Polyurethane urea and method for preparing same

Abstract

The present invention relates to a polyurethaneurea having low tensile stress, high elongation rate and excellent heat resistance, or a preparation method thereof. The polyurethaneurea of ​​the present invention is prepared by a) reacting modified PolyTHF with a diisocyanate to obtain a prepolymer, b) adding a chain extender and optionally a chain terminator to the prepolymer to obtain a polyurethaneurea solution, and c) spinning or casting the solution obtained in step b) to obtain a polyurethaneurea.

Description

[Technical field]

[0001] The present invention relates to a polyurethaneurea and a method for preparing the same. The present invention further relates to a polyurethaneurea fiber or film having low tensile stress, high elongation and excellent heat resistance, which is made from modified PolyTHF, isocyanate, a chain extender and, if necessary, a chain terminator. [Background technology]

[0002] Commercially available polyurethaneurea fibers, i.e., spandex fibers, are produced by a process which includes a) reacting a polymeric glycol or polyol with an isocyanate to form a polyurethane prepolymer; and b) then reacting the polyurethane prepolymer with a chain extender, optionally a chain terminator, and additional additives to form a polyurethaneurea.

[0003] Polyurethane urea fibers with excellent elasticity are widely used in textile fields such as sportswear, general wear, and stockings, and in non-textile fields such as sanitary products. Due to the diversification of downstream applications, the requirements for comfort and appearance of elastic fibers are also increasing. On the one hand, lower tensile stress, higher elongation rate, and higher elastic recovery rate are required to make elastic fabrics easier to stretch and less restrictive to the body. On the other hand, polyurethane urea fibers need to be woven with polyester, nylon, cotton, etc., dyed, and spun, and the dyeing temperature of polyester is about 130°C, and the dry spinning temperature is over 160°C, so excellent heat resistance is also required. If the heat resistance of polyurethane urea fibers is not high enough, the functionality and appearance of the fabric prepared from polyurethane urea fibers may be affected.

[0004] US Patent No. 5,000,899A discloses low modulus polyurethaneurea fibers using copolymer glycols of tetrahydrofuran and 3-methyltetrahydrofuran as the soft segment of the material, which improves the thermosetting properties of the fibers, however at the expense of the heat resistance of the fibers.

[0005] US Patent Publication No. 20070117951A discloses low tensile stress spandex prepared from high molecular weight copolymers of tetrahydrofuran and ethylene oxide, however, the spandex exhibits high residual deformation.

[0006] US 20090182113A discloses a polyurethaneurea made by a) reacting a polymeric glycol with a reactive material to form an OH-terminated prepolymer; b) reacting the OH-terminated prepolymer with a diisocyanate to form an isocyanate-terminated prepolymer; c) reacting the isocyanate-terminated prepolymer with a chain extender, and optionally a chain terminator and additives to form a polyurethaneurea; and d) spinning the polyurethaneurea to form a fiber. However, the heat resistance of the fiber is not disclosed.

[0007] Chinese Patent No. 101555634A discloses a method of increasing the ratio of hard segment components 4,4'-methylenediphenyldiisocyanate (4,4'-MDI) or 1,2-ethylenediamine to improve the heat resistance of polyurethaneurea fibers. Chinese Patent No. 1310991C discloses a method of introducing polyols with aromatic functional groups to improve the heat resistance of polyurethaneurea fibers. However, neither discloses a fiber with low tensile stress, and generally, increasing the ratio of hard segments leads to a decrease in elongation and an increase in tensile stress. In addition, increasing the ratio of hard segments reduces the solubility of polyurethaneurea fibers in dimethylacetamide or dimethylformamide solvents.

[0008] Therefore, there is a need to provide a polyurethaneurea that has low tensile stress, high elongation, and good elastic recovery and heat resistance. Summary of the Invention [Problem to be solved by the invention]

[0009] It is an object of the present invention to provide a polyurethaneurea having low tensile stress, high elongation, and good elastic recovery and heat resistance.

[0010] Another object of the present invention is to provide a process for making the polyurethaneurea of ​​the present invention from modified PolyTHF, a diisocyanate, a chain extender, and a chain terminator.

