PL249352B1 - Plastic grease composition and method of producing it - Google Patents

Abstract

The subject of the invention is a plastic grease composition comprising: a base oil selected from mineral oil derived from the distillation of crude oil, paraffin oil, naphthenic oil, recycled oil, hydrocarbon oil containing lubricating oils, synthetic oil and mixtures thereof; a soap-type thickener of the formula R-Me, where R is derived from a hydroxy acid, a hydroxy acid ester containing 9-36 carbon atoms or mixtures thereof, and Me is calcium; a polyurea polymer thickener; characterized in that the polyurea polymer thickener present in an amount of 1-5 wt. is represented by the formula (R'-NH-CO-NH-Ar-NH-CO-NH-R")_n, where: R' comes from a primary amine containing 12-18 carbon atoms, R" comes from an aliphatic or aromatic diamine containing 2-16 carbon atoms, Ar is an aromatic hydrocarbon containing 6-20 carbon atoms, n is between 2 and 20. Another subject of the invention is a method for producing a plastic grease composition according to the invention, characterized in that it comprises the following steps: a. base oil is introduced into a reactor equipped with a stirrer at a temperature of about 15-40°C; b. then a primary amine with 12-18 carbon atoms and a secondary amine with 2-6 carbon atoms are added to the base oil in a molar ratio of 2:1 and heated under stirring to 40-70°C until a homogeneous mixture of amines is obtained; c. then a diisocyanate is added under normal pressure in a molar ratio of diisocyanate: primary amine: secondary amine of 2:2:1; d. after mixing, a hydroxy acid or hydroxy acid ester containing 9-36 carbon atoms, or a mixture thereof, is added in an amount of 4-6% based on the total weight of the lubricant composition and after it is dissolved in the polymer, a mixture of lime in base oil is added under normal pressure; e. the reactor is heated until the temperature inside the reactor is in the range of 100-120°C; f. after dehydration, base oil is added to the reactor in an amount of 25-30% based on the total weight of the lubricant composition and heated to 110-130°C until the reactor contents are thickened; g. after thickening is achieved, the mixture is cooled with base oil in an amount of 30-40% based on the total weight of the lubricant composition; h. optionally, additives are added to the obtained grease; i. the obtained grease is homogenized and deaerated.

Description

Description of the invention

The invention relates to a lubricating grease composition and a method for its production. The lubricating grease according to the invention is a multi-purpose grease that can be used, in particular, for all types of bearings, furnace chains, and joints, and in any case as a replacement for lubricating oil in the temperature range from -40 to 200°C.

The state of the art includes known solutions for the production of silicone greases, which envisage the use of the following components: methylsiloxane and phenylmethylsiloxane oils, polyalphaolefin oils, diphenyl ethers, perfluorinated alkyl polyethers and mineral oils, organic and inorganic thickeners such as polyureas, metallic salts of fatty acids, colloidal silica and additives: aromatic amines, phosphoric esters, benzotriazole derivatives and solid lubricants such as colloidal graphite and zinc diethyldithiocarbamate.

The plastic grease based on renewable dispersing phases disclosed in Polish patent description PL199440B1 is characterized in that it contains from 8 to 25% by weight of lithium 12-hydroxystearate and from 75 to 92% by weight of a triglyceride of higher fatty acids, preferably a natural oil with the following properties: iodine value in the range of 80-150 mgJ2/100 g, preferably from 108 to 138 mgJ2/100 g, kinematic viscosity at 40°C in the range of 25.0 ^mm2 /s to 50.0 ^mm2 /s, preferably 30 to 40 ^mm2 /s, viscosity index from 160 to 250, preferably from 190 to 240 and pour point from -25°C to 0°C, preferably from -17°C to 0°C.

The invention described in publication PL/EP3268455 T3 relates to a method for producing solid lubricants based on lignin derivatives, thickened with a polyurea thickener, the solid lubricants thus produced and the use of such solid lubricants, among others, in gears, synchronous joint shafts and sealed rolling bearings.

Polyurea lubricants are disclosed in numerous patent applications, including EP0435745A1, EP0508115A1, EP0558099A1 and EP0661378A1.

The constant velocity joint grease composition described in EP0508115A1 comprises a base oil containing a thickener and boron nitride powders and optionally an organozinc compound. The thickener used may be a soap-type thickener or a polyurea thickener.

