HOMOGENEOUS POLY(ALKYLENE) GUANIDINES AND METHOD FOR THE PRODUCTION THEREOF

Abstract

The invention relates to a method for producing poly(alkylene) guanidines, comprising at least the following steps: a) providing an alkylene diamine of the formula NH.sub.2(CH.sub.2)m-NH.sub.2 with m=4-12, in particular 6-10, in a reaction vessel and heating the alkylene diamine to a temperature greater than or equal to the melting temperature of the alkylene diamine in question, typically to a temperature in a range of 25 C. to 115 C., preferably 55 C. to 110 C., whereby a melt of the alkylene diamine is produced; b) adding a guanidinium salt, in particular guanidinium HCl, in portions and reacting same with the alkylene diamine until the formation of alkylene(guanidine) monomers is completed; c) reacting the monomers formed in step b), at at least the minimum temperature at which the polymerization to form the desired poly(alkylene) guanidine begins, until the formation of the poly(alkylene) guanidine is completed; wherein steps a) and b) for forming alkylene(guanidine) monomers are carried out at a temperature below the minimum polymerization temperature and the mixture is stirred during all method steps. The invention further relates to the homogeneous poly(alkylene) guanidines obtainable by means of the method described above, said poly(alkylene) guanidines having a content of at least 85 wt %, in particular at least 90% or 97%, of a desired linear poly(alkylene) guanidine having 3-14, preferably 4-10, alkylene monomer units in the molecule as a main product and a content of by-products, in particular branched isomers of said poly(alkylene) guanidine, of at most 15%, 10%, 5% or 3%.

Claims

1. A method for the production of poly(alkylene) guanidines, comprising at least the following steps: a) providing an alkylene diamine of the formula NH.sub.2(CH.sub.2).sub.mNH.sub.2 where m=4-12, in a reaction vessel and heating of the alkylene diamine to a temperature equal to or above a melting temperature of the alkylene diamine, as a result of which a melt of the alkylene diamine is formed; b) portion-wise adding of a guanidinium salt and reacting with the alkylene diamine until the formation of alkylene(guanidine) monomers is concluded; c) reacting the monomers formed in step b) at at least a minimum polymerization temperature at which a polymerization to a desired poly(alkylene) guanidine begins until a formation of the poly(alkylene) guanidine is concluded; wherein steps a) and b) for the formation of alkylene(guanidine) monomers are performed at a temperature below the minimum polymerization temperature and all of the steps are carried out while stirring.

2-13. (canceled)

14. The method according to claim 1, wherein step b) is performed at a temperature in a range from 20 C. to 115 C. for a period of time of 15 min to 20 h, and/or wherein step c) is performed for a period of time of 30 min to 25 h.

15. The method according to claim 1, wherein step (b) is conducted while stirring at a temperature in a range from 41 C. to 110 C., for a period of time of 15 min to 25 h, until the formation of alkylene(guanidine) monomers is concluded, and wherein step (c) comprises the following steps: c1) heating the monomers formed in step b) while stirring to the minimum temperature at which the polymerization to the desired poly(alkylene) guanidine begins; c2) keeping the reaction mixture at this temperature for a predetermined period of time; c3) slowly increasing the reaction temperature in steps, and after each increasing step keeping the reaction mixture at the respective increased temperature for a predetermined period of time; c4) keeping the reaction mixture at a predetermined maximum temperature for a predetermined period of time; c5) reducing the temperature of the reaction mixture to a predetermined value below the maximum temperature, but above the minimum temperature for polymerization and keeping the reaction mixture at this temperature for a predetermined period of time; and c6) cooling the reaction mixture to a temperature below the minimum polymerization temperature for the termination of polymerization, as a result of which the desired homogeneous poly(alkyene) guanidine is directly obtained.

16. The method according to claim 1, wherein the alkylene diamine is tetramethylenediamine, the monomer formation is performed in step b) at a temperature in a range from 25 C. to 110 C., and the minimum polymerization temperature is 120 C.

17. The method according to claim 1, wherein the alkylene diamine is hexamethylenediamine, octamethylenediamine or decamethylendiamine, the monomer formation is performed in step b) at a temperature in the range from 55 C. to 110 C., and the minimum polymerization temperature is 120 C.

