Process for treating residues from production of organic isocyanates

Abstract

The invention relates to a method for treating residues from the production of organic isocyanates by phosgenation of organic amines, comprising a mixing step of mixing a first residue A obtained from the production of 1, 5-pentane diisocyanates with a second residue B derived from a mixture different from 1, 5-pentane diisocyanates to obtain a residue mixture. The invention relates to the production of isocyanates of 1, 5-pentane diisocyanates. The invention also relates to the use of a first residue A from the production of 1, 5-pentane diisocyanates for stabilizing a second residue B from the production of at least one organic isocyanate different from 1, 5-pentane diisocyanates, and to the stabilized residue mixture.

Description

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

[0002] The industrial-scale production of isocyanates by reacting amines with phosgene is known and described in detail in the literature (eg Ullmanns et al., 1996). 13, pp. 347-357, Verlag Chemie, GmbH, D-6940 Weinheim, 1977 or EP 1575908 A1). The production of pure diisocyanates in a distillation process usually results in by-product streams which need to be disposed of as a residue after as much free isocyanate as possible has been separated off by distillation.

[0003] Such residues still contain reactive groups and therefore carry the risk of exothermic reactions up to thermal runaway (thermal runaway), i.e. uncontrolled overheating of the exothermic chemical reaction and the industrial plant in which the residue is stored. In order to avoid this, the thermal stability of the residues is studied with the aim of determining the released heat of reaction and the so-called onset temperature, i.e. the temperature at which the reaction starts and releases energy. In this case, the residues can only be stored for a certain period of time at a temperature that is within a safety range below the onset temperature.

[0004] Since it is advantageous to process the residue in liquid form and the freezing point increases with increasing concentration of high-boiling by-products in the residue, the residue must be diluted to a greater extent at lower starting temperatures and correspondingly lower permissible residue temperatures. As a result, either more of the product of value remains in the residue or additional measures, such as the addition of solvents, must be taken.

[0005] In order to avoid undesired reactions in the residues, it is usually necessary to treat the different residues separately instead of mixing them.

[0006] It was therefore an object of the present invention to provide a process which does not have the abovementioned disadvantages of the prior art and which enables an improved treatment of residue mixtures from the production of organic isocyanates.

[0007] According to the invention, this object is achieved by a process for treating residues from the production of organic isocyanates by phosgenation of organic amines, which process comprises 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 originates from the production of isocyanates other than 1,5-pentane diisocyanate.

[0008] Surprisingly, it has now been found that by 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, the risk of uncontrolled exothermic reactions does not increase, but is generally even reduced. This thus makes it possible to mix such residues without reducing process safety, thereby achieving positive technical effects, such as longer storage stability of the mixed residues or reducing equipment costs by saving additional residue storage.

[0009] According to the present invention, the term "comprising" or "containing" preferably means "consisting essentially of", particularly preferably "consisting of...." Further embodiments described in the claims and the description may be combined arbitrarily, as long as the context does not clearly indicate otherwise.

[0010] An "organic compound" or "organic group" contains at least one unit comprising a covalent carbon-hydrogen bond.

[0011] The term "aliphatic" is defined herein as a saturated or unsaturated non-aromatic hydrocarbon group.

[0012] The term "araliphatic" is defined herein as a hydrocarbon group consisting of an aromatic hydrocarbon group and a saturated or unsaturated hydrocarbon group directly attached to the aromatic group.

[0013] The term "cycloaliphatic" or "alicyclic" is defined herein as non-aromatic optionally substituted carbocyclic or heterocyclic compounds or units.

[0014] As used herein, "at least one" means 1 or more, for example 2, 3, 4, 5, 6, 7, 8, 9 or more. For the components of the compounds described herein, the data do not refer to the absolute number of molecules, but to the type of component. Thus, "at least one isocyanate other than pentamethylene diisocyanate" means, for example, that only one compound or a plurality of different types of such compounds may be contained, rather than making a statement about the amount of the various compounds.

[0015] Numerical ranges given in the format "from x to y" include the values ​​stated. If more preferred numerical ranges are given in this format, it should be understood that all ranges resulting from combinations of the individual endpoints are also encompassed.

[0016] For example, when batches of different organic isocyanates are run in a production plant for producing organic isocyanates, one of which is pentamethylene diisocyanate, the method of the invention can be advantageously used. In the preparation or purification of different organic isocyanates, the residue A and the second residue B are now produced at times staggered from one another and can be mixed, for example, in a residue reservoir to achieve the desired effects, in particular stabilization. Thus, there is no need to provide a dedicated residue reservoir for each different kind of residue, or if only one residue reservoir is available, it does not need to be completely emptied, let alone cleaned, when changing batches. Instead, a certain amount of residue mixture can always be retained so that the respective residue can reach an optimal concentration in the distillation and benefit from the stabilization achieved by mixing with the residue based on 1,5-pentane diisocyanate.