Additionally, European application EP3613832A1 describes a plastic grease and a method for its production, which comprises a polyurea/high-base calcium sulfonate composite thickener, colloidally dispersed solid particles of calcium carbonate in the form of calcite, a calcium borate composite or calcium borate, and a calcium soap of a fatty acid having 12 to 24 carbon atoms. The above components are uniformly dispersed in an oil phase medium.

US application No. US5084193A discloses a grease with improved dropping point and shear stability, containing polyurea and calcium soap, particularly derived from 12-hydroxystearic acid. It is worth noting that the polyurea used in the cited patent document is diurea produced under pressure and in an autoclave in the presence of water, which is detrimental to the isocyanate group, as water deactivates the isocyanate precursors of polyurea. The grease composition according to the cited US application No. US5084193A does not use tetraurea as a polyurea polymer thickener. Furthermore, the grease production technology itself is complex, and the total percentage of thickeners (polyurea and soap) is very high, exceeding 10%.

The goal of the invention was to develop a grease composition that retains lubricating properties at temperatures above 180°C, while also replacing the widespread use of lithium soap in greases due to the limited supply of lithium hydroxide (used in the production of automotive fuel cells). The goal was to reduce manufacturing costs and CO2 emissions. The goal was to obtain a grease as simply as possible, with a dropping point significantly above 200°C, good shear strength, limited thixotropy, mechanical stability, corrosion resistance, and good performance in the Brinell test. It also offered a positive economic benefit compared to lithium greases, which have dropping points below 200°C and therefore can be used below 130°C. Additionally, the developed technology allows for the in-situ production of various greases with different dropping points depending on the polymer content.

The subject of the invention is a plastic grease composition containing:

- a base oil selected from mineral oil derived from the distillation of crude oil, paraffin oil, naphthenic oil, recycled oil, hydrocarbon oil containing lubricating oils, synthetic oil and mixtures thereof;

- a soap-type thickener with the formula R-Me, where R comes from a hydroxy acid, a hydroxy acid ester containing 9-36 carbon atoms or mixtures thereof, and Me means calcium,

- polyurea polymer thickener;

is characterized in that the polyurea polymer thickener present in the amount of 1-5% by weight is represented by the formula (R'-NH-CO-NH-Ar-NH-CO-NH-R)n, where:

R' comes from a primary amine containing 12-18 carbon atoms,

R comes from an aliphatic or aromatic diamine containing 2-16 carbon atoms,

Ar is an aromatic hydrocarbon containing 6-20 carbon atoms, n is between 2 and 20.

Preferably, R is derived from 12-hydroxystearic acid, hydrogenated ricinoleic acid, a fatty acid of animal or vegetable origin containing from 9 to 36 carbon atoms, salicylic acid, hydroxybenzenesulfonic acid.

Preferably, R' is derived from a primary amine selected from the group consisting of primary amines of animal origin with 12-18 carbon atoms and a primary amine of plant origin C18H37N.

Preferably, the aliphatic diamine is ethylenediamine.

Preferably the molar ratio of base oil: soap type thickener: polyurea polymer type thickener is 2:1:2.

Furthermore, the lubricating grease composition according to the invention preferably additionally contains additives selected from the group consisting of: anti-corrosion, antioxidant, anti-aging, anti-wear, friction-reducing and high pressure resistance improving agents.

Another subject of the invention is a method for producing a plastic grease composition according to the invention, characterized in that it comprises the following steps:

a. a base oil selected from mineral oil derived from the distillation of crude oil, paraffin oil, naphthenic oil, recycled oil, hydrocarbon oil containing lubricating oils, synthetic oil and mixtures thereof is introduced into a reactor equipped with a stirrer at a temperature of 15-40°C;

b. then a primary amine with 12-18 carbon atoms and a secondary amine with 2-6 carbon atoms are added to the base oil in a molar ratio of 2:1 and heated to 40-70°C while stirring to obtain a homogeneous mixture of amines;

c. then diisocyanate is added under normal pressure in a molar ratio of diisocyanate: primary amine: secondary amine of 2:2:1;

d. after mixing, a hydroxy acid or hydroxy acid ester containing 9-36 carbon atoms, or a mixture thereof, is added in an amount of 4-6% based on the total weight of the lubricant composition and after its dissolution in the polymer, a mixture of lime in the base oil is added under normal pressure;

e. the reactor is heated until the temperature inside the reactor is in the range of 100-120°C;

f. after dehydration, base oil is added to the reactor in an amount of 25-30% based on the total weight of the lubricant composition and heated to 110-130°C until the reactor contents are thickened;

g. after achieving thickening, the mixture is cooled with base oil in an amount of 30-40% based on the total weight of the lubricant composition;

h. optionally, additives selected from the group including: anti-corrosion, antioxidant, anti-aging, anti-wear, friction-reducing and high-pressure resistance agents are added to the obtained grease;

i. the obtained grease is homogenized and deaerated.

