Polymeric MDI with low content of halogenated alicyclic hydrocarbons, and preparation method therefor and use thereof

Abstract

Provided in the present invention are polymeric MDI with a low content of halogenated alicyclic hydrocarbons, and a preparation method therefor and the use thereof. The polymeric MDI with a low content of halogenated alicyclic hydrocarbons as provided in present invention is used in a polyurethane adhesive to improve the open time of the polyurethane adhesive. In the polymeric MDI with a low content of halogenated alicyclic hydrocarbons, the content of the halogenated alicyclic hydrocarbons in the polymeric MDI is less than or equal to 15 ppm, preferably less than or equal to 10 ppm, more preferably less than or equal to 5 ppm, and further preferably less than or equal to 1 ppm.

Description

Polymeric MDI with low halogenated aliphatic cyclic hydrocarbon content, preparation method and application thereof Technical Field

[0001] The present invention relates to the technical field of polymeric MDI, in particular to a polymeric MDI with low halogenated aliphatic cyclic hydrocarbon content, a preparation method and application thereof. Background Art

[0002] Polymethylene polyphenyl polyisocyanate is one of the important raw materials for the preparation of polyurethane, mainly used in the production of polyurethane rigid foam, which is used in the fields of household appliances, cold storage, containers, building insulation materials, etc. As is well known, the current production method generally involves first condensing aniline and formaldehyde in the presence of an acid catalyst to produce DAM (a mixture of diaminodiphenylmethane and polyphenyl polymethylene polyamines, referred to as polyamines). DAM is then reacted with phosgene in an inert solvent through a liquid-phase phosgenation reaction to produce a reaction mixture. The reaction mixture is then subjected to phosgene removal, hydrogen chloride stripping, solvent removal, and refined separation to obtain the corresponding pure MDI (diphenylmethane series diisocyanates) and polymeric MDI products (a mixture of diphenylmethane diisocyanate and polyphenyl polymethylene polyisocyanates).

[0003] The methods disclosed in current patents primarily remove phenyl isocyanate impurities (PI) from polymerized MDI products. Numerous control schemes have been proposed in the art for reducing PI content. For example, patent application CN114044746A proposes that by adding a special catalyst during the alkali neutralization process of the DAM reaction solution, the PI precursor impurity content in the final DAM produced can be reduced, thereby obtaining isocyanates containing low PI substances. Patent application CN113474388A proposes adding a PI self-polymerization catalyst to the circulating solvent. This catalyzes the self-polymerization of PI in the solvent to form carbodiimide, which then reacts with the MDI in the system to form uretonimine, which ultimately enters the product without affecting product performance. Furthermore, to prevent the catalyst from recirculating into the system to catalyze MDI self-polymerization, a terminator must be added to deactivate the catalyst before the solvent is reused. Patent US4405527 describes a method for reducing the PI content in the system by reacting the PI in the solvent with a stoichiometrically excessive amount of polyamines or diols to convert it into carbamates or ureas.

[0004] Current methods for improving the quality of polymerized MDI products often require the introduction of new materials into the system, increasing operating costs and introducing new impurities, which can easily lead to new pollution. Furthermore, these changes to the existing process inevitably lead to other adverse effects that are difficult to assess. Furthermore, none of the aforementioned prior art addresses the control of halogenated alicyclic hydrocarbon impurities in polymerized MDI, nor does it address the impact of these impurities on the open time of polymerized MDI when used in polyurethane adhesives (e.g., potting compounds).

[0005] Summary of the Invention

[0006] The present invention provides a polymeric MDI with a low halogenated aliphatic cyclohydrocarbon content, a preparation method thereof, and an application thereof. The present invention provides a polymeric MDI with a controlled halogenated aliphatic cyclohydrocarbon content, which can be used in polyurethane adhesives to improve the open time of the polyurethane adhesives.

[0007] To achieve its purpose, the present invention provides the following technical solutions:

[0008] In one aspect, the present invention provides a polymeric MDI having a low halogenated aliphatic cyclic hydrocarbon content, wherein the halogenated aliphatic cyclic hydrocarbon content in the polymeric MDI is ≤15 ppm, preferably ≤10 ppm, more preferably ≤5 ppm, and further preferably ≤1 ppm.

[0009] The content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is, for example, 0-15 ppm, such as 0 ppm, 0.05 ppm, 0.1 ppm, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, 11 ppm, 12 ppm, 13 ppm, 14 ppm or 15 ppm, etc.; preferably 0-10 ppm; more preferably 0-5 ppm; further preferably 0-1 ppm, such as 0 ppm, 0.0001 ppm, 0.001 ppm, 0.01 ppm, 0.05 ppm, 0.1 ppm, 0.3 ppm, 0.5 ppm, 0.7 ppm, 1 ppm, etc.

[0010] In some embodiments, the content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is >0 and ≤15 ppm, for example, 0.0001-15 ppm, 0.01-15 ppm, 0.1-15 ppm, 0.5-15 ppm, etc. In some embodiments, the content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is >0 and ≤10 ppm, for example, 0.0001-10 ppm, 0.01-10 ppm, 0.1-10 ppm, 0.5-10 ppm, etc. In some embodiments, the content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is >0 and ≤5 ppm, for example, 0.0001-5 ppm, 0.01-5 ppm, 0.1-5 ppm, 0.5-5 ppm, etc. In some embodiments, the content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is >0 and ≤1 ppm, for example, 0.0001-1 ppm, 0.01-1 ppm, 0.1-1 ppm, 0.5-1 ppm, etc.

[0011] Furthermore, the halogenated aliphatic cyclic hydrocarbon substance is one or more compounds having the following structural formulas (I) and (II):

[0012] Wherein, each R in structural formula (I) and (II) is independently hydrogen, methyl, halomethyl, or halogen, and at least one of the R in structural formula (I) and (II) is halogen or halomethyl; that is, the halogenated alicyclic hydrocarbon substance of structural formula (I) or (II) contains one or more halogen atoms. In the present invention, the content of the halogenated alicyclic hydrocarbon substance refers to the sum of the mass percentages of the compounds satisfying the above structural formulas (I) and (II) contained in the polymeric MDI.