[0017] When two production and / or distillation devices for different organic isocyanates are located at the same place, another possibility will occur. In this case, residue A and residue B are generated simultaneously, and a mixing step can be performed according to the method of the present invention. This step can be performed in a pipeline, through which the residue is transferred to a collection container, a transport container or an incineration device, or in a residue storage. In order to mix in a pipeline, the residues can simply be merged in the pipeline. Preferably, a static mixer or a dynamic mixing unit (such as one or more mixing pumps, dispersers or stirring containers) is used to improve the mixing of residues A and B. If mixing is performed in a collecting container, the collecting container preferably has a respective dedicated inlet for different residues, which optionally has an immersion tube. Then a stirring device and / or a pumping circulation device are used to mix in the collecting container, and the pumping circulation device can also be used for the temperature adjustment of the residue. Preferably, a stirring device is used to mix in the collecting container.

[0018] Residue A is a liquid residue or suspension, preferably a liquid residue, which is obtained when producing pentamethylene diisocyanate and contains, in addition to PDI, compounds having a boiling point higher than PDI and formed based on PDI. These compounds can be, for example, PDI oligomers such as carbodiimides or trimers, ureas, carbamates, and chlorinated compounds such as carbamoyl chloride. Residue A is preferably a preferably liquid distillation residue, which is obtained at the bottom of the column, wherein PDI is separated from a substance mixture containing PDI. In the present case, this residue A is also referred to as "from the production of pentamethylene diisocyanate".

[0019] The residue B is a liquid residue or suspension, preferably a liquid residue, which is obtained when producing at least one isocyanate other than pentamethylene diisocyanate and contains, in addition to the at least one isocyanate, for example compounds formed on the basis of 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, which generates the residue B during its preparation and / or purification, 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 different from 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 meta-xylylene diisocyanate (hereinafter also referred to as XDI). In the present case, this residue B is also referred to as "from the production of at least one isocyanate different from pentamethylene diisocyanate". Preferably, the at least one isocyanate other than PDI is exactly one isocyanate other than PDI and optionally isomers thereof and is therefore also a residue based only on the one isocyanate other than PDI and optionally isomers thereof.

[0020] The production process, ie the synthesis itself, and the purification process are steps considered in this context as belonging to the production of isocyanates, so that in this context the term "production of isocyanates" relates not only to the preparation itself, but also to residues from the production of isocyanates which may also arise in the distillation.

[0021] 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.

[0022] In a preferred embodiment, the 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, the 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.

[0023] In order to maximize the yield of valuable products and thus improve the economy of the production process, it is desirable that the residue A and / or residue B contain as little of the corresponding valuable products as possible. However, too low a residual amount of monomeric isocyanate can lead to a serious increase in viscosity until the residue solidifies, so a compromise must always be found in practice. When taken out of the isocyanate production, the residue usually still contains about 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. In principle, the temperature can be selected arbitrarily. A higher temperature of the residue helps to maintain a low viscosity and thus achieve pumpability. However, the obstacle of increasing the temperature is that the components of the isocyanate residue may react exothermically with each other or with themselves. It has been proven that a temperature of 15°C to 180°C, preferably 40°C to 150°C, and particularly preferably 60°C to 110°C is a favorable compromise.

[0024] It is therefore also preferred that a temperature of 15 to 180° C., preferably 40 to 150° C., particularly preferably 60 to 110° C., is present at least temporarily, preferably continuously, during the mixing step.

[0025] In order to reduce temperature fluctuations and concentration fluctuations, the at least one residue mixture obtained by the mixing step is preferably stored in at least one residue container, 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. In this way, the amount of residue mixture present in the residue container buffers fluctuations of the newly inflowing residue flow.

[0026] The above considerations regarding the preferred temperatures in the mixing step also apply to the storage of the at least one residue mixture obtained in the mixing step. The storage is therefore carried out at least temporarily, preferably continuously, at a temperature of 15° C. to 180° C., preferably 40° C. to 150° C., particularly preferably 60° C. to 110° C. In particular during the longer-term storage of the residue mixture obtained, it is important to adhere to the temperature limits, since the likelihood of adverse effects such as solidification or exothermic decomposition of the residue increases with longer storage times. If storage of the residue is carried out, it is therefore advantageous to limit the residence time of the residue in the storage container. The residence time is preferably a maximum of 28 days, particularly preferably a maximum of 7 days, very particularly preferably a maximum of 2 days, most preferably a maximum of 1 day. Decisive is the calculated residence time, which is obtained when the available volume is divided by the volume flow of the residue stream flowing through the residue container. If the inflow and / or outflow of the residue is discontinuous or in the form of a non-constant volume flow, a time average value of the volume flow can be used.

