating or cooling devices. Sediments may also form at the bottom of the residue container, which can cause blockages. To prevent these problems, it is advantageous to agitate, preferably stir, the at least one residue mixture in the at least one residue container at least periodically, preferably continuously.

[0030] In a further preferred embodiment of the process according to the invention, in the mixing step, residue B is mixed with an effective amount of residue A, which results in stabilization of residue B, preferably accompanied by an increase in the onset temperature compared to residue B alone. Depending on the type of residue B, the effective amount of residue A may vary. This amount can be determined, for example, in preliminary tests by producing mixtures of residue A and residue B at various mixing ratios and then checking their thermal stability by differential scanning calorimetry (DSC) according to DIN EN ISO 11357-1:2017-02. The effective amount of residue A can be derived directly from the mixing ratio at which an increase in the onset temperature of the exothermic reaction of the residue is observed. If two or more exothermic reactions with different onset temperatures occur for residue B, the decisive one is the one with the lowest onset temperature at which the heat release exceeds a value of 100 J / g.

[0031] In a further embodiment of the process according to the invention, 10 to 80 parts by weight (preferably 30 to 75 parts by weight, particularly preferably 45 to 70 parts by weight) of residue A are mixed with 20 to 90 parts by weight (preferably 25 to 70 parts by weight, particularly preferably 30 to 55 parts by weight) of residue B, where residue B is in each case isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI) and / or 1,3- and 1,4-bis(isocyanatomethyl)norbornane (NBDI). (The residue A is a residue resulting from the production of m-cyclohexane, preferably a residue resulting from the production of isophorone diisocyanate), or 5 to 30 parts by weight (preferably 7 to 20 parts by weight) of residue A is mixed with 70 to 95 parts by weight (preferably 80 to 93 parts by weight) of residue B (in either case, residue B is a residue resulting from the production of xylylene diisocyanate, preferably a residue resulting from the production of m-xylylene diisocyanate).

[0032] The residue mixture obtained in the mixing step can be used, for example, as an additive to other isocyanates. However, due to the change in chemical composition and therefore in properties, this type of use is limited. In a preferred embodiment of the process according to the invention, thermal recovery of the residue obtained in the mixing step is carried out. For this purpose, the residue can be fed to incineration, either continuously or discontinuously. By mixing, the advantageous properties of the residue can be utilized. The residue can be handled, for example, at a relatively high temperature and therefore at a relatively low viscosity, which can reduce problems caused, for example, by blockages in the feed lances of combustion plants.

[0033] In a further preferred embodiment of the present invention, the monomeric diisocyanates are separated from the residual mixture obtained in the mixing step in a downstream process step. The separation of the monomeric diisocyanates is preferably carried out in at least one kneader, shovel, or roller dryer, preferably in a kneader or shovel dryer, particularly preferably in a shovel dryer, by producing a solid residue (preferably a flowable residue). The residual mixture obtained in the mixing step, optionally together with additives, is introduced into a dryer and separated into a gaseous fraction (hereinafter referred to as the gaseous mixture) essentially containing the monomeric diisocyanates and a residue significantly depleted in monomeric diisocyanates. This separation is carried out under negative pressure and at elevated temperature, which makes it possible to take advantage of the advantageous properties of the residue achieved by the mixing step of the process according to the invention, for example by allowing the use of higher temperatures.

[0034] The gaseous mixture of essentially monomeric diisocyanates obtained in this process step can be condensed to obtain a liquid mixture essentially comprising pentamethylene diisocyanate and at least one further diisocyanate different from pentamethylene diisocyanate. This liquid mixture can be used to produce polyurethanes, polythiourethanes and / or polyureas and is also an object of the present invention. If necessary, prior to the production of polyurethanes, polythiourethanes and / or polyureas, this liquid mixture can be subjected to further purification steps (e.g., distillation, filtration, crystallization and / or extraction) and / or mixed with additives. Preferably, the at least one further diisocyanate different from pentamethylene diisocyanate in the liquid mixture is hexamethylene diisocyanate, diisocyanatohexylmethane, isophorone diisocyanate (IPDI), bis(isocyanatomethyl)norbornane (NBDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane and / or xylylene diisocyanate, particularly preferably isophorone diisocyanate and / or xylylene diisocyanate, very particularly preferably isophorone diisocyanate and / or m-xylylene diisocyanate. Since the gas mixtures and residual liquid mixtures according to the invention recovered by the process according to the invention originate from the production of organic isocyanates by phosgenation of organic amines, they contain small amounts of additional compounds that are not present in the known directly produced process products. In connection with the liquid mixture according to the invention, the term "substantially" is understood to mean that preferably at least 95% by weight, particularly preferably at least 97% by weight, very particularly preferably at least 99% by weight, based on the total amount of the mixture, is pentamethylene diisocyanate and at least one further diisocyanate different from pentamethylene diisocyanate.