[0011] Surprisingly, it has been found that the above object can be achieved by the following embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein, the following terms have the following meanings ascribed to them unless otherwise specified:

[0013] The indefinite articles "a," "an," and "the" refer to one or more of the kind designated by the term following the article.

[0014] The term m-PolyTHF, denoting modified PolyTHF, means polyester alcohols resulting from the copolymerization of PolyTHF with dicarboxylic acids and / or their anhydrides and / or their esters.

[0015] Mn indicates the number average molecular weight (g / mol) and is tested according to ASTM E1899-2016.

[0016] The elongation at break (De) indicates the elongation percentage at the time of break of the test specimen.

[0017] Tensile stress in MPa indicates specimen stress at 300% elongation.

[0018] Strength retention indicates the stress retained by a test specimen after heat treatment at 300% elongation compared to the stress value before heat treatment at 300% elongation.

[0019] Elastic Recovery Percentage (RER%): The percent recovery of a test specimen after repeated stretching.

[0020] Energy loss coefficient (b5), which is the energy loss of a test specimen after repeated elongations of 300%.

[0021] In the context of this disclosure, any specific values ​​recited in relation to characteristics (including specific values ​​recited within a range as endpoints) can be recombined to form new ranges.

[0022] Further embodiments of the invention emerge from the claims, the description and the examples. It will be understood that the features of the subject matter of the invention not yet described above and below can be used not only in the combinations shown, but also in other combinations, without departing from the scope of the invention.

[0023] One aspect of the present invention is directed to a polyurethaneurea having a De of greater than 500%, a tensile stress of less than 10 MPa, a strength retention of greater than 80%, a RER% of greater than 85%, and a b5 of less than 15.

[0024] In a preferred embodiment, the polyurethaneurea according to the invention has a De of more than 650%, preferably more than 700%, more preferably more than 750%.

[0025] In a preferred embodiment, the polyurethaneurea according to the invention has a tensile stress of less than 9 MPa, preferably less than 8 MPa, more preferably less than 7.5 MPa.

[0026] In a preferred embodiment, the polyurethaneureas of the present invention have a strength retention of greater than 85%, preferably greater than 90%.

[0027] In a preferred embodiment, the RER% of the polyurethaneurea in the present invention is greater than 90%.

[0028] In a preferred embodiment, the polyurethaneurea herein has b5 less than 13, preferably less than 12.

[0029] One embodiment of the present invention is directed to a process for making the polyurethaneurea of ​​the present invention, the process comprising: a) reacting m-PolyTHF with a diisocyanate to obtain a prepolymer; b) adding a chain extender and, if desired, a chain terminator to the prepolymer to obtain a polyurethane urea solution; c) spinning or casting the solution obtained in step b) to obtain a polyurethaneurea.

[0030] In one embodiment, the m-PolyTHF used in the present invention can be prepared according to the method disclosed in US Patent Application Publication No. 2012 / 0059142A1. More specifically, the m-PolyTHF is prepared based on polytetrahydrofuran and dicarboxylic acids and / or their anhydrides and / or their esters.

[0031] In a preferred embodiment, m-PolyTHF is prepared based on polytetrahydrofuran and aromatic dicarboxylic acids and / or their anhydrides and / or their esters. Preferably, said aromatic dicarboxylic acids are selected from isophthalic acid, phthalic acid, terephthalic acid and mixtures thereof; more preferably, said aromatic dicarboxylic acid is isophthalic acid.

[0032] The Mn of the m-PolyTHF used in the present invention is preferably in the range of 2000 to 4000 g / mol, more preferably 2000 to 3500 g / mol.

[0033] In the present invention, the Mn of the polytetrahydrofuran used for preparing m-PolyTHF is preferably in the range of 200 to 2000 g / mol, more preferably 200 to 1800 g / mol, and most preferably 200 to 1500 g / mol.