Preferably, the diisocyanate is selected from the group consisting of toluene diisocyanate and diphenylmethylene 4,4'-diisocyanate.

Preferably, the hydroxy acid or ester of a hydroxy acid containing from 9 to 36 carbon atoms is selected from the group consisting of 12-hydroxystearic acid, hydrogenated ricinoleic acid, a fatty acid of animal or vegetable origin containing from 9 to 36 carbon atoms, salicylic acid, hydroxybenzenesulfonic acid.

Preferably, the primary amine is selected from the group consisting of primary amines of animal origin with 12-18 carbon atoms and a primary amine of plant origin C18H37N.

Furthermore, preferably the aliphatic diamine is ethylenediamine.

The advantage of the lubricating grease composition according to the invention is the reduction of the total thickener content to 7 to 9% while maintaining the desired properties and parameters of the grease. Furthermore, the developed production method involves the preparation of both the polyurea-type thickener and the soap-type thickener in situ at a lower temperature (110°C) and under normal atmospheric pressure conditions, without the need for increased pressure or the use of an autoclave. This makes the developed technology for producing the lubricating grease composition according to the invention significantly cheaper and less complicated than methods previously known in the art. The production of the lubricating grease composition according to the invention is carried out in conventional equipment without any additional modifications; only a mixer with a heating jacket and a frame agitator are required.

The plastic grease obtained by the method according to the invention has a dropping point according to ASTM above 250°C and is miscible in all proportions with other greases without changing the characteristics or side effects.

Examples of execution

Example 1

Production of 1 ton of plastic grease

300 kg of naphthenic base oil with a viscosity of 1.0x10-4 ^m2 /s at 40°C is fed into a reactor equipped with a frame mixer.

Then the following are added to the oil in the following molar proportions:

- primary amine of animal origin with 12-18 carbon atoms 23.2 kg

- secondary amine - ethylenediamine 99.9% 2.4 kg

While stirring, the reactor contents are heated to 60-70°C to obtain a homogeneous mixture of amines. Toluene diisocyanate (TDI) (14.4 kg) is then added.

The reaction takes place instantly under normal pressure.

After mixing, 40 kg of 12-hydroxystearic acid (12 HSA) is added and after it has dissolved in the polymer, a mixture of 6 kg of lime in 40 kg of naphthenic base oil with a viscosity of 1.0x10-4 ^m2 /s at 40°C is added.

The reactor is heated to reach an internal temperature of 100-120°C.

The saponification reaction takes place under normal pressure with the release of water.

After dewatering, 250 kg of base oil with a viscosity of 1.0x10'4 ^m2 /s at 40°C is added to the reactor and heated to 110-130°C until the reactor contents are concentrated.

After achieving thickening, the mixture is cooled with 300 kg of base oil with a viscosity of 1.0x10'4 ^m2 /s at 40°C.

The following additives are added to the obtained grease:

- anticorrosive - type sorbitol monooleate 10 kg

- antioxidant - phenolic type or alpha-naphthylamine 15 kg

- anti-wear - type zinc dialkyldithiophosphate (ZDDP) 5 kg

The resulting grease is homogenized and deaerated.

The resulting grease has the following characteristics:

- Penetration (according to ASTM D217 after 60 cycles in mm/10) 270-290

- Dropping point (according to ASTM D2265) 260°C

- Oil separation (according to SDM 433 after 24 h at 100°C) 1.2%

- Faux Brinell Effect 2.5 mg

Example 2

Production of 1 ton - Grease produced on the basis of synthetic oil type PAO (polyalphaolefin)

300 kg of synthetic oil (PAO) with a kinematic viscosity of 6.6x10' ⁵ m ² /s at 40°C is introduced into the reactor equipped with a frame mixer.

Then, as in example 1, we add to the oil a mixture of amines and toluene diisocyanate in molar proportions of 2:1:2, i.e.: primary amine of animal origin 23.2 kg, secondary amine - ethylenediamine 2.4 kg and toluene diisocyanate 14.4 kg.

