POLYURETHANE DISPERSIONS

Abstract

The present invention relates to a polyurethane dispersion comprising particles of a polyurethane dispersed in a dispersing medium, wherein the polyurethane is obtainable by reacting a polyol and an isocyanate, wherein the polyol comprises at least one dimer fatty residue selected from a dimer fatty diacid residue, a dimer fatty diol residue and a dimer fatty diamine residue; and at least one furan dicarboxylic acid residue. The invention also relates to a coating composition comprising the polyurethane dispersion, a polyol for making the polyurethane dispersion, the use of the polyol and a method of making the polyurethane.

Claims

1. A polyurethane dispersion comprising particles of a polyurethane dispersed in a dispersing medium, wherein the polyurethane is obtainable by reacting a polyol and an isocyanate, wherein the polyol comprises: a) at least one dimer fatty residue selected from a dimer fatty diacid residue, a dimer fatty diol residue and a dimer fatty diamine residue; and b) at least one furan dicarboxylic acid residue.

2. A polyurethane dispersion as claimed in claim 1 wherein the polyol comprises at least 20wt % and at most 80wt % of the at least one dimer fatty residue.

3. A polyurethane dispersion as claimed in claim 1 wherein the polyol comprises at least 5wt % and at most 40wt % of the at least one furan dicarboxylic acid residue.

4. A polyurethane dispersion as claimed in claim 1 wherein the weight ratio of dimer fatty residue to furan dicarboxylic acid residue in the polyol is at least 4:1 and at most 20:1.

5. A polyurethane dispersion as claimed in claim 1 wherein the polyol has a number average molecular weight of at least 500 and at most 5000.

6. A polyurethane dispersion as claimed in claim 1 wherein the polyol has a glass transition (Tg) temperature of at least 100 C. and at most 30 C.

7. A polyurethane dispersion as claimed in claim 1 wherein the polyol has a melting point (Tm) temperature of at most 80 C.

8. A polyurethane dispersion as claimed in claim 1 wherein the polyol further comprises: c) at least one residue of a C.sub.2 to C.sub.10 diol.

9. A polyurethane dispersion as claimed in claim 8 wherein the polyol comprises at least 10wt % and at most 50wt % of the at least one residue of a C.sub.2 to C.sub.10 diol.

10. A polyurethane dispersion as claimed in any preceding claim 1 wherein the average particle size of the particles of the polyurethane is from 40 nm to 200 nm when measured by laser correlation spectroscopy.

11. A polyurethane dispersion as claimed in claim 1 wherein the polyurethane dispersion is an aqueous polyurethane dispersion and the dispersing medium comprises water.

12. A coating composition comprising a polyurethane dispersion as claimed in claim 1.

13. A coating composition as claimed in claim 12 wherein the coating composition has a Knig hardness of at least 40s when measured according to DIN ISO 2815.

14. A coating composition as claimed in claim 12 wherein the coating composition dries at room temperature when applied to a substrate and does not undergo a curing reaction.

15. A polyol for use in making a polyurethane dispersion, wherein the polyol comprises: a) at least one dimer fatty residue selected from a dimer fatty diacid residue, a dimer fatty diol residue and a dimer fatty diamine residue; and b) at least one furan dicarboxylic acid residue.

16. A polyol as claimed in claim 15 wherein the polyol has a number average molecular weight of at least 500 and at most 5000.

17. A polyol as claimed in claim 15 wherein the polyol has a glass transition (Tg) temperature of at least 100 C. and at most 30 C.

18. A polyol as claimed in claim 15 wherein the weight ratio of dimer fatty residue to furan dicarboxylic acid residue is at least 4:1 and at most 20:1.

19. A polyol as claimed in claim 15 wherein the polyol further comprises: c) at least one residue of a C.sub.2 to C.sub.10 diol.

20. A method of making a polyurethane dispersion comprising reacting a polyol as claimed in claim 15 with an isocyanate to form a polyurethane which is then dispersed in a dispersing medium to form the polyurethane dispersion.

21. (canceled)

Description

EXAMPLES

[0152] The present invention will now be described further by way of example only with reference to the following Examples. All parts and percentages are given by weight unless otherwise stated.