18. The method according to claim 17, wherein the temperature at which monomer formation in step (b) is performed is 60 C. to 80 C. when the alkylene diamine is hexamethylenediamine, 70 C. to 90 C. when the alkylene diamine is octamethylenediamine, and 75 C. to 90 C. when the alkylene diamine is decamethylenediamine.

19. The method according to claim 1, wherein the conclusion of the monomer formation in step b) is ascertained by a cessation of foaming as a result of NH.sub.3 release and optionally a vacuum is generated in the reaction vessel for a predetermined period of time in order to promote foaming.

20. The method according to claim 19, wherein a pressure is present in a range from 2 mbar to 4000 mbar, in step b) in the reaction vessel for a period of time in a range from 10 to 240 min.

21. The method according to claim 1, wherein, in step b), unreacted alkylene diamine is distilled off prior to step c).

22. The method according to claim 1, wherein a molar ratio of alkylene diamine to guanidinium salt is from 1.2:1 to 1:1.

23. The method according to claim 22, wherein the molar ratio of alkylene diamine to guanidinium salt is from 1.1:1 to 1:1.

24. The method according to claim 22, wherein the molar ratio of alkylene diamine to guanidinium salt is about 1:1.

25. The method according to claim 1, wherein in step a) the temperature to which the alkylene diamine is heated is from 25 C. to 115 C.

26. A poly(alkylene) guanidine, obtainable with the method according to claim 1, which has a content of at least 85% by weight of a desired linear poly(alkylene) guanidine with 3-14 alkylene monomer units therein as a main product and a content of branched isomer byproducts of the poly(alkylene) guanidine of at most 15%.

27. The poly(alkylene) guanidine according to claim 26, which contains at least 90% or 97% by weight of the desired linear poly(alkylene) guanidine with 3-14 alkylene monomer units as the main product and contains at most 10% of the branched isomer byproducts of the poly(alkylene) guanidine.

28. The poly(alkylene) guanidine according to claim 26, wherein the content of the branched isomer byproducts of the poly(alkylene) guanidine is not more than 3%.

29. The poly(alkylene) guanidine according to claim 26, which has a molecular weight average in a range from 500 to 15,000 Dalton, wherein at most 15% of the polymer molecules have a molecular weight outside the molecular weight average.

30. The poly(alkylene) guanidine according to claim 29, wherein the molecular weight average is from 500 to 5000 Dalton.

Description

EXAMPLE 1

Production and Characterization of a Poly(hexamethylene)guanidine

[0045] The reactants hexamethylenediamine (HMDA) and guanidinium hydrochloride (GHC) were weighed out in a molar ratio of 1:1.

[0046] HMDA was filled into a reactor and GHC in powder or crystalline form was introduced into the receiver. The reactor was heated to an internal temperature IT of 60 C. and the stirrer was activated upon complete melting of the HMDA. When this IT temperature was reached, the temperature control was set to 65 C. with the stirrer running.

[0047] GHC was metered from the receiver at a constant temperature. The formation of ammonia began immediately. Foaming and temperature were controlled and, optionally, metering was varied and/or cooling was used. The reactor temperature was not supposed to leave the range from 60 C. to 80 C. and preferably supposed to lie in the range of 60-70 C.

[0048] After termination of GHC metering, the foaming significantly reduced and the temperature settled to 65 C. After increasing the stirrer speed and applying a vacuum of 10 mbar to 950 mbar, preferably 200 mbar to 600 mbar, slight foaming started again. As soon as the pressure was constant and no foaming or bubble formation was visible, the temperature was increased to IT 80 C. and the stirrer speed increased to maximum. After 20 min, the vacuum was removed and the stirrer speed was reduced again. Monomer formation was now concluded.

[0049] A sample was extracted from the reactor content and the HMDA content was determined. In the case of an excessive residual HDMA content, the pressure of the reactor can be reduced to, for example, 10 mbar and the HMDA be distilled off at a temperature of up to 60 C.

[0050] For polymerization, the temperature was increased to a temperature IT of 120 C. with the stirrer in operation and maintained at a constant temperature for 1 h. A slow increase in temperature in steps of 5 C. up to 140 C. was then effected, wherein the temperature was maintained for 30 min at each step. At 140 C., the reaction was stirred vigorously for 2 h. The temperature was then further increased to 150 C. in steps of 5 C. The temperature was maintained for 1 h after the first step, then kept at 150 C. for a further 2 h and the stirrer speed was increased. The temperature was then reduced to 120 C. and maintained there for 1 further hour.

