Liquid mixture of propoxylated para-toluidines

Abstract

To provide a propoxylated 4-toluidine that does not have the disadvantage of N,N-bis(2-hydroxypropyl)-p-toluidine, but can be used at least just as well or better as a polymerization accelerator or as a vulcanization accelerator or as a hardener component for epoxy resins in the polymer systems in which N,N-bis(2-hydroxypropyl)-p-toluidine can be used.SOLUTION: The invention relates to mixtures of propoxylated 4-toluidines containing two or more different di- or tri-propoxylated or higher propoxylated p-toluidines in specific weight ratios, to methods for preparing them and to their use as polymerization accelerators or vulcanization accelerators or as hardener components in epoxy resins.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to mixtures of propoxylated 4-toluidines (para-toluidines) containing two or more different di- or tri-propoxylated or more highly propoxylated p-toluidines in specific ratios, to a process for their preparation, and to their use as polymerization accelerators, vulcanization accelerators, or as hardener components for epoxy resins. [Background technology]

[0002] Crosslinked polymers can be produced by free radical polymerization. This includes, for example, the use of unsaturated polyesters. The polymerization process is also called curing. The polymerization is initiated by what are called curing agents for this group of polymers. These are generally free radical initiators, such as peroxides. The best-known and most widely used curing agent is dibenzoyl peroxide. This also includes the use of polymerization accelerators that accelerate the polymerization process and have a beneficial effect on the curing process and / or the properties of the polymer product. Some polymerization accelerators are advantageously incorporated into the polymer via additional functional groups. Tertiary amines, in the form of N,N-disubstituted toluidines, are an important group of such accelerators due to their low volatility and, moreover, their favorable toxicological profile, especially in the ethoxylated and propoxylated toluidine groups.

[0003] Individual compounds such as N,N-bis(2-hydroxypropyl)-p-toluidine [N,N-bis(2-hydroxypropyl)-4-toluidine, N,N-dipropoxy-p-toluidine, 1,1'-(p-tolylimino)dipropan-2-ol, CAS RN 38668-48-3; diisopropanol-p-toluidine, N,N-di(2-hydroxypropyl)-p-toluidine], i.e., "dipropoxylated" para-toluidine, are known. Their higher homologues have so far only been disclosed in general terms.

[0004] Patent Document 1 describes ethoxylated p-toluidines and a specific method for their preparation from 4-toluidine and 3 to 4 moles of ethylene oxide per mole of 4-toluidine at 80±5°C without the addition of solvents or catalysts. This results in a liquid mixture of ethoxylated 4-toluidines, but no further information is given about its composition. From the chemical yield, it can be inferred that the average degree of ethoxylation (the number of ethylene oxide units per molecule of 4-toluidine) is between 2 and 2.5. No information is given about the distribution of the individual homologs.

[0005] Patent Document 2 describes common homologues of N,N-bis(2-hydroxyalkyl)-p-toluidines, which contain less than 0.2% by weight of alkoxylated 3-toluidine, based on the alkoxylated 4-toluidine. Specifically disclosed is a process for their preparation from 4-toluidines containing less than 0.2% by weight of 3-toluidine and 2.2 to 5 moles, preferably 2.3 to 4 moles, more preferably 2.3 to 3.5 moles, and especially 2.5 to 2.6 moles of alkylene oxide per mole of 4-toluidine.

[0006] For example, when 4-toluidine containing less than 0.2% by weight of 3-toluidine, based on 4-toluidine, was reacted with 2.5 moles of ethylene oxide per mole of 4-toluidine used at 120°C without the addition of a solvent or catalyst, an ethoxylated 4-toluidine was obtained that no longer contained 4-toluidine (detection limit: 100 ppm), but which consisted of a mixture of less than 0.1% N-hydroxyethyl-4-toluidine, 50.1% N,N-bis(hydroxyethyl)-4-toluidine, and 43.7% N-oxyethyl-N-(hydroxyethyloxyethylene)-4-toluidine, 5.4% tetraoxyethyl-4-toluidine, 0.7% pentaoxyethyl-4-toluidine, and traces of hexaoxyethyl-4-toluidine.

[0007] When 4-toluidine containing less than 0.2% by weight of 3-toluidine, based on 4-toluidine, was reacted with 2.58 moles of ethylene oxide per mole of 4-toluidine used, without adding a solvent, using a 30% sodium methoxide solution as a catalyst at 120°C, an ethoxylated 4-toluidine was obtained, which consisted of 47.4% N,N-bis(hydroxyethyl)-4-toluidine, 43.4% N-oxyethyl-N-(hydroxyethyloxyethyl)-4-toluidine, and a trace amount of a mixture of more highly ethoxylated compounds. The document also contains descriptions of further examples, but does not describe the distribution of homologs therein.