[0153] It will be understood that all tests and physical properties listed have been determined at atmospheric pressure and room temperature (i.e. about 20 C.), unless otherwise stated herein, or unless otherwise stated in the referenced test methods and procedures.

[0154] Tests of polyurethane dispersions in coatings were performed at 23 C. with a relative humidity of 50%.

[0155] Compounds as used in the following examples are identified as follows: [0156] 1,4-butanediol (BDO)-a bio-based version is available from BioAmber [0157] 1,6-hexanediol (HDO) [0158] Adipic acid (C.sub.6 dicarboxylic acid)a bio-based version is available from Verdezyne [0159] 2,5-furan dicarboxylic acid (FDCA)available under the trade name YXY from Avantium [0160] PRIPOL 1006 (TM) dimer fatty diacidhydrogenated C.sub.36 dimer dicarboxylic acid ex Croda [0161] Dimethylolpropionic acid (DMPA) [0162] Isophorone diisocyanate (IPDI) [0163] N-methyl pyrrolidone (NMP) [0164] Ethylene diamine (EDA) [0165] Triethylamine (TEA)

[0166] Test methods used in the following examples are as follows: [0167] Number average molecular weight was determined by end group analysis with reference to the hydroxyl value. [0168] Weight average molecular weight was determined by end group analysis with reference to the hydroxyl value. [0169] The hydroxyl value is defined as the number of mg of potassium hydroxide equivalent to the hydroxyl content of 1 g of sample, and was measured by acetylation followed by hydrolysation of excess acetic anhydride. The acetic acid formed was subsequently titrated with an ethanolic potassium hydroxide solution. [0170] The acid value is defined as the number of mg of potassium hydroxide required to neutralise the free fatty acids in 1 g of sample, and was measured by direct titration with a standard potassium hydroxide solution. [0171] The isocyanate (NCO) value or content is defined as the weight % content of isocyanate in the sample and was determined by reacting with excess dibutylamine, and back titrating with hydrochloric acid.

Comparative Example P1

Formation of Polyol 1 (a FDCA Based Polyol)

[0172] This is a comparative example not according to the present invention. 100 parts by weight of 2,5-furan dicarboxylic acid and 106 parts by weight hexanediol were charged to a reactor equipped with a stirrer, a thermometer, a gas inlet and a condenser. In addition 0.1% by weight of stannous octoate as catalyst was added to the reactor. The temperature in the reactor was raised to 220-230 C. under normal pressure in a nitrogen atmosphere. An esterification reaction was conducted under these conditions until the desired acid and hydroxyl value were obtained. The evaluation results of the obtained polyester polyol gave an acid value of less than 1 mg KOH/g and a hydroxyl value of 56 mg KOH/g, equivalent to an number average molecular weight of about 2000 g/mol.

Examples P2 to P5

Formation of Polyols 2 to 5 (FDCA/Dimer Based Polyols)

[0173] Polyols 2 to 5 were made using the following general method. The specific amounts of APRIPOL 1006, B2,5-furan dicarboxylic acid and Chexanediol used to make Polyols 2 to 5 are given in Table 1 below.

[0174] General Method for Examples P2 to P5

[0175] A parts by weight PRIPOL 1006 and C parts by weight hexanediol were charged to a reactor equipped with a stirrer, a thermometer, a gas inlet and a condenser. The temperature in the reactor was raised to 180 C. under normal pressure in a nitrogen atmosphere. An esterification reaction was conducted under these conditions until a 50% reduction of the initial acid value was achieved. The temperature was then lowered to 160 C. where upon B parts weight 2,5-furan dicarboxylic acid and 0.1% by weight of stannous octoate as catalyst were added to the reactor. The temperature was raised to 220-230 C. under normal pressure in a nitrogen atmosphere. Under these conditions the esterification reaction was conducted until the desired acid and hydroxyl value were obtained. The evaluation results of the obtained polyols 2 to 5 gave an acid value of less than 1 mg KOH/g and a hydroxyl value of 56 mg KOH/g, equivalent to an number average molecular weight of about 2000 g/mol.