[0013] Specifically, the halogenated alicyclic hydrocarbon substance includes one or more alicyclic hydrocarbon substances that are mono- or poly-substituted with halogen elements. Further, the halogenated alicyclic hydrocarbon is, for example, a halomethylcyclohexane, a halomethylcyclohexene, or one or more of cyclohexane, cyclohexene, methylcyclohexane, methylcyclohexene, a halomethylcyclohexane, or a halomethylcyclohexene substituted with one or more halogen elements. Further, the halogen element is, for example, one or both of chlorine and bromine. Specifically, for example, the halogenated alicyclic hydrocarbon substance includes one or more of mono- or poly-halogenated chlorocyclohexane, bromocyclohexane, chlorocyclohexene, or bromocyclohexene.

[0014] Herein, the halomethyl group includes monohalomethyl and polyhalomethyl.

[0015] The present invention provides a polymeric MDI having a halogenated aliphatic cyclohydrocarbon content controlled within a specific, relatively low range. The inventors have discovered that the halogenated aliphatic cyclohydrocarbon content in the polymeric MDI affects the application performance of the polymeric MDI in polyurethane adhesives. If the content of the halogenated aliphatic cyclohydrocarbon content in the polymeric MDI is too high, the operable time of the polyurethane adhesive is excessively long. By using the polymeric MDI having a low halogenated aliphatic cyclohydrocarbon content in a polyurethane adhesive (e.g., a potting adhesive), the open time of the polyurethane adhesive can be improved. Specifically, the open time of the polyurethane adhesive can be shortened. For example, in some embodiments, the open time can be shortened to between 25 and 36 minutes, thereby improving the construction efficiency of the adhesive.

[0016] Currently, the MDI production process known in the art is mainly as follows: first, a liquid-phase phosgenation reaction is carried out between DAM (polyamine) and phosgene in a solvent to obtain a reaction mixture; then, the obtained reaction mixture is dephosgenated; the dephosgenated reaction mixture is subjected to a stripping heat treatment using HCl gas; the stripped reaction mixture is heated under negative pressure to remove the solvent; the desolvated liquid is further sent to a nitrogen stripping tower for nitrogen stripping to obtain crude MDI; and the crude MDI is then refined and separated to obtain the corresponding pure MDI and polymerized MDI products. In the prior art, the overhead condensate obtained by condensing the material collected from the overhead of the nitrogen stripping tower is directly combined with the reaction mixture obtained from the liquid-phase phosgenation reaction to enter the dephosgenation step. The present inventors have discovered that the outlet temperatures of the phosgenation, dephosgenation, hydrogen chloride stripping, and desolvation processes are all relatively low, only slightly above or below the boiling point of the solvent (e.g., chlorobenzene) at the equipment operating pressure. Consequently, the components removed in these processes are primarily solvents and other light components, such as phosgene, hydrogen chloride, and carbon tetrachloride. However, the operating pressure and temperature during the nitrogen stripping process are low, and the overhead outlet material of the nitrogen stripping column carries a large amount of MDI. The present inventors have discovered that, through research, most of the halogenated aliphatic cyclic hydrocarbons (e.g., chlorocyclohexane, bromocyclohexane, chlorocyclohexene, and bromocyclohexene) enter the overhead outlet material during the nitrogen stripping process and are removed. Subsequently, the halogenated aliphatic cyclic hydrocarbons are condensed and enter the overhead condensate, leaving only a small amount of the halogenated aliphatic cyclic hydrocarbons in the crude MDI. Since the MDI extracted from the top of the nitrogen stripping tower is of high value, in traditional processes, this stream is directly condensed and recycled back into the system. The inventors have discovered that this will cause halogenated aliphatic cyclic hydrocarbon impurities to accumulate in the poly-MDI preparation process system during continuous operation, with most of them eventually entering the crude MDI and then entering the poly-MDI during the refining and separation process, thereby affecting the poly-MDI product and its subsequent applications.

[0017] In addition, due to the relatively stable properties of halogenated aliphatic cyclic hydrocarbon impurities, they cannot be removed through reaction conversion methods in existing processes. At the same time, since the process for preparing polymerized MDI requires an unavoidable high-temperature process, this type of impurity cannot be solved at the source. Therefore, it is relatively difficult to remove halogenated aliphatic cyclic hydrocarbon impurities through the existing polymerized MDI process.

[0018] The present invention also provides a method for preparing the polymeric MDI having a low halogenated aliphatic cyclohydrocarbon content as described above. Specifically, it is also a method for reducing the content of halogenated aliphatic cyclohydrocarbons in the polymeric MDI. The method comprises the following steps:

[0019] S1, performing a phosgenation reaction of polyamine and phosgene in a solvent to obtain a reaction mixture, and performing phosgene removal treatment;

[0020] S2, subjecting the reaction mixture after the treatment in step S1 to a stripping heat treatment using hydrogen chloride gas;

[0021] S3, performing a solvent removal treatment on the reaction mixture after the treatment in step S2 to obtain a solvent-removed liquid;

[0022] S4, sending the liquid after the solvent removal in step S3 into a nitrogen stripping tower for stripping with nitrogen, condensing the material extracted from the top of the nitrogen stripping tower to obtain a top condensate, and obtaining crude MDI in the bottom of the nitrogen stripping tower; refining and separating the crude MDI to obtain pure MDI and polymerized MDI;

[0023] S5. The top condensate in step S4 is subjected to a treatment for removing halogenated aliphatic cyclic hydrocarbon substances and then sent to step S1 for mixing with the reaction mixture.

[0024] In the preparation method of the present invention, the condensate from the top of the nitrogen stripping tower is subjected to a treatment for removing halogenated aliphatic cyclohydrocarbon substances and then returned to step S1 to be mixed with the reaction mixture before phosgene removal for subsequent treatment. This can avoid the accumulation of halogenated aliphatic cyclohydrocarbon substances in the system and ultimately obtain polymeric MDI with a low content of halogenated aliphatic cyclohydrocarbon substances.

