Production of plant-based triglyceride-based isocyanate (izooleocyanate)

Abstract

The invention relates to a method of producing plant-based isocyanates (izooleocyanates) from waste materials starting from plant or animal triglycerides, which are renewable resources.

Description

[0001] PRODUCTION OF PLANT-BASED TRIGLYCERIDE-BASED ISOCYANATE (IZOOLEOCYANATE)

[0002] Technical Field

[0003] The invention relates to a method of producing plant-based isocyanates (izooleocyanates) from waste materials starting from plant or animal triglycerides, which are renewable resources.

[0004] State of the Art

[0005] Polyurethanes are polymers carrying groups referred to as urethane or carbamate (-0- C(=O)-NH-). Polyurethanes are synthesized by condensation reaction and are obtained by the reaction of two components called diol (or polyol) and diisocyanate (or polyisocyanate). Here, hydroxyl groups (-OH) in the diol combine with isocyanate groups (-N=C=O) to transform into urethane groups (-O-C(=O)-NH-). Because of their flexibility and sturdiness, polyurethanes have industrial applications in various fields, from health to the construction industry.

[0006] Polyurethanes can be solid materials or viscous liquids referred to as casting resins, which can be either dual-component or single-component. As mentioned above, the synthesis of polyurethanes generally requires two raw materials, polyisocyanate and polyol. Nowadays, although polyurethane production can be done through blocked isocyanates or cyclic carbonates, these are still new techniques and not common in the technical field.

[0007] In the synthesis of isocyanates, an amine is generally obtained first, and then these amines react with phosgene gas to form isocyanates. Currently, isocyanates such as HDI (hexamethylene diisocyanate), MDI (methylene diphenyl diisocyanate), TDI (toluene diisocyanate), and IDI (isophorone di isocyanate), which can be easily accessed in large quantities, are used in the synthesis of polyurethane. The production of these materials includes processes that involve nitration, reduction of nitro compounds to amines, and then the formation of isocyanates using phosgene. However, these methods are dangerous and not eco-friendly. The polyol component contains at least two hydroxyl groups. Polyol components can be small simple molecules such as ethylene glycol, propylene glycol, or they can be structures attached to a long polymeric chain. These structures are usually referred to as polyester polyamide polyol, polyester polyol, etc. It is possible to synthesize specific types of polyol according to their applications. In bio-based polyurethanes, plant or animal-based polyols are generally used as bio sources. These polyols are mostly obtained by epoxidation of plant-based triglycerides and the reaction of the resulting epoxy oil with a suitable organic acid, for example, formic acid, acetic acid, etc. The structure of a plant-based triglyceride is given below.

[0008] Plant-based triglyceride

[0009] The structure of an epoxidized triglyceride is given below.

[0010] Epoxidized plant-based triglyceride

[0011] Acid radical

[0012] Plant based polyol

[0013] The general structure of plant-based polyols obtained from epoxy oils reacting with carboxylic acids is given below. The methods in the state of the art for synthesizing isocyanates (especially the synthesis methods of aromatic-based isocyanates) can be summarized briefly as follows: • Nitration of aromatic compounds (at this stage, dinitro compound is obtained),

[0014] • Obtaining aromatic amines with the help of reducers such as iron, zinc, or tin that can be easily found or act like these substances depending on production conditions,

[0015] • Obtaining isocyanates as a result of the reaction of the obtained aromatic amines with phosgene.

[0016] Apart from these methods, isocyanates can also be synthesized by the reaction of acid chlorides with sodium azide. However, the most practical industrial method is the reaction of amine compounds with phosgene gas. Phosgene gas was used as a poisonous gas in wars in the past and is a very dangerous chemical.

[0017] Brief Description of the Invention:

[0018] The present invention is related to the production of plant-based triglyceride isocyanates (isooleocyanates), eliminating all disadvantages, fulfilling the requirements mentioned above, and bringing some additional advantages.

[0019] The main objective of the invention is to synthesize and produce plant-based isocyanates (isooleocyanates) from waste materials starting from renewable sources such as plantbased or animal triglycerides.

