Method for preparing poly(o-aminobenzamide), poly(o-aminobenzamide) and its uses

Abstract

The present invention relates to a process for preparing poly(o-aminobenzamide), which comprises the steps of: (A) providing an o-aminobenzoic acid ester, (B) converting the o-aminobenzoic acid ester in the presence of a catalyst by polycondensation with elimination of the alcohol on which the o-aminobenzoic acid ester is based to produce poly(o-aminobenzamide), and poly(o-aminobenzamide) obtainable in this way and their use in the production of fibres or composites.

Description

[0001] The present invention relates to a process for preparing poly(o-aminobenzamide), which comprises the steps of: (A) providing an o-aminobenzoic acid ester, (B) converting the o-aminobenzoic acid ester by polycondensation in the presence of a catalyst with elimination of the alcohol on which the o-aminobenzoic acid ester is based to produce poly(o-aminobenzamide), and poly(o-aminobenzamide) obtainable in this way and their use in the production of fibres or composites.

[0002] Aromatic polyamides in which the amide groups are bonded to aryl groups (also known as aramids) are known from the prior art and are distributed under trade names such as Kevlar, Twaron (poly(p-phenyleneterephthalamide)) or Nomex, Teijinconex (poly(m-phenyleneterephthalamide)). They can be used in various fields. A prominent example is the production of fibres, especially textile fibres. Fibres made of aramid are known for their extremely high strength, high impact resistance, high elongation at break and good vibration damping. They are additionally very heat-resistant and fire-resistant. A disadvantage is their high price compared to many other polymers. Aramids are generally prepared by polycondensation of aromatic dicarbonyl halides C1CO-Ar 1 -COGl and aromatic diamines H2N-Ar 2 -NH2, which necessarily results in a polymer structure having alternating units derived from the dicarboxylic acid and the diamine (-[-CO-Ar 1 -CO-NH-Ar 2 -NH]-; AABB polymer structure).

[0003] A.F. Amin, B.P. Suthar and S.R. Patel described in J. Macromol. Sci.-Chem. 1982, A17(3), 481-488 the preparation of poly(o-aminobenzamide) having 3 to 10 repeating units. Considering the relatively low number of repeating units, the product formed should rather be called an oligomer.

[0004] The reaction of isatoic anhydride with ammonia at various concentrations was described as early as 1947 by R.P. Staiger and E.C. Wagner (published in Journal of Organic Chemistry 1948, 13, 347 - 352 in 1948). At low ammonia concentrations, o - aminobenzamide is obtained with elimination of carbon dioxide. At higher ammonia concentrations, cyclic benzoylurea is obtained instead with elimination of water. Referring to earlier studies, the formation of "abnormal" products from ammonia and isatoic anhydride was also reported, especially when isatoic anhydride was treated with only half an equivalent of ammonia. This gives an amorphous product, which was described as a condensation product. The reference J. Macromol. Sci. - Chem. 1982, A17(3), 481 - 488 which has been cited also mentions the so - called "abnormal products" with reference to earlier studies (abnormal in that these products are insoluble in ethanol and melt over a wide temperature range). However, according to J. Macromol. Sci. - Chem. 1982, A17(3), 481 - 488, these abnormal products were never systematically characterized, and according to this reference, numerous reports suggest that such "abnormal" products are merely mixtures of "normal" products.

[0005] US 9,683,126 B2 describes polymers having a C - C backbone with up to 10 o - aminobenzamide units grafted onto the C - C backbone via a divalent bridge. The base polymers forming the C - C backbone are in particular differently substituted poly(methacrylates) or polymerized vinyl aromatics.

[0006] The formation of higher molecular weight poly(o - aminobenzamide) where the high molar mass is achieved by many o - aminobenzamide repeat units rather than by grafting onto another polymer (i.e., forming a "true" o - aminobenzamide polymer rather than an oligomer or copolymer with only a few repeat units) is not described in these references. Other more commonly used aramids, such as poly(p - phenylene terephthalamide) or poly(m - phenylene isophthalamide) mentioned at the beginning, although can be prepared at high molar mass (although this is complex in terms of equipment and process operation due to the use of acyl chlorides under extremely corrosive conditions) and also have very good application properties, are very expensive. In addition, the common methods used to prepare these aramids are based on polycondensation reactions to form an AABB polymer structure, which requires very precise adherence to reaction stoichiometry to form a polymer with high molar mass.

[0007] A. Hoorfar, W. David Ollis and J. Fraser Stoddart described in Tetrahedron Letters 1980, 21, 4211 - 4214 the formation of cyclic o - aminobenzamides from (linear) oligomeric o - aminobenzamides having up to four o - aminobenzamide units. The oligomeric o - aminobenzamides were in turn obtained by a complex multi - step synthesis.

