Process for the solvent-free, continuous preparation of polyureas

Abstract

The invention relates to a process for the solvent-free, continuous preparation of polyureas by reacting at least one isocyanate and/or isocyanurate having at least two NCO groups with at least one diamine and/or polyamine in an extruder, intensive kneader, intensive mixer or static mixer by thorough mixing and rapid reaction by briefly heating and subsequent cooling to isolate the end product.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a process for the solvent-free, continuous preparation of polyureas by reacting at least one diisocyanate and/or isocyanurate with at least one diamine in an extruder, intensive kneader, intensive mixer or static mixer by thorough mixing and brief reaction by heating and subsequent isolation of the end product by cooling.

[0003] 2. Description of the Related Art

[0004] Polyureas are disclosed in EP 1 184 399. They are prepared in solvents, as described therein. A disadvantage of this preparation method is that the batchwise preparation of the desired product polyurea in the solvent toluene is very time-consuming and energy inefficient, since the product has to be dried for several hours at elevated temperatures under reduced pressure. The method described is an extremely inconvenient and expensive one for the industrial production of polyureas.

[0005] It is an object of the present invention to provide a novel process for the preparation of polyureas, which does not have the disadvantages of the prior art.

[0006] Surprisingly, it was found that polyureas can be prepared rapidly and in an uncomplicated manner in an extruder, intensive kneader, intensive mixer or static mixer.

[0007] The present invention relates to a process for the solvent-free, continuous preparation of polyureas by reacting at least one isocyanate and/or isocyanurate having at least two NCO groups with at least one diamine and/or polyamine in an extruder, intensive kneader, intensive mixer or static mixer by thorough mixing and rapid reaction by briefly heating and subsequent isolation of the end product by cooling.

[0008] The principle of the process is that the reaction of the reactants is carried out continuously in an extruder, intensive kneader, intensive mixer or static mixer by thorough mixing and rapid reaction by briefly heating.

[0009] Temperatures of from 10 to 325° C. are used in the process, the temperature varying, as shown in the examples, depending on the product.

[0010] The residence time of the starting materials in the above mentioned units is usually from 3 seconds to 15 minutes, preferably from 3 seconds to 5 minutes, particularly preferably from 5 to 180 seconds. The reactants are rapidly reacted by briefly heating at temperatures of from 25 to 325° C., preferably from 50 to 250° C., very particularly preferably from 70 to 220° C. Depending on the nature of the starting materials and of the final products, these values for residence time and temperature may also have other preferred ranges.

[0011] It is possible to discharge continuously the resulting, homogeneous, generally crumbly material. Optionally, a continuous subsequent reaction may be carried out, otherwise the hot product is cooled (e.g. on a cooling belt) and further compounded (e.g. milled), if required.

[0012] Extruders, such as single-screw or multiscrew extruders, in particular twin-screw extruders, planetary roller extruders or annular extruders, intensive kneaders, intensive mixers, such as Turrax mixers, or static mixers are particularly suitable as units for the process according to the invention and are preferably used.

[0013] It was surprising that the reaction, which requires several hours in the batchwise process, takes place essentially to completion in a few seconds in the units. In addition, the product is obtained in solid, more or less granular form and can, after cooling is complete, be fed for further working-up (e.g. milling) or directly for storage (e.g. silo) or packing (e.g. bagging). The basic principle is the fact that a brief application of heat in conjunction with the mixing effect of the unit (e.g. intensive kneader) is sufficient to convert the reactants completely or substantially completely. By suitable equipping of the mixing chambers or assembly of the screw geometries, intensive kneaders permit rapid thorough mixing with simultaneous intense heat exchange. On the other hand, uniform flow in the longitudinal direction with as uniform a residence time as possible is also ensured. Moreover, different amounts of heat in the individual apparatus housings or sections may be generated.