The reaction takes place immediately and under normal pressure.

After obtaining the tetraurea polymer, we add 40 kg of 12-hydroxystearic acid (12 HSA) to this mixture and after it has dissolved at a temperature of about 60-70°C, a mixture of 6 kg of lime in 40 kg of PAO is added.

The reactor is heated to an internal temperature of 100-120°C. The saponification reaction occurs under normal pressure, with the release of water. After dehydration, 250 kg of PAO is added to the reactor and the reactor is heated to 110-120°C until the mixture in the reactor thickens.

The mixture is then cooled with 300 kg of PAO. Additives are added to the precipitated grease:

- anticorrosive - sorbitan monooleate 10 kg - Antioxidant - phenolic or amine type (alpha-naphthylamine) 15 kg - anti-wear - zinc dialkyldithiophosphate (ZDDP) 5 kg

The grease thus obtained is subjected to homogenization and deaeration, resulting in the following characteristics:

- NLGI consistency* 2 - Penetration (ASTM D217 after 60 cycles in mm/10) 270-290 - Dropping point (aStM D2265) minimum 250°C - Mechanical stability after 100,000 cycles mm/10 +30 points - Lifespan at 160 °C (according to ASTM D 3527-95) 80 h - Oil separation (according to SDM 433 after 24 hours at 100°C) 1-1.5% - EMCOR** corrosion 0-0 - * Brinell Effect (SNR 50 h test) 2.5 mg The NLGI (National Lubricating Grease Institute) classification divides greases into classes based on consistency: class 000 is the most fluid grease, while class 6 is very hard grease. ** The Emcor test method is used to determine the corrosion resistance of greases using grease-lubricated ball bearings under dynamic wet conditions. The results are graded as follows: 0 - no corrosion; 1 - no more than three corrosion spots, none larger than 1 mm in diameter; 2 - small areas of corrosion covering 1 percent of the surface; 3 - areas of corrosion covering 1 to 5 percent of the surface; 4 - areas of corrosion covering 5 to 10 percent of the surface; 5 - areas of corrosion covering more than 10 percent of the surface than the corrosion marks.

Example 3

Production of 1 ton of naphthenic mineral base oil 1.1x10 ^-4 m ² /s at 40°C

The following are introduced into the reactor equipped with a frame mixer as in examples 1 and 2 in molar proportions:

- base oil 1.0x10 ^{-4 m2} /s at 40°C 300 kg

- primary amine of plant origin C18H37N with a purity of 89% in the amount of 26 kg

- secondary amine ethylenediamine of 100% purity in the amount of 2.3 kg

While stirring, the reactor contents are heated to 60-70°C to obtain a homogeneous mixture of amines in the following proportions (9% primary amine and 91% secondary amine).

Then 14.70 kg of toluene 2,4-diisocyanate (TDI) is added.

The reaction takes place immediately under normal pressure.

After mixing and obtaining the tetraurea polymer, 40 kg of 12-hydroxystearic acid (12 HSA) is added and after it has been dissolved in the mixture of polymer with base oil, a mixture of 6 kg of lime in 40 kg of base oil is added.

The reactor is heated to an internal temperature of 100-120°C.

The saponification reaction takes place under normal pressure with the release of water.

After dehydration, 250 kg of base oil is added to the reactor and heated to 110-130°C until the reactor contents are concentrated.

After thickening the mixture, we cool the contents with 300 kg of base oil. We add the following additives to the resulting grease:

- anticorrosive - sorbitol monooleate 10 kg

- antioxidant - phenolic or amine type (alpha-naphthylamine) 15 kg

- anti-wear - type zinc dialkyldithiophosphate (ZDDP) 5 kg

The resulting grease is homogenized and deaerated.

The grease has the following characteristics:

- Consistency according to NLGI 2

- Penetration (according to ASTM D217 after 60 cycles in mm/10) 270-280

- Dropping point (per ASTM D566) - Oil separation (per SDM 433 after 24 hours at 100°C) - Faux Brinell effect - EMCOR corrosion - Mechanical stability after 100,000 cycles in mm/10 - Life at 160°C (per ASTM D 3527-95) - Shell Roller Test 100 hours at 66°C Example 4 Production of 1 ton of grease with reduced polymer content minimum 250°C 1-1.5% 2.5 mg 0-0 +30-40 points 80 h 2 g

To the reactor as in example 1, 2, 3 up to 300 kg of naphthenic base oil - 1.0x10'4 m ² /s at 40°C are introduced successively in molar proportions of 2:1:2:

- Primary amine of animal origin - Secondary amine ethylenediamine - Toluene diisocyanate (TDI) The reaction occurs immediately and under normal pressure. 11.6 kg 1.2 kg 7.2 kg

60 kg of 12-hydroxystearic acid (12 HSA) is added to the obtained tetraurea polymer and then a mixture of 9 kg of lime in 50 kg of base oil is added.