[0008] Since the reaction of 4-toluidine with ethylene oxide proceeds virtually quantitatively, at least when a catalyst is used, it can be estimated, based on chemical mass balance, that the average degree of ethoxylation (the sum of m and n in general formula (I) in this document) is close to the molar ratio between ethylene oxide and 4-toluidine.

[0009] N,N-bis(hydroxyethyl)-4-toluidine (CAS RN 3077-12-1) is commercially available from LANXESS Deutschland GmbH / Saltigo GmbH as a black to tan liquid or solid product for use as a hardener component for epoxy resins.

[0010] Similarly, "over-ethoxylated N,N-bis(hydroxyethyl)-4-toluidine," a colorless to light yellow-brown viscous liquid containing less than 0.2% by weight of ethoxylated 3-toluidine, for use as a hardener component for epoxy resins is also commercially available from LANXESS Deutschland GmbH / Saltigo GmbH under the name Accelerator PT25E / 2.

[0011] Patent Document 3 discloses the simpler N,N-bis(hydroxypropyl)aniline and its higher homologues, which are obtained by reacting N,N-bis(hydroxypropyl)aniline in the presence of 3 to 3.6 moles of ethylene oxide per mole of aniline used, in the presence of a catalyst such as an alkali metal hydroxide or mixed metal cyanide, at a temperature of 145 to 165°C.

[0012] N,N-bis(2-hydroxypropyl)-p-toluidine (CAS RN 38668-48-3) is known and is sold by suppliers such as LANXESS Deutschland GmbH / Saltigo GmbH as a pale yellow solidified melt for use as a hardener component for epoxy resins.

[0013] In the field of use of epoxy resin systems, experience has shown that ethoxylated aniline, ethoxylated toluidine, or N,N-bis(2-hydroxypropyl)-p-toluidine are advantageous. However, N,N-bis(2-hydroxypropyl)-p-toluidine has the disadvantage of being in the form of a solidified melt at room temperature. Therefore, N,N-bis(2-hydroxypropyl)-p-toluidine must be melted before use by heating the container containing the product. It has been discovered that the various isomers of N,N-bis(2-hydroxypropyl)-p-toluidine have different melting points. The effect of this is as follows: when the product is partially melted, the isomer with the lower melting point collects in the liquid phase, and after removing the already liquefied fraction, the melting point of the remaining solid becomes even higher. In this respect, this phenomenon is a kind of "unintentional melt refining." To avoid this phenomenon, N,N-bis(2-hydroxypropyl)-p-toluidine must be heated to a much higher temperature than, for example, N,N-bis(hydroxyethyl)-p-toluidine, which constitutes a practical disadvantage. Due to the chirality of the central carbon atom in propylene oxide, used as a reactant for the preparation, two molecules of R- or S-propylene oxide react with one molecule of 4-toluidine, N,N-bis(2-hydroxypropyl)-p-toluidine, resulting in the formation of a mixture of various isomers, such as RR, SS, or meso isomers. Additionally, the epoxy ring of 4-toluidine can be opened by bonding at the terminal CH group (predominantly) or the central CH group.

[0014] (Non-Patent Document 1) reveals that different structures are formed in the reaction of 4-toluidine with two molecules of racemic propylene oxide.

[0015] In-house analysis of the various melting fractions of N,N-bis(2-hydroxypropyl)-p-toluidine has shown that the optically inactive meso isomer melts at a higher temperature than the optically active isomer. This means that N,N-bis(2-hydroxypropyl)-p-toluidine has the technical difficulty of being in the form of a complex mixture in the form of a solidified melt, and can only be introduced into industrial applications in a complex manner as a homogeneous mixture of the individual components. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Russian Patent Application Publication No. 2063960A [Patent Document 2] European Patent Application Publication No. 1650184A1 [Patent Document 3] China Patent Publication No. 101200432A [Non-patent literature]

[0017] [Non-Patent Document 1] A. Zoltanski, et al.,Current Applied Polymer Science,2018,2(2),89~93,The structure of Propoxylated p-Toluidine,Used as a Polymerization Accelerator or in Unsaturated Polyester Resin Curing Summary of the Invention [Problem to be solved by the invention]

