HK1253691B - Method for the synthesis of polymer carbodiimides with added cesium salts, polymer carbodiimides and use thereof - Google Patents

Description

The present invention relates to processes for the production of polymeric carbodiimides with the addition of cesium salts, the polymeric carbodiimides produced by this process and their use as hydrolysing agents in polyurethane (PU) based systems, preferably thermoplastic TPU, PU adhesives, PU castings, PU elastomers or PU foams

Carbodiimides have proven themselves in many applications, e.g. as hydrolysate protectors for thermoplastic plastics, ester based polyols, polyurethanes, triglycerides and lubricating oils, etc.

The synthesis of carbodiimides is based on the state of the art from isocyanates obtained by basic or heterocyclic catalysis at CO_{2 and}- Carbodiimides can be broken down, whereby mono- or polyfunctional isocyanates can be converted into monomeric or polymeric carbodiimides.

The commonly used catalysts are alkaline or alkaline earth compounds, such as alkali alcohols, and heterocyclic compounds containing phosphorus, as described in the journal Applied Chemistry, see Appendices 1962, 74, 801-806 and 1981, 93, 855-866.

The production of sterically inhibited polymeric carbodiimides according to the state of the art can only be achieved with the help of phosphorus-containing catalysts (e.g. phospholes), see EP-A-2803660, WO 2005/111136 or EP-A 0628541.

The present invention was therefore intended to provide an improved process which allows the production of polymeric carbodiimides at high yields and, by extension, polymeric carbodiimides free from organic phosphorus compounds, so that they can be used in the manufacture and/or stabilization of PU systems.

Surprisingly, it has now been found that the above tasks are fulfilled when polymeric carbodiimides are converted (carbodiimidified) by the implementation of isocyanate group-containing compounds in the presence of at least one basic cesium salt at temperatures between 120 and 220 °C, preferably 160 and 200 °C, and most particularly 180 and 200 °C.

The present invention therefore concerns a process for the production of polymeric carbodiimides of formula (I) Other Other R^{1 and}- R^{2 and}- ((-N=C=N-R)^{2 and}-)_m- R^{1 and}(I) Other Other In the m corresponds to an integer from 2 to 500, preferably 3 to 20, particularly preferably 4 to 10^{2 and}= C_{1 and}- C.₁₈- Alkyl, C₅-C₁₈- Cycloalkyl, aryl, C₇-C₁₈ ^{- I 'm not .}Alkylarylenes and/or C₇-C₁₈- Aralkyl, preferably alkyllaryl and/or C₇-C₁₈- Aralkyl Other andR^{1 and}= -NCO, -NCNR^{2 and}- Not yet⁴, -NHCONR⁴R⁵or -NHCOOR⁶is wherein R^{1 and}independently of each other R⁴and R⁵are equal or different and a C_{1 and}C₆-Alkyl, C₆-C₁₀- Cycloalkyl or C₇-C₁₈- represent an aralkyl residue and R⁶a thickness of not more than 0,05 mm_{2 and}(b)_H- O- (CH)_{2 and}(b)_k- Oh, my God._{G. Other}- R⁷means,with h = 1-3, k = 1-3, g = 0-12 and R⁷= H or C_{1 and}-C₄- Alkyl, whether or not containing isocyanate groups - Compounds of the formula (II) Other Other O=C=N-R^{2 and}- R^{1 and}(ii) The Other Other where appropriate, in the presence of isocyanate group-containing compounds of formula (III) Other Other O=C=N-R^{2 and}(iii) The Other Other where R^{2 and}and R^{1 and}The following definitions are used: 'Caseum-based salt' means a salt which has the above meanings, and is converted (carbodiidized) in the presence of at least one basic cesium salt at temperatures between 120 and 220 °C, preferably 160 and 200 °C, and preferably 180 and 200 °C.

The basic salts of the invention are preferably cesium carbonate and/or cesium alcohols, preferably cesium methylate.

The basic cesium salts are preferably used in a concentration of 0.1 to 20% by weight, preferably 1 to 5%, preferably 2 to 4%.

The compounds of formula (II) containing isocyanate groups are particularly preferred, as the following compounds, used alone or in the combination given below: (IIa), (IIb), (IIc) or (IId) alone or (IIa) and (IIb) together, these compounds being those of the following formulae: Other

The compounds of formula (III) are preferably di- and/or Other The Commission shall adopt implementing acts laying down the rules for the application of this Regulation.