[0008] Yoshimoto Hamuro, Steven J. Geib and Andrew D. Hamilton also described in J. Am. Chem. Soc. 1996, 118, 7529 - 7541 oligomers based on o - aminobenzamide units. These products were obtained by a series of acylations, hydrogenations and acetylations using 2 - nitrobenzoyl chloride, methyl o - aminobenzoate and acetyl chloride as reactants.

[0009] Therefore, further improvements are needed in the field of aramid chemistry.

[0010] In view of this need, the subject of the present invention is thus a process for preparing poly(o - aminobenzamide), which comprises the steps of:

[0011] (A) providing an o - aminobenzoate (RO(O═C)(ortho - C6H4) - NH2),

[0012] (B) converting the o - aminobenzoate by (self) - polycondensation in the presence of a catalyst with elimination of alcohol (i.e., the alcohol ROH on which the o - aminobenzoate is based) to produce poly(o - aminobenzamide).

[0013] Another subject of the present invention is a poly(o - aminobenzamide) of the following formula

[0014] RO - [(O═C)(ortho - C6H4) - NH] n -H (I)

[0015] wherein R is an aliphatic organic group (derived from the alcohol ROH on which the o - aminobenzoate is based) and n refers to the number of repeating units.

[0016] Finally, the subject of the present invention is the use of the poly(o - aminobenzamide) of the present invention in the production of fibers or composites from poly(o - aminobenzamide) and (at least) one other material which comprises a metal, a mineral material or a polymer different from poly(o - aminobenzamide).

[0017] In the terminology of the present invention, an organic solvent is understood to mean a non - ionic organic solvent, as opposed to an ionic liquid ( = a salt with a low (i.e., below 100 °C) melting point).

[0018] In the present invention, the method crucial for determining the number of repeating units n is 1 1H NMR spectroscopy. This gives the average value of the number of repeating units, from which the number-average molar mass of poly(o-aminobenzamide) can be calculated. Details are described in the "Analysis" section below.

[0019] First, Overview various possible embodiments of the present invention.

[0020] In a first embodiment of the method of the present invention, which can be combined with all other embodiments, the catalyst used in step (B) comprises

[0021] (1) alkyl compounds of metals of Group 1, 4, 11, 12, 13 or 14 of the Periodic Table of the Elements,

[0022] · alkyl halide compounds,

[0023] · acetylacetonates,

[0024] · carboxylates,

[0025] · alcoholates, and / or

[0026] · chlorides

[0027] or

[0028] or

[0029] (2) Brønsted acids.

[0030] In a second embodiment of the method of the present invention as a specific configuration of the first embodiment, the metals of Group 1, 4, 11, 12, 13 or 14 of the Periodic Table of the Elements include Li, Ti, Cu, Zn, Al, Hf, Zr and / or Sn.

[0031] In a third embodiment of the method of the present invention as a specific configuration of the first and second embodiments, the alkyl compound includes diethyl zinc and / or triethyl aluminum.

[0032] In a fourth embodiment of the method of the present invention as a specific configuration of the first to third embodiments, the alkyl halide compound includes dichloro(ethyl)aluminum and / or chloro(diethyl)aluminum.

[0033] In a fifth embodiment of the method of the present invention as a specific configuration of the first to fourth embodiments, the acetylacetonate includes titanium(IV) acetylacetonate, zinc acetylacetonate and / or aluminum acetylacetonate.

[0034] In a sixth embodiment of the method of the present invention as a specific configuration of the first to fifth embodiments, the carboxylate includes zinc(II) acetate.

[0035] In a seventh embodiment of the method of the present invention in a specific configuration of the first to sixth embodiments, the alkoxide includes methoxide, ethoxide, isopropoxide, butoxide, isobutoxide, and / or phenoxide.

[0036] In an eighth embodiment of the method of the present invention in a specific configuration of the first to seventh embodiments, the alkoxide includes aluminum triisopropoxide, titanium tetrabutoxide, titanium tetra-isobutoxide, and / or lithium methoxide.

[0037] In a ninth embodiment of the method of the present invention in a specific configuration of the first to eighth embodiments, the chloride includes zinc dichloride and / or iron trichloride.

[0038] In a tenth embodiment of the method of the present invention in a specific configuration of the first to ninth embodiments, the Bronsted acid includes an inorganic acid selected from sulfuric acid, hydrochloric acid, nitric acid, and / or phosphoric acid.

[0039] In an eleventh embodiment of the method of the present invention combinable with all other embodiments, the o-aminobenzoate includes methyl o-aminobenzoate, ethyl o-aminobenzoate, propyl o-aminobenzoate, isopropyl o-aminobenzoate, butyl o-aminobenzoate, and / or isobutyl o-aminobenzoate.

[0040] In a twelfth embodiment of the method of the present invention combinable with all other embodiments, step (B) is carried out at a reaction temperature of 120°C to 300°C or 160°C to 280°C or 170°C to 250°C.