[0020] The use of petroleum-based isocyanates and their preparation with conventional methods, which are not environmentally friendly, can be seen as a disadvantage. However, the evaluation of waste materials and the use of relatively low amounts of diisocyanates in obtaining polyisocyanates can be considered as an advantage. For example, approximately 65 units of diisocyanate (as MDI) are required to obtain 150 units of plant-based polyisocyanate (isooleocyanate). From this perspective, less petroleum-based diisocyanate is required for the production of plant-based polyisocyanates. Therefore, plant-based polyisocyanates are relatively more eco-friendly materials.

[0021] The structural and characteristic features of the invention and all its advantages will be more clearly understood thanks to the detailed description given below, and therefore the evaluation should be made considering this detailed description.

[0022] Detailed Description of the Invention:

[0023] In this detailed description, preferred configurations of the invention are explained solely for a better understanding of the topic. The invention relates to a method for obtaining various isocyanates (isooleocyanates) starting from waste oils, which are renewable sources. In the method of the subject invention, first, epoxides obtained from waste oils are reacted with natural acids such as acetic, lactic, and oleic to obtain polyols. The obtained polyols are then reacted with diisocyanate in suitable stoichiometry (at least twice the number of -OH groups) to obtain polyisocyanates (isooleocyanates). The reactions involved in the mentioned synthesis method are given below.

[0024] Synthesis of the plant based polyisocyanate

[0025] Examples related to the process steps constituting the production of plant-based triglyceride-based isocyanate (isooleocyanate) within the scope of the invention are given below. These examples are provided as examples of the application and effectiveness of the invention without any restrictive meaning.

[0026] Example 1. Epoxidation of Waste Oils

[0027] 5 kilograms of waste oil with an iodine index of 100 or above is added to a 25-liter reactor. (If the iodine index of the waste oil is below 100, oils with high unsaturation are added to complete it to at least 100). 10 liters of dichloromethane is added, and the mixture is cooled (between 0-5°C). The mixture is homogenized. 2.4 kg of formic acid is added, and the mixture is stirred for another half hour. At the end of this period, 1.8 kg of 50% hydrogen peroxide is slowly added to the mixture. The mixture is left to be stirred in the reactor overnight. Then, the mixture is taken to separators and washed 4 times with a suitable amount of distilled water. Then, the water is removed from the epoxidized waste oil, and it is used in the next steps without further purification.

[0028] 10 kg of epoxidized soy oil (ESO) is put into a 25- 1 iter reactor. 2 kg of acetic acid is added, and it is refluxed at 130°C for at least 8 hours. At the end of the period, the acidity of the obtained product is checked; the product with an acid amount close to 0 is used in the next steps. If acid residue remains in the medium, the product is vacuumed to remove the residual acid. The obtained product is used in the next steps without further purification.

[0029] 8 liters of tetrahydrofuran and 7.7 kg of methylene diphenyl diisocyanate (MDI) are put into a 25-liter reactor. The mixture is stirred until it is homogeneous. Nitrogen gas is passed through the system during this time. The temperature of the homogeneous mixture is raised to 60°C. Then, slowly, 11 .32 kg of polyol from Example 2 is added, and the addition process is completed in approximately 3 hours. The system is kept at this temperature for 4 more hours. Then, the solvent in the medium is removed by distillation.

[0030] 8 liters of tetrahydrofuran and 5.1 kg of hexamethylene diisocyanate (HMDI) are put into a 25-liter reactor. The mixture is stirred until homogeneous. Nitrogen gas is passed through the system during this time. The temperature of the homogeneous mixture is raised to 60°C. Then, slowly, 11.32 kg of polyol from Example 2 is added, and the addition process is completed in approximately 3 hours. The system is kept at this temperature for 4 more hours. Then, the solvent in the medium is removed by distillation.

Claims

AMENDED CLAIMS received by the International Bureau on 05 February 2024 (05.02.2024)1. A method for the production of plant-based isocyanate (isoleucine), characterized by:• The reaction involving the opening of the rings of epoxidized vegetable oils obtained from waste oils and the reaction of polyols, obtained through this reaction, with diisocyanate in an amount at least 2 to 3 times the quantity of the -OH group they possess, resulting in at least 50% of the mass being plantbased isocyanate (isoleucine) derived from renewable sources.

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