TABLE-US-00001 TABLE 1 Parts by Weight of components A to C in Polyols 1 to 5 A - PRIPOL 1006 B - FDCA C - hexanediol Weight ratio parts by parts by parts by Polyol A/B (A:B) weight weight weight 1 0/100 100 106 2 50/50 (1:1) 100 100 113.2 3 70/30 (2.33:1) 100 42.8 64.5 4 80/20 (4:1) 100 25 49.3 5 90/10 (9:1) 100 11.1 37.4

Comparative Example P6

Formation of Polyol 6 (a Dimer Based Polyol)

[0176] This is a comparative example not according to the present invention. 100 parts by weight PRIPOL 1006 and 28 parts by weight hexanediol were charged to a reactor equipped with stirrer, a thermometer, a gas inlet and condenser. In addition 0.1% by weight of stannous octoate as catalyst was added. The temperature in the reactor was raised to 220-230 C. under normal pressure in a nitrogen atmosphere. An esterification reaction was conducted under these conditions until the desired acid and hydroxyl value were obtained. The evaluation results of the obtained polyester polyol gave an acid value<1 mg KOH/g and a hydroxyl value of 56 mg KOH/g, equivalent to an number average molecular weight of about 2000 g/mol

Comparative Example P7

Formation of Polyol 7 (a Dimer/Adipic Based Polyol)

[0177] This is a comparative example not according to the present invention. 100 parts by weight PRIPOL 1006, 11.1 parts by weight adipic acid and 38 parts by weight hexanediol, were charged to a reactor equipped with stirrer, a thermometer, a gas inlet and condenser. In addition 0.1% by weight of stannous octoate as catalyst was added. The temperature in the reactor was raised to 220-230 C. under normal pressure in a nitrogen atmosphere. An esterification reaction was conducted under these conditions until the desired acid and hydroxyl value were obtained. The evaluation results of the obtained polyester polyol gave an acid value <1 mg KOH/g and a hydroxyl value of 56 mg KOH/g, equivalent to an number average molecular weight of about 2000 g/mol.

Example T1

Thermographic Analysis of the Polyols 1 to 6

[0178] A thermographic analysis of the Polyols 1 to 6 was performed to determine glass transition temperature (Tg) and melting point (Tm) of the polyols. The analysis was performed using DSC (differential scanning calorimetry) with the following method and instrument settings.

[0179] Instrument: [0180] Module: DSC822 (Name: DSC822-LT) [0181] Manufacturer: Mettler Toledo

[0182] Method 1:-150(10).200(2)/20 N2=30

[0183] Temperature program: [0184] Isotherm Segment 1:10 min at -150 C. [0185] Dynamic Segment 2: [0186] Start temperature: 150 C. [0187] End temperature: 200 C. [0188] Heating rate: 20 C./min [0189] Isotherm Segment 3: 1 min at 200 C. [0190] Dynamic Segment 4: [0191] Start temperature: 200 C. [0192] End temperature: 150 C. [0193] Heating rate: 20 C./min [0194] Isotherm Segment 5: 10 min at 150 C. [0195] Dynamic Segment 6: [0196] Start temperature: 150 C. [0197] End temperature: 200 C. [0198] Heating rate: 20 C./min

[0199] Method 2:100(10).200(2)/10 N2=30

[0200] Temperature program: [0201] Isotherm Segment 1: 10 min at 100 C. [0202] Dynamic Segment 2: [0203] Start temperature: 100 C. [0204] End temperature: 200 C. [0205] Heating rate: 10 C./min [0206] Isotherm Segment 3: 1 min at 200 C. [0207] Dynamic Segment 4: [0208] Start temperature: 200 C. [0209] End temperature: 100 C. [0210] Heating rate: 10 C./min [0211] Isotherm Segment 5:10 min at 100 C. [0212] Dynamic Segment 6: [0213] Start temperature: 100 C. [0214] End temperature: 200 C. [0215] Heating rate: 10 C./min

[0216] Atmosphere: [0217] Purge gas: N2

[0218] Flow rate: 30 ml/min

[0219] Sample: [0220] Size: 15 mg [0221] Pan: 40 l Aluminium crucible with automatic pierceable lid

[0222] An average of the results from Method 1 and Method 2 was obtained for each polyol and the average results of the Differential Scanning calorimetry analysis are given in Table 2 below.