[0034] The diisocyanate used in step a) above can be any desired organic diisocyanate. Preferred diisocyanates include linear aliphatic isocyanates such as 1,2-ethylene diisocyanate, 1,3-propylene diisocyanate, 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,8-octamethylene diisocyanate, 1,5-diisocyanato-2,2,4-trimethylpentane, 3-oxo-1,5-pentane diisocyanate and mixtures thereof; cycloaliphatic diisocyanates such as isophorone diisocyanate, cyclohexane ... Diisocyanates or mixtures thereof, preferably 1,4-cyclohexane diisocyanate, 4,4'-diisocyanato-dicyclohexylmethane (HMDI); and aromatic diisocyanates such as 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate, mixtures of various monomeric diphenylmethane diisocyanates, 2,4- or 2,6-tolylene diisocyanate (TDI) or mixtures thereof, naphthylene diisocyanate (NDI) or mixtures thereof. Particularly preferred diisocyanates are 4,4'-MDI and 2,4- or 2,6-tolylene diisocyanate, with 4,4'-MDI being preferred.

[0035] In another embodiment, the diisocyanate used in step a) is used in excess. Preferably, the molar ratio of m-PolyTHF to diisocyanate is in the range of 1:1.2 to 1:3, more preferably 1:1.3 to 1:2. The reaction is initiated by mixing m-PolyTHF and diisocyanate at a temperature of 20 to 120°C, preferably 50 to 100°C, more preferably 70 to 90°C. The reaction is preferably carried out without a solvent. If a solvent is used, preferably the solvent is a polar aprotic solvent, for example N,N-dimethylacetamide or N,N-dimethylformamide. The reaction preferably proceeds without a catalyst. If a catalyst is used, for example phosphoric acid can be used at a concentration of preferably 50 to 200 ppm based on the reaction mixture.

[0036] Useful chain extenders include compounds having two isocyanate reactive hydrogen atoms and a molecular weight of less than 500 g / mol. For example, ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butanediamine, 1,5-diaminopentane, hydrazine, m-xylylenediamine, p-xylylenediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,3-diamine-4-methylcyclohexane, 1-amino-3-aminoethyl-3,5,5-trimethylcyclohexane (isophoronediamine), 1,1'-methylenebis(4,4'-diaminohexane), toluenediamine, piperazine, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or mixtures thereof can be used. Diamines such as ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butanediamine, 1,5-diaminopentane, hydrazine, m-xylylenediamine, p-xylylenediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,3-diamine-4-methylcyclohexane, 1-amino-3-aminoethyl-3,5,5-trimethylcyclohexane (isophoronediamine), 1,1'-methylenebis(4,4'-diaminohexane) and mixtures thereof are particularly preferred, especially ethylenediamine, 1,2-propylenediamine and mixtures thereof.

[0037] In a preferred embodiment, the chain extender in the present invention further comprises an aromatic diamine as a co-chain extender, the aromatic diamine having two hydrogen atoms reactive with isocyanate groups; preferably, the aromatic diamine is selected from toluene diamine, 1,3-m-phenylenediamine, 1,4-p-phenylenediamine, 4,4'-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 4,4'-diaminobenzenesulfone, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 1,6-naphthalenediamine or a mixture thereof. The molar ratio of aromatic diamine to aliphatic diamine is 2:98-50:50, preferably 2:98-40:60, more preferably 5:95-30:70, most preferably 10:90-25:75.

[0038] In further embodiments, useful chain terminators include secondary amines such as dimethylamine, dibutylamine, dicyclohexylamine; or primary amines such as ethanolamine or primary alcohols such as n-butanol (alone or in mixtures). Preferably, the chain terminator is a monofunctional amine.

[0039] In embodiments, certain amines are optionally used, examples being diethylenetriamine or diethanolamine at levels that do not affect smoothing production.

[0040] When using not only a chain extender but also a chain terminator and / or a specific amine, the proportion of one or more chain extenders is preferably 85% by weight or more, more preferably 90% by weight or more, based on the total weight of the chain extender, the chain terminator and the specific amine.

[0041] These chain terminators and certain amines may each be used alone or together with the chain extenders, by alone, it is meant that the components can be added simultaneously in different streams or at different times.

[0042] The ratio of isocyanate groups to amine groups is preferably in the range of 1:1 to 1:1.15, and more preferably 1:1 to 1:1.05.