[0035] The present invention further provides a gaseous or liquid mixture obtained or produced by the process according to the invention. The gaseous or, optionally, liquid mixture can be subjected to a distillation operation in a further process step if required to isolate the monomeric pentamethylene diisocyanate and at least one diisocyanate different from pentamethylene diisocyanate.

[0036] The present invention further provides the use of a first residue A resulting from the production of 1,5-pentane diisocyanate to stabilize a second residue B resulting from the production of at least one organic isocyanate other than 1,5-pentane diisocyanate, wherein the stabilization is preferably accompanied by an increase in the onset temperature compared to residue B alone. Preferably, the residue in the use according to the invention is substantially derived from the production of an organic isocyanate by the phosgenation of an organic amine. Particularly preferred is the use of a first residue A resulting from the production of 1,5-pentane diisocyanate to stabilize a second residue B resulting from the production of at least one organic isocyanate other than 1,5-pentane diisocyanate, wherein the stabilization is preferably accompanied by an increase in the onset temperature compared to residue B alone, and wherein the residue is derived from the production of an organic isocyanate by the phosgenation of an organic amine.

[0037] The onset temperatures of individual residues or mixtures of various residues can be determined, for example, in preliminary tests using differential scanning calorimetry (DSC) according to DIN EN ISO 11357-1:2017-02. The onset temperatures of the exothermic reactions of the isocyanate residues are important. If two or more exothermic reactions with different onset temperatures are observed for a residue, the one with the lowest onset temperature at which the heat release exceeds a value of 100 J / g is important.

[0038] In a further preferred embodiment of the use according to the invention, the second residue B originates from the production of at least one aliphatic, cycloaliphatic or araliphatic diisocyanate different from 1,5-pentane diisocyanate, preferably from the production of an araliphatic or cycloaliphatic diisocyanate, particularly preferably from the production of hexamethylene diisocyanate, diisocyanatohexylmethane, isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane and / or xylylene diisocyanate, very particularly preferably from the production of IPDI and / or xylylene diisocyanate, most preferably from the production of IPDI or XDI.

[0039] In a further preferred embodiment of the use according to the invention, residue A and / or residue B, preferably residue A and residue B, are distillation residues. The use according to the invention is particularly suitable for distillation residues, since corresponding optimizations can be carried out in the preceding distillation steps. For example, the residual monomer content in the bottom product of the distillation column can be reduced, which can result in a reduction in the loss of valuable substances or a saving in part of the cooling capacity required to cool the residues to the respective acceptable storage temperature.

[0040] The present invention further provides a stabilized residue mixture comprising 10% to 80% by weight of a first residue A (derived from the production of 1,5-pentane diisocyanate) and 20% to 90% by weight of a residue B (derived from the production of isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI), or 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, preferably derived from the production of isophorone diisocyanate); or a stabilized residue mixture comprising 5% to 30% by weight of a first residue A (derived from the production of 1,5-pentane diisocyanate) and 70% to 95% by weight of a second residue B (derived from the production of xylylene diisocyanate, preferably derived from the production of m-xylylene diisocyanate).

[0041] Stabilization preferably means that the onset temperature is increased compared to residue B alone. Depending on the type of residue B, the effective amount of residue A may vary. This amount can be determined, for example, in preliminary tests by producing mixtures of residue A and residue B at various mixing ratios and then checking their thermal stability by differential scanning calorimetry (DSC) according to DIN EN ISO 11357-1:2017-02. The effective amount of residue A can be derived directly from the mixing ratio at which an increase in the onset temperature of the exothermic reaction of the residue is observed. If two or more exothermic reactions with different onset temperatures occur for residue B, the one with the lowest onset temperature is decisive. [Example]

[0042] Example The present invention will be described below with reference to FIGS. 1 and 2 and the following examples, but the present invention is not limited thereto.

