Composition consisting of a Bronsted acid and a monoamine

Abstract

To provide compositions that contain salts of strong Bronsted acids, which are of particularly good suitability as catalysts of epoxy formulations, and do not have disadvantages described herein, and a process for preparing the compositions and the use of the compositions.SOLUTION: The present invention provides compositions consisting of a) at least one metal salt, ammonium salt or phosphonium salt of a strong Bronsted acid and b) at least one primary aliphatic monoamine.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composition containing a strong Bronsted acid, a method for producing the composition and the use of the composition. The subject of the present invention is also a catalyst formulation containing a strong Bronsted acid, since the composition according to the invention is particularly suitable as a catalyst composition, in particular for curing epoxy resins. [Background technology]

[0002] Epoxy resins, especially those made from bisphenol A and epichlorohydrin, are well known raw materials for producing high quality casting resins, coating compositions, composites and adhesives. Aromatic epoxy resins cured with polyamines have good bond strength to many substrates, as well as good chemical and solvent resistance.

[0003] Catalysts can be used to accelerate the cure of epoxy-amine coating systems (US 3,492,269 A, US 5,470,896 A, GB 1,105,772 A).

[0004] EP 0 083 813 A1, EP 2 957 584 A1, US 5,441,000 A, US 5,629,380 A and WO 96 / 09352 A1 disclose the catalytic curing of epoxy resins with a variety of amines.

[0005] US 8,980,979 B2 discloses inter alia the curing of epoxy resins with cyclic diamines selected from piperazines or homopiperazines, optionally in the presence of a catalyst.

[0006] EP 0 969 030 A1 discloses an epoxy / amine coating system, in which the amine component is an aliphatic amine. The composition may comprise a catalyst.

[0007] US 4,775,734 A discloses the curing of epoxy resins with aminoethylpiperazine using catalytic amounts of tetrafluoroborate or hexafluorophosphate salts of various amines. In a comparative example (Example 2), furthermore, a test of the curing of epoxy resins with aminoethylpiperazine in the presence of lithium tetrafluoroborate is disclosed. However, the ratio of epoxy groups:NH groups used does not allow the reaction to take place. A further example (Example 14) discloses the reaction of ammonium hexafluorophosphate with diethylamine.

[0008] US 5,134,239 A discloses an adduct of a heterocyclic nitrogen-containing compound with a salt. Example 58 discloses the synthesis of a butylamine-tetrabutylphosphonium fluoroborate complex in a methanolic solution as a non-inventive example.

[0009] WO 2017 / 074810 A1 discloses a composition comprising an epoxy resin, a polyetheramine, a further amine hardener, which may in particular be an aliphatic amine, and optionally a metal triflate catalyst.

[0010] The applications EP 3 569 629 A1, EP 3 569 630 A1, EP 3 569 631 A1 and EP 3 569 632 A1 disclose compositions comprising at least one epoxy resin, at least one cyclic amine having at least two amino groups and at least one salt of a Brønsted acid.

[0011] It is desirable to accelerate the cure of epoxy formulations with catalysts so that energy and reaction time can be saved. Strong Bronsted acids (i.e., with a pK of less than 2) have been found to be particularly suitable. a value), especially salts of very strong Bronsted acids (i.e., those with a pK value below -9.01). a These are salts of epoxides (those having a value of 0.1 to 100%). However, their disadvantage is that they are solids and can only be homogenized in the liquid epoxide formulations with difficulty. Also, prior dissolution or dispersion in a solvent is disadvantageous - in the case of dispersion or dissolution of the catalyst in an inert solvent, this increases the VOC (volatile organic content) proportion of the epoxy composition. In contrast, reactive solvents lead to precipitation, discoloration and reduced reactivity. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Pat. No. 3,492,269 [Patent Document 2] U.S. Pat. No. 5,470,896 [Patent Document 3] British Patent No. 1105772 [Patent Document 4] European Patent Application Publication No. 0083813 [Patent Document 5] European Patent Application Publication No. 2957584 [Patent Document 6] U.S. Patent No. 5,441,000 [Patent Document 7] U.S. Patent No. 5,629,380 [Patent Document 8] International Publication No. 96 / 09352 [Patent Document 9] U.S. Pat. No. 8,980,979 [Patent Document 10] European Patent Application Publication No. 0969030 [Patent Document 11] U.S. Pat. No. 4,775,734 [Patent Document 12] U.S. Pat. No. 5,134,239 [Patent Document 13] International Publication No. 2017 / 074810 [Patent Document 14] European Patent Application Publication No. 3569629 [Patent Document 15] European Patent Application Publication No. 3569630 [Patent Document 16] European Patent Application Publication No. 3569631 [Patent Document 17] European Patent Application Publication No. 3569632 [Non-patent literature]

[0013] [Non-Patent Document 1] FG Bordwell, “Equilibrium Acidities in Dimethylsulfoxide Solution”, Acc. Chem. Res. 1988, 21, 456-463 Summary of the Invention [Problem to be solved by the invention]

[0014] It is therefore an object of the present invention to provide compositions which contain salts of strong Bronsted acids and which are highly suitable as catalysts for epoxy formulations and which do not have the above-mentioned disadvantages.