[0018] The technical problem addressed here was therefore to provide a propoxylated 4-toluidine that does not have the disadvantages of N,N-bis(2-hydroxypropyl)-p-toluidine but that can be used at least equally well or better as a polymerization accelerator, vulcanization accelerator, or hardener component for epoxy resins in polymer systems in which N,N-bis(2-hydroxypropyl)-p-toluidine can be used. [Means for solving the problem]

[0019] This object has surprisingly been achieved by providing: Mixtures containing two or more different compounds of general formula (I) [ka] [In the formula, R 1 is hydrogen or methyl, but the R on the immediately adjacent carbon atom 1 groups are not both hydrogen or both methyl, and m and n represent integers, wherein 4-toluidine is present in a proportion of less than or equal to 2% by weight, preferably between 0.001% and 1% by weight, based on the total mass of all compounds of formula (I) in the mixture, and Among them, the compound of formula (I) in which the total sum of m and n is an integer 2 is present in the mixture at a ratio of 20% by weight or less, preferably 0.01% by weight to 20% by weight, more preferably 0.01% by weight to 12% by weight, based on the total mass of all compounds of formula (I), and Among them, compounds of formula (I) in which the total sum of m and n is at least an integer of 6 are present in the mixture at a ratio of 40% by weight or less, preferably 0.01% by weight to 40% by weight, more preferably 0.01% by weight to 20% by weight, based on the total mass of all compounds of formula (I). DETAILED DESCRIPTION OF THE INVENTION

[0020] Thus, the present invention provides a mixture of the present invention comprising two or more different compounds of formula (I). The phrase "comprising two or more different compounds" excludes the presence of only one homologue, such as N,N-bis(2-hydroxypropyl)-p-toluidine or N,N-bis(2-hydroxypropyloxypropylene)-p-toluidine. Compounds of formula (I) in which the total sum of m and n is the same are homologues of N,N-bis(2-hydroxypropyl)-p-toluidine with respect to the total sum of m and n. Thus, homologues refer to compounds of formula (I) in which the total number of oxypropylene units therein is different.

[0021] The distribution corresponding to the degree of propoxylation can be ascertained, for example, by GC-MS. It is also possible to determine the weight percent by gas chromatography by calibrating the GC measurement with calibration materials.

[0022] The mixture of the present invention preferably contains compounds of formula (I) in which the total sum of m and n is the integer 3 in a proportion of 7% by weight to 49% by weight, particularly preferably 15% by weight to 49% by weight, based on the total mass of all compounds of formula (I).

[0023] It is also preferred that the mixture of the present invention contains compounds of formula (I) in which the total sum of m and n is the integer 4 in a proportion of 10% by weight to 49% by weight, more preferably 10% by weight to 40% by weight, based on the total mass of all compounds of formula (I).

[0024] In a further preferred embodiment, in the mixture of the present invention, each homologous group of compounds of formula (I) is present in the mixture in a proportion of less than 50 weight percent, based on the total mass of all compounds of formula (I) in the mixture. A homologous group of compounds of formula (I) refers to various groups of compounds in which the sum of m and n is the same, but the combination of m and n may be different. For example, the group of homologous compounds in which the sum of m and n=4 includes the following compounds: m=0 and n=4, or m=4 and n=0, m=1 and n=3, or m=3 and n=1, and m=n=2 and the individual isomers of compounds having the above values ​​of m and n.

[0025] This has the advantage that the substance mixture may be classified as a polymer in chemical substance legislation in certain regions or countries and therefore be subject to different conditions under chemical substance legislation as individual substances.

[0026] In an equally preferred embodiment, the mixture according to the invention has a proportion of 4-toluidine of less than 0.1% by weight, based on the total mass of all compounds of formula (I) in the mixture.

[0027] The mixture of the present invention may further contain additional components in addition to the compound of formula (I). These may be catalyst residues, water, or other polymerization reaction products of propylene oxide. The weight percentages of all compounds of formula (I) and the weight percentages of these additional components add up to 100 weight percent. Typically, the mixture of the present invention contains 96 to 100 weight percent of the compound of formula (I).

