Process for the production of polyurethane catalyst

Abstract

The present invention relates to a simple, safe and ecofriendly process for producing a bismuth or a zinc boron carboxylate comprising mixing carboxylic acids with metal oxide by adding boric acid esters. The present invention also provides the use of bismuth or zinc boron carboxylate as polyurethane catalyst preferably in coatings, adhesives, sealants, elastomers, flexible foams and rigid foams.

Description

[0001] PROCESS FOR THE PRODUCTION OF POLYURETHANE CATALYST

[0002] Technical Field

[0003] The present invention relates to a process for producing a bismuth or a zinc boron carboxylate and its use as polyurethane catalyst.

[0004] Background

[0005] Polyurethanes are polymers consisting of organic units joined by urethane (carbamate) linkages, which are produced through the reaction between isocyanates and polyols. These materials exhibit a wide range of properties and are used in various industries for their versatility, durability, and performance characteris tic s .

[0006] Polyurethane systems typically use catalysts to facilitate the chemical reactions involved in their formation. These catalysts play a crucial role in controlling the reaction rate, curing time, and final properties of the polyurethane material. Tin catalysts or organotin compounds, such as dibutyltin dilaurate (DBTDL) and dibutyltin diacetate (DBTDA), tire commonly used as catalysts in polyurethane reactions. They are effective in promoting the urethane linkage formation in polyurethane synthesis. Bismuth compounds like bismuth octanoate are used as alternatives to tin catalysts due to environmental and health concerns associated with tin compounds. They can catalyze the polyurethane reaction, particularly in rigid foam and coatings applications. Zinc compounds, such as zinc octoate, can act as catalysts in polyurethane systems, especially in flexible foam production.

[0007] Both bismuth and zinc catalysts are used in polyurethane systems as alternatives to tin-based catalysts due to environmental and health concerns associated with tin compounds. While bismuth or zinc catalysts offer certain advantages as alternatives to tin-based catalysts in polyurethane systems, they also have some disadvantages that need to be considered. Compared to tin catalysts, they may have lower catalytic activity which can result in longer reaction times or require higher catalyst concentrations to achieve comparable reaction rates.

[0008] Additionally, bismuth or zinc catalysts are sensitive to temperature variations and may exhibit reduced catalytic activity or effectiveness at elevated temperatures commonly used in polyurethane processing. The lower catalytic activity of bismuth or zinc catalysts may result in variations in product quality, properties, or consistency. Inconsistent catalytic performance can lead to batch- to- batch variability, affecting the uniformity and reliability of polyurethane materials.

[0009] Therefore, there is a need for a polyurethane catalyst showing consistent and high catalytic performance produced by a simple, safe and ecofriendly process.

[0010] Detailed Description of the Invention

[0011] The present invention provides a process for producing a bismuth or a zinc boron carboxylate comprising the steps of, a) Mixing a carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc, b) Adding to the mixture an aliphatic carboxylic acid having 2 to 5 carbons and mixing, c) Adding to the mixture a boric acid ester and mixing, therein the process is performed with a continuous distillation. Herein, the continuous distillation offers improved efficiency, high purity, consistent quality and reduced waste. It has been found that a more streamlined and cost-effective production process can be performed with a continuous distillation.

[0012] As herein referred, continuous distillation is the method of separating components from a liquid mixture continuously, without interrupting the process. Thus, according to the present invention, the distillation in the production method starts with the first step of the process and stops after the collection of final products.

[0013] The inventors have found that continuous distillation is crucial for the yield of boron carboxylate and also for its viscosity and purity properties. In the presence of water, boron compounds can be degraded, and this can lead to side products or reduced yields. Thus, the inventors removed water or undesired volatiles to minimize the degradation and to maintain the integrity of the boron compound. In the boron carboxylate compounds, boron form coordination complexes with the oxide of bismuth or zinc. Water molecules in the system compete with the oxides for coordination sites on boron. Thus, continuous distillation results in higher purity of the final compound. Continuous distillation can also be designed for energy efficiency of the process. In one embodiment of the present invention, the process or at least one of the steps of the process is performed while gradually increasing the temperature to a value in the range of 105°C and 200°C and more preferably 140°C and 180°C. During the reaction, the inventors gradually increased the temperature and they have found that gradually increasing the temperature accelerate the reaction rate and additionally, allows for better control over the stability of reactants and the final product. It is also important for the water and volatile products removals.

[0014] In one preferred embodiment of the present invention, the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc is performed at the temperature in the range of 40°C and 180°C, preferably 85°C and 140°C.

[0015] The temperature while mixing the carboxylic acid with the oxide, hydroxide or carbonate of metal can be different for zinc and bismuth processes. To obtain zinc boron carboxylate, the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of zinc is performed at the temperature in the range of 40°C and 100°C, preferably 85°C and 95°C. To obtain bismuth boron carboxylate, the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth is performed at the temperature in the range of 105°C and 180°C, preferably 110°C and 140°C.