[0043] For differential scanning calorimetry (DSC), in each case, a few milligrams of the residue mixture were weighed under nitrogen into a gold-plated steel crucible and sealed with a crucible press. The samples thus prepared were then analyzed in a DSC analyzer against a reference crucible filled with inert aluminum oxide. The analyzer met the requirements of DIN EN ISO 11357-1:2017-02. Both crucibles were heated at a heating rate of 3 K / min (so-called screening DSC), and the difference between the heat flux into the crucible containing the residue mixture and the heat flux into the reference crucible was recorded. According to DIN EN ISO 11357-1:2017-02, at the exothermic peak, i.e., at the reaction accompanied by the release of heat, the heat flux into the test sample crucible is lower than that into the reference crucible, and the recorded curve passes through a minimum accordingly. To assess thermal stability, the onset temperature of the first exothermic peak at which the heat release exceeded a value of 100 J / g, i.e., the temperature at which the difference in recorded heat flux began to diverge from the baseline of the test sample, was measured.

[0044] Example 1 Residues from the distillation of isophorone diisocyanate (IPDI) were mixed with residues from the distillation of pentamethylene diisocyanate (PDI) at various mixing ratios. The IPDI:PDI mass fraction ratios in the residue mixtures were 100:0, 90:10, 70:30, 50:50, 30:70, and 10:90. The mixtures were then analyzed by differential scanning calorimetry to measure the onset temperature of the exothermic reaction for each residue mixture.

[0045] Example 2 Residues from the distillation of isophorone diisocyanate (IPDI) were mixed with residues from the distillation of hexamethylene diisocyanate (HDI) at various mixing ratios. The IPDI:HDI mass fraction ratios in the residue mixtures were 100:0, 90:10, 70:30, 50:50, 30:70, and 10:90. The mixtures were then analyzed by differential scanning calorimetry to measure the onset temperature of the exothermic reaction for each residue mixture.

[0046] Discussion of Examples 1 and 2: The onset temperatures of Examples 1 and 2, respectively, were normalized so that a 100:0 mixture (i.e., stillage from the distillation of IPDI) achieved a value of 100. These normalized onset temperatures are recorded in FIG.

[0047] In the diagram of Figure 1, normalized onset temperature is plotted on the Y-axis and mass fraction of PDI or HDI residue is plotted on the X-axis. The graph of square data points represents the results for Example 1 (IPDI / PDI), and the graph of triangle data points represents the results for Example 2 (IPDI / HDI).

[0048] From the graph in Figure 1, it is clear that blends with PDI ranging from about 10 wt% to about 80 wt% PDI increase the onset temperature, resulting in stabilization of the residue blend, while none of the test blends exhibit a normalized onset temperature >100 due to the incorporation of HDI. Instead, the normalized onset temperature passes through a minimum, so the incorporation of HDI residue leads to destabilization of the IPDI residue blend.

[0049] Example 3 The residue from the distillation of m-xylylene diisocyanate (XDI) was mixed with the residue from the distillation of pentamethylene diisocyanate in various ratios. The XDI content:PDI content ratios in the residue mixtures were 100:0, 95:5, 90:10, 50:50, and 10:90. The mixtures were then investigated by differential scanning calorimetry. The normalized onset temperatures (normalized to a value of 100 for the pure XDI residue) are shown in Figure 2.

[0050] In the diagram of Figure 2, normalized onset temperature is plotted on the Y-axis and mass fraction of PDI residue is plotted on the X-axis. The graph of round data points represents the results of Example 3 (XDI / PDI).

[0051] From the graph in Figure 2, it is clear that blends with PDI residues having PDI contents ranging from about 5 wt% to about 30 wt% increase the normalized onset temperature, resulting in stabilization of the residue blends. [Brief explanation of the drawings]

[0052]

Claims

1. 1. A process for treating residues resulting from the production of organic isocyanates by the phosgenation of organic amines, the process comprising a mixing step of mixing a first residue A with a second residue B to obtain a residue mixture, wherein residue A is obtained from the production of 1,5-pentane diisocyanate and residue B is obtained from the production of an isocyanate other than 1,5-pentane diisocyanate.