[0027] Storage in a residue container can lead to the residue components being deposited on the walls of the residue container. The risk of deposits is high, especially in the area of ​​heating or cooling devices. Sediments can also form which settle on the bottom of the residue container and can cause blockages. In order to prevent these problems, it is advantageous to agitate, preferably stir, the at least one residue mixture in at least one residue container at least temporarily, preferably continuously.

[0028] In another preferred embodiment of the process of the invention, in the mixing step, the residue B is mixed with an effective amount of residue A, so that the residue B is stabilized, wherein stabilization preferably means that the starting temperature is increased relative to the residue B alone. Depending on the type of residue B, the effective amount of residue A may be different. For example, the amount can be determined in preliminary tests by preparing a mixture of residue A and the residue B in question in different mixing ratios and then determining their thermal stability by differential scanning calorimetry (DSC) similar to DIN EN ISO 11357-1: 2017-02. The effective amount of residue A can then be directly derived from the mixing ratio at which the starting temperature of the exothermic reaction of the residue is observed to increase. If residue B undergoes multiple exothermic reactions with different starting temperatures, the reaction with the lowest starting temperature and a heat release value exceeding 100 J / g is decisive.

[0029] 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, wherein each 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 from the production of isophorone diisocyanate, or 5 to 30 parts by weight, preferably 7 to 20 parts by weight, of residue A are mixed with 70 to 95 parts by weight, preferably 80 to 93 parts by weight of residue B, wherein each residue B is a residue from the production of xylylene diisocyanate, preferably from the production of xylylene diisocyanate.

[0030] The residue mixture obtained in the mixing step can be used, for example, as an additive for other isocyanates. However, due to different chemical compositions and the resulting performance fluctuations, this use is limited. Therefore, in a preferred embodiment of the method of the present invention, the residue obtained in the mixing step is thermally recycled. For this reason, the residue can be supplied to incineration continuously or discontinuously. The advantageous properties of the residue achieved by mixing can be utilized. For example, the residue can be processed at higher temperatures and therefore lower viscosities, thereby reducing the problems caused by the clogging of the feed gun in the incineration plant.

[0031] In another preferred embodiment of the invention, monomeric diisocyanates are separated from the residue mixture obtained in the mixing step in a downstream process step. The separation of monomeric diisocyanates is preferably carried out by preparing a solid, preferably free-flowing residue in at least one kneader, shovel or drum dryer, preferably in a kneader or shovel dryer, particularly preferably in a shovel dryer. The residue mixture obtained in the mixing step is optionally introduced into a dryer together with additives and separated into a gaseous part (hereinafter referred to as a gaseous mixture) which essentially contains monomeric diisocyanates and a residue depleted in monomeric diisocyanates. The separation is carried out under negative pressure and high temperature so that the advantageous properties of the residue achieved by the mixing step of the method according to the invention can also be utilized here, which can be carried out, for example, by utilizing higher temperatures.

[0032] The gaseous mixture of the essentially monomeric diisocyanates obtained in this method step can be condensed to obtain a liquid mixture that essentially comprises pentamethylene diisocyanate and at least one other diisocyanate that is different from pentamethylene diisocyanate. This liquid mixture can be used for the preparation of polyurethane, polythiourethane and / or polyurea, and is equally a theme of the present invention. If desired, the liquid mixture can be subjected to further purification steps, for example distillation, filtration, crystallization and / or extraction, and / or additives are added thereto before the preparation of polyurethane, polythiourethane and / or polyurea. Preferably, the at least one further diisocyanate in the liquid mixture which is different from pentamethylene diisocyanate 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 meta-xylylene diisocyanate. Since the gaseous mixture recovered by the process according to the invention and the liquid mixture according to the invention originate from residues from the production of organic isocyanates by phosgenation of organic amines, they contain small amounts of other compounds which are not present in the known directly prepared process products. In the context of the liquid mixture according to the invention, the term "substantially" is to be understood as meaning that preferably 95% by weight or more, particularly preferably 97% by weight or more, very particularly preferably 99% by weight or more, based on the total amount of the mixture, are pentamethylene diisocyanate and at least one further diisocyanate different from pentamethylene diisocyanate.