The reactor is heated as in Example 1 under normal pressure. The reaction proceeds with the release of water.

After dehydration, we add 250 kg of base oil to the reactor and heat it to 110-120°C until the mixture thickens in the reactor.

The mixture is then cooled with 300 kg of base oil.

We add refining additives such as:

- Anti-corrosion - sorbitan monooleate - Antioxidant - phenolic or amine type (alpha-naphthylamine) - Anti-wear - zinc dialkyldithiophosphate type (ZDDP) 10 kg 15 kg 5 kg

The obtained grease is homogenized and deaerated, as a result of which the resulting grease has the following characteristics:

- Penetration (according to ASTM D217 after 60 cycles in mm/10) - Dropping point (according to ASTM D566) - Oil separation (according to SDM 433 after 24 hours at 100°C) 275 205°C 1.2%

The effect of the reduced amount of tetraurea polymer is a significant drop in the dropping point.

Example 5 - Production of 1 ton of tetraurea grease and calcium soap hydrogenated castor oil

As in the previous examples, up to 300 kg of naphthenic base oil with a viscosity of 1.0x10 ^-4 m ² /s is introduced into the reactor at 40°C in the following molar proportions:

- primary amine of animal origin in the amount of 23.2 kg

- secondary amine ethylenediamine 2.4 kg

- toluene diisocyanate (TDI) 14.4 kg

After obtaining the tetraurea polymer as in the previous examples, 50 kg of hydrogenated castor oil is added to its mixture and after dissolving it at 70°C, a mixture of 8 kg of lime in 40 kg of base oil is introduced.

The contents of the reactor are heated to a temperature of 100-120°C.

After the saponification reaction is complete, add 250 kg of base oil and continue heating the reactor to 100-120°C until the mixture thickens.

The mixture is then cooled with 300 kg of base oil.

As in the previous production examples, refining additives are added:

- anticorrosive - sorbitol monooleate 10 kg

- antioxidant - phenolic or amine type (alpha-naphthylamine) 15 kg

- anti-wear - type zinc dialkyldithiophosphate (ZDDP) 5 kg

The resulting grease is homogenized and deaerated.

The produced grease has the following characteristics:

- penetration (according to ASTM D217 after 60 cycles in mm/10) 275

- dropping point (according to ASTM D566) 265°C

- oil separation (according to SDM 433 after 24 h at 100°C) 1.2%

Example 6

Production of 1 ton of plastic grease based on tetraurea with MDI - 4,4'-diphenylmethylene diisocyanate

In the reactor, in 300 kg of naphthenic mineral base oil with a viscosity of 1.0x10'4 m ² /s at 40°C we add successively in molar proportions of 2:1:2:

- primary amine of animal origin 22.4 kg

- secondary amine - ethylenediamine 2.4 kg

- 4,4'-diphenylmethylene diisocyanate (MDI) 20 kg

The reaction takes place at a temperature of 60-70°C under normal pressure.

After obtaining tetraurea, we add 40 kg of 12-hydroxystearic acid and after it has dissolved, we add a mixture of 6 kg of lime in 40 kg of base oil, heating the reactor to a temperature of 100-120°C.

After the saponification reaction and the separation of water and the addition of 250 kg of base oil, the mixture is further heated until the reactor contents thicken and cooled with 300 kg of base oil.

Then we add refining additives as in the previous examples:

- anticorrosive - sorbitol monooleate 10 kg

- antioxidant - phenolic or amine type (alpha-naphthylamine) 15 kg

- anti-wear - type zinc dialkyldithiophosphate (ZDDP) 5 kg and grease are homogenized and deaerated.

The resulting grease has the following characteristics:

- penetration (according to ASTM D217 after 60 cycles in mm/10) 258

- dropping point (according to ASTM D566) 258°C

- oil separation (according to SDM 433 after 24 h at 100°C) 1.4%

- EMCOR0-0 corrosion

The plastic grease according to the invention is a multi-purpose grease that can be used in any case where the use of other agents such as oil is impossible in the temperature range from -40°C to 200°C.