[0025] In a preferred embodiment, in step S5, the removal of the halogenated aliphatic cyclic hydrocarbon substance comprises the following steps:

[0026] S5a, sending the overhead condensate to a flash heat exchanger for treatment, and the halogenated aliphatic cyclohydrocarbon substance separated from the overhead condensate enters the gas phase material of the flash heat exchanger; the liquid phase material obtained in the flash heat exchanger is a material rich in MDI, which is sent to step S1 and mixed with the reaction mixture before phosgene treatment, and then circulated into the process system. Through the above step S5a, the accumulation of toxic and harmful impurities (such as halogenated aliphatic cyclohydrocarbon substances) in the system can be avoided, the content of halogenated aliphatic cyclohydrocarbon substances in the final polymerized MDI product can be effectively reduced, and the application performance and application safety of the polymerized MDI product can be improved.

[0027] Further preferably, the method further includes step S5b: passing the gaseous material from step S5a into a distillation tower for treatment to separate the solvent from the gaseous material, obtaining a gaseous solvent fraction at the top of the tower and an impurity fraction containing the halogenated aliphatic cyclic hydrocarbon in the bottom of the tower. This impurity fraction also contains some solvent and may contain other impurities. The impurity fraction containing the halogenated aliphatic cyclic hydrocarbon can be directly sealed and subsequently incinerated to avoid secondary hazards caused by other treatment methods.

[0028] More preferably, in step S5b, the vapor phase solvent is partially condensed to obtain a condensate, which is then transferred to a solvent storage tank. For example, the condensate can be subsequently treated to remove impurities and then used as a recycled solvent in the liquid-phase phosgenation reaction. Another portion of the condensate from the vapor phase solvent is then refluxed to the distillation column in step S5b. The treatment in step S5b allows for the separation and recovery of a portion of the solvent, thereby reducing solvent loss and lowering production costs.

[0029] In some embodiments, in step S5a, the flash heat exchanger is a rising film evaporator or a falling film evaporator;

[0030] Preferably, when the flash heat exchanger is a rising film evaporator, the operating pressure of the rising film evaporator is 20-60 kPa, for example, 20, 25, 30, 35, 40, 45, 50, 55, or 60 kPa, preferably 30-60 kPa, and more preferably 40-50 kPa; and the operating temperature is 80-150° C., for example, 80° C., 90° C., 100° C., 110° C., 120° C., 130° C., 140° C., or 150° C., preferably 90-150° C., and more preferably 110-130° C. The preferred process conditions facilitate more thorough separation of halogenated aliphatic cyclohydrocarbons from the overhead condensate, thereby further reducing the content of halogenated aliphatic cyclohydrocarbons in the polymeric MDI product.

[0031] In a preferred embodiment, in step S5b, the distillation tower is a packed tower, and the number of theoretical plates of the packing is 20-50, preferably 25-50, such as 25, 30, 35, 40, 45, 50, etc., more preferably 30-40; the reflux ratio is controlled to be 0.2-0.6, such as 0.2, 0.3, 0.4, 0.5, 0.6, etc., preferably 0.4-0.5. The preferred process conditions are conducive to more thorough separation of the halogenated aliphatic cyclohydrocarbon substances from the gaseous phase material obtained in step S5a, and are conducive to further reducing the content of the halogenated aliphatic cyclohydrocarbon substances in the recovered solvent. When the solvent is subsequently reused in the system, it is conducive to reducing the content of the halogenated aliphatic cyclohydrocarbon substances in the polymerized MDI. In some embodiments, in step S5b, the content of the halogenated aliphatic cyclohydrocarbon substances in the condensate obtained after the gaseous phase solvent is partially condensed can be controlled to <5ppm. In step S5b, the packing in the distillation tower can be a packing commonly used in the art, such as metal structured packing (M500Y, M452Y, M252Y, etc.), metal random packing (IR, IMTP, Raschig rings, rectangular saddle rings, Pall rings, etc.), etc., without any particular limitation.

[0032] In some embodiments, in step S5b, the bottom of the distillation tower is provided with a reboiler, and the top of the tower is provided with a condenser;

[0033] In some embodiments, the gas phase fraction at the reboiler outlet is controlled to be between 10-20%, such as 10%, 12%, 15%, 17%, 20%, etc., preferably 10-16%, such as 12-16%;

[0034] In some embodiments, the operating pressure at the top of the distillation tower is 25-50 kPa, for example, 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, etc., preferably 30-50 kPa, more preferably 35-40 kPa; the preferred operating conditions are conducive to more thorough separation of halogenated aliphatic cyclic hydrocarbons.

[0035] In some embodiments, the operating temperature of the distillation tower kettle is 100-140°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, etc., preferably 110-130°C; using the preferred operating conditions is conducive to more thorough separation of halogenated aliphatic cyclic hydrocarbons.

[0036] In some embodiments, the operating temperature of the condenser at the top of the distillation tower is 30°C-70°C, preferably 40-50°C.

[0037] In the present invention, polyamine refers to a mixture of diaminodiphenylmethane and polyphenylpolymethylenepolyamine (DAM), which can also be referred to as diphenylmethane series diamines and polyamines. The preparation of a reaction mixture by liquid-phase phosgenation of polyamines and phosgene in a solvent can be carried out using conventional processes in the art, and the present invention is not particularly limited thereto. The preparation of polymeric MDI by liquid-phase phosgenation of polyamines and phosgene in a solvent is described in detail in many documents, such as CN116217439A, CN111961185B, CN108147979B, CN116034102A, CN104755458B, CN111170891B, etc. In some embodiments, the solvent used for the liquid-phase phosgenation reaction is, for example, one or more of chlorobenzene, dichlorobenzene, diethyl carbonate, and cyclohexanone, preferably chlorobenzene. In some embodiments, for reference, the conditions for liquid-phase phosgenation reaction include: reaction temperature of 60-160° C., reaction pressure of 2-30 bar, mass ratio of polyamine to solvent of 1:(1.1-5), and mass ratio of polyamine to phosgene of 1:(1.1-5).