[0016] In one preferred embodiment of the present invention, the addition of the aliphatic carboxylic acid having 2 to 5 carbons can be continuous for a period in the range of 0,5 to 6 hours, preferably for a period in the range of 1 to 2 hours. It means that the predetermined amount of aliphatic carboxylic acid having 2 to 5 carbons is slowly and continuously added to the reactor over the course of the predetermined time period, while continuing to mix the reactants. After the completion of the addition of aliphatic carboxylic acid having 2 to 5 carbons, the temperature is gradually increased to a value in the range of 105°C and 200°C and more preferably 140°C and 180°C.

[0017] In one preferred embodiment, before adding aliphatic carboxylic acid, the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc can continue for a period ranging from 1 to 24 hours, preferably 1 to 14 hours, more preferably 2 to 6 hours. Preferably, the aliphatic carboxylic acid used in the process is more reactive than the carboxylic acid having 2 to 24 carbons. For example, propionic acid can be used as aliphatic carboxylic acid and neodecanoic acid can be used as other carboxylic acid having 2 to 24 carbons. Thus, the inventors prefer that most of the neodecanoic acid reacts before adding propionic acid, in order to provide the desired molecular structure.

[0018] According to the preferred embodiment of the present invention, the process is performed under a nitrogen flow. Thus, an inert atmosphere is created inside the reaction vessel and the oxidation in the reaction is prevented. The nitrogen flow also reduces the moisture levels in the reaction vessel. This provides higher yield and lower impurity.

[0019] According to the present invention, a carboxylic acid having 2 to 25 carbons is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, 9-hexadecenoic acid, cis-9-octadecenoic acid, 11 -octadecenoic acid, cis, cis- 9,12-octadecadienoic acid, 9,12,15-octadecatrienoic acid, 6,9,12-octadecatrienoic acid, 9,11,13- octadecatrienoic acid, eicosanoic acid, 8,11-eicosadienoic acid, 5,8,11-eicosatrienoic acid, 5,8,11,14-eicosatetraenoic acid, tung oil acid, linseed oil acid, soybean oil acid, resin acid, tall oil fatty acid, rosin acid, abietic acid, neoabietic acid, palustric acid, pimaric acid, dehydroabietic acid, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, 2-ethylhexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, isononanoic acid, decanoic acid, neodecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid and naphthenic acid, more preferably selected from the group consisting of hexanoic acid, 2-ethylhexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, isononanoic acid, decanoic acid and neodecanoic acid.

[0020] In one preferred embodiment, the carboxylic acid can have 6 to 18 carbons, more preferably 8 to 13 carbons.

[0021] According to the present invention, aliphatic carboxylic acid having 2 to 5 carbons is selected from the group consisting of propionic acid, acetic acid, butanoic and pentanoic acid and preferably propionic acid or acetic acid. For bismuth boron carboxylate, the ratio between the molar amount of aliphatic carboxylic acid having 2 to 5 carbons and the molar amount of carboxylic acid having 2 to 25 carbons is 1:2. For zinc boron carboxylate, the ratio between the molar amount of aliphatic carboxylic acid having 2 to 5 carbons and the molar amount of carboxylic acid having 2 to 25 carbons is 1:1. According to the present invention boric acid ester is selected from the group consisting of trimethyl borate, triethyl borate, tripropyl borate and tributyl borate and preferably the boric acid ester is trimethyl borate. The ratio between the molar amount of oxide, hydroxide or carbonate of bismuth or zinc and boric acid ester is 3:1.

[0022] In one preferred embodiment of the present invention, the addition of the boric acid esters can be continuous for a period in the range of 0,5 to 6 hours, preferably for a period in the range of 1 to 2 hours. Herein, the addition of the boric acid ester is performed at the temperature in the range of 120°C and 180°C.

[0023] According to the present invention, the process may further comprise the step of adding a solvent which is selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, alcohols and carboxylic acids.

[0024] In one preferred embodiment of to the present invention, the process may further comprise the step of mixing a carboxylic acid having 2 to 25 carbons, preferably having 6 to 18 carbons, more preferably having 8 to 13 carbons, and an aliphatic carboxylic acid having 2 to 6 carbons with a solvent before mixing with an oxide of bismuth or zinc. Accordingly, all of the products except the oxide of bismuth or zinc are fed into the reactor and mixed for a predetermined period of time, preferably for a time range of 5 to 20 minutes. Herein, the temperature may be in the range of 100°C and 140°C, preferably 120°C.

[0025] After adding an oxide of bismuth or zinc, the temperature is gradually increased to a value in the range of 140°C and 170°C, while continuing mixing. The reaction continues all oxides of bismuth or zinc has reacted.