[0014] The reactants are metered into the units as a rule in separate reactant streams. In the case of more than two reactant streams, they may also be combined before being fed in. The material streams may also be divided and fed to the units in different amounts at different points. In this way, specific concentration gradients are established, which results in complete reaction. The entry points and time of entry of the reactant streams in the sequence may be varied.

[0015] For preliminary reaction and/or completion of the reaction, a plurality of units may also be combined.

[0016] The cooling following the rapid reaction can be integrated in the reaction part, in the form of a multizone embodiment, as in the case of extruders or Contema machines. It is also possible to use: tube bundles, pipe coils, chillrolls, air conveyors and conveyor belts of metal.

[0017] The end product may be compounded by being first brought to a suitable temperature by further cooling by appropriate means above, depending on the viscosity of the end product leaving the intensive kneader zone or the postreaction zone. Pelletizing or comminution of the end product to a desired particle size is then carried out by means of crushing rolls, a pinned disk mill, a hammer mill, an air separation ball mill, a flaking mill or the like.

[0018] All known aliphatic, cycloaliphatic, araliphatic and aromatic isocyanates having at least two NCO groups and the isocyanurates thereof in pure form or as mixtures with one another, may be used for the preparation of the polyureas. The following may be mentioned by way of example: cyclohexane diisocyanates, methylcyclohexane diisocyanates, ethylcyclohexane diisocyanates, propylcyclohexane diisocyanates, methyldiethylcyclohexane diisocyanates, phenylene diisocyanates, tolylene diisocyanates, bis(isocyanatophenyl)methane, propane diisocyanates, butane diisocyanates, pentane diisocyanates, hexane diisocyanates (e.g. hexamethylene diisocyanate (HDI) or 1,5-diisocyanato-2-methylpentane (MPDI)), heptane diisocyanates, octane diisocyanates, nonane diisocyanates (e.g. 1,6-diisocyanato-2,4,4-trimethylhexane and 1,6-diisocyanato-2,2,4-trimethylhexane (TMDI)), nonane triisocyanates (e.g. 4-isocyanatomethyl-1,8-octane diisocyanate (TIN)), decane di- and triisocyanates, undecane di- and triisocyanates, dodecane di- and triisocyanates, isophorone diisocyanate (IPDI), bis(isocyanatomethyl-cyclohexyl)methane (H12MDI), isocyanatomethyl-methylcyclohexyl isocyanates, 2,5(2,6)bis(isocyanatomethyl)bicyclo[2.2.1]heptane (NBDI), 1,3-bis(isocyanatomethyl)cyclohexane (1,3-H6-XDI) and 1,4-bis(isocyanatomethyl)cyclohexane (1,4-H6-XDI). The list does of course include all regioisomers and stereoisomers of the isocyanates mentioned by way of example. HDI, IPDI, MPDI, TMDI, 1,3- and 1,4-H6-XDI, NBDI and mixtures of HDI and IPDI are preferably used. Preferred polyureas in the context of the invention are those which consist of IPDI, IPDI-isocyanurate, HDI or HDI-isocyanurate and any desired mixtures thereof.

[0019] All aliphatic, (cyclo)aliphatic, cycloaliphatic and aromatic diamines and/or polyamines (C5-C18) can be used in the invention.

[0020] Diamines which are suitable in principle are 1,2-ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-butylenediamine, 1,3-butylenediamine, 1,4-butylenediamine, 2-(ethylamino) ethylamine, 3-(methylamino)propylamine, 3-(cyclohexylamino)propylamine, 4,4′-diaminodicyclohexylmethane, isophoronediamine, 4,7-dioxadecane-1,10-diamine, N-(2-aminoethyl)-1,2-ethanediamine, N-(3-aminopropyl)-1,3 -propanediamine, N,N″-1,2-ethanediylbis(1,3-propanediamine) and hexamethylenediamines, which may also carry one or more C1-C4-alkyl radicals. Mixtures of said diamines can also be used. Isophoronediamine is preferably used.