[0038] The main improvement in the preparation method of the present invention is that, in step S5, the overhead condensate obtained by condensing the overhead material in the nitrogen stripping column is treated to separate the halogenated aliphatic cyclic hydrocarbons therein. After the halogenated aliphatic cyclic hydrocarbons are separated, the material is returned to step S1, thereby entering the process system. The corresponding process operations and process conditions in steps S1-S4 of the preparation method of the present invention can be carried out using corresponding conventional process operations and conditions in the art, and there are no particular limitations.

[0039] In some embodiments, in step S1, the phosgene removal treatment is to heat treat the reaction mixture to remove phosgene; preferably, the temperature of the heat treatment is 100-150°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc.

[0040] In some embodiments, in step S2, the temperature of the stripping heat treatment with hydrogen chloride gas is 100-200°C, for example, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, etc., the residence time is preferably 1-20 min, for example, 1 min, 5 min, 10 min, 15 min, 20 min, and the mass ratio of hydrogen chloride to the reaction mixture is 0.01-0.1, for example, 0.01, 0.05, 0.1, etc.

[0041] In some embodiments, in step S3, the solvent removal treatment is to remove the solvent by heating under negative pressure, preferably under the conditions of an operating pressure of 20-50 kPa (e.g., 20 kPa, 30 kPa, 40 kPa, 50 kPa, etc.) and a temperature of 120-240°C (e.g., 120°C, 150°C, 200°C, 240°C, etc.).

[0042] In some embodiments, in step S4, the operating pressure of the nitrogen stripping tower is 20-60 kPa, for example, 20 kPa, 30 kPa, 40 kPa, 50 kPa, 60 kPa; the temperature is 150-230° C., for example, 150° C., 180° C., 200° C., 230° C., etc.; the mass ratio of nitrogen to the liquid after desolvation (stripping mass ratio) is 0.005-0.1, for example, 0.005, 0.01, 0.05, 0.1, etc. The temperature at which the overhead gas phase at the top of the nitrogen stripping tower is condensed is 20-60° C., for example, 20° C., 30° C., 40° C., 50° C., 60° C., etc.

[0043] In the present invention, the pressure involved refers to absolute pressure unless otherwise specified.

[0044] In some embodiments, the crude MDI is refined and separated in step S4 in a distillation tower. The process conditions of the distillation tower include, for example, controlling the bottom temperature of the tower to 180-250°C, for example, 180°C, 200°C, 230°C, 250°C, etc., and controlling the top pressure of the tower to 10-1000Pa, for example, 10Pa, 50Pa, 100Pa, 1000Pa, etc., to obtain a polymerized MDI product in the bottom of the tower.

[0045] In some embodiments, in step S4, the content of the halogenated aliphatic cyclic hydrocarbon substance in the overhead condensate is between 10-10000 ppm.

[0046] By adopting the above-mentioned preparation method of the present invention, the content of halogenated aliphatic cyclic hydrocarbon substances in polymeric MDI can be reduced, and polymeric MDI with a halogenated aliphatic cyclic hydrocarbon substance content that meets the required requirements can be obtained.

[0047] As mentioned above, some impurities are inevitably generated during the DAM production process. The high-temperature treatments during the phosgenation reaction, hydrogen chloride stripping, and desolventization stages generate halogenated aliphatic cyclic hydrocarbon impurities. The present inventors have discovered that because some substances have boiling points higher than or close to that of the solvent (e.g., chlorobenzene), they cannot be completely removed during the desolventization process, resulting in a small amount of halogenated aliphatic cyclic hydrocarbons entering the polymeric MDI product. On the one hand, since these substances are generally volatile, they can evaporate into the environment during downstream applications at excessively high temperatures, posing a potential safety risk. On the other hand, the present inventors have discovered that these substances can affect the product's performance, particularly the open time (operable time) after the polymeric MDI reacts with white material (e.g., polyether polyols) in downstream potting applications. Excessive levels of these impurities can result in an excessively long open time, affecting process operations and reducing construction efficiency. Therefore, reducing the content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI product is beneficial for improving the performance and safety of the polymeric MDI product in downstream applications and reducing its environmental impact.

[0048] The present invention also provides a method for improving the open time of a polyurethane adhesive. The polyurethane adhesive comprises polymeric MDI as a raw material, and the content of halogenated aliphatic cyclohydrocarbons in the polymeric MDI is controlled to be ≤15 ppm, preferably ≤10 ppm, more preferably ≤5 ppm, and even more preferably ≤1 ppm. The present inventors have discovered that by controlling the content of halogenated aliphatic cyclohydrocarbons in the polymeric MDI used in the polyurethane adhesive to meet the above requirements, the open time of the polyurethane adhesive can be improved. Specifically, for example, the open time can be shortened compared to polymeric MDI containing halogenated aliphatic cyclohydrocarbons that do not meet the above requirements, thereby improving application efficiency. For example, the open time can be shortened to between 25 and 36 minutes.

[0049] Furthermore, the halogenated aliphatic cyclic hydrocarbon substance is one or more compounds having the following structural formulas (I) and (II):

[0050] wherein each R in structural formula (I) and (II) is independently hydrogen, methyl, halomethyl or halogen, and at least one of the R in structural formula (I) or (II) is halogen or halomethyl;

[0051] Specifically, for example, the halogenated alicyclic hydrocarbon is one or more of halogenated methylcyclohexane, halogenated methylcyclohexene, cyclohexane, cyclohexene, methylcyclohexane, methylcyclohexene, halogenated methylcyclohexane, and halogenated methylcyclohexene substituted with one or more halogen elements;

[0052] For example, the halogen element is one or both of chlorine and bromine.

[0053] Specifically, for example, in some embodiments, the halogenated aliphatic cyclic hydrocarbon substance includes one or more of monohalogenated or polyhalogenated chlorocyclohexane, bromocyclohexane, chlorocyclohexene, bromocyclohexene, and the like.

[0054] In some embodiments, in the method for improving the open time of the polyurethane adhesive, the content of the halogenated aliphatic cyclic hydrocarbon substance in the polymeric MDI used is controlled to be 0-15ppm, for example, 0ppm, 0.05ppm, 0.1ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 11ppm, 12ppm, 13ppm, 14ppm or 15ppm, etc.; preferably 0-10ppm; more preferably 0-5ppm; further preferably 0-1ppm, for example, 0ppm, 0.0001ppm, 0.001ppm, 0.01ppm, 0.05ppm, 0.1ppm, 0.3ppm, 0.5ppm, 0.7ppm, 1ppm, etc.

