Process for producing (cyclo)aliphatic polycarbonate polyols having low reactivity

Abstract

The present invention relates to a process for producing (cyclo)aliphatic polycarbonate polyols comprising the steps of a) reaction of at least one (cyclo)aliphatic polyol and at least one alkyl carbonate in the presence of at least one basic catalyst and b) neutralization by addition of at least one organic sulfonic acid having a molecular weight of 250 to 1000 g/mol and at least one branched or unbranched alkyl substitution having at least four carbon atoms,
wherein step b) is performed after step a).

Claims

1. A process for producing (cyclo)aliphatic polycarbonate polyols comprising the steps of a) reacting at least one (cyclo)aliphatic polyol and at least one alkyl carbonate in the presence of at least one basic catalyst and b) neutralizing by addition of at least one organic sulfonic acid having a molecular weight of 250 to 1000 g/mol and at least one branched or unbranched alkyl substitution having at least four carbon atoms, wherein step b) is performed after step a).

2. The process according to claim 1, wherein the catalyst is a basic salt selected from the group consisting of alkali metals.

3. The process according to claim 1, wherein the catalyst is a sodium alkoxide or a potassium alkoxide.

4. The process according to claim 1, wherein that the organic sulfonic acid is selected from the group consisting of tetrapropylenebenzenesulfonic acid, dodecylbenzenesulfonic acid and a technical isomer mixture of the dodecylbenzenesulfonic acid.

5. The process according to claim 1, wherein the catalyst is employed in a concentration between 1 ppm to 10 000 ppm, based on the total weight of the employed (cyclo)aliphatic polyols and alkyl carbonates.

6. The process according to claim 1, wherein the alkyl carbonate is a dialkyl carbonate.

7. The process according to claim 1, wherein the organic sulfonic acid is employed in a molar ratio of 0.7 to 3.0, to the basic equivalent of the catalyst.

8. The process according to claim 1, wherein the (cyclo)aliphatic polyol is selected from the group consisting of 1,5-pentanediol and 1,6-hexanediol and mixtures thereof.

9. A method of reducing reactivity of polycarbonate polyols in polycarbonate polyol production, the method comprising including at least one organic sulfonic acid having a molecular weight of 250 to 1000 g/mol and at least one branched or unbranched alkyl substitution having at least four carbon atoms as a stopper.

10. The process according to claim 1, wherein the catalyst is employed in a concentration between 5 ppm and 500 ppm based on the total weight of the employed (cyclo)aliphatic polyols and alkyl carbonates.

11. The process according to claim 1, wherein the catalyst is employed in a concentration between 20 ppm and 150 ppm based on the total weight of the employed (cyclo)aliphatic polyols and alkyl carbonates.

12. A method of increasing clouding stability of polycarbonate polyols in polycarbonate polyol production, the method comprising including at least one organic sulfonic acid having a molecular weight of 250 to 1000 g/mol and at least one branched or unbranched alkyl substitution having at least four carbon atoms as a stopper.

Description

EXAMPLES

(1) Unless otherwise stated all percentages relate to weight percent.

(2) Determination of the NCO contents in % was undertaken by back titration with 0.1 mol/l of hydrochloric acid after reaction with butylamine based on DIN EN ISO 11909:2007.

(3) The OH number was determined in accordance with DIN 53240-1:2013.

(4) Viscosity measurements of the polycarbonate polyols were performed at 23 C. with a plate-plate rotational viscometer, RotoVisko 1 from Haake, DE, at a shear rate of 47.94/s according to DIN EN ISO 3219:1990.

Example 1 (Inventive)

Production of a Polycarbonate Diol with Potassium Methoxide as Catalyst (Starting Material for Examples 2, 3, 4 and 5)

(5) In a 15 L stainless steel reactor fitted with a stirrer, high-performance condenser and thermometer, 6643 g of 1,6-hexanediol were initially charged and dewatered for 2 hours at 120 C. under a vacuum of about 20 mbar. The batch was cooled to 80 C., vented with nitrogen and initially 7101 g of dimethyl carbonate, and then 0.8 g of potassium methoxide, were added. The pressure was then set with nitrogen to approximately 2 bar and the mixture was heated with stirring to 150 C.; this caused the pressure to increase to about 6 bar. After 24 hours the apparatus was cooled to 60 C. and the elevated pressure released. A Claisen bridge with a collection vessel was fitted and a further 0.8 g of potassium methoxide was added to the reaction mixture. The temperature was then slowly increased to 150 C. over two hours and then held for six hours at this temperature; a dimethyl carbonate/methanol mixture began to be distilled off. The temperature was then lowered to 90 C. and the pressure was slowly reduced to 15 mbar over two hours. The temperature was then slowly increased to 190 C. while maintaining the same vacuum and then held at this temperature for eight hours. After the reduction of the temperature to 80 C. the OH number of the resin was determined as 48 mg KOH/g. A further 78 g of 1,6-hexanediol were added and the mixture stirred under vacuum for a further eight hours at 190 C. A resin which was cloudy at 80 C., had an OH number of 58 mg KOH/g and was solid at room temperature was obtained.