[0041] In a thirteenth embodiment of the method of the present invention combinable with all other embodiments, step (B) is carried out at 0.10 bar (abs.) to <1.0 bar (abs.) or 1.0 bar (abs.) to 1.5 bar (abs.) under pressure.

[0042] In a fourteenth embodiment of the method of the present invention combinable with all other embodiments, if it is not contemplated to use a solvent in step (B), step (B) is carried out in the absence of a solvent, where after step (B)

[0043] (C)(i) Dissolve poly(o-aminobenzamide) in an inorganic acid to obtain an inorganic acid solution of poly(o-aminobenzamide);

[0044] (D)(i) Separate poly(o-aminobenzamide) dissolved in the inorganic acid from the inorganic acid solution, which includes the step of precipitation in water.

[0045] In a fifteenth embodiment of the method of the present invention in a specific configuration as the fourteenth embodiment, the inorganic acid comprises sulfuric acid, hydrochloric acid, nitric acid, and / or phosphoric acid, especially sulfuric acid.

[0046] In a sixteenth embodiment of the method of the present invention which can be combined with all other embodiments except those excluding the use of a solvent in step (B) or envisioning suspension polymerization for this step, step (B) is carried out in the presence of a solvent, where the solvent comprises an organic solvent, an ionic liquid, or a mixture of the above solvents in liquid form under the reaction conditions of step (B) (especially at the reaction temperature), and in step (B), poly(o-aminobenzamide) is obtained in a manner suspended in the solvent, where after step (B):

[0047] (C)(ii) Dissolve the poly(o-aminobenzamide) suspended in the solvent in an inorganic acid and remove the solvent to obtain an inorganic acid solution of poly(o-aminobenzamide);

[0048] (D)(ii) Separate the poly(o-aminobenzamide) dissolved in the inorganic acid from the inorganic acid solution, which includes the step of precipitation in water.

[0049] In a seventeenth embodiment of the method of the present invention in a specific configuration as the sixteenth embodiment, the inorganic acid comprises sulfuric acid, hydrochloric acid, nitric acid, and / or phosphoric acid, especially sulfuric acid.

[0050] In an eighteenth embodiment of the method of the present invention in a specific configuration as the sixteenth and seventeenth embodiments, the solvent is removed in step (C)(i) by filtration, centrifugation, or phase separation.

[0051] In a nineteenth embodiment of the method of the present invention which can be combined with all other embodiments except those excluding the use of a solvent in step (B) or envisioning suspension polymerization for this step, step (B) is carried out in the presence of a solvent, where the solvent comprises an ionic liquid or a mixture of an ionic liquid and an organic solvent in liquid form at the reaction temperature, and in step (B), poly(o-aminobenzamide) is obtained in a manner dissolved in the solvent, where after step (B):

[0052] (D)(iii) Separate the poly(o-aminobenzamide) dissolved in the solvent from the solution in the solvent, which includes the step of precipitation in water.

[0053] In a twentieth embodiment of the method of the present invention in a specific configuration as the sixteenth to nineteenth embodiments, the organic solvent comprises diphenyl ether, N-methyl-2-pyrrolidone (especially containing CaCl2), 1,3-dimethyl-2-imidazolidinone (DMI), and / or hexamethylphosphoramide.

[0054] In a twenty - first embodiment of the method of the invention in a specific configuration as the sixteenth to twentieth embodiments, the ionic liquid comprises 1 - ethyl - 3 - methylimidazolium acetate, 1 - butyl - 3 - methylimidazolium acetate, 1 - butyl - 3 - methylimidazolium butyrate, 1 - butyl - 3 - methylimidazolium nitrate, 1 - butyl - 3 - methylimidazolium methanesulfonate, and / or dialkylimidazolium phosphate (such as in particular butyl - 3 - methylimidazolium phosphate, dimethylimidazolium diethyl phosphate ("MMIM - DEP") and ethylmethylimidazolium diethyl phosphate ("EMIM - DEP")).

[0055] In a twenty - second embodiment of the method of the invention which can be combined with all embodiments, the provision of the anthranilate in step (A) starts from anthranilic acid.

[0056] In a twenty - third embodiment of the method of the invention in a specific configuration as the twenty - second embodiment, step (A) comprises converting anthranilic acid to anthraniloyl chloride, wherein anthraniloyl chloride is reacted with an alcohol (i.e., the alcohol on which the anthranilate is based) to produce the anthranilate.

[0057] In a twenty - fourth embodiment of the method of the invention in a second specific configuration as the twenty - second embodiment, step (A) comprises converting anthranilic acid to isatoic anhydride, wherein isatoic anhydride is reacted with an alcohol (mainly the alcohol on which the anthranilate is based) to produce the anthranilate.

[0058] In a twenty - fifth embodiment of the method of the invention in a third specific configuration as the twenty - second embodiment, step (A) comprises reacting anthranilic acid with an alcohol (i.e., the alcohol on which the anthranilate is based) to produce the anthranilate, wherein the reaction is carried out especially at a pressure of 1 mbar (abs.) to 100 mbar (abs.) and a temperature of 50 °C to 100 °C (to minimize the yield loss caused by the reaction of anthranilic acid to produce aniline).