[0033] Another subject of the present invention is the gaseous or liquid mixture obtainable or produced by the process according to the invention. The gaseous mixture or the optional liquid mixture can be subjected to a distillative treatment in a further process step if necessary to separate monomeric pentamethylene diisocyanate and the at least one diisocyanate different from pentamethylene diisocyanate.

[0034] Another subject of the present invention is the use of a first residue A from the production of 1,5-pentane diisocyanate for stabilizing a second residue B from the production of at least one organic isocyanate other than 1,5-pentane diisocyanate, wherein the stabilization preferably means an increase in the starting temperature relative to the residue B alone. In the use according to the invention, the residue preferably originates essentially from the production of organic isocyanates by phosgenation of organic amines. Particularly preferred is the use of a first residue A from the production of 1,5-pentane diisocyanate for stabilizing a second residue B from the production of at least one organic isocyanate other than 1,5-pentane diisocyanate, wherein the stabilization preferably means an increase in the starting temperature relative to the residue B alone and wherein the residue originates from the production of organic isocyanates by phosgenation of organic amines.

[0035] For example, the onset temperature of individual residues or mixtures of different residues can be determined in preliminary tests using differential scanning calorimetry (DSC) analogously to DIN EN ISO 11357-1: 2017-02. The respective onset temperature of the exothermic reaction of the isocyanate residues is decisive. If multiple exothermic reactions with different onset temperatures are observed for one residue, the reaction with the lowest onset temperature and a heat release of more than 100 J / g is decisive.

[0036] 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 other than 1,5-pentane diisocyanate, preferably from the production of araliphatic or cycloaliphatic diisocyanates, 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 and / or XDI.

[0037] In another 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 in this case corresponding optimizations can be carried out in the upstream distillation steps. Thus, for example, the residual monomer content in the distillation bottoms can be reduced, resulting in less loss of valuable substances or part of the cooling power required for cooling the residue to its respectively permissible storage temperature can be saved.

[0038] The present invention also provides a stabilized residue mixture containing 10 to 80% by weight of a first residue A from the production of 1,5-pentane diisocyanate and 20 to 90% by weight of a residue B from the production of isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI) or 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, preferably isophorone diisocyanate, or containing 5 to 30% by weight of a first residue A from the production of 1,5-pentane diisocyanate and 70 to 95% by weight of a second residue B from the production of xylylene diisocyanate, preferably meta-xylylene diisocyanate.

[0039] The stabilization here preferably means that the starting temperature is increased relative to the residue B alone. The effective amount of residue A may vary depending on the type of residue B. For example, the amount can be determined in preliminary tests by preparing mixtures of residue A with the residue B in question in different mixing ratios and then determining their thermal stability by differential scanning calorimetry (DSC) analogously to DIN EN ISO 11357-1: 2017-02. The effective amount of residue A can then be derived directly from the mixing ratio in which an increase in the starting temperature of the exothermic reaction of the residue is observed. If residue B undergoes multiple exothermic reactions with different starting temperatures, the reaction with the lowest starting temperature is decisive. Example

[0040] Now refer to Figure 1 and Figure 2 The present invention is illustrated with reference to the following examples, but the present invention is not limited thereto.

[0041] For differential scanning calorimetry (DSC), a few milligrams of the residue mixture are weighed into a gold-plated steel crucible under a nitrogen atmosphere and closed with a crucible press. The samples prepared in this way are then analyzed in a DSC measuring device relative to a reference crucible filled with inert aluminum oxide. The measuring device is here in accordance with the requirements of DIN EN ISO 11357-1:2017-02. Both crucibles are heated at a heating rate of 3K / min (so-called screening DSC), and the difference between the heat flow entering the crucible filled with the residue mixture and the heat flow entering the reference crucible is recorded. According to DIN EN ISO 11357-1:2017-02, in the exothermic peak (i.e., the reaction in which heat is released), the heat flow entering the sample crucible is lower than the heat flow entering the reference crucible, and the recorded curve therefore passes through a minimum. In order to evaluate the thermal stability, the starting temperature of the first exothermic peak with a heat release exceeding a value of 100 J / g is determined, i.e., the temperature at which the recorded heat flow difference begins to deviate from the sample baseline.

[0042] Example 1

[0043] The residue from the distillation of isophorone diisocyanate (IPDI) was mixed with the residue from the distillation of pentamethylene diisocyanate (PDI) in different mixing ratios. The mixing ratio of the mass ratio of IPDI: the mass ratio of PDI in the residue mixture was 100:0, 90:10, 70:30, 50:50, 30:70 and 10:90. The mixture was then analyzed by differential scanning calorimetry and the onset temperature of the exothermic reaction of the respective residue mixture was determined.