[0055] In some embodiments, in the method for improving the open time of the polyurethane adhesive, the content of the halogenated aliphatic cyclic hydrocarbon substance in the polymeric MDI used is controlled to be >0 and ≤15 ppm, for example, 0.0001-15 ppm, 0.01-15 ppm, 0.1-15 ppm, 0.5-15 ppm, etc. In some embodiments, the content of the halogenated aliphatic cyclic hydrocarbon substance in the polymeric MDI used is controlled to be >0 and ≤10 ppm, for example, 0.0001-10 ppm, 0.01-10 ppm, 0.1-10 ppm, 0.5-10 ppm, etc. In some embodiments, the content of the halogenated aliphatic cyclic hydrocarbon substance in the polymeric MDI used is controlled to be >0 and ≤5 ppm, for example, 0.0001-5 ppm, 0.01-5 ppm, 0.1-5 ppm, 0.5-5 ppm, etc. In some embodiments, the content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI used is controlled to be >0 and ≤1 ppm, for example, 0.0001-1 ppm, 0.01-1 ppm, 0.1-1 ppm, 0.5-1 ppm, etc.

[0056] Regarding the method for improving the open time of a polyurethane adhesive provided by the present invention, the polymeric MDI used can be prepared by the method for preparing polymeric MDI with a low halogenated aliphatic cyclic hydrocarbon content described above.

[0057] Specifically, the raw materials of the polyurethane adhesive include component A (black material) and component B (white material), wherein component A includes at least the polymerized MDI as the black material, and component B includes at least a polyether polyol as the white material. The formulation of the polymerized MDI-based polyurethane adhesive (including but not limited to the selection and dosage of each component) can be conventional in the art and is not particularly limited. The key to the present invention is to achieve improved open time by controlling the content of halogenated aliphatic cyclic hydrocarbons in the polymerized MDI used in this type of polyurethane adhesive to meet the specific requirements of the present invention.

[0058] In some embodiments, as an example, the mass ratio of the component A to the component B is 1:(1-10), for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.

[0059] In some embodiments, as an example, in addition to the polyether polyol, component B may also contain other components that are allowed to be added in the field of polyurethane adhesives, such as but not limited to flame retardants, plasticizers, antioxidants, modifiers, defoaming agents, grafting agents, etc. The amount of these components can be specifically determined according to application requirements. In some examples, for example, the mass proportion of these components in component B is less than 0.5%.

[0060] The polyether polyol used in the polyurethane adhesive can be any of the conventional polyether polyols in the art, without particular limitation. For example, the polyether polyol in component B can be one or more of polyethylene oxide polyol, polypropylene oxide polyol, polytetrahydrofuran, and copolyether polyols thereof, and the molecular weight of the polyether polyol can be, for example, 200-10,000 g / mol.

[0061] Those skilled in the art know that the polyurethane adhesive can be used in, for example, the fields of electronics and electrical appliances, aviation equipment, medical industry, construction, and the like.

[0062] As used herein, "open time" refers to the time interval from the application of a polyurethane adhesive to the surface of an adherend to the time when the adhesive can no longer be effectively applied. Effective application operations include brushing or rolling the adhesive or transferring it to another adherend. The effective time for these operations is called the open time. In other words, the open time can also be understood as the maximum time that a polyurethane adhesive can be left in the air after being applied to the adherend surface before the adherends are bonded.

[0063] In another aspect, the present invention provides a polyurethane adhesive comprising component A and component B, wherein component A comprises at least the polymerized MDI described above, and component B comprises at least a polyether polyol. Preferably, the mass ratio of component A to component B is 1:1-10. For other descriptions of the polyurethane adhesive, reference may be made to the corresponding description of the method for improving the open time of a polyurethane adhesive, and will not be repeated here.

[0064] The technical solution provided by the present invention has the following beneficial effects:

[0065] 1) The present invention provides a polymeric MDI with a low halogenated aliphatic cyclohydrocarbon content in which the content of the halogenated aliphatic cyclohydrocarbon substance is controlled. When the polymeric MDI provided by the present invention is used in a polyurethane adhesive, the open time can be significantly improved compared to the use of polymeric MDI without controlling the content of the low halogenated aliphatic cyclohydrocarbon substance, and an excessively long open time can be shortened, thereby improving construction efficiency.

[0066] 2) The present invention provides a method for preparing polymeric MDI with a low content of halogenated aliphatic cyclohydrocarbon substances. The method comprises the following steps: the condensate from the top of the nitrogen stripping tower is separately treated during the production process of polymeric MDI, and the MDI, solvent and halogenated aliphatic cyclohydrocarbon impurities are separated therein. The separated MDI-rich logistics are recycled back to the system, the solvent can enter the solvent storage tank for subsequent reuse, and the concentrated portion containing halogenated aliphatic cyclohydrocarbon impurities no longer enters the process system. The solution proposed by the present invention has a simple process flow and operation, requires relatively little modification to the existing process, is easy to transform, and does not have any adverse effects on the existing process. At the same time, the solution of the present invention can avoid the accumulation of halogenated aliphatic cyclohydrocarbon impurities in the system, effectively reduce the content of halogenated aliphatic cyclohydrocarbon impurities in the polymeric MDI produced, control the content of halogenated aliphatic cyclohydrocarbon impurities in the polymeric MDI within the desired range, and improve the application performance of the polymeric MDI product and the safety of downstream applications.

[0067] 3) The method for preparing polymeric MDI with low halogenated aliphatic cyclic hydrocarbon content provided by the present invention has the characteristics of simple process, low operating cost, and easy operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG1 is a schematic diagram of a process for removing halogenated aliphatic cyclic hydrocarbon impurities in one embodiment.