[0059] In a twenty - sixth embodiment of the method of the invention in a specific configuration as the twenty - fourth and twenty - fifth embodiments, the reaction of (isatoic anhydride or anthranilic acid) with the alcohol in step (A) is carried out in the presence of a catalyst.

[0060] In a twenty - seventh embodiment of the method of the invention in a specific configuration as the twenty - sixth embodiment, the catalyst used in step (A) comprises

[0061] (1) of metals of Group 1, 4, 11, 12, 13 or 14 of the Periodic Table

[0062] · Alkyl compounds,

[0063] · Alkyl halide compounds,

[0064] · Acetylacetonates,

[0065] · Carboxylates,

[0066] · Alcoholates, and / or

[0067] · Chlorides

[0068] or

[0069] (2) Bronsted acids,

[0070] wherein the preferred configuration of the catalyst is those shown above for the second to tenth embodiments.

[0071] In the twenty-eighth embodiment of the method of the present invention which is a specific configuration of the twenty-sixth and twenty-seventh embodiments, step (B) is carried out without previously removing the catalyst used in step (A), and no catalyst different from the catalyst used in step (A) is added (i.e., steps (A) and (B) are carried out with the same catalyst).

[0072] In the twenty-ninth embodiment of the method of the present invention which is a specific configuration of the twenty-second to twenty-eighth embodiments, anthranilic acid is obtained by fermentation of a raw material comprising

[0073] · Fermentable carbon-containing compounds

[0074] known

[0075] · Nitrogen-containing compounds.

[0076] In the thirtieth embodiment of the method of the present invention which is a specific configuration of the twenty-ninth embodiment, the fermentable carbon-containing compounds comprise hydrolysis products of starch, sugar cane juice, beet juice, and / or hydrolysis products of lignocellulosic raw materials, and the nitrogen-containing compounds comprise ammonia, aqueous ammonia, ammonium salts, and / or urea.

[0077] In the thirty-first embodiment of the method of the present invention which can be combined with all other embodiments, the polycondensation process is controlled by removing the alcohol eliminated in the reaction in step (B).

[0078] In a thirty-second embodiment of the process according to the invention, which can be combined with all other embodiments, poly(o-aminobenzamide) of formula (I) is obtained by the process according to the invention, wherein n is in the range of 20 to 2500, preferably in the range of 40 to 2500, more preferably in the range of 50 to 2400, even more preferably in the range of 70 to 2000, very particularly preferably in the range of 70 to 200, in particular 70 to 100.

[0079] In the present invention which can be combined with all other embodiments Poly(anthranilamide) In a first embodiment, R is methyl, ethyl, propyl, isopropyl, butyl or isobutyl.

[0080] In a second embodiment of the method of the invention, which can be combined with all other embodiments, n is in the range of 20 to 2500, preferably in the range of 40 to 2500, more preferably in the range of 50 to 2400, even more preferably in the range of 70 to 2000, very particularly preferably in the range of 70 to 200, in particular 70 to 100.

[0081] In a first embodiment of the use of the invention, which can be combined with all other embodiments, the fibers or composite materials are used to produce protective equipment (especially, but not limited to, clothing articles such as protective suits and protective vests) to protect against fire, fragmentation, fragment penetration, mechanical impact (including shooting) or cuts.

[0082] In a second embodiment of the use according to the invention, which can be combined with all other embodiments, the fibers or composite materials are used for producing sports equipment.

[0083] The above-summarized embodiments of the present invention and further possible embodiments are explained in detail below. Here, all embodiments can be combined with each other arbitrarily, unless otherwise stated or clearly evident from the context.

[0084] In step (A) of the method of the present invention, an anthranilate (which comprises a mixture of different anthranilates) is provided for subsequent polycondensation. Here, anthranilate can in principle be prepared by all methods known in the professional field for synthesizing such compounds. Usually, the synthesis starts with anthranilic acid (= anthranilic acid). Preferred anthranilates are methyl anthranilate, ethyl anthranilate, propyl anthranilate, isopropyl anthranilate, butyl anthranilate and / or isobutyl anthranilate.

[0085] Anthranilic acid can be prepared by known chemical methods. An example of a suitable chemical method is the reaction of phthalimide with sodium hypochlorite. Phthalimide itself can be obtained from phthalic anhydride and ammonia. The whole method is well-known. Industrial methods are also described in the patent literature; see, for example, DE 29 02 978 A1 and EP 0 004635 A2. In addition, a fermentation preparation route for anthranilic acid has recently been disclosed, which starts from renewable raw materials and can thus protect fossil raw materials and reduce the so-called CO2 footprint; see, for example, WO 2018 / 002088 A1, page 13, line 26 to page 22, line 15, and the documents cited therein. This fermentation method can also be used in the method of the present invention. In this embodiment, step (A) of the method of the present invention thus includes the fermentation of a raw material comprising

[0086] · Fermentable carbon-containing compounds, preferably starch hydrolysis products, sugarcane juice, beet juice, hydrolysis products of lignocellulosic raw materials or mixtures thereof,

[0087] known

[0088] · Nitrogen-containing compounds, preferably ammonia gas, aqueous ammonia, ammonium salts, urea or mixtures thereof.