Claims (11)

Patent claims 1. A plastic grease composition comprising: - a base oil selected from mineral oil derived from the distillation of crude oil, paraffin oil, naphthenic oil, recycled oil, hydrocarbon oil containing lubricating oils, synthetic oil and mixtures thereof; - a soap-type thickener with the formula R-Me, where R comes from a hydroxy acid, a hydroxy acid ester containing 9-36 carbon atoms or mixtures thereof, and Me means calcium, - polyurea polymer thickener; characterized in that the polyurea polymer thickener present in an amount of 1-5% by weight is represented by the formula (R'-NH-CO-NH-Ar-NH-CO-NH-R)n, where: R' comes from a primary amine containing 12-18 carbon atoms, R comes from an aliphatic or aromatic diamine containing 2-16 carbon atoms, Ar is an aromatic hydrocarbon containing 6-20 carbon atoms, n is between 2 and 20. 2. A plastic grease composition according to claim 1, characterized in that R is derived from 12-hydroxystearic acid, hydrogenated ricinoleic acid, a fatty acid of animal or vegetable origin containing from 9 to 36 carbon atoms, salicylic acid, hydroxybenzenesulfonic acid. 3. A grease composition according to claim 1, characterized in that R' is derived from a primary amine selected from the group consisting of primary amines of animal origin with 12-18 carbon atoms and a primary amine of plant origin C18H37N. 4. The lubricating grease composition of claim 1, wherein the aliphatic diamine is ethylenediamine. 5. A lubricating grease composition according to claim 1, characterized in that the molar ratio of base oil: soap-type thickener: polyurea polymer-type thickener is 2:1:2. 6. A plastic grease composition according to any one of claims 1 to 5, characterized in that it additionally contains additives selected from the group consisting of: anti-corrosion, antioxidant, anti-aging, anti-wear, friction-reducing and high-pressure resistance improving agents. 7. A method for producing a lubricating grease composition according to any one of claims 1 to 6, characterized in that it comprises the following steps: a. a base oil selected from mineral oil derived from the distillation of crude oil, paraffin oil, naphthenic oil, recycled oil, hydrocarbon oil containing lubricating oils, synthetic oil and mixtures thereof is introduced into a reactor equipped with a stirrer at a temperature of 15-40°C; b. then a primary amine with 12-18 carbon atoms and a secondary amine with 2-6 carbon atoms are added to the base oil in a molar ratio of 2:1 and heated to 40-70°C while stirring to obtain a homogeneous mixture of amines; c. then diisocyanate is added under normal pressure in a molar ratio of diisocyanate: primary amine: secondary amine of 2:2:1; d. after mixing, a hydroxy acid or hydroxy acid ester containing 9-36 carbon atoms, or a mixture thereof, is added in an amount of 4-6% based on the total weight of the lubricant composition and after its dissolution in the polymer, a mixture of lime in the base oil is added under normal pressure; e. the reactor is heated until the temperature inside the reactor is in the range of 100-120°C; f. after dehydration, base oil is added to the reactor in an amount of 25-30% based on the total weight of the lubricant composition and heated to 110-130°C until the reactor contents are thickened; g. after achieving thickening, the mixture is cooled with base oil in an amount of 30-40% based on the total weight of the lubricant composition; h. optionally, additives selected from the group including: anti-corrosion, antioxidant, anti-aging, anti-wear, friction-reducing and high-pressure resistance agents are added to the obtained grease; i. the obtained grease is homogenized and deaerated. 8. The method according to claim 7, characterized in that the diisocyanate is selected from the group consisting of toluene diisocyanate and diphenylmethylene 4,4'-diisocyanate. 9. The method according to claim 7, characterized in that the hydroxy acid or ester of a hydroxy acid containing from 9 to 36 carbon atoms is selected from the group consisting of 12-hydroxystearic acid, hydrogenated ricinoleic acid, a fatty acid of animal or vegetable origin containing from 9 to 36 carbon atoms, salicylic acid, hydroxybenzenesulfonic acid. 10. The method according to claim 7, characterized in that the primary amine is selected from the group consisting of primary amines of animal origin with 12-18 carbon atoms and a primary amine of plant origin C18H37N. 11. The method according to claim 7, characterized in that the aliphatic diamine is ethylenediamine.