Example 2 (Comparative)

Neutralization with Camphor-10-Sulfonic Acid of a Polycarbonate Dial Produced with Potassium Methoxide

(6) 1000 g of the polycarbonate dial from example 1 were weighed into a 21 glass flask and heated to 100 C. 0.66 g of camphor-10-sulfonic acid were added and the mixture was stirred for about one hour. The resin remained very cloudy in the melt.

Example 3 (Comparative)

Neutralization with p-Toluenesulfonic Acid of a Polycarbonate Diol Produced with Potassium Methoxide

(7) 1000 g of the polycarbonate diol from example 1 were weighed into a 21 glass flask and heated to 100 C. 0.54 g of p-toluenesulfonic acid were added and the mixture was stirred for about one hour. The resin remained very cloudy in the melt.

Example 4 (Comparative)

Neutralization with Dibutyl Phosphate of a Polycarbonate Diol Produced with Potassium Methoxide

(8) 1000 g of the polycarbonate dial from example 1 were weighed into a 21 glass flask and heated to 100 C. 0.60 g of dibutyl phosphate were added and the mixture was stirred for about one hour. The resin obtained was clear in the melt.

Example 5 (Inventive)

Neutralization with Dodecylbenzenesulfonic Acid of a Polycarbonate Diol Produced with Potassium Methoxide

(9) 1000 g of the polycarbonate diol from example 1 were weighed into a 21 glass flask and heated to 100 C. 0.93 g of dodecylbenzenesulfonic acid were added and the mixture was stirred for about one hour. The resin obtained was clear in the melt.

Example 6

Testing the Reactivity of the Neutralized Polycarbonate Dials from Examples 2, 3, 4 and 5

(10) To test the reactivity of the polycarbonate dials these were dissolved in an 80% concentration in xylene and reacted with double the amount (in terms of NCOOH ratio) of methylenediphenyl diisocyanate (Desmodur 2460M, Covestro AG, Leverkusen, NCO:OH=2.0) at 50 C. The reaction was performed with constant control of the viscosity in a Haake Viskotester VT550 (D=90/s). At the beginning of measurement the mixtures have a viscosity of about 660 mPas (at 50 C.).

(11) TABLE-US-00001 Ex- After After After ample Stopper 10 min 60 min 90 min 2 camphor- 1020 4180 6620 (comp.) sulfonic mPas mPas mPas acid 3 p-toluene- 939 3290 4980 (comp.) sulfonic mPas mPas mPas acid 4 dibutyl 13800 not not (comp.) phosphate mPas deter- deter- minable minable 5 dodecyl- 931 2390 3610 (inv.) benzene- mPas mPas mPas sulfonic acid

(12) It is clearly apparent that the viscosity (as an indicator of the progress of the NCOOH reaction and thus of reactivity) increases only moderately with the three sulfonic acids from examples 2, 3 and 5 while the dibutyl phosphate in example 4 results in a markedly higher reactivity. However, the products of examples 2 and 3 are cloudy.

Example 7 (Inventive)

Production of a Polycarbonate Diol with Sodium Methoxide as Catalyst (Starting Material for Examples 8, 9, 10 and 11)