[0015] Surprisingly, it has been found that salts of strong or very strong Bronsted acids, in particular the salts of trifluoromethanesulfonic acid (triflates), have good solubility in primary aliphatic monoamines, and it has been surprisingly found that primary aliphatic monoamines dissolve the salts much better than secondary aliphatic monoamines or other monoamines.

[0016] The subject of the present invention is therefore a composition comprising a) at least one metal, ammonium or phosphonium salt of a strong Bronsted acid and b) at least one primary aliphatic monoamine.

[0017] Preferably, the composition contains 10 to 95% by mass of component a) and 5 to 90% by mass of component b) based on the mass (Einwaagen; weighed amount) of components a) and b), more preferably, the composition contains 30 to 70% by mass of component a) and 70 to 30% by mass of component b) based on the mass of components a) and b), and even more preferably, the composition contains 40 to 60% by mass of component a) and 60 to 40% by mass of component b) based on the mass of components a) and b).

[0018] The composition according to the invention contains at least one metal, ammonium or phosphonium salt of a strong Bronsted acid. The corresponding salts are good catalysts. Such strong acids are understood in the present context to be acids whose pKa value (or the pKa value of the first protolysis step in the case of polyprotic acids) is less than or equal to 2. Preferably, the pKa of the corresponding acid is less than or equal to -2.

[0019] The pKa is defined as the negative logarithm to the base 10 of the equilibrium constant Ka and is considered a measure of the strength of an acid. The smaller the pKa value, the stronger the acid. aThe values ​​are determined as disclosed in FG Bordwell, "Equilibrium Acidities in Dimethylsulfoxide Solution", Acc. Chem. Res. 1988, 21, 456-463.

[0020] Preferred salts are the corresponding salts of strong acids summarized in column 1 of Table 1 below: Table 1: [Table 1]

[0021] Preferably, the salt is a salt of a very strong acid, where such a very strong acid is understood in the present context to be an acid whose pKa value (or the pKa value of the first protolysis step in the case of polyprotic acids) is less than or equal to -9.01. Preferably, the pKa value of said very strong acid is between -9.5 and -25, particularly preferably between -9.9 and -21.

[0022] Most preferably, component a) is a salt of a Bronsted acid selected from perchloric acid, trifluoromethanesulfonic acid, hydrogen iodide, hexafluorophosphoric acid and hexafluoroantimonic acid.

[0023] Even more preferably, the salt is a triflate, ie, a salt of trifluoromethanesulfonic acid.

[0024] Said strong Bronsted salt is metal salt, ammonium salt or phosphonium salt.Metal salt is understood here as the salt containing metal ion (i.e. has at least one ion derived from at least one metal, preferably has at least one ion derived from at least one metal atom, particularly preferably has exactly one ion derived from at least one metal atom) as well as metal-containing (i.e. also has non-metallic components) ion.Therefore, the counterion of said acid is selected from metal ion, metal-containing ion, phosphonium ion and ammonium ion.

[0025] Preferred metal ions are alkaline earth metal cations, especially the ions of beryllium, magnesium, calcium, strontium and barium, as well as the ions of lithium, aluminum, bismuth, zinc and europium.

[0026] A metal-containing ion is an ion that contains at least one metal, but is not a pure metal ion, preferably a metal compound ion, such as the tetraphenylstibonium ion.

[0027] The ammonium ion is unsubstituted (=NH4 + ), alkylated and / or arylated. The phosphonium ion may be unsubstituted (=PH4 + ), alkylated and / or arylated. The preferred ammonium ion is NH4 + The preferred phosphonium ion is PH4 + Very particular preference is given to the ammonium ion.

[0028] Preferred salts of strong acids are calcium triflate, europium triflate, barium triflate, aluminum triflate, bismuth triflate, lithium triflate, lithium perchlorate, barium perchlorate, lithium hexafluorophosphate and zinc perchlorate. Very particular preference is given to calcium triflate, europium triflate, lithium hexafluorophosphate and lithium perchlorate.

[0029] Best results are achieved with calcium triflate.

[0030] The composition further comprises at least one primary aliphatic monoamine. Primary aliphatic monoamines are in this context understood to be primary monoamines (i.e. amines with only one primary amino group) that have exclusively aliphatic, i.e. linear or branched, alkyl, cycloalkyl and / or (cyclo)alkyl groups. (Cyclo)alkyl groups are in this context understood to be groups that have both cyclic and linear or branched alkyl moieties. Preferred aliphatic groups each have 3 to 30, particularly preferably 3 to 10, most preferably 3 to 6 carbon atoms. The monoamines may be substituted on one of their alkyl, cycloalkyl and / or (cyclo)alkyl groups by hydroxy groups. However, no other substituents are present. Preferably, furthermore, all aliphatic groups of the monoamines are unsubstituted.