[0089] Preferably, the fermentable carbon-containing compounds comprise starch hydrolysis products, sugarcane juice, beet juice and / or hydrolysis products of lignocellulosic raw materials, and the nitrogen-containing compounds therein comprise ammonia gas, aqueous ammonia, ammonium salts and / or urea. Microorganisms suitable for carrying out the fermentation are especially Escherichia coli, Pseudomonas putida, Corynebacterium glutamicum, Ashbya gossypii, Pichia pastoris, Hansenula polymorpha, Yarrowia lipolytica, Zygosaccharomyces bailii or Saccharomyces cerevisiae.

[0090] In one possible embodiment, anthranilic acid is first converted into anthraniloyl chloride, which reacts with an alcohol to produce the desired anthranilic acid ester. Suitable for the conversion to acyl chloride are conventional methods known in the art, such as the reaction with thionyl dichloride.

[0091] As an alternative to conversion to acyl chloride, anthranilic acid can be converted to isatoic anhydride, which is then reacted with an alcohol to produce an anthranilic acid ester. For this purpose, anthranilic acid can be reacted with phosgene, especially in a hydrochloric acid medium. Instead of phosgene, diphosgene, triphosgene or other phosgenating agents known in the prior art, such as oxalyl chloride, 1,1-carbonyldiimidazole and dimethyl carbonate, can also be used. It is also possible for anthranilic acid to react with carbon monoxide in the presence of a catalyst, especially in the presence of a Pd or Pt catalyst, to obtain isatoic anhydride.

[0092] It is also possible to react anthranilic acid directly with an alcohol to produce the desired anthranilic acid ester. To avoid yield losses due to the formation of aniline from the reaction of anthranilic acid, it is appropriate to carry out this esterification at low temperature (50 °C to 100 °C) and low pressure (1 mbar (abs.) to 100 mbar (abs.) ).

[0093] In all cases, the reaction with the alcohol can be promoted by using a catalyst, especially in the case of the reaction of isatoic anhydride with an alcohol and the direct esterification of anthranilic acid. Suitable Catalyst are especially:

[0094] (1) Metal

[0095] · alkyl compounds,

[0096] · alkyl halide compounds,

[0097] · acetylacetonates,

[0098] · carboxylates,

[0099] · alkoxides, and / or

[0100] · chlorides

[0101] or

[0102] (2) Brønsted acids.

[0103] Preferably, the following options apply to the catalyst:

[0104] · Suitable metals of Groups 1, 4, 11, 12, 13 or 14 of the periodic table are especially Li, Ti, Cu, Zn, Al, Hf, Zr and / or Sn.

[0105] · Suitable alkyl compounds are especially diethylzinc and / or triethylaluminium.

[0106] · Available alkyl halide compounds are preferably dichloro(ethyl)aluminium and / or chloro(diethyl)aluminium.

[0107] · Examples of suitable acetylacetonates include titanium(IV) acetylacetonate, zinc acetylacetonate and / or aluminium acetylacetonate.

[0108] · Suitable carboxylates are especially zinc(II) acetate.

[0109] · Available alkoxides are preferably methoxides, ethoxides, isopropoxides, butoxides, isobutoxides and / or phenoxides. More preferably, the alkoxide comprises aluminium triisopropoxide, titanium tetrabutoxide, titanium tetra-isobutoxide and / or lithium methoxide.

[0110] · Suitable chlorides especially include zinc chloride and / or iron(III) chloride.

[0111] · Finally, the Bronsted acid used is preferably an inorganic acid selected from sulfuric acid, hydrochloric acid, nitric acid and / or phosphoric acid.

[0112] In step (B) of the process according to the invention, the anthranilate provided in step (A) is polycondensed. Since the anthranilate reacts "with itself" here, this is also referred to as "self-condensation". The alcohol on which the anthranilate is based is eliminated (except for the end groups).

[0113] n RO(O=C)(ortho-C6H4)NH2→RO-[(O=C)(ortho-C6H4)-NH] n -H+(n-1)ROH

[0114] Suitable catalysts for this are the same as those described above for step (A). The preferred configurations of these catalysts are also the same as those described above for step (A). This opens up the possibility of carrying out step (B) without prior removal of the catalyst used in step (A), and furthermore without adding a catalyst different from the catalyst used in step (A), i.e. steps (A) and (B) are carried out with the same catalyst. Then only the reaction conditions are appropriately adjusted to initiate the polycondensation (see the following paragraphs in this regard).