In a preferred embodiment of the method of the invention, the basic cesium salts are filtered after carbodiimidification and/or separated by extraction by means of a solvent, preferably water and/or alcohol.

Carbodiimidification can be carried out in both substance and solvent.₇- C.₂₂- Alkylbenzoles, paraffin oils, polyethylene glycoldimethyl ether, ketones or lactones are used.

If the reaction mixture has the desired content of NCO groups corresponding to a mean condensation degree of m = 2 to 500, preferably 3 to 20, and preferably 4 to 10, the polycarbodiimidification shall preferably be stopped.

In one embodiment of the present invention, the temperature of the reaction mixture is reduced to 50-120 °C, preferably 60-100 °C, and preferably 80-90 °C, and the basic cesium salts are separated by filtration or extraction.

In a further embodiment of the present invention, the free terminal isocyanate groups of the carbodiimides are then combined with aliphatic and/or aromatic amines, alcohols and/or alkoxypolyoxyalkylenes, preferably in a small excess of -NH, -NH,_{2 and}- and/or -OH groups, if necessary in the presence of a catalyst known to the professional, preferably tert. Amines or organocinnamic compounds, preferably DBTL (dibutyltin dihydrate or DOTL (dioctyltin dihydrate), are deactivated.

In another embodiment of the present invention, to interrupt the carbodiidisation, the temperature of the reaction mixture is reduced to 50-120 °C, preferably 60-100 °C, preferably 80-90 °C and, if necessary, after addition of a solvent, preferably selected from the group of C₇- C.₂₂-Alkylbenzoles, preferably toluene, the free terminal isocyanate groups of the carbodiimides are preferably combined with aliphatic and/or aromatic amines, alcohols and/or alkoxypolyoxyalkylenes in a small excess of -NH, -NH_{2 and}- and/or -OH groups, if necessary in the presence of a PU catalyst known to the professional, preferably tert. Amines or organocinnamic compounds, preferably DBTL (dibutyltin dilaurate or DOTL (dioctyltin dilaurate), are deactivated.

In another embodiment of the invention, the polymeric carbodiimides of the invention are produced by a partial, preferably < 50%, preferably < 40%, final functionalization of the free NCO groups in the isocyanate group-containing compounds of the formula (I) with R^{1 and}= - NCO with primary or secondary amines or alcohols and/or alkoxypolyoxyalkyl alcohols in the diisocyanates and subsequent carbodiimidification by decomposition of carbon dioxide at 80 to 200 °C in the presence of caesium salts and solvents where appropriate.

Preferably, the carbodiimides of the invention are cleaned after manufacture. The raw products can be purified by distillation and/or by solvent extraction.₇- C.₂₂-Alkylbenzoles, paraffin oils, alcohols, ketones or esters are commonly used solvents.

A further subject matter of the present invention is the production of polymeric carbodiimides of formula (I) by the process of the invention.

A further subject matter of the present invention is stabilizers containing at least 90% polymeric carbodiimides of formula (I), preferably obtained by the method of the invention, with a content of less than 1 ppm of organic phosphorus compounds, preferably phosphoenoxides.

In another preferred embodiment of the invention, the stabilizers of the invention preferably contain no more than 1000 ppm, preferably no more than 100 ppm and particularly preferably no more than 10 ppm of caesium salts.

The stabilizers provide excellent hydrolysis protection.

The present invention also covers processes for the production of polyurethanes (PU), preferably thermoplastic polyurethanes, whereby the conversion of the polyols, preferably polyester polyols, with the isocyanates is carried out in the presence of the polymeric carbodiimides of the invention and/or the polymeric carbodiimides of the invention are added to the polyurethane after conversion.

In another preferred embodiment of the invention, the process is performed in the presence of PU catalysts and auxiliaries or additives.

The production of polyurethanes is preferably as described in WO 2005/111136 A1.

Polyurethanes are formed by the polyoaddition reaction of polyisocyanates with polyvalent alcohols, the polyols, preferably polyester polyols, almost quantitatively.