[0069] Among them, E1 is a flash heat exchanger, E2 is a tower top condenser, E3 is a tower bottom reboiler, C1 is a distillation tower, P1 is a reboiler circulation and extraction pump, and D1 is a halogenated aliphatic cyclic hydrocarbon impurity storage tank. DETAILED DESCRIPTION

[0070] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0072] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. Reagents or instruments used without specifying the manufacturer are all commercially available conventional products.

[0073] Method for testing the content of halogenated aliphatic cyclic hydrocarbons: dilute the sample to be tested 10 times its mass with dichloromethane and then directly use gas chromatography for analysis. The test conditions are as follows:

[0074] Gas chromatograph: Agilent 7890A, column HP-5 (30 m × 0.25 μm × 320 μm). Chromatographic conditions: column temperature: 50°C for 0.5 min, then increased to 80°C at 5°C / min for 1 min; then increased to 280°C at 10°C / min for 10 min; inlet temperature: 280°C, detector temperature: 295°C; septum purge gas flow rate: 3.0 mL / min; carrier gas (nitrogen) flow rate: 3 mL / min; air flow rate: 350 mL / min; hydrogen flow rate: 35 mL / min; makeup gas (nitrogen) flow rate: 25 mL / min; split injection, split ratio 1:10, injection volume 0.5 μL.

[0075] In the following examples, the content of halogenated aliphatic cyclic hydrocarbons refers to the sum of the mass contents of chlorocyclohexane, bromocyclohexane, chlorocyclohexene, and bromocyclohexene, wherein the halogenated aliphatic cyclic hydrocarbons include monohalogenated and polyhalogenated corresponding compounds.

[0076] The open time of potting compound is measured using an Ecory GT-2 gel time tester. After mixing components A and B, immediately add the test sample to a test tube and proceed as follows: Immerse the test tube in a thermostat. Insert a stirring glass rod into the test tube, which is connected to a torsion wire driven by a synchronous motor at a speed of 1 rpm. The test timer begins and the gel timer monitors the test process until the gel point is reached. The displayed gel time is the open time.

[0077] Ingredients Description:

[0078] Diphenylmethane series diamines and polyamines (DAM): Wanhua Chemical (Ningbo) Co., Ltd., purity >99.99%; specifically, DAM preparation method is as follows: aniline and 32wt% hydrochloric acid are mixed in a molar ratio of 1:0.3 at 60°C and 1 bar to produce aniline hydrochloride, which is then reacted with formaldehyde (the molar ratio of formaldehyde to aniline is 0.4:1) at 120°C for 2 hours. A transposition liquid is obtained through a condensation and transposition process, which is neutralized with a 32wt% sodium hydroxide aqueous solution and then washed with water to obtain polyamines, which are then distilled and stripped at 200°C and 10kPa to obtain DAM.

[0079] Chlorobenzene: Wanhua Chemical (Ningbo) Co., Ltd., purity >99.9%.

[0080] Phosgene: Wanhua Chemical (Ningbo) Co., Ltd., purity >95.0%.

[0081] Polyether polyol: Hydrophobic polyether polyol D3201, manufacturer Dow.

[0082] Example 1

[0083] A diphenylmethane series diamine and polyamine (DAM) are mixed with chlorobenzene to obtain a mixed solution with an amine concentration of 30 wt%, a phosgene chlorobenzene solution with a phosgene concentration of 60 wt% (the mass ratio of DAM to phosgene is 1:2.4) is added to the mixed solution, and the mixture is reacted at 3 barg and 100° C. for 1 hour to obtain a reaction mixture; phosgene is removed from the reaction mixture at 0.1 MPa and 135° C., and then stripping is performed with hydrogen chloride at a temperature of 180° C., with a mass ratio of HCl to the reaction mixture of 0.05 and a residence time of 5 minutes; then, the stripped reaction mixture is dechlorobenzened at 35 kPa and 205° C., and the dechlorobenzened MDI (i.e., the desolvated reaction solution) is fed into a nitrogen stripping tower for treatment at 40 kPa and 200° C., with the mass ratio of nitrogen to the desolvated reaction solution being controlled to be 0.03;

[0084] The material extracted from the top of the nitrogen stripping tower was condensed to obtain a top condensate, wherein the content of halogenated aliphatic cyclic hydrocarbon substances in the top condensate was 1000 ppm. The top condensate was sent to a rising film evaporator E1 and treated at an operating pressure of 40 kPa and a temperature of 120°C. The liquid phase material was sent to a phosgene removal step and mixed with the reaction mixture before phosgene removal. The gas phase material obtained from the rising film evaporator E1 was sent to a distillation tower C1; the distillation tower C1 was a packed tower filled with Sulzer M452Y metal structured packing, with 40 theoretical plates and a reflux ratio of 0.5. The bottom of the distillation tower C1 was equipped with a reboiler E3, and the top of the tower was equipped with a condenser E2. The top operating pressure of the distillation tower C1 was 35 kPa, the bottom temperature was 120°C, the gas phase fraction at the outlet of the reboiler E3 was 10%, and the operating temperature of the condenser E2 was 45°C. Gaseous chlorobenzene is withdrawn from the top of distillation tower C1. After condensing this gaseous chlorobenzene at 45°C, part of the resulting chlorobenzene condensate is sent to a crude chlorobenzene storage tank, while part is refluxed back into distillation tower C1. The chlorobenzene condensate contains 0.5 ppm of halogenated aliphatic hydrocarbons. The impurities containing these halogenated aliphatic hydrocarbons withdrawn from the bottom of distillation tower C1 are then sent to halogenated aliphatic hydrocarbon impurity storage tank D1.

[0085] The crude MDI (chlorobenzene content of 800 ppm) obtained in the bottom of the nitrogen stripping tower is sent to the downstream distillation tower for refining. The process conditions of the distillation tower are a top pressure of 20 Pa and a bottom temperature of 200°C. The polymerized MDI product is obtained in the bottom of the distillation tower.

[0086] The content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI product prepared by the process of Example 1 is 1 ppm.

[0087] The polymeric MDI prepared in Example 1 was used to prepare a potting compound, wherein component A (black material) was the polymeric MDI prepared in Example 1, and component B (white material) was a polyether polyol. Components A and B were mixed in a mass ratio of 1:5. The open time of the potting compound was measured to be 30 minutes.

