A kind of water-resistant refrigeration oil and preparation method thereof

Abstract

The invention relates to the technical field of refrigeration oil, in particular to a water-resistant refrigeration oil and a preparation method thereof, which solves the problem that water is mixed into the refrigeration oil during heat exchange, causing ester group hydrolysis, thereby causing damage to machinery and equipment and poor refrigeration effect. The refrigeration oil comprises 30-50 parts of mineral oil, 50-80 parts of synthetic oil and 4-8 parts of repair additives by weight; the synthetic oil comprises: a water-resistant composite ester prepared by esterification reaction of a C4-C9 straight-chain or branched fatty acid and propanol, amyl alcohol or heptanol with site-symmetrical branches; the repair additive comprises 2-3 parts of a modified 4A molecular sieve, 5-8 parts of a modified aluminum silicate and 0.5-3 parts of carbodiimide by weight; the refrigeration oil of the invention has greater tolerance to water, stronger hydrolysis resistance and good refrigeration effect.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration oil, and in particular to a water-resistant refrigeration oil and a preparation method thereof. Background Art

[0002] Refrigeration oil is a special oil for refrigeration equipment. It is not only used to lubricate the external working parts of the refrigeration equipment, but also used in the compressor and pipelines of the refrigeration device to lubricate the moving parts of the compressor, thereby reducing wear and avoiding obstruction of the operation of the compressor. It also has the function of reducing frictional heat and cleaning the friction surface.

[0003] However, in addition to refrigeration oil, the compressor also contains refrigerant. Since the refrigeration system is a heat exchange system, after the water molecules in the air come into contact with the refrigerant during the heat exchange process, the moisture in the air condenses and mixes into the refrigerant and refrigeration oil, which not only reduces the viscosity of the refrigeration oil, resulting in poor lubrication effect, but also causes the water to be dispersed in the oil in the form of extremely small water particles due to long-term friction work, forming a very finely dispersed suspended state of water, which is difficult to remove.

[0004] The presence of water can cause electrochemical corrosion. Water combines with the hydrophilic ester groups in the engine oil to form alcohols and organic acids that are corrosive to the metal surface, causing the organic acids to corrode the metal. The refrigeration system needs to exchange heat with the air. The oxygen in the air first dissolves in the water film during the electrochemical corrosion process. The water film acts as an electrolyte solution. The anode metal loses electrons, and the oxygen dissolved in the water film on the cathode gains electrons to form hydroxyl groups, thereby forming metal hydroxides. The high-molecular organic acids in the refrigeration oil will not directly corrode the metal at low temperatures, but the salts and water generated by reacting with the metal hydroxides will cause indirect corrosion to the metal.

[0005] When Freon refrigerant meets water, hydrochloric acid and hydrofluoric acid will be produced. The specific reaction formula is as follows:

[0006] 2H2O+CF2CL2→2HCL+2HF+CO2

[0007] The hydrofluoric acid thus formed causes unevenly distributed pitting of the metal surface, resulting in significant mechanical damage.

[0008] Regarding this problem, in a refrigeration oil with application publication number CN201680042676.4, pentaerythritol is used with specific fatty acids to form specific complex esters, thereby improving the compatibility between the refrigerant and the refrigeration oil, and solving the problem of incompatibility between the refrigeration oil and difluoromethane refrigerant. However, the problem of hydrolysis of its ester group has not been improved, and hydrolysis reaction will occur in a microenvironment with water to produce organic acid; in a mineral oil-type refrigeration oil composition with authorization announcement number CN114317073B, paraffin-based mineral oil and cycloalkyl mineral oil are used to balance the relationship between viscosity and pour point, thereby solving the problem of insufficient kinematic viscosity at lower temperatures. However, with the increase of water content in the refrigeration oil and the use of Freon refrigerant, the "ice plug" phenomenon will inevitably occur, forming residues that affect the lubrication of components, and thus causing damage to the system using the refrigeration oil. Summary of the Invention