[0115] The polycondensation can in principle be carried out in a wide temperature range, where the maximum temperature is only limited by the decomposition temperature of the starting materials. Step (B) is preferably carried out at a reaction temperature of from 120 °C to 300 °C, preferably from 160 °C to 280 °C, in particular from 170 °C to 250 °C.

[0116] There are likewise no special requirements for the pressure. For example, step (B) can be carried out at ambient pressure or a slightly elevated pressure, especially in the range from (abs.) 1.0 bar (abs.) to 1.5 bar. However, it is also possible to carry out step (B) under reduced pressure (especially in the range from 0.10 bar (abs.) to <1.0 bar (abs.)within the range). Therefore, the eliminated alcohol can evaporate more easily, and thus the reaction can proceed in the desired direction.

[0117] The polycondensation can be carried out (i) without a solvent ("neat", "bulk polymerization") or in the presence of a solvent. In the latter case, suitable solvents are (ii) organic solvents that are liquid at the reaction temperature, (iii) ionic liquids, or (iv) a mixture of both. Solvents suitable for case (ii) are especially diphenyl ether, N-methyl-2-pyrrolidone (preferably in combination with CaCl2 as a solubilizer), 1,3-dimethyl-2-imidazolidinone (DMI), and / or hexamethylphosphoramide. These are in liquid form at a suitable reaction temperature (see above). For case (iii), it is in principle conceivable to use ionic liquids known in the art, especially 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium butyrate, 1-butyl-3-methylimidazolium nitrate, 1-butyl-3-methylimidazolium methanesulfonate, and / or dialkylimidazolium phosphate (such as especially butyl-3-methylimidazolium phosphate, dimethylimidazolium diethyl phosphate ("MMIM-DEP"), and ethylmethylimidazolium diethyl phosphate ("EMIM-DEP")).

[0118] In the case of carrying out ROP without a solvent (i), the o-aminobenzoate is converted in the molten state. In the case of without a solvent, the polycondensation starts in the homogeneous phase (in the melt). However, as the polymerization progresses, the formed polymer rapidly precipitates, so that a suspension of the polymer in the unreacted monomer is obtained. As the polymerization further progresses, the entire reaction mixture usually solidifies substantially.

[0119] In this case, the post-treatment preferably includes the following steps:

[0120] (C) (i) Dissolving the poly(o-aminobenzamide) in an inorganic acid to obtain an inorganic acid solution of poly(o-aminobenzamide);

[0121] (D) (i) Separating the poly(o-aminobenzamide) dissolved in the inorganic acid from the inorganic acid solution, which includes the step of precipitation in water.

[0122] Suitable inorganic acids for carrying out step (C) (i) are especially sulfuric acid, hydrochloric acid, nitric acid, and / or phosphoric acid. Sulfuric acid is preferred, especially sulfuric acid with a mass concentration of 96% to 100%, preferably 96% to 98%. This dissolution is preferably carried out at a temperature of 20°C to 100°C.

[0123] If used Organic solvent(ii), a suspension of poly(anthranilamide) is usually obtained in step (B) (suspension polymerization). In this case, the post-treatment of the process product in step (B) preferably includes the steps of:

[0124] (C)(ii) Dissolving the poly(anthranilamide) suspended in a solvent in an inorganic acid and removing the solvent to obtain an inorganic acid solution of poly(anthranilamide);

[0125] (D)(ii) Separating the poly(anthranilamide) dissolved in the inorganic acid from the inorganic acid solution, which includes the step of precipitation in water.

[0126] The preferred conditions for the dissolution and separation steps mentioned above for case (i) also apply to case (ii). The removal of the organic solvent additionally required here is preferably carried out by filtration, centrifugation or phase separation. This removal can be carried out either before dissolving the poly(anthranilamide) in the inorganic acid (in this case, the solid poly(anthranilamide) still usually containing entrained organic solvent is filtered out and then dissolved in the inorganic acid), or after it (at this time, the organic solvent precipitated in or insoluble in the inorganic acid is removed).

[0127] If the solvent used in step (B) is an ionic liquid (iii), a solution of poly(anthranilamide) is usually obtained in this step (solution polymerization). Since the polymerization product is already in solution in this case, a dissolution step (step (C) in cases (i) and (ii)) is not required. In this case, the post-treatment of the process product in step (B) therefore preferably includes the steps of:

[0128] (D)(iii) Separating the poly(anthranilamide) dissolved in the solvent from the solution in the solvent, which includes the step of precipitation in water.

[0129] The preferred conditions for the separation step mentioned above for case (i) also apply to case (iii).

[0130] If a mixture of an organic solvent and an ionic liquid (iv) is used in step (B), whether the process product is a solution or a suspension depends on the mixing ratio. Depending on the situation, further post-treatment is carried out as described above for case (iii) (solution) or case (ii) (suspension).