[0088] Example 2

[0089] The same process conditions were modified as in Example 1, with the following differences: Specifically, the operating pressure of the rising film evaporator was adjusted to 20 kPa, and the temperature was adjusted to 80°C. The distillation tower used to process the gaseous material from the rising film evaporator had 20 theoretical plates, a reflux ratio of 0.2, an operating pressure at the top of the distillation tower of 25 kPa, and a bottom temperature of 130°C. All other operations were the same as in Example 1.

[0090] Results: In Example 2, the content of halogenated aliphatic cyclic hydrocarbon substances in the chlorobenzene condensate was 50 ppm, and the content of halogenated aliphatic cyclic hydrocarbon substances in the finally prepared polymeric MDI product was 12 ppm.

[0091] The polymeric MDI prepared in Example 2 was used to prepare a potting compound according to the operation of Example 1. The open time of the obtained potting compound was measured to be 36 minutes.

[0092] Example 3

[0093] The same process conditions were modified as in Example 1, with the following differences: Specifically, the operating pressure of the rising film evaporator was adjusted to 35 kPa, and the temperature was adjusted to 105°C. The distillation column used to process the vapor phase of the rising film evaporator had 30 theoretical plates, a reflux ratio of 0.3, an operating pressure at the top of the distillation column of 25 kPa, and a bottom temperature of 130°C. All other operations were the same as in Example 1.

[0094] Results: In Example 3, the content of halogenated aliphatic cyclic hydrocarbons in the chlorobenzene condensate was 30 ppm, and the content of halogenated aliphatic cyclic hydrocarbons in the finally prepared polymeric MDI product was 8 ppm.

[0095] The polymeric MDI prepared in Example 3 was used to prepare a potting compound according to the operation of Example 1. The open time of the obtained potting compound was measured to be 34 minutes.

[0096] Example 4

[0097] The same process conditions were modified as in Example 1, with the following differences: Specifically, the operating pressure of the rising film evaporator was adjusted to 35 kPa, and the temperature was adjusted to 110°C. The distillation column used to process the vapor phase of the rising film evaporator had 35 theoretical plates and a reflux ratio of 0.4. All other operations were the same as in Example 1.

[0098] Results: In Example 4, the content of halogenated aliphatic cyclic hydrocarbons in the chlorobenzene condensate was 5 ppm, and the content of halogenated aliphatic cyclic hydrocarbons in the finally prepared polymeric MDI product was 2 ppm.

[0099] The polymeric MDI prepared in Example 4 was used to prepare a potting compound according to the operation of Example 1. The open time of the obtained potting compound was measured to be 32 minutes.

[0100] Comparative Example 1

[0101] A diphenylmethane series diamine and polyamine (DAM) and chlorobenzene are mixed to obtain a mixed solution with an amine concentration of 30 wt%, a phosgene chlorobenzene solution with a phosgene concentration of 60 wt% (the mass ratio of DAM to phosgene is 1:2.4) is added to the mixed solution, and the mixture is reacted at 3 barg and 100° C. for 1 h to obtain a reaction mixture; the reaction mixture is then dephosgeneated at 0.1 MPa and 135° C., and then stripped with hydrogen chloride at a temperature of 180° C., with a mass ratio of HCl to the reaction mixture of 0.05 and a residence time of 5 min; and the stripped reaction mixture is then subjected to a filtration step at 35 kPa and 205° C. The method comprises the following steps: performing dechlorobenzene treatment, feeding the dechlorobenzeneed MDI (i.e., the reaction liquid after desolvation) into a nitrogen stripping tower for treatment at 40 kPa and 200°C, with the mass ratio of nitrogen to the reaction liquid after desolvation being controlled at 0.03; condensing the material extracted from the top of the nitrogen stripping tower to obtain a top condensate, and directly feeding the top condensate into a phosgene removal step to mix with the reaction mixture before dephosgene removal; feeding the crude MDI (chlorobenzene content of 800 ppm) obtained in the bottom of the nitrogen stripping tower into a distillation tower for refining, and the process conditions of the distillation tower are a top pressure of 20 Pa and a bottom temperature of 200°C, and obtaining a polymerized MDI product in the bottom of the distillation tower.

[0102] Results: The content of halogenated aliphatic cyclic hydrocarbons in the obtained polymeric MDI product was 20 ppm. The polymeric MDI obtained in Comparative Example 1 was used to prepare a potting compound according to the procedure of Example 1. The open time of the obtained potting compound was measured to be 40 minutes.

[0103] As can be seen from the above experimental results, in the embodiments of the present invention, the halogenated aliphatic cyclohydrocarbon content of the polymerized MDI obtained is controlled to be below 15 ppm. Compared with Comparative Example 1, its application in the potting compound can shorten the open time from 40 minutes in Comparative Example 1 to between 25-36 minutes, which can take into account good construction operability and construction efficiency. Preferably, in Examples 1-4, the halogenated aliphatic cyclohydrocarbon content of the polymerized MDI is 1, 12, 8, and 2 ppm, respectively, and the open time of the resulting potting compound is 30, 36, 34, and 32 minutes, respectively, with the open time being around 30 minutes. It can be seen that the lower the content of the halogenated aliphatic cyclohydrocarbon, the more significantly the open time is shortened, and it is still between 25-36 minutes.

[0104] It will be readily understood that the above embodiments are merely examples for clarity of description and are not intended to limit the present invention to these examples. Those skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A polymeric MDI having a low content of halogenated aliphatic cyclic hydrocarbon substances, characterized in that: The content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is ≤15ppm, preferably ≤10ppm, more preferably ≤5ppm, and further preferably ≤1ppm; The content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is, for example, 0-15 ppm, for example, >0 and ≤15 ppm, for example, >0 and ≤10 ppm, for example, >0 and ≤5 ppm, for example, >0 and ≤1 ppm.

2. The polymeric MDI according to claim 1, characterized in that The halogenated aliphatic cyclic hydrocarbon substance is one or more compounds having the following structural formula (I) and (II): wherein each R in the structural formula (I) and (II) is independently hydrogen, methyl, halomethyl or halogen, and at least one of the R in the structural formula (I) or (II) is halogen or halomethyl; For example, the halogen element is one or both of chlorine and bromine.