[0009] In order to solve the problem that water intrudes into refrigeration oil during heat exchange, causing ester hydrolysis, and the resulting organic acid and alcohol, under the electrochemical action, cause damage and corrosion to the compressor or other metal surfaces, resulting in refrigerant decomposition and affecting the refrigeration effect, the present invention adopts the following technical solutions, the specific solutions are as follows:

[0010] First, the present application provides a water-resistant refrigeration oil, which comprises 30-50 parts by weight of mineral oil, 50-80 parts by weight of synthetic oil, and 4-8 parts by weight of a repair additive;

[0011] The synthetic oil comprises: a water-resistant composite ester prepared by esterification of a C4-C9 straight-chain or branched fatty acid with a site-symmetrical branched propanol, pentanol or heptanol;

[0012] The repair additive consists of 2-3 parts of modified 4A molecular sieve, 5-8 parts of modified aluminum silicate and 0.5-3 parts of carbodiimide in parts by weight.

[0013] The water-resistant refrigeration oil of the present application is compounded by selecting mineral oil and synthetic oil of different components. The mineral oil used is obtained by petroleum cracking and does not contain substances such as polyol esters or polyethylene glycol in conventional synthetic oils. Mineral oil naturally has a good water-isolating effect, is not easy to absorb water, and has a high initial resistance to the intrusion of water. The water-resistant composite ester used in the synthetic oil of the present application is formed by esterification of fatty acids with propanol, pentanol or heptanol with site-symmetrical branches, and has strong resistance to ester hydrolysis caused by water intrusion into the refrigeration oil.

[0014] In the process of synthesizing water-resistant composite esters, the present application uses an alcohol containing a side group structure. After the esterification reaction, the presence of the side group makes it difficult to form an intermediate in the hydrolysis process, thereby hindering the progress of hydrolysis; the hydrolysis of the ester bond is the reverse reaction of the esterification reaction, and will promote the progress of hydrolysis in an acidic or alkaline environment; when water and oxygen are mixed in the engine oil, electrochemical corrosion will occur with the metal surface to form hydroxyl groups. The nucleophilic ion hydroxyl group, in the form of a nucleophilic reagent, first forms a tetrahedral anion intermediate with the carbon atom on the carbonyl group. This intermediate is extremely unstable and then decomposes into carboxylic acid and alcohol. Therefore, preventing the formation of tetrahedral anion intermediates is an important means to effectively prevent ester hydrolysis.

[0015] This application also uses a repair additive in the refrigeration oil to absorb water between the complex ester molecules. The 4A grade molecular sieve used can effectively attract and absorb water molecules. The 4A micropores will not adsorb substances such as mineral oil or synthetic oil, but will absorb small molecules of water, reducing the contact and hydrolysis of water on the complex ester and other mineral oils. Modified aluminum silicate is added to repair the metal corrosion that has occurred, and it will settle on the wall of the corrosion depression and act on the damaged area, thereby forming a repair.

[0016] Furthermore, the pentanol or heptanol with site-symmetrical branching is one of 2,2-dimethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, and 2,6-dihydroxymethyl-1,7-heptanediol.

[0017] The propylene glycol used in this application has two methyl side chains on the second carbon atom, which can inhibit the formation of tetrahedral anion intermediates, and the hydroxyl groups on the carbon atoms at both ends of pentanediol will also be affected by the ethyl groups at positions 2 and 4, thereby reducing the occurrence of hydrolysis. The hydroxymethyl groups at positions 2 and 6 on heptanediol are close to the hydroxyl groups at positions 1 and 7. Therefore, after the ester group is formed, the respective carbonyl groups and fatty acid chains have greater steric hindrance, making the complex ester not easily hydrolyzed and having strong water resistance.

