PREPARATION METHOD FOR DIPHENYLMETHANE DIISOCYANATE

Abstract

Disclosed is a preparation method for preparing diphenylmethane diisocyanate. The preparation method comprises: under a catalyst condition, performing a pyrolysis reaction on diphenylmethane dicarbamate in an inert solvent having a boiling point lower than that of diphenylmethane diisocyanate to obtain diphenylmethane diisocyanate.

Claims

1. A preparation method for diphenylmethane diisocyanate, comprising: in the presence of a catalyst, subjecting diphenylmethane dicarbamate to a pyrolysis reaction in an inert solvent having a lower boiling point than diphenylmethane diisocyanate to obtain diphenylmethane diisocyanate.

2. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein the catalyst is selected from an elementary substance and/or an alloy of a metal in Group IB, Group IIB, Group IIIA, Group IVA, Group IVB, Group VB and Group VIII of the periodic table.

3. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein a mass ratio of the catalyst to diphenylmethane dicarbamate is 1:(5-25).

4. The preparation method for diphenylmethane diisocyanate according to claim 3, wherein the mass ratio of the catalyst to diphenylmethane dicarbamate is 1:(15-20).

5. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein the catalyst is any one or a combination of at least two of iron, copper, nickel, a copper-aluminum alloy or a copper-nickel alloy, optionally copper and/or the copper-nickel alloy; and optionally, the copper comprises any one or a combination of at least two of copper powder, copper foam or nano-copper.

6. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein a mass ratio of diphenylmethane dicarbamate to the inert solvent is 1:(7-50).

7. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein the inert solvent is selected from an alkane inert solvent and/or a halogenated hydrocarbon inert solvent; optionally, the inert solvent is any one or a combination of at least two of chlorobenzene, orthodichlorobenzene, o-xylene or p-xylene.

8. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein the pyrolysis reaction is conducted for 0.1-10 h, optionally 1-5 h.

9. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein the pyrolysis reaction is conducted at a temperature of 140-280° C. under a pressure of 0.2-1 MPa, optionally 0.2-0.8 MPa.

10. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein diphenylmethane dicarbamate comprises any one or a combination of at least two of methyl diphenylmethane dicarbamate, ethyl diphenylmethane dicarbamate, propyl diphenylmethane dicarbamate or butyl diphenylmethane dicarbamate.

11. The preparation method for diphenylmethane diisocyanate according to claim 1, wherein diphenylmethane diisocyanate comprises any one or a combination of at least two of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate or polymeric diphenylmethane diisocyanate.

12. The preparation method for diphenylmethane diisocyanate according to claim 1, comprising the following steps: in the presence of a catalyst, subjecting diphenylmethane dicarbamate to a pyrolysis reaction in an inert solvent having a lower boiling point than diphenylmethane diisocyanate for 0.1-10 h at a temperature of 140-280° C. under a pressure of 0.2-1 MPa to obtain diphenylmethane diisocyanate.

Description

DETAILED DESCRIPTION

[0035] Technical solutions of the present application are further described below through detailed embodiments. Those skilled in the art are to understand that examples described herein are merely used for a better understanding of the present application and are not to be construed as a specific limitation to the present application.

Example 1

[0036] A preparation method for 4,4′-diphenylmethane diisocyanate is described below.

[0037] Methyl 4,4′-diphenylmethane dicarbamate, nano-copper and a solvent p-xylene were added to a 1000 mL reaction kettle and then reacted for 2 h at a temperature of 220° C. under a pressure of 0.35 MPa.

[0038] A mass ratio of nano-copper to methyl 4,4′-diphenylmethane dicarbamate was 1:20, and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent p-xylene was 1:19.

Examples 2 to 6

[0039] Examples 2 to 6 differ from Example 1 only in that nano-copper was added in different amounts and a mass ratio of nano-copper to methyl 4,4′-diphenylmethane dicarbamate was controlled to be 1:5 (Example 2), 1:15 (Example 3), 1:25 (Example 4), 1:4 (Example 5) or 1:30 (Example 6).