[0131] The recycled solvent is preferably recycled in all cases. For this purpose, purification may be required, which can be achieved by methods known in the art. Due to their high cost, the recycling of ionic liquids is particularly important. For this purpose, the ionic liquid obtained in the separation of poly(o-aminobenzamide) in step (D)(iii) or step (D)(iv) is dried at elevated temperature and reduced pressure, in particular at a temperature of 50 °C to 100 °C and 1 mbar (abs.) to 100 mbar (abs.) pressure.

[0132] When the process product from step (B) is in solution form, it is also conceivable to directly further process this solution to obtain the desired final product, in particular to spin fibers of poly(o-aminobenzamide) directly from the solution.

[0133] The process of the present invention is capable of forming high molecular weight poly(o-aminobenzamide). The number of repeating units and thus the molar mass can be controlled by removing the alcohol eliminated in the reaction. By determining the amount of alcohol removed, the degree of polymerization (Carothers equation) can be determined from the (known) amount of o-aminobenzoate used. Once the desired degree of polymerization is reached, the reaction can be stopped.

[0134] By the process of the present invention, poly(o-aminobenzamide) of the following formula can be obtained

[0135] RO-[(O=C)(ortho-C6H4)-NH] n -H (I)

[0136] wherein R is an aliphatic organic group and n refers to the number of repeating units. Preferably, R represents methyl, ethyl, propyl, isopropyl, butyl or isobutyl. The number of repeating units n is, for example, in the range from 20 to 2500, preferably in the range from 40 to 2500, more preferably in the range from 50 to 2400, still more preferably in the range from 70 to 2000, very particularly preferably in the range from 70 to 200, especially 70 to 100. The target number of repeating units of course depends on the intended field of use of the poly(o-aminobenzamide); thus, values different from those given above may optionally also be used.

[0137] The poly(o-aminobenzamide) obtainable according to the invention is suitable for various applications. Another subject of the invention is therefore the use of the poly(o-aminobenzamide) of the invention in the production of fibres or composite materials from poly(o-aminobenzamide) and (at least) one other material which comprises a metal, a mineral material (such as concrete) or a polymer different from poly(o-aminobenzamide) (such as polyurethane). The fibres or composite materials are preferably used for the production of protective equipment (in particular, but not limited to, articles of clothing such as protective clothing and protective vests) against fire, fragment formation, fragment penetration, mechanical shock (including shooting) or cuts. The fibres or composite materials can likewise be used for the production of sports equipment.

[0138] The invention is illustrated in detail below with reference to the examples. Examples:

[0139] Analysis

[0140] The number-average molar mass (M n ) of the poly(o-aminobenzamide) obtained was determined by 1 1H NMR spectroscopy (from Bruker, AV III HD 600, 600 MHz; pulse sequence zg30, delay time d1: 10 s, 64 scans). The samples were dissolved separately in deuterated sulfuric acid. 1 The relevant resonances in the 1H NMR spectrum (based on TMS = 0 ppm) were as follows:

[0141] The signal at 8.5 - 7.1 ppm was for the aromatic protons of o-aminobenzamide (corresponding to an integration of 4 protons). The resonance of the protons of the methyl ester end group had a shift of 3.56 ppm (methyl, corresponding to an integration of 3 protons).

[0142] The molar mass M n of the polymer was calculated according to equation (I) below, where the following abbreviations were used:

[0143] · F(A) = resonance area of the aromatic protons (4 protons) at 8.5 - 7.1 ppm

[0144] · F(M) = resonance area of the methyl of methyl o-aminobenzoate (3 protons) at 3.56 ppm

[0145] The number of repeating units (n) from oAB in the polymer was calculated according to equation (I) below:

[0146]

[0147] The molar mass M n of the polymer was calculated from the value of n according to equation (II) below:

[0148] Mn = 150.16 g / mol + n·120.14 g / mol + 1 g / mol (II)

[0149] Example 1 (of the present invention): Preparation of poly(anthranilamide) by polycondensation of methyl anthranilate in the presence of Ti(OiPr)4 as a catalyst Preparation of poly(anthranilamide)

[0150] A 500 mL four-necked flask was equipped with a distillation bridge, a precision glass stirrer (KPG stirrer), a temperature probe, a nitrogen feed, and a gas outlet / gas outlet with a pressure relief valve. Subsequently, 50 g of methyl anthranilate and 9.4 g of Ti(OiPr)4 were weighed in. Nitrogen was introduced at 10 L / h for 20 minutes, and the solution was stirred at 300 revolutions per minute. Thereafter, the solution was stirred at 180 °C for 9 hours.

[0151] The molar mass M was determined by NMR in D2SO4 n .