[0026] In one preferred embodiment, the present invention provides a process for producing a bismuth or a zinc boron carboxylate comprising the steps of, a) Mixing neodecanoic acid with an oxide of bismuth or zinc, b) Adding propionic acid to the mixture and mixing for a period ranging from 2 to 4 hours, c) Adding tributyl borate to the mixture and mixing, d) Collecting butyl propionate, and e) Filtering the final product, wherein the process is performed with a continuous distillation and under nitrogen flow. The present invention also provides the use of bismuth boron carboxylate, zinc boron carboxylate or combinations thereof as polyurethane catalyst. Herein the bismuth boron carboxylate, zinc boron carboxylate or combinations thereof, as polyurethane catalyst, can be used in coatings, adhesives, sealants, elastomers, flexible foams and rigid foams.

[0027] Bismuth or zinc boron carboxylate used as polyurethane catalyst according to the present invention has lower viscosity which is in the range of from 1 to 500 cP, preferably 5 to 300 cP. According to the viscosity values, it has been found that it is easier to mix and disperse these catalysts within polyurethane formulations. They can be more readily incorporated into the reaction mixture, leading to better distribution of catalyst throughout the system. This improves reaction uniformity find reduces the risk of localized variations in polymerization or curing.

[0028] The catalysts according to the present invention enhance reaction kinetics by promoting faster mixing and reaction initiation. They accelerate the formation of polyurethane chains.

[0029] Examples

[0030] Example 1

[0031] 335g of neodecanoic acid and 445 g of solvent D60 are fed into the reactor. The distillation system and nitrogen flow to the reaction vessel are opened while starting to mix the reactants. During the mixing, distillation is always open. The temperature is set to 120°C. 227 g of bismuth oxide is added to the reactor, and mixed and reacted for 2 hours. 72 g of propionic acid is added continuously into the system over the course of 1 hour. After the feeding of propionic acid is terminated, the temperature is gradually increased to 160°C. During this time, the distillation continues, and the resulting water is collected via distillation. The reaction continues until all bismuth is dissolved. 75 g of tributyl borate (TBB) is continuously fed into the reactor at 160°C over the course of 1 hour. After the TBB feed is complete, the temperature is gradually increased to 180°C, and the resulting butyl propionate is collected via distillation. When the liquid output ends, the product is filtered. The percentage of bismuth obtained is 20% and the viscosity of the final product is 15 cP.

[0032] Example 2

[0033] 498g of neodecanoic acid, 259 g of solvent D60 and 52 g of water are fed into the reactor. The distillation system and nitrogen flow to the reaction vessel are opened while starting to mix the reactants. During the mixing, distillation is always open. 235 g of zinc oxide is added to the reactor. The temperature is set to 90°C. The reactants are mixed and reacted for 2 hours. 214 g of propionic acid is added continuously into the system over the course of 1 hour. After the feeding of propionic acid is terminated, the temperature is gradually increased to 160°C. During this time, the distillation continues, and the resulting water is collected via distillation. The reaction continues until all zinc is dissolved. 222 g of tributyl borate (TBB) is continuously fed into the reactor at 160°C over the course of 1 hour. After the TBB feed is complete, the temperature is gradually increased to 180°C, and the resulting butyl propionate is collected via distillation. When the liquid output ends, the product is filtered. The percentage of zinc obtained is 18% and the viscosity of the final product is 250 cP.

[0034] Example 3

[0035] In this example, a flexible foam producing test is performed to observe the effect of different catalysts on the reaction in the standard formulation.

[0036] In this case, catalysts were used to equalize the amount of metal in the mixture.

[0037] The polyol used in the recipe is a 3-function polyol with OH number 28. Water was used as a blowing agent, a silicone -based chemical as a defoamer, methylene chloride as a stabilizer, and an amine catalyst as an accelerator. The isocyanate used in the recipe was chosen 80 / 20 TDI. The isocyanate index number for the foam made is 115.

[0038] Every material except TDI is mixed. Then, TDI is added to the mixture and the reaction starts, while mixing all materials at 2000 rpm by high-shear mixer. Finally, a foam is obtained.

[0039] In the foaming reactions, the zinc and tin based boron neodecanoate mixture showed the closest performance to the reference catalyst. It met the requirements of the reference catalyst with a faster reaction start and a more balanced reaction progress.

[0040] Example 4

[0041] The coatings with metal catalyst are prepared according to the following example.

[0042] All ingredients except IPDI are mixed with a high-speed mixer at approximately 1000 RPM for 10 minutes. In one coating, dibutyltin dilaurate - DBTL (metal content: 18%) is used as metal catalyst and in the second coating, the mixture (1: 1) of Bi Boron Neodecanoate (metal content: 20%) and Zn Boron Neodecanoate (metal content 18%) is used as metal catalyst. After a homogeneous mixture is achieved, IPDI is added to the mixture and mixed until a homogeneous mixture is obtained. The resulting mixture is applied on the glass surface and the coating is made.