[0031] Preference is given to using monoamines having a boiling point (measured at 1013.25 hPa) of 30 to 300° C., preferably 30 to 200° C.

[0032] Most preferably, the monoamine is selected from the group consisting of n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine and ethanolamine.

[0033] Even more preferably, the monoamine is n-butylamine.

[0034] Best results are achieved when component a) is calcium triflate and component b) is n-butylamine.

[0035] The present invention furthermore relates to a process for the preparation of the composition according to the invention, by mixing a) at least one metal, ammonium or phosphonium salt of a strong Brønsted acid and b) at least one aliphatic monoamine with one another, optionally in the presence of further components.

[0036] The subject of the present invention is also the use of the compositions according to the invention as catalyst compositions. In particular, the compositions according to the invention are suitable as catalyst compositions for the curing of epoxy resins, very preferably for the curing of epoxy resins with amines. EXAMPLES

[0037] Example 1) Model experiments are compared with each other to demonstrate the special reactivity of the claimed catalysts. For this, 0.025 mol (3.75 g) of 1,2-epoxy-3-phenoxypropane is added to a mixture of 22.7 g of toluene (solvent) and 2.08 g of tetradecane (internal standard). To this is added 0.025 mol (2.13 g) of piperidine and 0.06 g of calcium triflate dissolved in the same amount of amine or alcohol as a comparison. Immediately after the mixture is measured by GC and the content of 1,2-epoxy-3-phenoxypropane is compared with that of tetradecane. After 4 h at room temperature (RT), the residual content of 1,2-epoxy-3-phenoxypropane (EP) is determined by GC analysis (calibrated with tetradecane internal standard). The following results are obtained: [Table 2]

[0038] The claimed monoamines are suitable as solvents for calcium triflate and do not lead to a significant decrease in its reactivity (residual EP content after 4 hours max. 10%), whereas pure alcohols, dialcohols or diamines lead to a clear decrease in said reactivity.

[0039] The embodiments of the present invention are as follows: 1. a) at least one metal salt, ammonium salt or phosphonium salt of a strong Bronsted acid; b) at least one primary aliphatic monoamine; A composition comprising: 2. The composition according to 1., characterized in that the composition contains 10 to 95 mass % of component a) and 5 to 90 mass % of component b), based on the masses of components a) and b). 3. The composition according to 1. or 2., characterized in that the salt a) is a salt of an acid selected from the group consisting of oxalic acid, p-toluenesulfonic acid, trifluoroacetic acid, tetrafluoroboric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, perchloric acid, trifluoromethanesulfonic acid, hydrogen iodide, hexafluorophosphoric acid and hexafluoroantimonic acid. 4. The Bronsted acid has a pK of -9.01 or less. a 4. The composition according to any one of 1. to 3., characterized in that it has a value. 5. The composition according to any one of 1. to 4., characterized in that the monoamine b) has exclusively aliphatic groups having 3 to 30 carbon atoms. 6. The composition according to any one of 1. to 5., wherein the monoamine b) has a boiling point, measured at 1013.25 hPa, of 30 to 300°C. 7. The composition according to any one of 1. to 6., characterized in that the amine b) is selected from the group consisting of n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine and ethanolamine. 8. The composition according to any one of 1. to 7., characterized in that the salt of the strong Bronsted acid a) is calcium triflate and the monoamine b) is n-butylamine. 9. The composition according to any one of 1. to 8., characterized in that the salt a) is calcium triflate and the monoamine b) is n-butylamine. 10. A method for producing a composition according to any one of 1. to 9. above, by mixing together a) at least one metal, ammonium or phosphonium salt of a strong Bronsted acid and b) at least one primary aliphatic monoamine. 11. Use of a composition according to any one of 1. to 9. as a catalyst composition. 12. Use of the composition according to claim 11 as a catalyst composition for the curing of epoxy resins.

Claims

1. a) calcium triflate; b) at least one primary aliphatic monoamine; A composition comprising:

2. 2. The composition of claim 1, wherein the composition comprises 10 to 95% by weight of component a) and 5 to 90% by weight of component b), based on the weights of components a) and b).

3. 3. The composition according to claim 1, wherein the monoamine b) contains exclusively aliphatic groups having 3 to 30 carbon atoms.

4. 4. The composition according to claim 1, wherein the monoamine b) has a boiling point, measured at 1013.25 hPa, of 30 to 300° C.

5. 5. The composition according to claim 1, wherein the amine b) is selected from the group consisting of n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine and ethanolamine.

6. The composition according to claim 1, wherein the monoamine b) is n-butylamine.

7. 7. A method for producing a composition according to any one of claims 1 to 6 by mixing together a) calcium triflate and b) at least one primary aliphatic monoamine.

8. 7. Use of a composition according to any one of claims 1 to 6 as a catalyst composition.

9. 9. Use of the composition according to claim 8 as a catalyst composition for the curing of epoxy resins.

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