[0043] The conversion of the prepolymer to the polyurethaneurea of ​​the invention is preferably carried out in solution. Polar aprotic solvents can be used. Polar aprotic solvents are solvents that dissolve the prepolymer but do not essentially react with the isocyanate groups. Examples of such solvents are N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, etc. It is preferable to use N,N-dimethylacetamide or N,N-dimethylformamide, in particular N,N-dimethylacetamide. Preferably, the prepolymer, the chain extender, if necessary the chain terminator and, if necessary, the specific amine are dissolved in a solvent in each case and the resulting solutions are then mixed with each other. Preferably, each solution is added separately to the solution of the prepolymer. This can be done at the same time or at different times. Alternatively, the solutions of the chain extender, the chain terminator and the specific amine can be mixed before being added to the prepolymer. The temperature at which the reaction takes place is preferably in the range of 0 to 80°C, more preferably 8 to 50°C, most preferably 10 to 35°C. Conventionally, all isocyanate-reactive materials are used in amounts such that there is a slight excess of isocyanate-reactive groups, generally amino groups.

[0044] The fully reacted solution is subsequently spun to form fibers. Any spinning process can be used that can produce the fibers of the present invention. Such spinning processes are described, for example, in "Kunststoffhandbuch, 7, Polyurethane", Carl Hanser Verlag, 3rd edition 1993, Chapter 13.2. These include dry spinning or wet spinning processes, preferably dry spinning processes. In the spinning process, the spinning solution containing the polyurethaneurea of ​​the present invention is spun through a spinneret die to form threads. The spinning solvent is removed, for example in a drying or coagulation bath, to obtain the polyurethaneurea fiber of the present invention.

[0045] The polyurethaneurea of ​​the present invention may further comprise additives. Any additive known for the subdivided polyurethaneurea fiber may be used herein. For example, matting agents, fillers, antioxidants, dyes, pigments, dye strengtheners, such as Methacrol 2462B, and stabilizers against heat, light, UV radiation, chlorinated water, and against the action of gas odors and air pollution, such as NO or NO2, may be included. Examples of antioxidants, stabilizers against heat, light or UV radiation are sterically hindered phenols, such as Cyanox 1790, hindered amine light stabilizers, stabilizers from the group of triazines, benzophenones and benzotriazoles. Examples of pigments and matting agents are titanium dioxide, magnesium stearate, silicone oil, zinc oxide and barium sulfate. Examples of dyes are acid dyes, disperse dyes and pigments, and optical brighteners. Examples of stabilizers against fiber degradation by chlorine or chlorinated water are zinc oxide, magnesium oxide or coated or uncoated magnesium aluminum hydroxycarbonates, such as hydrotalcite or huntite.

[0046] The polyurethaneureas of the present invention have advantageous properties in terms of De, tensile stress, strength retention, elastic recovery and energy loss, which are characterized by the use of solution cast polyurethaneurea films, which are obtained by casting a polyurethaneurea solution onto a planar surface and drying to remove the solvent.

[0047] The polyurethaneureas of the present invention are useful in making stretchable fabrics, such as spandex fibers for woven fabrics, knit fabrics, and other textile products.

[0048] Preferably, the viscosity of the polyurethaneurea in the spinning solution of the present invention is 120,000 to 500,000 mPa·s, and the rate of increase in viscosity is less than 5,000 mPa·s / h.

[0049] The following examples further illustrate the invention.

[0050] In the present invention, the test methods for various properties are as follows: For handling and reproducibility, the mechanical properties of polyurethaneurea were measured on films. To this end, the prepared polyurethaneurea solutions were converted into films by casting them on a precisely horizontally aligned glass plate and drying in a gentle N2 flow at 50 °C. The amount and concentration of the solutions as well as the area of ​​the plate were matched to each other to produce films with a thickness of about 0.20-0.26 mm.

[0051] The trends observed in the membranes are essentially identical to those in the fibers, and the effects of polymer chain orientation seen in the fibers and imparted by the spinning process are not reflected in the membranes. These differences are not intended to interfere with the spirit of the present invention.

[0052] According to De:ISO 37:2005, membrane samples of standard shape and dimensions of polyurethaneurea are taken and the length of the stretched sample is varied, expressed as a % of the original length when the sample breaks.

[0053] Tensile stress: According to ISO37:2005, a polyurethaneurea membrane sample having a standard shape and dimensions is taken, and according to ISO37:2005, the stress of the sample at an elongation rate of 300% is taken in MPa.