[0152] Example 2 (of the present invention): Preparation of poly(anthranilamide) by polycondensation of methyl anthranilate in the presence of Ti(OiPr)4 as a catalyst and diphenyl ether as a solvent

[0153] The reaction was carried out analogously to Example 1, but in the presence of 50 mL of diphenyl ether.

[0154] Example 3: Preparation of poly(anthranilamide) by polycondensation of methyl anthranilate under reduced pressure in the presence of Ti(OiPr)4 as a catalyst and diphenyl ether as a solvent

[0155] The reaction was carried out analogously to Example 2, but at a pressure of 0.80 bar (abs.) .

[0156] Example 4 (comparative): Preparation of poly(anthranilamide) by polycondensation of methyl anthranilate in the absence of Ti(OiPr)4 as a catalyst Preparation of poly(anthranilamide)

[0157] The reaction was carried out analogously to Example 1, but without a catalyst. Here no monomers were converted into the resulting poly(o-aminobenzamide).

[0158] The following table compares the results with each other:

[0159]

[0160] (n.b. = not determined).

Claims

1. A method for preparing poly(o-aminobenzamide), which comprises the steps of: (A) providing an o-aminobenzoic acid ester, (B) converting the o-aminobenzoic acid ester by polycondensation in the presence of a catalyst at a reaction temperature of 120 °C to 300 °C and an absolute pressure of 0.10 bar to <1.0 bar or 1.0 bar to 1.5 bar with elimination of alcohol to produce poly(o-aminobenzamide), wherein the catalyst used in step (B) comprises a titanium alkoxide.

2. The method according to claim 1, wherein the alkoxide comprises methoxide, ethoxide, isopropoxide, butoxide, phenoxide or a mixture thereof.

3. The method according to claim 2, wherein the alkoxide comprises titanium tetra-isobutoxide.

4. The method according to any one of claims 1 to 3, wherein the o-aminobenzoic acid ester comprises methyl o-aminobenzoate, ethyl o-aminobenzoate, propyl o-aminobenzoate, butyl o-aminobenzoate or a mixture thereof.

5. The method according to claim 4, wherein the propyl o-aminobenzoate comprises isopropyl o-aminobenzoate and the butyl o-aminobenzoate comprises isobutyl o-aminobenzoate.

6. The method according to any one of claims 1 to 3, wherein step (B) is carried out in the absence of a solvent, and after step (B): (C)(i) dissolving the poly(o-aminobenzamide) in an inorganic acid to obtain an inorganic acid solution of poly(o-aminobenzamide); (D)(i) separating the poly(o-aminobenzamide) dissolved in the inorganic acid from the inorganic acid solution, which comprises the step of precipitation in water.

7. The method according to any one of claims 1 to 3, wherein step (B) is carried out in the presence of a solvent, wherein the solvent comprises an organic solvent, an ionic liquid or a mixture of the above solvents which is in liquid form under the reaction conditions of step (B), and in step (B), the poly(o-aminobenzamide) is obtained in a manner suspended in the solvent, and after step (B): (C)(ii) dissolving the poly(o-aminobenzamide) suspended in the solvent in an inorganic acid and separating the solvent to obtain an inorganic acid solution of poly(o-aminobenzamide); (D)(ii) separating the poly(o-aminobenzamide) dissolved in the inorganic acid from the inorganic acid solution, which comprises the step of precipitation in water.

8. The method according to any one of claims 1 to 3, wherein step (B) is carried out in the presence of a solvent, wherein the solvent comprises an ionic liquid or a mixture of an ionic liquid and an organic solvent which is in liquid form at the reaction temperature, and in step (B), the poly(o-aminobenzamide) is obtained in a manner dissolved in the solvent, and after step (B): (D)(iii) separating the poly(o-aminobenzamide) dissolved in the solvent from the solution, which comprises the step of precipitation in water.

9. The method according to claim 7, wherein the organic solvent comprises diphenyl ether, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide or a mixture thereof, and The ionic liquid comprises 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium butyrate, 1-butyl-3-methylimidazolium nitrate, 1-butyl-3-methylimidazolium methanesulfonate, dialkylimidazolium phosphate or a mixture thereof.

10. The method according to claim 8, wherein the organic solvent comprises diphenyl ether, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide or a mixture thereof, and the ionic liquid comprises 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium butyrate, 1-butyl-3-methylimidazolium nitrate, 1-butyl-3-methylimidazolium methanesulfonate, dialkylimidazolium phosphate or a mixture thereof.

11. The method according to any one of claims 1 to 3, wherein step (A) comprises converting anthranilic acid into isatoic anhydride and reacting the isatoic anhydride with an alcohol to produce an anthranilic acid ester; or wherein step (A) comprises reacting anthranilic acid with an alcohol to produce an anthranilic acid ester.

12. The method according to claim 11, wherein the reaction with the alcohol in step (A) is carried out in the presence of a catalyst, and step (B) is carried out without pre-removing the catalyst used in step (A) and without adding a catalyst different from the catalyst used in step (A).

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