The reaction between diisocyanate and polyol depends on the molar ratio of the components. Intermediate steps with desired average molecular weight and desired end groups can be obtained. These intermediate steps can then be implemented (chain extended) at a later stage with a diol or diamine, forming the desired polyurethane or polyurethane-polyharmonic hybrid.

Polyoles suitable for the production of prepolymers are polyalkyleneglycolite ethers, polyethers or polyester with finite hydroxyl groups (polyester polyoles).

The polyols of the invention are compounds with a molecular weight (in g/mol) preferably in the range of 500 to 2000 and preferably in the range of 500 to 1000.

The term polyol for the purposes of the invention includes both diols and triols, as well as compounds with more than three hydroxyl groups per molecule.

The preferred polyoles are polyester polyoles and/or polyether ester polyoles.

It is advantageous if the polyol has an OH number of up to 200, preferably between 20 and 150, and particularly preferably between 50 and 115.

In particular, polyester polyoles are suitable which are reaction products of various polyols with aromatic or aliphatic dicarboxylic acids and/or polymers of lactones.

The preferred products are aromatic dicarboxylic acids, which can be used to form suitable polyester polyoles, and especially terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride and substituted dicarboxylic acid compounds with benzene sulphate.

The aliphatic dicarboxylic acids are preferable to those that can be used to form suitable polyesters, in particular sebac acid, adipic acid and glutaric acid.

Polymers of lactones are preferable for use in the formation of suitable polyesters, in particular polycaprolactone.

Both the dicarboxylic acids and the polymers of lactones are commonly traded substances.

Particular preference shall be given to polyoles which can be used to form suitable polyester polyoles, in particular ethylene glycol, butandiol, neopentyl glycol, hexandiol, propylene glycol, dipropylene glycol, diethylene glycol and cyclohexandimethanol.

Another preferred embodiment of the invention is polyols, polyether ester polyoles.

For this purpose, the reaction products of various polyols mentioned above with aromatic or aliphatic dicarboxylic acids and/or polymers of lactones (e.g. polycaprolactone) are preferred.

The polyols used in the present inventions are commercially available compounds sold by Bayer MaterialScience AG under the trade names Baycoll® or Desmophen®.

The preferred diisocyanate is aromatic and aliphatic diisocyanate, with particular preference for toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, phenylenediisocyanate, 4,4-diphenylmethandiisocyanate, methylene bis- (((4-phenylisocyanate), naphthalene-1,5-diisocyanate, tetramethylene-1,4-diisocyanate and/or hexamethylene-1,6-diisocyanate, and in particular preference for toluene-2,4-diisocyanate and toluene-2,6-diisocyanate.

The diisocyanates used in the present inventions are commercially available compounds, e.g. from Bayer MaterialScience AG under the trade name Desmodur®.

In a further embodiment of the invention, the composition additionally contains at least one diamine and/or diol.

The diamine used for the chain extension is preferably 2-methylpropyl-3,5-diamino-4-chlorobenzene, bis- ((4,4'-amino-3-chlorophenyl) -methane, 3,5-dimethylthio-2,4-toluylendiamine, 3,5-dimethylthio-2,4-toluylendiamine, 3,5-diethyl-2,4-toluylendiamine, 3,5-diethyl-2,6-toluylendiamine, 4,4'-methyl bis-chloro-2,6-diethylaniline) and 1,3-propandiol bis- ((4-aminobenzene).

The diols used are butandiol, neopentyl glycol, hexandiol, propylene glycol, dipropylene glycol, diethylene glycol and/or cyclohexandimethanol.

The diamines or diols used for chain extension within the meaning of the invention are commercially available compounds sold by Rheinchemie Rheinau GmbH under the trade name Addolink®.

The catalytic converter is preferably dibutylzinc diurea or triethylenediamine in dipropylene glycol.

The catalysts used in the present inventions are commercially available compounds sold by Rheinchemie Rheinau GmbH under the trade name Addocat®.

In a particularly preferred embodiment of the present invention, the polymer carbodiamide of formula (I) is used in a quantity of 0.1-2% by weight, preferably 0.5-1.5% by weight, and preferably 1.0-1.5% by weight, in relation to the total mixture.

The present invention also relates to the use of the polymeric carbodiimide of formula (I) of the invention in processes for the production of polyurethanes as a hydrolysis stabilizer.