[0054] Strength retention: According to ISO37:2005, take a standard polyurethaneurea film sample, place it in an oven at 175°C for 10 minutes, and test the stress at 300% elongation according to ISO37:2005. Strength retention = (stress at 300% elongation after heat treatment / stress at 300% elongation before heat treatment) * 100.

[0055] RER%: According to ISO37:2005, take a film sample of standard shape and size of polyurethaneurea, stretch the sample to 300% elongation 5 times, then test the length of the sample according to DIN53835-2:1981. RER%=(1-(5th recovery length at 300% elongation-start length) / (length at 300% elongation-start length))*100.

[0056] b5: According to ISO37:2005, take a polyurethaneurea membrane sample of standard shape and dimensions, and stretch the sample 5 times to 300% elongation according to DIN53835-2:1981. b5=(1st 300% elongation stress-5th 300% elongation stress) / 1st 300% elongation stress*100. EXAMPLES

[0057] Materials used in the examples Lupranate® M: MDI manufactured by BASF DDM: BASF 4,4'-diaminodiphenylmethane DMAC: Dimethylacetamide manufactured by SINOPHARM EDA: BASF 1,2-ethylenediamine DEA: Diethylamine manufactured by BASF PPD: 1,4-p-phenylenediamine from Sigma-Aldrich Irgonox® 245: CAS 36443-68-2 manufactured by BASF Tinuvin® 622: CAS 70198-29-7 from BASF

[0058] m-PolyTHF: Modified PolyTHF® based on the following procedure m-PolyTHF-1 is m-PolyTHF prepared according to the procedure of Example 1 of US Patent Publication No. 2012 / 0059143. 857 parts of PolyTHF® 650 were reacted with 166 parts of isophthalic acid by gradually increasing the temperature to 220° C. and reducing the pressure to 20 mbar under the catalysis of 20 ppm by weight of tetrabutyl orthotitanate relative to PolyTHF® 650. When the acid value reached 1 mg KOH / g or less, the temperature was cooled to 200° C., 20 ppm of 85 wt.% phosphoric acid was added, and further cooled, and the resulting m-PolyTHF-1 had an OH value of 36 mg KOH / g. m-PolyTHF-2 and m-PolyTHF-3 were prepared according to the same procedure as described above for m-PolyTHF-1. The number average molecular weights Mn of the starting PolyTHF® and the Mn of the corresponding m-PolyTHF are summarized in Table 1, both of which were tested according to ASTM E1899-2016.

[0059] [Table 1]

[0060] Example 1 200.00 parts by weight of m-PolyTHF-1 and 27.42 parts by weight of Lupranate® M were placed in a reactor purged with N2 and reacted at 80°C for 120 minutes to produce a prepolymer with an NCO% content of 1.66% by weight; the temperature was lowered to below 50°C, and the resulting prepolymer was dissolved in 277.95 parts by weight of DMAC (referred to as DMAC-1 in Table 2). A solution of 2.27 parts by weight of EDA, 0.45 parts by weight of PPD, 0.72 parts by weight of DEA and 156.49 parts by weight of DMAC (referred to as DMAC-2 in Table 2) was added to this diluted prepolymer solution by high speed mixing to obtain a homogeneous polyurethaneurea solution. 0.2% (based on the weight of polyurethaneurea, the same below) of heat stabilizer Irgonox® 245 and 0.1% of ultraviolet stabilizer Tinuvin® 622 were added to the polyurethaneurea solution additive dope to obtain polyurethaneurea spinning solution. The relevant properties of the obtained spinning solution were tested using a cast film. The film thickness was controlled within 200±30 μm, the same below.

[0061] Examples 2 to 6 and Comparative Example 1 A polyurethaneurea film was prepared in a manner similar to that of Example 1, except that the corresponding raw materials and their amounts were used as illustrated in Table 2. The properties of the polyurethaneurea film thus obtained were tested according to the above methods, and the measurement results are summarized in Table 3.

[0062] [Table 2]

[0063] remarks: Co-CE means co-chain extender. m-PolyTHF type: As shown in Table 1, m-PolyTHF-1 is 1, m-PolyTHF-2 is 2, and m-PolyTHF-3 is 3.