[0028] The mixture of the present invention is typically a substance in a liquid state at room temperature and / or temperatures of 5 to 40°C. In addition, it is preferred that the mixture of the present invention does not contain any solid components. It is also preferred that the mixture of the present invention is not a suspension. Therefore, it is preferred that the mixture of the present invention can be handled as a homogeneous liquid at ambient temperature. This is advantageous in that when the mixture of the present invention is used as a polymerization accelerator, a vulcanization accelerator, or a curing agent component, it can be simply dispensed from a container in a precise amount and with a stable, predetermined composition, and can be used in that precise amount and with a stable, predetermined composition in that application. In the present invention, a mixture is considered to be in a liquid state if it has a dynamic viscosity of 0.1 to 20,000 mPas (milliPascal-second) at 25°C.

[0029] The dynamic viscosity can be measured by various methods, for example, by a capillary viscometer or a rotational viscometer. Unless otherwise specified, the dynamic viscosity is measured at a given temperature using a rotational viscometer according to DIN 53019, based on the principle of the cone-plate measuring system (reference: DIN 53019-2, chapter 10.3). The mixture of the present invention preferably has a dynamic viscosity of 500 to 20,000 mPas, measured at a temperature of 25°C using a rotational viscometer according to DIN 53019.

[0030] The mixture of the present invention is a reaction product obtained directly from the manufacturing process of the present invention.

[0031] The present invention therefore also provides the mixtures according to the invention which are obtainable by the process according to the invention.

[0032] The mixture of the present invention can be surprisingly produced by a simple and stable process. When the detection limit by gas chromatography is 100 ppm, it is preferable that no unconverted 4-toluidine is detected in the mixture of the present invention. This is very important because toluidine that is not alkylated on the nitrogen is classified as a severe hemotoxin and carcinogen.

[0033] This process of the invention for preparing such mixtures includes the step of preparing a compound of formula (I) where R 1 is hydrogen or methyl, provided that R on the immediately adjacent carbon atom 1 The method includes reacting N,N-dipropoxy-p-toluidine (wherein m and n are not both hydrogen or both methyl groups and where m and n are the integer 1) with 1.0 to 4.0 moles, preferably 1.25 to 2.50 moles, of propylene oxide (1,2-epoxypropane) per mole of 4-toluidine used, in the presence of a catalyst.

[0034] The N,N-dipropoxy-p-toluidine used as a reactant in the process of the present invention, i.e., 1 is hydrogen or methyl, provided that R on the immediately adjacent carbon atom 1 The compounds of formula (I), in which the groups are neither both hydrogen nor both methyl, and in which m and n are the integer 1, are either commercially available as products, or are reactants obtained separately by in-house preparation and subsequent isolation, or are reactants obtained in-house without separate isolation, in the latter case being prepared in the reaction vessel in which the process of the present invention is carried out.

[0035] The process of the present invention is preferably carried out at temperatures between 80 and 150° C., preferably between 100 and 150° C. At lower temperatures, the conversion may be incomplete, which in any case leads to a lengthy reaction which is uneconomical and which, if the metering rate of propylene oxide is not regulated, may result in a significant and therefore dangerous pressure buildup in the reactor. In contrast, at higher temperatures (in particular, the limiting temperature T 1 , which is 150° C. in the case of N,N-dipropoxy-p-toluidine), exo Temperatures exceeding those specified in TRAS410 may result in destruction due to uncontrolled heating accompanied by pressure buildup.

[0036] In the process of the present invention, the catalyst used is preferably an alkali metal and alkaline earth metal hydroxide, an alkali metal and alkaline earth metal carbonate, an alkali metal, an alkyl lithium, sodium hydride, a complex hydride such as lithium aluminum hydride, sodium bis(methoxyethoxy)aluminum dihydride, or an alkali metal alkoxide. The catalyst used is more preferably an alkali metal hydroxide, an alkali metal and alkaline earth metal carbonate, and most preferably sodium hydroxide or potassium hydroxide. In the process of the present invention, 1 is hydrogen or methyl, but the R on the immediately adjacent carbon atom 1 Preferably, 0.01 to 0.05 moles, more preferably 0.02 to 0.035 moles, of catalyst are used per mole of compound of formula (I) (N,N-dipropoxy-p-toluidine), wherein the groups are neither both hydrogen nor both methyl, and wherein m and n are the integer 1.

[0037] For the process of the present invention, the N,N-dipropoxy-p-toluidine reactant, i.e., 1 is hydrogen or methyl, but the R on the immediately adjacent carbon atom 1The compound of formula (I), in which m and n are not both hydrogen or both methyl groups and in which m and n are the integer 1, can be obtained by reacting 4-toluidine with 1.8 to 2.2 moles, preferably 1.9 to 2.1 moles, of propylene oxide per mole of 4-toluidine used, at a temperature of 80 to 150°C, preferably 100 to 150°C, more preferably 110 to 150°C, in the absence of a catalyst.