The polyurethane (PU) based systems produced by this process are characterised by excellent hydrolysis stability.

The present invention also relates to the use of the polymeric carbodiimides of the invention according to formula (I) for hydrolysis protection, preferably in polyurethanes.

The scope of the invention covers all of the general or preferential residue definitions, indices, parameters and explanations listed above and below, interrelated to each other, including between the respective ranges and preferential ranges in any combination.

The following examples are intended to illustrate the invention without being limiting.

Examples of implementations:

Example 1:Production of a polymeric carbodiimide by transformation of the compound of formula (IIc) with caesium carbonate (as described).Example 2:Production of a polymeric carbodiimide by transformation of the compound of formula (IIc) with potassium methanolate (comparison).Example 3:Production of a polymeric carbodiimide by transformation of the compound of formula (IIc) with potassium carbonate (comparison).Example 4:Production of a polymeric carbodiimide by transformation of the compound of formula (IIc) with sodium carbonate (comparison).Example 5:Production of a polymeric carbodiimide by transformation of the compound of formula (IIc) with phosphenoxide (comparison).

General manufacturing procedure for examples 1 to 5:

30 g of the isocyanate group compound of formula (IIc) were weighed in a 100 ml triangular flask equipped with an internal thermometer, a return cooler and a protective gas inlet, and then 0.9 g (3 wt%) of the respective catalyst was added to examples 1 to 4 and 5.0 g (0.1 wt%) to examples 1 to 5._{2 and}The protective gas was removed and the reaction mixture cooled to about 100°C was then filtered by stirring vigorously for 3 h at 190 °C (examples 1 and 5) or 12 h at 190 °C (examples 2) and 6 h at 190 °C (examples 3 and 4). Tabelle 1: Ausbeuten der Synthese des Carbodiimids

1	Cäsiumcarbonat	190	3	> 98%	<1,0%	< 1,0%
2	K-Methanolat	190	12	< 60 %	> 30 %	> 5,0%
3	Kaliumcarbonat	190	6	< 1 %	99 %	n. b.
4	Natriumcarbonat	190	6	0 %	100 %	-
5	Phospolenoxid	190	3	> 95%	< 1,0%	> 1,0%

Surprisingly, the cesium carbonate for carbodiimidification shows a high catalytic activity and yields over 98% after 3 hours of reaction time, which is significantly better than the synthesis by K-methanolate or K- or Na-carbonate.

In addition, the catalyst of the invention can be separated simply by filtration, whereas in the case of a catalyst using a catalyst containing phosphorus (methyl phosphorus oxide), an elaborate distillation in vacuum is required for separation.

Manufacture of ester based PU adhesives (hot melt) and their characterisation Example 6:

A linear copolyester based melt adhesive with primary hydroxyl functions and an average molecular weight of 3500 g/mol (Dynacoll® 7360) was produced and added according to the following table: Other Carbodiimide has been used: (A) 2 weight % polymeric carbodiamide of formula (I) with m = 4 - 5 and R^{1 and}= -NHCOOR⁶where R⁶is a polyethylene glycol residue produced by catalysis with caesium carbonate (as described in the invention, but end-functionalised with polyethylene glycol according to example 1), and^{2 and}= Characterisation: No organic phosphorus compound detectable (< 1 ppm phosphorus) ((B) 2 weight % polymeric carbodiamide of formula (I) with m = 4 - 5 and R^{1 and}= -NHCOOR⁶where R⁶is a polyethylene glycol residue produced by catalysis with methylphospholenoxide (comparison, see also method WO-A 2005/111136), and^{2 and}= Characterisation: phosphorus residues are detectable.

All quantities are given in % by weight of the total mixture.

The melt adhesive was manufactured as follows: Other First, the linear copolyester with primary hydroxyl functions was evacuated for 30 minutes at 120 °C, then 11,67% by weight of Diphenylmethandioisocyanate (MDI) was added to the overall formulation and it was converted to polyurethane adhesive for 60 minutes at 120 °C.

The respective carbodiimides indicated in Table 2 were then incorporated into the melt adhesive and an action time of 1 hour was ensured.

The resulting adhesives (hot melt) were aged in a cartridge at 130°C for 48 hours, then aged in an aluminium cartridge (light and moisture resistant) and aged in an air-tight oven for 48 hours at 130°C.