[0018] Furthermore, the C4-C9 straight-chain or branched fatty acid is one of succinic acid, 2-methylbutyric acid, 3-methylbutyric acid, 2,2,6,6-tetramethylpimelic acid, 3-ethylheptanoic acid, octanoic acid, 3-methyloctanoic acid, 4-methyloctanoic acid, 5-methyloctanoic acid, 6-methyloctanoic acid, adipic acid, and suberic acid.

[0019] Furthermore, the preparation method of the modified 4A molecular sieve comprises the following steps:

[0020] S1. Grind the spherical 4A molecular sieve using a jet mill to obtain 4A molecular sieve powder;

[0021] S2, preparing a nonionic surfactant glyceryl monooleate and 4A molecular sieve powder and mechanically ball milling and mixing them;

[0022] S3. After ball milling, a modified 4A molecular sieve is obtained, and the modified 4A molecular sieve is placed in mineral oil and homogenized at a high speed for later use. The homogenization speed is 9000-10000 r / min and the time is 20 min.

[0023] The present application uses monoolein to mechanically modify the 4A molecular sieve, which can largely retain the active sites of the molecular sieve without destroying the molecular sieve's ability to form hydrogen bonds. After modification with monoolein, the 4A molecular sieve has excellent dispersibility, thereby absorbing water molecules in the oil without affecting the lubricity of the refrigeration oil. Monoolein can also reduce the friction coefficient between the 4A molecular sieve and the inner wall of the refrigeration device, preventing the 4A molecular sieve as a hard material from causing damage to the mechanical device.

[0024] Furthermore, the particle size of the modified 4A molecular sieve is ≤10 μm.

[0025] Furthermore, the mass ratio of monoolein to 4A molecular sieve powder in S2 is 1:50-60, the ball milling speed is 500-700 r / min, the ball-to-material mass ratio of the ball milling is 80:1, and the ball milling time is 12 h.

[0026] Furthermore, the modification method of the modified aluminum silicate comprises the following steps:

[0027] 1 part of aluminum silicate raw material, 2 parts of magnesium stearate and 1 part of paraffin wax were put into a ball mill by weight, and mechanically ground at a speed of 100 r / min for 60 minutes to obtain modified aluminum silicate.

[0028] By modifying the aluminum silicate material with magnesium stearate and paraffin, the phase properties of the aluminum silicate material in the refrigeration oil are changed, so that it can flow better in the refrigeration oil and will not agglomerate to affect the performance of the refrigeration oil. It is also easier for the aluminum silicate material to be used as a repair material to repair and restore the corroded parts.

[0029] After modification, the modified 4A molecular sieve and the modified aluminum silicate are both connected with long-chain alkyl groups, which facilitates the formation of grid-covering links at the damaged parts of the metal surface. The multiple long-chain alkyl groups on the surfaces of the 4A molecular sieve and the aluminum silicate particles are interlaced at the damaged grooves. Then, carbodiimide is compounded to prevent the long-chain alkyl groups on the surfaces of the 4A molecular sieve and the aluminum silicate particles from being affected by small molecules of water and hydrolyzed, thereby avoiding the long-chain alkyl groups from leaving the 4A molecular sieve and the aluminum silicate particles. The presence of carbodiimide can also combine with unreacted organic carboxylic acid groups, and the two carboxyl groups remove a molecule of water to form amide and urea, thereby reducing the acid value, further preventing corrosion, and improving the repair effect of the metal surface.

[0030] Furthermore, the ratio of the total molar number of carboxyl groups of the fatty acid to the total molar number of hydroxyl groups of the propanol, pentanol or heptanol is 1.15-1.35:1.

[0031] The water-resistant refrigeration oil of the present application can be applied to refrigeration compression devices.