[0021] Polyamines such as, for example, 4-aminomethyl-1,8-octanediamine, diethylenetriamine, dipropylenetriamine, triethylenetetramine and tetraethylenepentamine can also be used.

[0022] In general, polyureas having an NCO/NH2 ratio of 0.8 to 1.2:1 are prepared. With the use of equimolar amounts having an NCO/NH2 ratio of 1:1, infinitely crosslinked, solid and brittle polymers which melt only above 240° C. with decomposition and are insoluble in solvents are obtained.

[0023] Preferred polyureas in the context of the invention are those which consist of IPD and IPDI and/or IPDI-isocyanurate and/or HDI and/or HDI-isocyanurate. These have molar masses of more than 4000 and contain at least 8% by weight, preferably 20% by weight, particularly preferably from 40 to 100% by weight, of isocyanurates and/or amines having a functionality of >2, preferably isocyanurates, preferably IPDI- and/or HDI-isocyanurate. Polyureas obtained from pure isocyanurates and IPD are also preferred.

[0024] The subject of the invention is explained below with reference to examples.

EXAMPLES

[0025] 1. Preparation of Polyurea by Reacting a Solution of IPDI-isocyanurate in Isophorone Diisocyanate (IPDI) With Isophoronediamine (IPD)

[0026] The polyurea is prepared from a mixture of 40% by weight of IPDI-isocyanurate and 60% by weight of IPDI as isocyanate component and IPD as amine.

[0027] The molar ratio of NCO groups to NH2 groups is 3.00:3.20. Both material streams are fed in liquid form into a twin-screw extruder having corotating screws. The extruder has barrels which are separately temperature-controllable (heatable and coolable).

[0028] Barrel 1 is operated at room temperature. Two following barrels are heated to 25 to 60° C. and further following barrels are temperature-controlled at 80 to 180° C. The temperature at which the product emerges is from 130 to 180° C.

[0029] The isocyanate mixture is metered into barrel 1 at a rate of 8.95 kg/h. The diamine IPD is added to barrel 3 with a throughput of 5.04 kg/h. The extruder speed is from 100 to 250 rpm. The emerging, white, crumbly product is cooled on a cooling belt.

[0030] 2 . Preparation of Polyurea by Reacting HDI-isocyanurate With Isophoronediamine (IPD)

[0031] The molar ratio of NCO groups to NH2 groups is 1.00:1.00. Both material streams are fed in liquid form into a twin-screw extruder having corotating screws. The extruder has barrels which are separately temperature-controlled (heatable and coolable).

[0032] Barrel 1 is temperature-controlled at from 60 to 90° C. Barrel 2 is heated to 100 to 190° C. and three following barrels are temperature-controlled at from 200 to 310° C. There follow two barrels, which are operated at from 130 to 310° C. The temperature at which the product emerges is from 170 to 220° C.

[0033] The isocyanate mixture is metered into barrel 1 at a rate of 4.07 kg/h. A pressure control valve adjusted to 8 to 10 bar is required. The diamine IPD is added to barrel 3 with a throughput of 1.78 kg/h.

[0034] The extruder speed is from 150 to 250 rpm.

[0035] The emerging, white, crumbly product is cooled on a cooling belt.

[0036] 3. Preparation of Polyurea by Reacting IPDI-isocyanurate With Isophoronediamine (IPD)

[0037] The molar ratio of NCO groups to NH2 groups is 3.00:3.40. The extruder has barrels which are separately temperature-controlled (heatable and coolable).

[0038] Barrel 1 is temperature-controlled at from 25 to 60° C. Barrel 2 is heated to 70 to 120° C. and the following three barrels are temperature-controlled at from 160 to 190° C. There follow two barrels, which are operated at 110 to 180° C. The temperature at which the product emerges is from 120 to 170° C.

[0039] The isocyanurate is metered into barrel 1 in the form of a coarse powder at a rate of 4.04 kg/h. The diamine IPD is added in liquid form to barrel 4 with a throughput of 0.83 kg/h.