[0051] In order to terminate polymerization, cooling was performed to an IT of below 95 C. with maximum stirring.

[0052] The product was characterized by means of LC-MS and nitrogen determination.

[0053] The theoretical nitrogen ratio (N setpoint) for the ideal (linear) polymer with a predefined molecular weight average and degree of polymerization and for corresponding branched isomers can be calculated on the basis of the respective structure formulae and compared with the actual nitrogen ratio of the obtained polymer (N actual). The theoretical nitrogen ratio of the isomers is always higher and the level of excess nitrogen (relative to N setpoint) therefore represents a measure for the respective isomer ratio.

[0054] The following tables show characteristic product parameters of various samples in comparison.

[0055] The samples designated as Laboratory Test 1 and Laboratory Test 2 were obtained with the method according to the invention, the other samples with various conventional methods. The key method parameters are also indicated in Table 1.

TABLE-US-00001 TABLE 1 Determination of the average degree of polymerization with LC-MS, MALDI-TOF, GC Method Reactants Reaction Temperature Time Polymer State of Temperature Temperature Max Total Min/Max/- Sample Aggregation Melt Monomer Temp Hours Average Laboratory HMDA liquid/ 55 70 150 6 n4/n8/n6 Test 1 GHC solid Laboratory HMDA liquid/ 55 65 145 8 n3/n8/n5 Test 2 GHC solid China HMDA liquid/ 180 180 210 7 n4/n11/n6 Powder GHC liquid 1000 China HMDA liquid/ 180 140 190 6 n4/n10/n6 Crystal GHC liquid 1000 Laboratory HMDA liquid/ 180 130 190 5 n27/n199/n72 Test 36/182 GHC liquid Laboratory HMDA liquid/ 180 130 230 5 n32/n240/n82 Test 36/184 GHC liquid Laboratory HMDA liquid/ 180 130 190 3 n16/n160/n54 Test 36/192 GHC liquid

TABLE-US-00002 TABLE 2 Comparison of the theoretical nitrogen ratio (N setpoint) for the ideal (linear) polymer with the indicated molecular weight average and degree of polymerization with the actual nitrogen ratio of the obtained polymer (N actual), as measured by means of DumaTherm (DUMATHERM rapid nitrogen determination in accordance with DUMAS from the manufacturer Gerhardt) with 1 g polymer Reactants Reaction State of N N Polymer Sample Aggregation setpoint actual Mw D Laboratory HMDA liquid/ 245.72 281.3 1083.30 Test 1 GHC solid Laboratory HMDA liquid/ 247.53 265.8 905.60 Test 2 GHC solid China HMDA liquid/ 245.72 378.2 1083.30 Powder GHC liquid 1000 China HMDA liquid/ 245.72 344.6 1083.30 Crystal GHC liquid 1000 Laboratory HMDA liquid/ 237.30 316.2 12,811.44 Test 36/182 GHC liquid Laboratory HMDA liquid/ 237.21 321.8 14,588.44 Test 36/184 GHC liquid Laboratory HMDA liquid/ 237.56 324.6 9612.84 Test 36/192 GHC liquid

TABLE-US-00003 TABLE 3 Derivation of the respective ratio of isomers and (linear) polymer on the basis of the measured nitrogen excess as a function of the degree of polymerization Reactants Reaction State of Polymer Isomer Polymer Sample Aggregation % % Mw D Laboratory HMDA liquid/ 85.52% 14.48% 1083.30 Test 1 GHC solid Laboratory HMDA liquid/ 92.62% 7.38% 905.60 Test 2 GHC solid China HMDA liquid/ 46.09% 53.91% 1083.30 Powder GHC liquid 1000 China HMDA liquid/ 59.76% 40.24% 1083.30 Crystal GHC liquid 1000 Laboratory HMDA liquid/ 66.75% 33.25% 12,811.44 Test 36/182 GHC liquid Laboratory HMDA liquid/ 64.34% 35.66% 14,588.44 Test 36/184 GHC liquid Laboratory HMDA liquid/ 63.36% 36.64% 9612.84 Test 36/192 GHC liquid

[0056] It is apparent that the samples obtained with the method according to the invention have a significantly lower isomer ratio than the conventional samples.