[0043] Drying is monitored with a “pendulum hardness tester” every 24 hours. This test works on the basis of the damping time of a pendulum oscillating on a surface, depending on the surface hardness. A more dried material releases for a shorter period of time. In this way, the effect of catalysts on drying time is monitored. The ranges of the results taken from different points of the surface are stated in the table.

[0044] In addition, a thicker coating was applied with the same application and the hardness results were measured with the Shore D Shoremeter after 3 days.

[0045] All of the results are as follows:

Claims

CLAIMS1. A process for producing a bismuth or a zinc boron carboxylate comprising the steps of, a) Mixing a carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc, b) Adding to the mixture an aliphatic carboxylic acid having 2 to 5 carbons and mixing, and c) Adding to the mixture a boric acid ester and mixing, wherein the process is performed with a continuous distillation.

2. The process according to claim 1, wherein the process or at least one of the steps of the process is performed while gradually increasing the temperature to a value in the range of 105°C and 200°C.

3. The process according to claim 1 or 2, wherein the process or at least one of the steps of the process is performed while gradually increasing the temperature to a value in the range of 140°C and 180°C.

4. The process according to claim 1, wherein the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc is performed at the temperature in the range of 40°C and 180°C.

5. The process according to claim 4, wherein the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc is performed at the temperature in the range of 85°C and 140°C.

6. The process according to any one of the preceding claims, wherein the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc lasts for a period ranging from 1 to 24 hours.

7. The process according to claim 6, wherein the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc lasts for a period ranging from 1 to 14 hours.

8. The process according to claim 7, wherein the mixing of carboxylic acid having 2 to 25 carbons with an oxide, hydroxide or carbonate of bismuth or zinc lasts for a period ranging from 2 to 6 hours.

9. The process according to any one of the preceding claims, wherein the process is performed under a nitrogen flow.

10. The process according to any one of the preceding claims, wherein the carboxylic acid having 2 to 25 carbons is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, 9-hexadecenoic acid, cis-9- octadecenoic acid, 11 -octadecenoic acid, cis, cis-9,12-octadecadienoic acid, 9,12,15- octadecatrienoic acid, 6,9,12-octadecatrienoic acid, 9,11,13-octadecatrienoic acid, eicosanoic acid, 8,11-eicosadienoic acid, 5,8,11-eicosatrienoic acid, 5,8,11,14-eicosatetraenoic acid, tung oil acid, linseed oil acid, soybean oil acid, resin acid, tall oil fatty acid, rosin acid, abietic acid, neoabietic acid, palustric acid, pimaric acid, dehydroabietic acid, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, 2-ethylhexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, isononanoic acid, decanoic acid, neodecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid and naphthenic acid.

11. The process according to claim 10, wherein the carboxylic acid having 2 to 25 carbons is selected from the group consisting of hexanoic acid, 2-ethylhexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, isononanoic acid, decanoic acid and neodecanoic acid.

12. The process according to claim 11, wherein the carboxylic acid having 2 to 25 carbons is neodecanoic acid.

13. The process according to any one of the preceding claims, wherein the aliphatic carboxylic acid having 2 to 5 carbons is selected from the group consisting of propionic acid, acetic acid, butanoic and pentanoic acid.

14. The process according to claim 13, wherein the aliphatic carboxylic acid having 2 to 5 carbons is propionic acid or acetic acid.

15. The process according to any one of the preceding claims, wherein the boric acid ester is selected from the group consisting of trimethyl borate, triethyl borate, tripropyl borate and tributyl borate.

16. The process according to any one of the preceding claims, wherein the addition of the boric acid esters can be continuous for a period in the range of 0,5 to 6 hours.

17. The process according to any one of the preceding claims, wherein the addition of the boric acid esters can be continuous for a period in the range of 1 to 2 hours.

18. The process according to any one of the preceding claims, wherein the addition of the boric acid ester is performed at the temperature in the range of 120°C and 180°C.

19. Use of bismuth boron carboxylate, zinc boron carboxylate or its combination as polyurethane catalyst.

20. Use according to claim 19 in coatings, adhesives, sealants, elastomers, flexible foams and rigid foams.

21. Use according to claim 19 or 20, wherein bismuth boron carboxylate or zinc boron carboxylate has a viscosity in the range of 1 to 500 cP.

22. Use according to claim 21, wherein bismuth boron carboxylate or zinc boron carboxylate has a viscosity in the range of 5 to 300 cP.

23. Use according to any one of the claims 19 to 22, wherein bismuth boron carboxylate or zinc boron carboxylate is obtained by the process according to any one of the claims 1 to 18.

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