METHOD FOR PRODUCING POLYESTER POLYOLS

Abstract

The present invention relates to a process for preparing polyester polyols and also to the polyester polyols obtainable by the process.

Claims

1. A process for preparing polyester polyols comprising reacting at least one dicarboxylic acid DC or at least one dicarboxylic anhydride DCA and also furandicarboxylic acid with at least one at least bifunctional alcohol A, wherein in a first step (1), the dicarboxylic acids DC and dicarboxylic anhydrides DCA are reacted with the at least bifunctional alcohols A with removal of the water of condensation at a temperature in the range from 100 to 300° C. until at least 80% by weight of the water of condensation have been removed, based on the total amount of water which can be produced by condensation of the reactants, with the amount of the water of condensation being determined by means of the water removed by distillation from the reaction vessel, and with the dicarboxylic acid DC not being furandicarboxylic acid and with all dicarboxylic anhydrides DCA being phthalic anhydride, and in a second step (2a), after the reaction mixture has reached a temperature in the range from 50 to 150° C., furandicarboxylic acid is added and subsequently in a next step (2b), the reaction mixture is reacted further at a temperature in the range from 150 to 300° C. until an acid number of less than or equal to 1 mg KOH/g has been reached, with an additional organic solvent being used in none of the process steps.

2. The process for preparing polyester polyols according to claim 1, wherein the reaction in step (2b) is carried out to an acid number of less than or equal to 0.7 mg KOH/g.

3. The process for preparing polyester polyols according to claim 1, wherein the temperature in the first step (1) is in the range from 150 to 250° C.

4. The process for preparing polyester polyols according to claim 1, wherein the temperature in step (2a) is in the range from 80 to 120° C.

5. The process for preparing polyester polyols according to claim 1, wherein the temperature in step (2b) is in the range from 160 to 280° C.

6. The process for preparing polyester polyols according to claim 1, wherein at least one of the dicarboxylic acids DC are selected from the group consisting of aliphatic and aromatic dicarboxylic acids.

7. The process for preparing polyester polyols according to claim 1, wherein at least one of the dicarboxylic acids DC are adipic acid.

8-10. (canceled)

11. The process for preparing polyester polyols according to claim 1, wherein no fatty acids are used.

12. The process for preparing polyester polyols according to claim 1, wherein no monocarboxylic acids are used.

13. (canceled)

14. The process for preparing polyester polyols according to claim 1, wherein at least one of the bifunctional alcohols A are selected from the group consisting of aliphatic and aromatic bifunctional alcohols.

15. The process for preparing polyester polyols according to claim 1, wherein at least one of the bifunctional alcohols A are selected from the group consisting of aliphatic bifunctional alcohols.

16. The process for preparing polyester polyols according to claim 1, wherein at least one of the bifunctional alcohols A are selected from the group consisting of diethylene glycol (DEG), methyl ethyl glycol (MEG), 2-methyl-1,3-propanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, trimethylolpropane, and polyether polyols.

17. The process for preparing polyester polyols according to claim 1, wherein at least one of the bifunctional alcohols A are selected from the group consisting of DEG, MEG, and polyether polyols.

18. The process for preparing polyester polyols according to claim 1, wherein at least one of the bifunctional alcohols A is DEG.

19. The process for preparing polyester polyols according to claim 1, wherein the OH number of the product is in the range from 50 to 300 mg KOH/g.

20. The process for preparing polyester polyols according to claim 1, wherein the product is a liquid at 25° C. having a viscosity of 1 to 40,000 mPas.

21. The process for preparing polyester polyols according to claim 1, wherein the product has a viscosity at 75° C. of less than or equal to 40,000 mPas, where the viscosity is determined in accordance with DIN EN ISO 3219 (Oct. 1, 1994 edition) by means of a Rheotec RC 20 rotational viscometer using spindle CC 25 DIN (spindle diameter: 12.5 mm; internal diameter of measuring cylinder: 13.56 mm) at a shear rate of 50 l/s at 25° C.

22. The process for preparing polyester polyols according to claim 1, wherein the proportion of furandicarboxylic acid is from 5 to 45% by weight, based on the total batch.

23. A polyester polyol preparable by the process of claim 1, and having an acid number of less than or equal to 1 mg KOH/g.

24. (canceled)

25. The polyester polyol according to claim 23, wherein the polyester polyol is liquid at 25° C. and/or the polyester polyol has a viscosity at 75° C. of less than or equal to 40,000 mPas, where the viscosity is determined in accordance with DIN EN ISO 3219 (Oct. 1, 1994 edition) by means of a Rheotec RC 20 rotational viscometer using spindle CC 25 DIN (spindle diameter: 12.5 mm; internal diameter of measuring cylinder: 13.56 mm) at a shear rate of 50 l/s at 25° C.