[0038] This means that the process of the invention for preparing the mixture of the invention further comprises reacting 4-toluidine with 1.8 to 2.2 moles, preferably 1.9 to 2.1 moles of propylene oxide per mole of 4-toluidine used, at a temperature of 80 to 150°C, preferably 100 to 150°C, more preferably 110 to 150°C, in the absence of a catalyst, to form a reactant, i.e., a propylene oxide, in the formula R 1 is hydrogen or methyl, but the R on the immediately adjacent carbon atom 1 The method includes obtaining a compound of formula (I), wherein m and n are not both hydrogen or both methyl groups, and wherein m and n are the integer 1, and then reacting the reactant with 1.0 to 4.0 moles, preferably 1.25 to 2.50 moles, of propylene oxide per mole of 4-toluidine used, in the presence of a catalyst.

[0039] The process of the present invention is typically carried out by selecting a temperature at which the component to be propoxylated, i.e., 4-toluidine or N,N-dipropoxy-p-toluidine, is in liquid form before the reaction is initiated. The reactor is then inerted with an inert gas, such as nitrogen, and the internal pressure is then reduced to a pressure of about 50 to 700 hectopascals (hPa). In the propoxylation of N,N-dipropoxy-p-toluidine of the present invention, it is preferred to add a catalyst before closing the reactor. The catalyst of the present invention is preferably added in solid form, for example, in the form of flakes, beads, or powder. It can also be used as an aqueous solution, in which case water can be distilled off before further reaction, or this water removal can be omitted.

[0040] Preferably, propylene oxide is still present in the reactor after purging the 4-toluidine or N,N-dipropoxy-p-toluidine reactants with an inert gas.

[0041] Typically, the reaction of 4-toluidine or N,N-dipropoxy-p-toluidine with propylene oxide is carried out in a sealed pressure-resistant reactor, such as an autoclave. During the reaction, the pressure rises from a preset pressure until a pressure typically in the range of 400 hPa to 2000 hPa is reached. An absolute pressure in the reactor of more than 0.3 megapascals (MPa) is typically not reached. However, if gaseous propylene oxide is added entirely to the 4-toluidine or N,N-dipropoxy-p-toluidine component to be propoxylated in the reactor either before or after the reaction temperature is reached, or if it is metered into the reactor too rapidly, these pressures may be significantly exceeded. Both of these situations should be avoided in practice from a safety standpoint. Typically, propylene oxide is metered into the reaction mixture formed from the 4-toluidine or N,N-dipropoxy-p-toluidine to be propoxylated and the propylene oxide components, while ensuring that the pressure does not exceed about 0.2 MPa.

[0042] Propylene oxide is typically used in the form of its commercially available racemate, which has a purity of at least 99%. In the process of the present invention, it is also possible to use the individual enantiomers, i.e., R- and / or S-propylene oxide, or any desired mixtures thereof.

[0043] The reaction of N,N-dipropoxy-p-toluidine with propylene oxide according to the present invention is always carried out using a catalyst, in contrast to the propoxylation of 4-toluidine to give N,N-dipropoxy-p-toluidine, which is carried out in the absence of a catalyst.

[0044] It is preferred to carry out the process of the present invention in the absence of a solvent.

[0045] In a preferred embodiment of the process of the present invention, the N,N-dipropoxy-p-toluidine reactant is obtained by reacting 4-toluidine having a ratio of 3-toluidine of not more than 0.5% by weight, based on 4-toluidine. In an alternative preferred embodiment of the process of the present invention, the N,N-dipropoxy-p-toluidine reactant is obtained by reacting 4-toluidine having a ratio of 3-toluidine of not more than 0.2% by weight, based on 4-toluidine.

[0046] To obtain specific, particularly pure, 4-toluidine with a limited 3-toluidine content, it is necessary to remove 3-toluidine from technical grade 4-toluidine by careful distillation, since the boiling points of the two isomers are close to each other (boiling point of 4-toluidine: 200.5°C; boiling point of 3-toluidine: 203.4°C).