[0040] The extruder speed is from 75 to 225 rpm. The emerging, white solid is cooled on a cooling belt.

[0041] DE 10221047.0, May 10, 2002, is hereby incorporated by reference.

Claims

1. A process for the solvent-free, continuous preparation of polyureas comprising: reacting at least one compound selected from the group consisting of isocyanate(s) having at least two NCO groups and isocyanurate(s) having at least two NCO groups, and mixtures thereof, with at least one compound selected from the group consisting of diamine(s) and polyamine(s), and mixtures thereof, in an extruder, intensive kneader, intensive mixer or static mixer by thorough mixing and rapid reaction by briefly heating and subsequent cooling to isolate the end product.

2. The process as claimed in claim 1, wherein the isocyanate(s) and isocyanurate(s) is/are selected from the group consisting of aliphatic, cycloaliphatic, araliphatic and aromatic, isocyanates and isocyanurates, and mixtures thereof.

3. The process as claimed in claim 1, wherein the diamine(s) and polyamine(s) is/are selected from the group consisting of cyclohexane diisocyanates, methylcyclohexane diisocyanates, ethylcyclohexane diisocyanates, propylcyclohexane diisocyanates, methyldiethylcyclohexane diisocyanates, phenylene diisocyanates, tolylene diisocyanates, bis(isocyanatophenyl)methane, propane diisocyanates, butane diisocyanates, pentane diisocyanates, hexane diisocyanates, such as hexamethylene diisocyanate (HDI) or 1,5-diisocyanato-2-methylpentane (MPDI), heptane diisocyanates, octane diisocyanates, nonane diisocyanates, such as 1,6-diisocyanato-2,4,4-trimethylhexane or 1,6-diisocyanato-2,2,4-trimethylhexane (TMDI), nonane triisocyanates, such as 4-isocyanatomethyl-1,8-octane diisocyanate (TIN), decane di- and triisocyanates, undecane di- and triisocyanates, dodecane di- and triisocyanates, isophorone diisocyanate (IPDI), bis(isocyanatomethyl-cyclohexyl)methane (H12MDI), isocyanatomethyl-methylcyclohexyl isocyanates, 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane (NBDI), 1,3-bis(isocyanatomethyl)cyclohexane (1,3-H6-XDI) or 1,4-bis(isocyanatomethyl)cyclohexane (1,4-H6-XDI), and the isocyanurates thereof, and mixtures thereof.

4. The process as claimed in claim 1, wherein the isocyanate(s) and isocyanurate(s) is/are selected from the group consisting of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), the isocyanurates thereof, and mixtures thereof.

5. The process as claimed in claim 1, wherein the diamine(s) is/are an aliphatic, a cycloaliphatic, an araliphatic or aromatic diamine(s), or mixtures thereof.

6. The process as claimed in claim 1, wherein the diamine(s) is/are 1,2-ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-butylenediamine, 1,3-butylenediamine, 1,4-butylenediamine, 2-(ethylamino)ethylamine, 3-(methylamino)propylamine, 3-(cyclohexylamino)propylamine, 4,4′-diaminodicyclohexylmethane, isophoronediamine, 4,7-dioxadecane-1,10-diamine, N-(2-aminoethyl)-1,2-ethanediamine, N-(3-aminopropyl)-1,3-propanediamine, N,N″-1,2-ethanediylbis(1,3-propanediamine) and hexamethylenediamines, which may be substituted by one or more C1-C4-alkyl radicals, or mixtures thereof.

7. The process as claimed in claim 1, comprising IPDI and isophoronediamine (IPD).

8. The process as claimed in claim 1, comprising an isocyanurate of IPDI and IPD.

9. The process as claimed in claim 1, comprising a mixture of IPDI and IPDI-isocyanurate and IPD.

10. The process as claimed in claim 1, comprising HDI and IPD.

11. The process as claimed in claim 1, comprising an isocyanurate of HDI and IPD.

12. The process as claimed in claim 1, comprising a mixture of HDI and HDI-isocyanurate and IPD.

13. The process as claimed in claim 1, comprising a mixture of IPDI- and HDI-isocyanurate and IPD.

14. The process as claimed in claim 1, wherein the reaction is carried out with an NCO/NH2 ratio of 0.8 to 1.2:1.

15. The process as claimed in claim 1, wherein the reaction is carried out in a single-screw, twin-screw or multiscrew extruder, annular extruder or planetary roller extruder.