TABLE-US-00002 TABLE 2 Results of Differential Scanning Calorimetry Tg Tm Physical form at room Polyol ( C.) ( C.) temperature 1 13 144 White solid 2 41 121 White solid 3 48 96 White solid/waxy 4 52 69 Waxy 5 56 35 Semi-transparent/liquid 6 51 2 Liquid Tg: glass transition Tm: melting point

Examples PUD 5 and 7

Formation of Polyurethane Dispersions from Polyols 5 and 7

[0223] Test methods for Polyurethane Dispersions: [0224] Average particle size of the polyurethane particles in dispersion was measured by laser correlation spectroscopy using a Malvern Autosizer II from Malvern Instruments Limited. The particle size is determined using a dynamic light scattering mode to obtain an average particle volume measurement which is then converted to a linear particle size assuming spherical particles. Therefore the average particle size is an effective average particle diameter. [0225] Knig hardness was tested using DIN ISO 2815 [0226] Chemical resistance was evaluated according to DIN12720:1997-10 in which coating samples were spot tested for a predetermined time and given a rating from 0=undamaged to 5=complete damage

[0227] Synthesis of the Polyurethane Dispersions PUD5 and PUD7

[0228] Polyurethane dispersion (PUD) synthesis of PUD5 and PUD7 was performed using the acetone process.

[0229] Ingredients:

TABLE-US-00003 150 g Polyol P5 or P7 12 g Dimethylolpropionic acid (DMPA) 56.3 g Isophorone diisocyanate (IPDI)) 27.8 g N-methyl pyrrolidone (NMP) 386 g water 3.4 g Ethylene diamine (EDA) 9.0 g Triethylamine (TEA)
The polyester polyol P5 or P7, DMPA and NMP (solvent) are dried at 120 C. under nitrogen. After cooling to 70 C., DBTL catalyst (0.05% wt on pre-polymer) and slowly IPDI (aliphatic diisocyanate) are added to the reaction until the desired NCO % has been reached. Then at 60 C. TEA is added for neutralising the DMPA carboxylic acid groups, during 0.5 to 1 hour, followed by cooling to 40-55 C. Then the prepolymer is diluted with acetone. At 30-40 C. the prepolymer is chain extended with EDA, added drop-wise and reacted 2 hours. The demineralised water is adding slowly during 1 hour and dispersed under vigorous stirring. Result is a 35% solids polyurethane dispersion (PUD) in water as a dispersing medium. Acetone can be used as processing aid, to reduce viscosity, and distilled off from the final PUD.

[0230] Formation of coatings from PUD5 and PUD7

[0231] Glass was used as a substrate on which 100 m films of the above described dispersions PUD5 and PUD7 were applied with the aid of an applicator frame (BYK PA-2030). The applied films were dried for 24 hours under ambient conditions to form a coating. The coatings thus formed from PUD5 and PUD7 were tested for Knig hardness and chemical resistance as described above. The results are given in Table 3 below.

TABLE-US-00004 TABLE 3 Physical properties of PUDs 5 and 7 and coatings formed from PUDs 5 and 7 PUD7 from PUD5 from Polyol 7 Polyol 5 (comparative) Proportion of total dispersion 35 36 weight which is solid particles (wt % of solids) Average particle size (nm) 89 139 Knig hardness (s) 56 35 Chemical resistance to: Ammonia (10% soln) after 2 min 2 4 EtOH (50% soln) after 1 hour 2 2 Water after 16 hours 1 5 Acetic acid after 1 hour 2 2
It can be seen from the results in Table 3 that the polyurethane dispersion PUD5 made from the FDCA/Dimer acid based Polyol 5 forms a coating with an improved Knig hardness over the polyurethane dispersion PUD7 made from the adipic acid/Dimer acid based comparative Polyol 7. Furthermore the overall resistance to the tested chemicals is higher for PUD5 than for PUD7 because PUD5 has lower damage ratings (0=undamaged and 5=complete damage).

[0232] The results in Table 3 demonstrate the improved properties provided to a coating composition formed from a polyurethane dispersion according to the present invention.

[0233] It is to be understood that the invention is not to be limited to the details of the above embodiments, which are described by way of example only. Many variations are possible.