3. The method for preparing polymeric MDI with low halogenated aliphatic cyclic hydrocarbon content according to claim 1 or 2, characterized in that: The steps include: S1, performing phosgene removal treatment on a reaction mixture obtained by liquid-phase phosgenation reaction of polyamine and phosgene in a solvent; S2, subjecting the reaction mixture after the treatment in step S1 to a stripping heat treatment using hydrogen chloride gas; S3, performing solvent removal treatment on the reaction mixture after the treatment in step S2 to obtain a liquid after the solvent is removed; S4, sending the liquid after the solvent removal in step S3 into a nitrogen stripping tower to be stripped with nitrogen, condensing the material extracted from the top of the nitrogen stripping tower to obtain a top condensate, and The crude MDI is obtained from the bottom of the tower; the crude MDI is refined and separated to obtain pure MDI and polymerized MDI; S5, subjecting the tower top condensate in step S4 to a treatment for removing halogenated aliphatic cyclic hydrocarbon substances and then sending it to step S1 for mixing with the reaction mixture.

4. The preparation method according to claim 3, characterized in that: In step S5, the removal of the halogenated aliphatic cyclic hydrocarbon substances comprises the following steps: S5a, sending the tower top condensate to a flash heat exchanger for treatment, and the halogenated aliphatic cyclic hydrocarbon substances separated from the tower top condensate enter the gas phase material; sending the liquid phase material obtained in the flash heat exchanger to the step S1 to be mixed with the reaction mixture; Preferably, the method further comprises step S5b: sending the gas phase material in step S5a into a distillation tower for treatment to separate the solvent in the gas phase material, obtaining a gas phase solvent portion at the top of the tower, and obtaining an impurity portion containing the halogenated aliphatic cyclic hydrocarbon substance at the bottom of the tower; further preferably, in step S5b, condensing the gas phase solvent portion to obtain a condensate, and sending part of the condensate into a solvent storage tank; Preferably, in step S5a, the flash heat exchanger is a rising film evaporator or a falling film evaporator; when the flash heat exchanger is a rising film evaporator, the operating pressure of the rising film evaporator is 20-60 kPa, preferably 30-60 kPa, more preferably 40-50 kPa; the operating temperature is 80-150°C, preferably 90-150°C, more preferably 110-130°C.

5. The preparation method according to claim 4, characterized in that: In step S5b, the distillation tower is a packed tower, and the number of theoretical plates of the packing is 20-50, preferably 25-50, and more preferably 30-40; the reflux ratio is controlled to be 0.2-0.6, preferably 0.4-0.

5.

6. The preparation method according to claim 5, characterized in that: In step S5b, the bottom of the distillation tower is provided with a reboiler, and the top of the tower is provided with a condenser; Preferably, the gas phase fraction at the outlet of the reboiler is controlled between 10-20%, preferably 10-16%; Preferably, the operating pressure at the top of the distillation tower is 25-50 kPa, preferably 30-50 kPa, more preferably 35-40 kPa; Preferably, the operating temperature of the distillation tower reactor is 100-140°C, preferably 110-130°C; Preferably, the operating temperature of the condenser at the top of the distillation tower is 30°C-70°C, preferably 40-50°C.

7. The preparation method according to any one of claims 3 to 6, characterized in that: Preferably, in step S1, the phosgene removal treatment is to heat-treat the reaction mixture to remove phosgene, and the temperature of the heat treatment is 100-150° C.; Preferably, in step S2, the temperature of the stripping heat treatment with hydrogen chloride gas is 100-200° C., the residence time is preferably 1-20 min, and the mass ratio of hydrogen chloride to the reaction mixture is 0.01-0.1; Preferably, in step S3, the solvent removal treatment is carried out under the conditions of an operating pressure of 20-50 kPa and a temperature of 120-240° C.; Preferably, in step S4, the operating pressure of the nitrogen stripping tower is 20-60 kPa, the temperature is 150-230° C., and the mass ratio of nitrogen to the liquid after the solvent is removed is 0.005-0.1; Preferably, the solvent used for the liquid phase phosgenation reaction is one or more of chlorobenzene, dichlorobenzene, diethyl carbonate and cyclohexanone.

8. The preparation method according to any one of claims 4 to 7, characterized in that: In step S4, the content of the halogenated aliphatic cyclic hydrocarbon substance in the tower top condensate is between 10-10000 ppm; And / or, in step S5b, the content of the halogenated aliphatic cyclic hydrocarbon substance in the condensate obtained after the gas phase solvent is partially condensed is less than 5 ppm.

9. A method for improving the open time of a polyurethane adhesive, wherein the raw material used in the polyurethane adhesive includes polymerized MDI, characterized in that: Controlling the content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI to ≤15ppm, preferably ≤10ppm, more preferably ≤5ppm, and further preferably ≤1ppm; The content of halogenated aliphatic cyclic hydrocarbon substances in the polymeric MDI is, for example, 0-15 ppm, for example, >0 and ≤15 ppm, for example, >0 and ≤10 ppm, for example, >0 and ≤5 ppm, for example, >0 and ≤1 ppm; The halogenated aliphatic cyclic hydrocarbon substance is one or more compounds having the following structural formula (I) and (II): Wherein, each R in the structural formula (I) and (II) is independently hydrogen, methyl, halomethyl or halogen, and at least one of the R in the structural formula (I) or (II) is halogen or halomethyl; for example, the halogen element is one or both of chlorine and bromine; Preferably, the raw materials of the polyurethane adhesive include component A and component B, wherein the component A includes at least the polymerized MDI; the component B includes at least a polyether polyol; preferably, the mass ratio of the component A to the component B is 1:1-10.

10. A polyurethane adhesive, characterized in that: The polyurethane adhesive comprises component A and component B, wherein component A comprises at least the polymerized MDI according to claim 1 or 2, and component B comprises at least polyether polyol. Preferably, the mass ratio of component A to component B is 1:1-10.

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