(13) In a 15 L stainless steel reactor fitted with a stirrer, high-performance condenser and thermometer, 6643 g of 1,6-hexanediol were initially charged and dewatered for 2 hours at 120 C. under a vacuum of about 20 mbar. The batch was cooled to 80 C., vented with nitrogen and initially 6583 g of dimethyl carbonate, and then 2.67 g of sodium methoxide (as a 30% solution in methanol), were added. The mixture was subsequently heated to about 90 C. with stirring until a slight reflux was apparent in the condenser. After 24 hours the apparatus was cooled down to 60 C. and a Claisen bridge with a collection vessel was fitted. The temperature was then slowly increased to 150 C. over two hours and then held for six hours at this temperature; a dimethyl carbonate/methanol mixture began to be distilled off. The temperature was then lowered to 90 C. and the pressure was slowly reduced to 15 mbar over two hours. The temperature was then slowly increased to 190 C. while maintaining the same vacuum and then held at this temperature for eight hours. After the reduction of the temperature to 80 C. the OH number of the resin was determined as 154 mg KOH/g. A further 849 g of dimethyl carbonate were added and a high-performance condenser installed. The mixture was subsequently heated to about 90 C. with stirring until a slight reflux was apparent in the condenser. After 24 hours the apparatus was cooled down to 60 C. and a Claisen bridge with a collection vessel was fitted. The temperature was then slowly increased to 150 C. over two hours and then held for six hours at this temperature; a dimethyl carbonate/methanol mixture began to be distilled off. The temperature was then lowered to 90 C. and the pressure was slowly reduced to 15 mbar over two hours. The temperature was then slowly increased to 190 C. while maintaining the same vacuum and then held at this temperature for eight hours. After reduction of the temperature to 80 C. the OH number of the resin was this time determined as 47 mg KOH/g. 80 g of 1,6-hexanediol were then added and the mixture stirred under vacuum for a further eight hours at 190 C. A resin which was cloudy at 80 C., had an OH number of 57 mg KOH/g and was solid at room temperature was obtained.

Example 8 (Comparative)

Neutralization with Dibutyl Phosphate of a Polycarbonate Dial Produced with Sodium Methoxide

(14) 1000 g of the polycarbonate diol from example 7 were weighed into a 21 glass flask and heated to 100 C. 0.39 g of dibutyl phosphate were added and the mixture was stirred for about one hour. The resin obtained was clear in the melt.

Example 9 (Comparative)

Neutralization with Dibutyl Phosphate of a Polycarbonate Dial Produced with Sodium Methoxide

(15) 1000 g of the polycarbonate dial from example 7 were weighed into a 21 glass flask and heated to 100 C. 0.78 g of dibutyl phosphate were added and the mixture was stirred for about one hour. The resin obtained was clear in the melt.

Example 10 (Inventive)

Neutralization with Dodecylbenzenesulfonic Acid of a Polycarbonate Diol Produced with Sodium Methoxide

(16) 1000 g of the polycarbonate diol from example 7 were weighed into a 21 glass flask and heated to 100 C. 0.61 g of 4-dodecylbenzenesulfonic acid were added and the mixture was stirred for about one hour. The resin obtained was clear in the melt.

Example 11 (Inventive)

Neutralization with Dodecylbenzenesulfonic Acid of a Polycarbonate Diol Produced with Sodium Methoxide

(17) 1000 g of the polycarbonate diol from example 7 were weighed into a 21 glass flask and heated to 100 C. 0.73 g of 4-dodecylbenzenesulfonic acid were added and the mixture was stirred for about one hour. The resin obtained was clear in the melt.

Example 12

Testing the Reactivity of the Neutralized Polycarbonate Diols from Examples 8, 9, 10 and 11

(18) To test the reactivity of the polycarbonate diols these were dissolved in an 80% concentration in xylene and reacted with double the amount (in terms of NCOOH ratio) of methylenediphenyl diisocyanate (Desmodur 2460M, Covestro AG, Leverkusen, NCO:OH=2.0) at 50 C. The reaction was performed with constant control of the viscosity in a Haake Viskotester VT550 (D=90/s). At the beginning of measurement the mixtures have a viscosity of about 660 mPas (at 50 C.).

(19) TABLE-US-00002 Ex- After After After ample Stopper 10 min 60 min 90 min 8 dibutyl 3040 10300 12400 (comp.) phosphate mPas mPas mPas (100%) 9 dibutyl 2730 9310 10500 (comp.) phosphate mPas mPas mPas (200%) 10 dodecyl- 882 3400 5660 (inv.) benzene- mPas mPas mPas sulfonic acid (100%) 11 dodecyl- 767 2140 3140 (inv.) benzene- mPas mPas mPas sulfonic acid (120%)

(20) Here too it is apparent that neutralization with the sulfonic acid markedly retards the increase in viscosity and thus very markedly reduces reactivity. Even considerable overdosing of the dibutyl phosphate hardly provides a remedy. On the other hand a slight overdosing of dodecylbenzenesulfonic acid is able to further enhance the effect of reactivity reduction.