2. 2. The process according to claim 1, characterized in that residue A and / or residue B, preferably residue A and residue B, are distillation residues.

3. 3. The process according to claim 1 or 2, characterized in that residue B originates from the production of at least one aliphatic, cycloaliphatic or araliphatic diisocyanate different from 1,5-pentane diisocyanate, preferably from the production of at least one araliphatic or cycloaliphatic diisocyanate.

4. 4. The process according to claim 1 , wherein residue B originates from the production of hexamethylene diisocyanate, diisocyanatohexylmethane, isophorone diisocyanate, bis(isocyanatomethyl)norbornane, 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane and / or xylylene diisocyanate, preferably from the production of isophorone diisocyanate and / or xylylene diisocyanate, particularly preferably from the production of isophorone diisocyanate and / or m-xylylene diisocyanate.

5. 5. The process according to claim 1, wherein the temperature of the mixing step is at least periodically, preferably continuously, between 15°C and 180°C, preferably between 40°C and 150°C, particularly preferably between 60°C and 110°C.

6. 6. The process according to claim 1, wherein the mixing step results in at least one residue mixture that is stored in at least one residue container, and wherein the mixing step can be carried out in a separate mixing device upstream of the residue container or, preferably, in the residue container itself.

7. 7. The process according to claim 6, characterized in that the temperature during storage is at least periodically, preferably continuously, between 15°C and 180°C, preferably between 40°C and 150°C, particularly preferably between 60°C and 110°C.

8. 8. The process according to claim 6 or 7, characterized in that the at least one residue mixture is agitated, preferably stirred, at least periodically, preferably continuously, in the at least one residue container.

9. 9. The process according to any one of claims 1 to 8, characterized in that the step of mixing an effective amount of residue A with residue B results in a stabilization of residue B, wherein said stabilization is preferably accompanied by an increase in onset temperature compared to residue B alone.

10. 10. The process according to claim 1, characterized in that 10 to 80 parts by weight of residue A are mixed with 20 to 90 parts by weight of residue B, wherein residue B is a residue from the production of isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI) and / or 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, preferably a residue from the production of isophorone diisocyanate, or 5 to 30 parts by weight of residue A are mixed with 70 to 95 parts by weight of residue B, wherein residue B is a residue from the production of xylylene diisocyanate, preferably a residue from the production of m-xylylene diisocyanate.

11. 11. Process according to any one of claims 1 to 10, characterized in that the residue is fed, continuously or discontinuously, to incineration.

12. 1. Use of a first residue A derived from the production of 1,5-pentane diisocyanate for stabilizing a second residue B derived from the production of at least one organic isocyanate different from 1,5-pentane diisocyanate, wherein the stabilization is preferably accompanied by an increase in the onset temperature compared to residue B alone, and wherein the residue is derived from the production of an organic isocyanate by phosgenation of an organic amine.

13. 13. Use according to claim 12, characterized in that the second residue B originates from the production of at least one aliphatic, cycloaliphatic or araliphatic diisocyanate other than 1,5-pentane diisocyanate, preferably from the production of at least one araliphatic or cycloaliphatic diisocyanate, particularly preferably from the production of hexamethylene diisocyanate, diisocyanatohexylmethane, isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane and / or xylylene diisocyanate, very particularly preferably from the production of isophorone diisocyanate and / or xylylene diisocyanate, most preferably from the production of isophorone diisocyanate and / or m-xylylene diisocyanate.

14. 14. Use according to claim 12 or 13, characterized in that residue A and / or residue B, preferably residue A and residue B, are distillation residues.

15. 1. A stabilized residue mixture comprising 10% to 80% by weight of a first residue A (wherein residue A is derived from the production of 1,5-pentane diisocyanate) and 20% to 90% by weight of a residue B (wherein residue B is derived from the production of isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI) or 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, preferably derived from the production of isophorone diisocyanate); or 5% to 30% by weight of a first residue A (wherein residue A is derived from the production of 1,5-pentane diisocyanate) and 70% to 95% by weight of a second residue B (wherein residue B is derived from the production of xylylene diisocyanate, preferably derived from the production of m-xylylene diisocyanate).

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