[0047] Another method for preparing 4-toluidine having a 3-toluidine content of at most 0.2% by weight is to recrystallize technical-grade N-acetyl-4-toluidine, followed by hydrolysis and distillation.In a preferred method, 4-toluidine having a 3-toluidine content of less than 0.2% by weight is prepared by first nitrating toluene, removing two undesired 2- and 3-nitrotoluene isomers from the resulting isomer mixture of 2-, 3-, and 4-nitrotoluene by distillation, with the reflux ratio optimized to obtain the desired purity, and then subjecting the resulting 4-nitrotoluene to hydrogenation to form 4-toluidine of the desired purity.In this way, it is possible to obtain 4-toluidine having a 3-toluidine content of less than 0.2% by weight, preferably less than 0.1% by weight, even in industrial quantities.

[0048] The mixtures of the present invention cannot be prepared in one step starting from 4-toluidine by adding either the entire amount of propylene oxide and catalyst required, or the entire amount of propylene oxide required without catalyst, to an initial charge of 4-toluidine, as in such cases there is a significant formation of undesirable by-products and / or incomplete conversion of the 4-toluidine used.

[0049] In carrying out a preferred embodiment of the process of the present invention, in order to achieve the desired narrow distribution of the individual homologues of the propoxylated 4-toluidine of formula (I), it is extremely important to pay attention to the narrow limits of the parameters related to the molar ratio between propylene oxide and 4-toluidine and / or between the catalyst and 4-toluidine, and / or the reaction temperature. These parameters influence each other, so that combinations of these parameters above or below all of the limits, in conjunction with other parameters such as the metering rate, the reaction phase of the liquid 4-toluidine, the catalyst, and the mixture of the metered gaseous propylene oxide, may in individual cases result in the formation of a mixture of propoxylated 4-toluidines that are not in accordance with the present invention. However, a person skilled in the art will be able to easily and without particular difficulty determine the suitable combination of parameters by adjusting these parameters within these strict limits depending on the experimental configuration or the size of the reaction vessel, thereby obtaining the mixture of the present invention within the above-mentioned limits.

[0050] The yield of the propoxylation of this invention is virtually quantitative, limited only by losses in handling, such as those caused by adhesion of residual materials to the walls of the reactor during transfer. After propoxylation is complete, it has been found useful to cool the reaction mixture to a temperature in the range of 60-100°C and pass nitrogen through the reaction mixture for a period of time to remove any propylene oxide present from the system.

[0051] The reaction mixture can be worked up by methods known to those skilled in the art or can alternatively be used directly in a further step.

[0052] The use of propylene oxide as a propoxylation agent has the advantage over other reactants (e.g., 1-chloropropan-2-ol, 1-bromopropan-2-ol, or 1-iodopropan-2-ol) that it does not require the use of an auxiliary reactant (e.g., a stoichiometric amount of base as a hydrogen halide scavenger) and therefore does not produce salts that must be removed in a separate step. Another disadvantage of using halopropanols is, for example, corrosion of the metallic equipment used.

[0053] The present invention further provides the use of the mixture of the present invention as a polymerization accelerator or vulcanization accelerator in the polymerization of polyesters, especially unsaturated polyesters, or as a curing agent component for epoxy resins. It has been found useful to use the mixture of the present invention in an amount of 0.1 to 5% by weight. The polymerization in which the mixture of the present invention can be used is preferably free-radical polymerization.

[0054] In polymerization systems in which the known N,N-dipropoxy-p-toluidine is used more advantageously than ethoxylated or other alkylated 4-toluidines, the mixtures of the present invention have improved handling properties, better processability, lower dosages, and / or higher reactivity. By replacing N,N-dipropoxy-p-toluidine, which is known to be in the form of a solid melt in the free-radical polymerization of polyesters, especially unsaturated polyesters, or as a curing agent component for epoxy resins, with the liquid mixtures of the present invention, the physicochemical and / or physicomechanical properties of the polymers produced therewith can be advantageously influenced.

[0055] In an alternative embodiment, a feature of the mixtures of the invention containing only a small proportion of propoxylated 3-toluidine is that they can be used particularly advantageously as polymerization accelerators or vulcanization accelerators in the preparation of colorless polymers, since their use does not result in any discoloration of the polymer. Depending on the desired use of the polymer, this is of great importance and is not achievable with any of the polymerization accelerators and vulcanization accelerators of the prior art.