Examples 7 to 10

[0040] Examples 7 to 10 differ from Example 1 only in that a solvent p-xylene was added in different amounts and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent p-xylene was controlled to be 1:7 (Example 7), 1:50 (Example 8), 1:4 (Example 9) or 1:55 (Example 10).

Examples 11 and 12

[0041] Examples 11 and 12 differ from Example 1 only in that nano-copper was replaced with a copper-nickel alloy (Example 11) or iron (Example 12).

Example 13

[0042] A preparation method for 4,4′-diphenylmethane diisocyanate is described below.

[0043] Methyl 4,4′-diphenylmethane dicarbamate, copper fiber and a solvent p-xylene were added to a 1000 mL reaction kettle and then reacted for 2 h at a temperature of 220° C. under a pressure of 0.55 MPa.

[0044] A mass ratio of copper fiber to methyl 4,4′-diphenylmethane dicarbamate was 1:19, and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent p-xylene was 1:19.

Example 14

[0045] A preparation method for 4,4′-diphenylmethane diisocyanate is described below.

[0046] Propyl 4,4′-diphenylmethane dicarbamate, copper foam and a solvent p-xylene were added to a 1000 mL reaction kettle and then reacted for 2 h at a temperature of 250° C. under a pressure of 0.55 MPa.

[0047] A mass ratio of copper foam to methyl 4,4′-diphenylmethane dicarbamate was 1:9, and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent p-xylene was 1:9.

Example 15

[0048] A preparation method for 4,4′-diphenylmethane diisocyanate is described below.

[0049] Butyl 4,4′-diphenylmethane dicarbamate, copper powder and a solvent p-xylene were added to a 1000 mL reaction kettle and then reacted for 2 h at a temperature of 250° C. under a pressure of 0.55 MPa.

[0050] A mass ratio of copper foam to methyl 4,4′-diphenylmethane dicarbamate was 1:19, and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent p-xylene was 1:19.

Example 16

[0051] A preparation method for 4,4′-diphenylmethane diisocyanate is described below.

[0052] Methyl 4,4′-diphenylmethane dicarbamate, copper foam and a solvent o-xylene were added to a 1000 mL reaction kettle and then reacted for 2 h at a temperature of 270° C. under a pressure of 0.55 MPa.

[0053] A mass ratio of copper foam to methyl 4,4′-diphenylmethane dicarbamate was 1:19, and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent o-xylene was 1:10.

Example 17

[0054] A preparation method for polymeric diphenylmethane diisocyanate is described below.

[0055] Polymeric methyl diphenylmethane dicarbamate, copper powder and a solvent chlorobenzene were added to a 1000 mL reaction kettle and then reacted for 2 h at a temperature of 250° C. under a pressure of 0.55 MPa.

[0056] A mass ratio of copper foam to polymeric methyl diphenylmethane dicarbamate was 1:20, and a mass ratio of polymeric methyl diphenylmethane dicarbamate to the solvent chlorobenzene was 1:20.

Example 18

[0057] A preparation method for 4,4′-diphenylmethane diisocyanate is described below.

[0058] Methyl 4,4′-diphenylmethane dicarbamate, nano-copper and a solvent p-xylene were added to a 1000 mL reaction kettle and then reacted for 0.1 h at a temperature of 280° C. under a pressure of 0.2 MPa.

[0059] A mass ratio of nano-copper to methyl 4,4′-diphenylmethane dicarbamate was 1:20, and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent p-xylene was 1:19.

Example 19

[0060] A preparation method for 4,4′-diphenylmethane diisocyanate is described below.

[0061] Methyl 4,4′-diphenylmethane dicarbamate, nano-copper and a solvent p-xylene were added to a 1000 mL reaction kettle and then reacted for 10 h at a temperature of 140° C. under a pressure of 1 MPa.