[0064] [Table 3]

Claims

1. A polyurethaneurea, the elongation at break (De) of which is greater than 500%, the tensile stress of which is less than 10 MPa, the strength retention of which is greater than 80%, the elastic recovery ratio RER% of which is greater than 85% and the energy loss factor (b5) of which is less than 15, wherein the De, tensile stress and strength retention of said polyurethaneurea are tested according to ISO 37:2005.

2. The polyurethaneurea of ​​claim 1, wherein the De of the polyurethaneurea of ​​the present invention is greater than 650%, preferably greater than 700%, more preferably greater than 750%.

3. 3. The polyurethaneurea according to claim 1 or 2, wherein the tensile stress of the polyurethaneurea is less than 9 MPa, preferably less than 8 MPa, more preferably less than 7.5 MPa.

4. The polyurethaneurea according to any one of claims 1 to 3, wherein the strength retention of said polyurethaneurea is more than 85%, preferably more than 90%.

5. The polyurethaneurea according to any one of claims 1 to 4, wherein the RER% of the polyurethaneurea is greater than 90%.

6. The polyurethaneurea according to any one of claims 1 to 5, wherein the polyurethaneurea has an energy loss factor (b5) of less than 13, preferably less than 12.

7. A process for making the polyurethaneurea of ​​any one of claims 1 to 6, comprising: a) reacting m-PolyTHF with a diisocyanate to obtain a prepolymer; b) adding a chain extender and, if desired, a chain terminator to the prepolymer to obtain a polyurethane urea spinning solution; c) spinning or casting the solution obtained in step b) to obtain a polyurethaneurea. The process includes:

8. 8. The process according to claim 7, wherein the m-PolyTHF used in step a) is obtained from the condensation of polytetrahydrofuran with dicarboxylic acids and / or their anhydrides and / or their esters; preferably, the dicarboxylic acid is an aromatic dicarboxylic acid; more preferably, the dicarboxylic acid is isophthalic acid, phthalic acid, terephthalic acid or a mixture thereof; most preferably, the dicarboxylic acid is isophthalic acid.

9. The process according to claim 7 or 8, wherein the Mn (number average molecular weight) of the polytetrahydrofuran is from 200 to 2000 g / mol, preferably from 200 to 1800 g / mol, most preferably from 200 to 1500 g / mol.

10. The process according to any one of claims 7 to 9, wherein the Mn of m-PolyTHF is from 2000 to 4000 g / mol, preferably from 2000 to 3500 g / mol.

11. The process according to any one of claims 7 to 10, wherein the diisocyanate used in step a) comprises 4,4'-diisocyanate, preferably more than 60% 4,4'-diisocyanate, more preferably more than 80% 4,4'-diisocyanate, most preferably more than 95% 4,4'-diisocyanate.

12. The process according to any one of claims 7 to 11, wherein the molar ratio of m-PolyTHF to diisocyanate is from 1:1 to 1:3, preferably from 1:1.2 to 1:3, more preferably from 1:1.3 to 1:

2.

13. 13. The process of any one of claims 7 to 12, wherein the chain extender comprises an aliphatic diamine having two hydrogen atoms reactive with isocyanate groups; preferably, the aliphatic diamine is selected from 1,2-ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,4-cyclohexanediamine and mixtures thereof; more preferably, the aliphatic diamine is 1,2-ethylenediamine.

14. 14. The process of any one of claims 7 to 13, wherein the chain extender further comprises an aromatic diamine, the aromatic diamine having two hydrogen atoms reactive with isocyanate groups; preferably, the aromatic diamine is selected from 1,4-benzenedimethylamine, toluenediamine, 1,3-m-phenylenediamine, 1,4-p-phenylenediamine, 4,4'-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 4,4'-diaminobenzenesulfone, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 1,6-naphthalenediamine or mixtures thereof.

15. The process according to any one of claims 7 to 14, wherein the molar ratio of aromatic diamine to aliphatic diamine is from 2:98 to 50:50, preferably from 2:98 to 40:60, more preferably from 5:95 to 30:70, and most preferably from 10:90 to 25:

75.

16. 16. The process according to any one of claims 7 to 15, wherein the chain terminator is an alkyl alcohol and / or diallylamine; preferably, the chain terminator is selected from N-butanol, cyclohexanol, ethanolamine, diethanolamine, N,N-diethylamine, N,N-dibutylamine or mixtures thereof.

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