[0056] The present invention also provides polymeric reaction products obtainable by polymerizing preferably polyesters, in particular unsaturated polyesters, in the presence of the mixtures of the present invention as polymerization accelerators or vulcanization accelerators or as hardener components for epoxy resins. The polymerizations in which the mixtures of the present invention can be used are preferably free-radical polymerizations. [Example]

[0057] Examples 1a-1e: Preparation of propoxylated toluidine starting from N,N-dipropoxy-p-toluidine Example 1a A 3-liter stainless steel autoclave equipped with a stirrer, internal thermometer, a submerged inlet tube for propylene oxide, and a riser tube for removal was initially charged with 1425 g of molten 98% N,N-dipropoxy-p-toluidine (a compound of Formula (I) where m and n are each integers 1; 6.25 moles) and 10.9 g of approximately 90% potassium hydroxide flakes (0.175 moles). The autoclave was closed and inerted by injecting nitrogen, depressurizing, and venting to approximately 670 hectopascals (hPa) (absolute pressure). The contents were heated to above 80°C to mostly melt the N,N-dipropoxy-p-toluidine. The melt was then heated to the desired reaction temperature (120°C). At this temperature, the expected amount of propylene oxide (in this case 690.1 g = 11.88 mol, corresponding to 1.9 molar equivalents based on N,N-dipropoxy-p-toluidine, i.e., a total of 3.9 molar equivalents based on 4-toluene) was metered in at a rate of about 163 g / h, and a pressure of 0.18 MPa (absolute) was reached within a short time. Typically, this pressure was not exceeded in the other examples either. Approximately 90 minutes after the end of the metered addition, the total pressure dropped to about 800 hPa, which remained constant for about 15 minutes thereafter. This was followed by stirring at reaction temperature for a further 60 minutes, then cooling to 40°C, replacing the vacuum with nitrogen, purging any remaining propylene oxide with nitrogen, and dispensing the mixture through a clarification filter. 2109.3 g (yield: 99.2%, based on the amount used) of reaction product was obtained, which had the following distribution of homologues of formula (I) (units, weight percent):

[0058] [Table 1]

[0059] Examples 1b-1e were similarly carried out in 0.5 liter autoclaves where appropriate. Rather than the volumes assumed in Example 1a, Examples 1b-1e were carried out using the data specified in Table 1.

[0060] [Table 2]

[0061] Examples 2a to 2e: Preparation of propoxylated toluidine starting from 4-toluidine Example 2a A 3-liter stainless steel autoclave equipped with a stirrer, an internal thermometer, a submerged inlet tube for propylene oxide, and a riser tube for removal was initially charged with 672.1 g of molten 99.7% 4-toluidine (6.25 mol). The autoclave was closed and inerted by injecting nitrogen, depressurizing, and venting to approximately 670 hPa (absolute). The contents were initially heated, without stirring, to a temperature above 45°C to completely melt the 4-toluidine. The melt was then further heated to the desired reaction temperature (120°C). At that temperature, 726.4 g of propylene oxide (12.49 mol) was metered in at a rate of approximately 163 g / h in the absence of a catalyst, resulting in a maximum pressure of 0.27 MPa (absolute) within a short period of time. Typically, this pressure was not exceeded in other examples. Approximately 3.5 hours after the end of the metered addition, the total pressure dropped to approximately 770 hPa, which remained constant for approximately 15 minutes. Stirring was then continued at the reaction temperature for a further 60 minutes, after which the mixture was cooled to 80-100°C and the reduced pressure was replaced with nitrogen. By means of sampling, it was possible to verify whether N,N-dipropoxy-p-toluidine of typical composition was obtained.

[0062] The expected amount of solid, approximately 90% potassium hydroxide (2.8 mol %, based on the 4-toluidine used) was then added, the autoclave was closed again, inerted and degassed as described above, and heated to the desired reaction temperature of 120° C. Afterwards, a further 690.1 g (11.88 mol) of propylene oxide was metered in at about 163 g / h, and a pressure increase was observed from about 760 hPa to a final pressure of about 0.143 MPa (absolute). Approximately 50 minutes after the end of the metered addition, the total pressure had dropped back to the original pressure of 670 hPa. This was followed by stirring for a further 60 minutes at reaction temperature, then cooling to 40° C., replacing the vacuum with nitrogen, purging any remaining propylene oxide with nitrogen, and dispensing the mixture through a clarification filter. 2087.4 g (yield: 99.4%, based on the amount used) of reaction product was obtained, which had the following distribution of homologues of formula (I) (units, weight percent):

[0063] [Table 3]

[0064] Examples 2b-2e were carried out similarly, where appropriate, in a 0.5 liter autoclave. Rather than the volumes assumed in Example 2a, Examples 2b-e were carried out using the data specified in Table 2.