[0044] Example 2

[0045] The residue from the distillation of isophorone diisocyanate (IPDI) was mixed with the residue from the distillation of hexamethylene diisocyanate (HDI) in different mixing ratios. The mixing ratio of the mass ratio of IPDI: the mass ratio of HDI in the residue mixture was 100:0, 90:10, 70:30, 50:50, 30:70 and 10:90. The mixture was then analyzed by differential scanning calorimetry and the starting temperature of the exothermic reaction of the respective residue mixture was determined.

[0046] Discussion of Examples 1 and 2:

[0047] The starting temperatures of Example 1 and Example 2 were each normalized so that a 100:0 mixture, ie the distillation residue from the distillation of IPDI, obtained the value 100. The thus normalized starting temperatures are reported in Figure 1 middle.

[0048] exist Figure 1 In the diagram of , the normalized onset temperature is plotted on the Y axis and the mass ratio of the PDI or HDI residue is plotted on the X axis. The diagram with square measuring points represents the results of Example 1 (IPDI / PDI), and the diagram with triangular measuring points represents the results of Example 2 (IPDI / HDI).

[0049] from Figure 1 As can be seen from the graph in , mixtures containing PDI with a PDI proportion of about 10% by weight to about 80% by weight lead to an increase in the onset temperature and thus stabilize the residue mixture, while none of the tested mixtures has a normalized onset temperature > 100 due to the admixture of HDI. Instead, the normalized onset temperature passes through a minimum, so that the admixture of HDI residues leads to a destabilization of the IPDI residue mixture.

[0050] Example 3

[0051] The residue from the distillation of meta-xylylene diisocyanate (XDI) was mixed with the residue from the distillation of pentamethylene diisocyanate in different mixing ratios. The mixing ratios of XDI ratio:PDI ratio in the residue mixture were 100:0, 95:5, 90:10, 50:50 and 10:90. The mixture was then analyzed by differential scanning calorimetry. Figure 2 Normalized onset temperatures are plotted (the onset temperature of pure XDI residue is normalized to a value of 100).

[0052] exist Figure 2 In the diagram of Example 3 (XDI / PDI), the normalized onset temperature is plotted on the Y-axis and the mass ratio of the PDI residue is plotted on the X-axis. The diagram with circular measuring points represents the results of Example 3 (XDI / PDI).

[0053] from Figure 2 As is evident from the graph in , a mixture of PDI residues having a PDI proportion of about 5 wt. % to about 30 wt. % leads to an increase in the normalized onset temperature, thus stabilizing the residue mixture.

Claims

1. A process for treating residues from the production of organic isocyanates by phosgenation of organic amines, 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 originates from the production of an isocyanate other than 1,5-pentane diisocyanate.

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

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

4. The method according to any one of claims 1 to 3, characterized in that The 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 meta-xylylene diisocyanate.

5. The method according to any one of claims 1 to 4, characterized in that Temperatures of 15 to 180° C., preferably 40 to 150° C., particularly preferably 60 to 110° C., are present at least temporarily, preferably continuously, during the mixing step.

6. The method according to any one of claims 1 to 5, characterized in that By means of a mixing step, at least one residue mixture is obtained, which residue mixture is stored in at least one residue container, 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. The method according to claim 6, characterized in that The storage is carried out at least temporarily, preferably continuously, at a temperature of 15°C to 180°C, preferably 40°C to 150°C, particularly preferably 60°C to 110°C.

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

9. The method according to any one of claims 1 to 8, characterized in that The step of mixing effective amounts of residue A with residue B results in a stabilization of residue B, wherein the stabilization preferably means an increase in the starting temperature relative to residue B alone.

10. The method according to any one of claims 1 to 9, 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 originates from the production of isophorone diisocyanate, bis(isocyanatomethyl)norbornane (NBDI) and / or 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, preferably 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 originates from the production of xylylene diisocyanate, preferably from the production of meta-xylylene diisocyanate.

11. The method according to any one of claims 1 to 10, characterized in that The residue is supplied continuously or discontinuously to incineration.

12. Use of a first residue A from the production of 1,5-pentane diisocyanate for stabilizing a second residue B from the production of at least one organic isocyanate other than 1,5-pentane diisocyanate, wherein the stabilization preferably means an increase in the starting temperature relative to the residue B alone, and wherein the residue originates from the production of an organic isocyanate by phosgenation of an organic amine.

13. The 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 meta-xylylene diisocyanate.

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

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