After ageing, the age of the samples was assessed visually.

The results of the measurements are summarised in Table 2: Other

Beispiel 6A (erf.)	Keine Schaumbildung, Keine oder sehr geringe Blasenbildung,
Beispiel 6B (V)	Schaum- bzw. starke Blasenbildung,

V = Vergleichsbeispiel; erf. = erfindungsgemäß

The following summary:

These tests show that the use of the phosphorus-free carbodiimides of the invention does not produce any significant foaming-related undesirable effects; on the contrary, carbodiimides catalyzed with phosphorus oxide and still containing traces of phosphorus-organic compounds show the corresponding foaming disadvantages.

Claims (12)

1. Process for producing polymeric carbodiimides of formula (I)         R¹-R²-(-N=C=N-R²-)_m-R¹     (I), in which

   m represents an integer from 2 to 500, preferably 3 to 20, very particularly preferably 4 to 10,

   R² = C₁-C₁₈-alkylene, C₅-C₁₈-cycloalkylene, arylene, C₇-C₁₈-alkylarylene and/or C₇-C₁₈-aralkylene, preferably alkylarylene and/or C₇-C₁₈-aralkylene and

   R¹ = -NCO, -NCNR², -NHCONHR⁴, -NHCONR⁴R⁵ or -NHCOOR⁶,

   wherein in R¹ independently of one another R⁴ and R⁵ are identical or different and represent a C₁-C₆-alkyl, C₆-C₁₀-cycloalkyl or C₇-C₁₈-aralkyl radical and R⁶ represents a polyester or a polyamide radical or -(CH₂)_h-O-[(CH₂)_k-O]_g-R⁷,

   where h = 1-3, k = 1-3, g = 0-12 and

   R⁷= H or C₁-C₄-alkyl, characterized in that isocyanate-containing compounds of formula (II)         O=C=N-R²-R¹     (II),

   optionally in the presence of isocyanate-containing compounds of formula (III)         O=C=N-R²     (III)'

   wherein R¹ and R² are as defined above,

   are converted (carbodiimidized) in the presence of at least one basic cesium salt at temperatures between 120°C to 220°C, preferably 160°C to 200°C, very particularly preferably 180°C to 200°C.
2. Process according to Claim 1, characterized in that the basic cesium salt employed is cesium carbonate and/or cesium alkoxide, preferably cesium methoxide.
3. Process according to Claim 1 or 2, characterized in that the isocyanate-containing compounds employed are the following compounds: (IIa), (IIb), (IIc) or (IId) alone or (IIa) and (IIb) together, wherein these compounds correspond to the following formulae
4. Process according to any of Claims 1 to 3, characterized in that the basic cesium salt are employed in a concentration of 0.1 to 20 wt%, preferably 1 to 5 wt%, particularly preferably 2 to 4 wt%, based on the overall mixture.
5. Process according to any of Claims 1 to 4, characterized in that following the carbodiimidization the basic cesium salts are filtered off and/or removed by extraction using a solvent, preferably water and/or alcohol.
6. Process according to any of Claims 1 to 5, characterized in that the carbodiimidization takes place in a solvent.
7. Process according to Claim 6, characterized in that the solvents employed are C₇-C₂₂-alkylbenzenes.
8. Stabilizer containing at least 90% of polymeric carbodiimides produced according to any of Claims 1 to 7 and less than 1 ppm of organic phosphorus compounds.
9. Process for producing polyurethanes, preferably thermoplastic polyurethanes, characterized in that the reaction of the polyester polyols with the isocyanates is performed in the presence of polymeric carbodiimides produced according to any of Claims 1 to 7 or the polymeric carbodiimides produced according to any of Claims 1 to 7 are added following the reaction.
10. Process according to Claim 9, characterized in that the polymeric carbodiimide is employed in an amount of 0.1 to 2 wt%, preferably 0.5 to 1.5 wt%, particularly preferably 1.0 to 1.5 wt%, based on the overall mixture.
11. Use of the polymeric carbodiimides produced according to any of Claims 1 to 7 in a process for producing polyurethanes.
12. Use of the polymeric carbodiimides produced according to any of Claims 1 to 7 for hydrolysis protection, preferably in polyurethanes.