[0065] [Table 4]

Claims

1. A mixture comprising two or more different compounds of general formula (I), 【Chemistry 1】 [In the formula, R １ is hydrogen or methyl, but R on the immediately adjacent carbon atom １ groups are not both hydrogen or both methyl, and m and n are integers; 4-toluidine is present in a proportion of 2% by weight or less, based on the total mass of all compounds of formula (I) in the mixture; and the compound of formula (I), wherein the total sum of m and n is an integer 2, is present in the mixture in an amount of 20% by weight or less, based on the total mass of all compounds of formula (I); the compound of formula (I), wherein the total sum of m and n is the integer 3, is present in the mixture in a proportion of 7% to 49% by weight, based on the total mass of all compounds of formula (I); The compound of formula (I), wherein the total sum of m and n is the integer 4, is present in the mixture in a proportion of 10% to 49% by weight, based on the total mass of all compounds of formula (I); and A mixture characterized in that the compound of formula (I) in which the total sum of m and n is at least an integer of 6 is present in the mixture in a proportion of 40% by weight or less, based on the total mass of all compounds of formula (I).

2. 2. The mixture of claim 1, wherein each homologous group of compounds of formula (I) is present in the mixture in a proportion of less than 50 weight percent, based on the total mass of all compounds of formula (I) in the mixture.

3. 3. The mixture according to claim 1 or 2, characterized in that it contains 4-toluidine in a proportion of less than 0.1% by weight, based on the total mass of all compounds of formula (I) in the mixture.

4. 4. The mixture according to claim 1, wherein the mixture is in a liquid state at a temperature of 5 to 40°C.

5. 5. The mixture according to claim 1, characterized in that it has a dynamic viscosity of 500 to 20,000 mPas, measured in accordance with DIN 53019 using a rotational viscometer at a temperature of 25°C.

6. 6. The mixture according to claim 1, comprising from 96% to 100% by weight of the compound of formula (I).

7. A method for producing the mixture according to any one of claims 1 to 6, comprising the step of: １ is hydrogen or methyl, but R on the immediately adjacent carbon atom １ A method for producing a compound of formula (I), wherein the groups are not both hydrogen or both methyl, and wherein m and n are an integer of 1, in the presence of a catalyst, with 1.0 to 2.50 moles of propylene oxide per mole of 4-toluidine used.

8. 8. The method for producing a mixture according to claim 7, wherein the reaction is carried out at a temperature of 80 to 150°C.

9. The reaction is carried out using a compound of formula (I) in which R １ is hydrogen or methyl, but R on the immediately adjacent carbon atom １ 9. A method for producing the mixture according to claim 7 or 8, wherein the method is carried out in the presence of 0.01 to 0.05 moles of a catalyst selected from the group consisting of alkali metal and alkaline earth metal hydroxides, alkali metals, alkyllithium, sodium hydride, complex hydrides (e.g., lithium aluminum hydride, sodium bis(methoxyethoxy)aluminum dihydride), alkali metal alkoxides, and alkali metal and alkaline earth metal carbonates, per mole of the compound of formula (I) (N,N-dipropoxy-p-toluidine) wherein m and n are not both hydrogen or both methyl, and wherein m and n are an integer of 1.

10. 4-Toluidine is reacted with 1.8 to 2.2 moles of propylene oxide per mole of 4-toluidine used in the absence of a catalyst at a temperature of 80 to 150° C. to obtain the compound represented by formula (I) R １ is hydrogen or methyl, but R on the immediately adjacent carbon atom １ 8. A method for producing the mixture according to claim 7, comprising producing a compound of formula (I) (N,N-dipropoxy-p-toluidine) in which the groups are not both hydrogen or both methyl, and in which m and n are the integer 1.

11. A method for producing a mixture according to any one of claims 7 to 10, characterized in that the reaction is carried out in the absence of a solvent.

12. 12. The method for producing a mixture according to claim 7, wherein the 4-toluidine contains 3-toluidine in a proportion of 0.2% by weight or less, based on 4-toluidine.

13. Use of the mixture according to any one of claims 1 to 6 as a polymerization accelerator or vulcanization accelerator or as a hardener component for epoxy resins.

14. A method for producing a polymer product by polymerizing a polyester in the presence of a mixture according to any one of claims 1 to 6 as a polymerization accelerator or vulcanization accelerator.

15. A method for producing a polymer product by curing an epoxy resin in the presence of a mixture according to any one of claims 1 to 6 as a hardener component.

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