[0062] A mass ratio of nano-copper to methyl 4,4′-diphenylmethane dicarbamate was 1:20, and a mass ratio of methyl 4,4′-diphenylmethane dicarbamate to the solvent p-xylene was 1:19.

Comparative Example 1

[0063] Comparative Example 1 differs from Example 1 in that nano-copper was replaced with nano-copper(II) oxide as a catalyst.

Comparative Example 2

[0064] Comparative Example 2 differs from Example 1 in that nano-copper was not added as a catalyst.

Comparative Example 3

[0065] Comparative Example 3 differs from Example 1 in that solvent p-xylene was replaced with dioctyl sebacate.

Performance Test

[0066] A performance test was performed on diphenylmethane diisocyanate provided in Examples 1 to 19 and Comparative Examples 1 to 3 by a method described below.

[0067] (1) Conversion rate of a reactant: the system was subjected to a chromatographic analysis after its volume was precisely adjusted with methanol/water solution, and a quantitative analysis was performed using an Agilent-1200 high-performance liquid chromatograph developed by Agilent Technologies, Inc. of the United States.

[0068] (2) Yield of a product: the system was subjected to the chromatographic analysis after its volume was precisely adjusted with methanol/water solution, and the quantitative analysis was performed using the Agilent-1200 high-performance liquid chromatograph developed by Agilent Technologies, Inc. of the United States.

[0069] The results of the test are shown in Table 1.

TABLE-US-00001 TABLE 1 Conversion rate Yield of Sample of Reactant/% Product/% Example 1 98.9 98.7 Example 2 99.2 96.5 Example 3 99.1 97.3 Example 4 99.5 97.1 Example 5 99.6 92.3 Example 6 98.2 92.5 Example 7 98.5 72.5 Example 8 99.2 98.4 Example 9 98.9 50.3 Example 10 99.4 98.7 Example 11 97.4 78.2 Example 12 96.2 72.5 Example 13 99.2 90.8 Example 14 99.9 96.6 Example 15 98.6 92.6 Example 16 99.9 96.6 Example 17 98.5 96.2 Example 18 40.3 15.2 Example 19 100 54.2 Comparative Example 1 92.5 67.8 Comparative Example 2 91.6 48.7 Comparative Example 3 90.6 75.5

[0070] From the examples and the performance test, it can be seen that the preparation method for diphenylmethane diisocyanate provided by the present application has the advantages of mild reaction conditions and a relatively high yield, where the conversion rate of the reactant is up to more than 97% and the yield of the product is up to more than 90%.

[0071] As can be seen from the comparison of Examples 1 to 6, in the present application, when the mass ratio of the catalyst to the reactant is 1:(5-25), the yield of MDI is relatively high. As can be seen from the comparison of Example 1 with Examples 7 to 10, when the mass ratio of the inert solvent to the reactant is (7-50):1, the yield of MDI is relatively high; when the mass ratio of the inert solvent to the reactant is (19-50):1, the yield of MDI is higher. As can be seen from the comparison of Example 1 with Comparative Example 1, when the metal oxide is selected as the catalyst, the metal oxide has a poorer effect than a metal or a metal alloy. As can be seen from the comparison of Example 1 with Comparative Example 2, when the catalyst is not added, the conversion rate of diphenylmethane dicarbamate is relatively low due to a relatively low reaction temperature and reaction pressure so that the yield of MDI is relatively low. As can be seen from the comparison of Example 1 with Comparative Example 3, when a solvent with a high boiling point is selected, since MDI and methanol are evaporated simultaneously during the reaction, a reversible side reaction is easy to occur and MDI with too high a concentration is easy to polymerize so that the yield of MDI is relatively low.

[0072] The applicant states that although the preparation method for diphenylmethane diisocyanate of the present application is described through the preceding examples, the present application is not limited to the preceding examples, which means that implementation of the present application does not necessarily depend on the preceding examples.