Description

EXAMPLES

Example 1

[0056] 619.7 g of adipic acid and 563.6 g of 2-methyl-1,3-propanediol are firstly introduced into a 2000 ml round-bottom flask provided with thermometer, nitrogen inlet, stirrer and heating mantle. The water of reaction formed is continuously removed from the mixture by distillation.

[0057] After 105 g of distillate have been collected, the mixture is cooled to 100° C. and 220.5 g of furandicarboxylic acid are added. The mixture is subsequently condensed further at 200° C. until a product having an acid number of <1.0 mg KOH/g is obtained (samples of the reaction mixture were taken every two to three hours in order to determine the acid number). The total reaction time was 19 hours.

[0058] The polymer obtained has the following properties:

[0059] Acid number: 0.163 mg KOH/g

[0060] Hydroxyl number: 60.23 mg KOH/g

[0061] Viscosity at 75° C.: 2352 mPas

Example 2

[0062] 573.6 g of phthalic anhydride and 1531.3 g of diethylene glycol are placed in a 3000 ml round-bottom flask provided with thermometer, nitrogen inlet, stirrer and heating mantle, heated to 180° C. and the distillate formed is continuously removed by distillation (30 g of distillate). The mixture is subsequently cooled to 100° C. and 604.5 g of furandicarboxylic acid are added. The mixture is subsequently condensed further at 200° C. until a product having an acid number of <1.0 mg KOH/g is formed (samples of the reaction mixture were taken every two to three hours in order to determine the acid number). The total reaction time was 12 hours.

[0063] The polymer obtained has the following properties:

[0064] Acid number: 0.69 mg KOH/g

[0065] Hydroxyl number: 293.3 mg KOH/g

[0066] Viscosity at 25° C.: 10 100 mPas

Example 3

[0067] 189.6 g of adipic acid and 297.5 g of 1,4-cyclohexanedimethanol (mixture of isomers) are introduced into a 500 ml round-bottom flask provided with thermometer, nitrogen inline, stirrer and heating mantle and heated to 180° C. Here, 42.4 g (90.6% by weight) of aqueous distillate are removed by distillation. The mixture is subsequently cooled to 100° C. and 67.5 of furandicarboxylic acid are added. The mixture is condensed further at 200° C. until a product having an acid number of <1.0 mg KOH/G is formed (samples of the reaction mixture were taken every two to three hours in order to determine the acid number). The total reaction time was 9 hours.

[0068] The polymer obtained has the following properties:

[0069] Acid number: <0.1 mg KOH/g

[0070] Hydroxyl number: 68.5 mg KOH/g

[0071] Viscosity at 75° C.: 37100 mPas

Example 4

[0072] In a manner analogous to the preceding examples, 159.87 g of adipic acid, 57.11 g of trimethylolpropane and 341.08 g of neopentyl glycol are placed in a reaction vessel and condensed at 180° C. with continuous removal of the water. 38.8 g (96% by weight) of the distillate were removed and the mixture was subsequently cooled to 100° C. After this temperature has been reached, 170.8 g of 2,5-furandicarboxylic acid are added and the mixture is again heated to 200° C. The reaction was continued until the product attained an acid number of <1 mg KOH/g (samples of the reaction mixture were taken every two to three hours in order to determine the acid number). The OHN was set by addition of 6.8 g of neopentyl glycol which was reacted at 180° C. for 3 hours. The product was obtained within a reaction time of 13 hours.

[0073] The polyester polyol had the following properties

[0074] Acid number: <0.2 mg KOH/g

[0075] OHN: 118 mg KOH/g

[0076] Viscosity at 75° C.: 13 030 mPas

TABLE-US-00001 Acid number <0.2 mg KOH/g OH number 118 mg KOH/g Karl-Fischer 0.009% Cone-plate viscometer, 75° C. 13 030 mPa*s

Comparative Example 1

[0077] 163.6 g of adipic acid, 174.7 g of 2,5-furandicarboxylic acid and 58.4 g of trimellitic acid are placed in a 500 ml round-bottom flask provided with thermometer, nitrogen inlet, stirrer and heating mantle and heated to 120° C. When the temperature has been attained, 40 ppm of titanium tetrabutoxide are added as catalyst. The homogeneous mixture was subsequently heated further to 180° C. and the water of condensation formed was continuously removed. After the amount of water distilled off decreased, the reaction temperature was increased to 200° C. and vacuum was applied. The vacuum was broken and 40.7 g of neopentyl glycol were additionally added to the mixture in order to set the OHN. Even after a reaction time of 24 hours, an acid number of <1 mg KOH/g could not be attained (samples of the reaction mixture were taken every two to three hours in order to determine the acid number).

[0078] The product obtained had the following properties:

[0079] Acid number: 6.8 mg KOH/g

[0080] OH number: 114.6 mg KOH/g

[0081] Cone-plate viscometer, 75° C.: 36 720 mPa*s

[0082] The experimental data make it clear that the two-stage, solvent-free process for preparing a PESOL gives a significantly lower acid number of the product compared to the single-stage process.