16. The process as claimed in claim 1, wherein the reaction is carried out in a twin-screw extruder.

17. The process as claimed in claim 1, wherein the reaction is carried out in an intensive mixer or intensive kneader.

18. The process as claimed in claim 1, wherein the reaction is carried out in a static mixer.

19. The process as claimed in claim 1, wherein the reaction is carried out in an extruder, intensive kneader, intensive mixer or static mixer having a plurality of identical or different housings which can be thermally controlled independently of one another.

20. The process as claimed in claim 1, wherein the temperature in the extruder, intensive kneader, intensive mixer or static mixer is from 10 to 325° C.

21. The process as claimed in claim 1, wherein, by appropriate equipment in the mixing chambers and design of the screw geometry, the extruder or intensive kneader firstly gives rapid, thorough mixing and rapid reaction with simultaneous intense heat exchange and, secondly, produces uniform flow in the longitudinal direction with a uniform residence time.

22. The process as claimed in claim 1, wherein the reaction is carried out in the presence of catalyst(s) and/or additive(s).

23. The process as claimed in claim 1, wherein starting materials and/or catalyst(s) and/or additive(s) are fed together or in separate reaction streams, in liquid or solid form, to the extruder, intensive kneader, intensive mixer or static mixer.

24. The process as claimed in claim 23, wherein additive(s) are combined with starting materials to give one reactant stream.

25. The process as claimed in claim 23, wherein, if there are more than two reactant streams, these are combined before being fed in.

26. The process as claimed in claim 23, wherein one or both reactant streams are divided.

27. The process as claimed in claim 23, wherein catalyst(s) is/are combined with one of the reactant streams, or is initially introduced in solution in one of the streams.

28. The process as claimed in claim 23, wherein additive(s) is/are combined with one of the reactant streams, or is initially introduced in solution in one of the streams.

29. The process as claimed in claim 23, wherein the entry points of the reactant streams in the sequence can be varied and can be offset timewise.

30. The process as claimed in claim 1, wherein a post-reaction is carried out.

31. The process as claimed in claim 30, wherein the post-reaction is carried out in a continuously operated system.

32. The process as claimed in claim 1, wherein a compounding is first initiated after further cooling to a temperature sufficient for subsequent filling/silo storage, depending on the viscosity of the product leaving the extruder, intensive kneader, intensive mixer or static mixer and/or a post-reaction zone.

33. The process as claimed in claim 1, wherein a residence time of reactant materials is from 3 seconds to 15 minutes.

34. The process as claimed in claim 1, wherein the reaction takes place at temperatures of from 25 to 325° C.

35. A polyurea obtained by solvent-free, continuous reaction of at least one isocyanate and/or isocyanurate having at least two NCO groups with at least one diamine and/or polyamine in an extruder, intensive kneader, intensive mixer or static mixer by thorough mixing and rapid reaction by briefly heating and subsequent cooling to isolate the end product.

36. The process as claimed in claim 30, wherein the post-reaction is carried out in a tubular reactor, a stirred or unstirred dwell tank or a tube bundle.

37. The process as claimed in claim 1, wherein a residence time of reactant materials is from 3 seconds to 5 minutes.

38. The process as claimed in claim 1, wherein a residence time of reactant materials is from 5 to 180 seconds.

39. The process as claimed in claim 1, wherein the reaction takes place at temperatures from 50 to 250° C.

40. The process as claimed in claim 1, wherein the reaction takes place at temperatures from 70 to 220° C.