[0032] On the other hand, the present application also provides a method for preparing water-resistant refrigeration oil, the preparation method comprising the following steps:

[0033] Step 1: Preparation of synthetic oil: fatty acids and corresponding alcohols are placed in a reaction kettle, stirred, and heated to 130-180°C; a catalyst is added, and the temperature is continued to rise to 180-200°C until the acid value is less than 10 mgKOH / g to obtain synthetic oil;

[0034] Step 2: Mix and stir the synthetic oil, mineral oil and repair additive at a temperature of 170-220°C for 40-60 minutes, and filter to obtain a water-resistant refrigeration oil. The viscosity of the refrigeration oil composition is 20-30 mm 2 / s.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present application adopts a compound of synthetic motor oil and mineral motor oil, which not only has a strong water-isolating ability to prevent the mixing of water molecules, but also utilizes a special alcohol molecular structure to form a large steric hindrance by virtue of the side chain groups on the alcohol molecular chain, thereby preventing the formation of tetrahedral negative ion intermediates and having a strong resistance to hydrolysis. Therefore, it will not produce organic acids and alcohols, will not cause corrosion to the metal surface of mechanical equipment, and will not produce particulate impurities, thereby improving the quality of the refrigeration oil and the refrigeration effect.

[0037] 2. The present invention uses a repair additive in the refrigeration oil to further absorb the moisture in the refrigeration oil, thereby reducing the contact between water molecules and ester groups, and performing minor repairs and isolation on corrosion gaps or other gaps on the mechanical surface;

[0038] 4A molecular sieve is used in the repair additive. Relying on its 4A-level micropores, it can adsorb water molecules. The unique small micropores will not adsorb other carbon chains and substances except water molecules, thereby further enhancing the refrigeration oil's tolerance to water. Before being added to the refrigeration oil, the 4A molecular sieve is also modified with monoolein, so that the molecular sieve will not agglomerate in the oil composed of complex esters and has good dispersibility. After modification, after deposition near the repair area, the modified groups not only facilitate the formation of a protective film at the damaged area, but also can provide targeted protection against further erosion by water molecules and organic acids. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a line graph showing the acid value changes of the embodiments of the present invention and the comparative example. DETAILED DESCRIPTION

[0040] The following will refer to the attached Figure 1 The embodiments of the present invention are described in detail. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0041] The catalyst is tetraethoxy zirconium or tetrabutyl titanate, with a concentration of 20 ppm;

[0042] Preparation Example 1

[0043] Preparation of synthetic oil:

[0044] 47 parts by weight of 2,4-diethyl-1,5-pentanediol and 53 parts by weight of adipic acid were added to a reactor, nitrogen was introduced, the temperature was raised to 150° C., tetrabutyl titanate was added and reacted for 2 hours, and then the temperature was raised to 180° C. and kept warm until the acid value was less than 10 mgKOH / g, and the unreacted matter was removed by distillation;

[0045] Preparation of modified 4A molecular sieve:

[0046] The commercially available LAT-FZS-4A spherical 4A molecular sieve (alkali metal aluminosilicate) was crushed by weight using a jet mill to obtain a molecular sieve powder with a particle size of 6-10 μm; a nonionic surfactant, glyceryl monooleate, and the molecular sieve powder were prepared and ball-milled in a weight ratio of 1:55, the ball milling speed was 600 r / min, the ball-to-material mass ratio was 80:1, and the ball milling time was 12 h; after ball milling, a modified 4A molecular sieve was obtained, and the modified 4A molecular sieve was placed in mineral oil and stirred at high speed for homogenization and then set aside. The homogenization speed was 10000 r / min and the time was 20 min.

[0047] Preparation of modified aluminum silicate:

[0048] According to weight, 1 part of aluminum silicate raw material, 2 parts of magnesium stearate and 1 part of paraffin were put into a ball mill and mechanically ground at a speed of 100 r / min for 60 minutes to obtain modified aluminum silicate.

[0049] Preparation Example 2

[0050] Preparation of synthetic oil:

[0051] 30 parts by weight of 2,2-dimethyl-1,3-propanediol and 70 parts by weight of 2-methylbutyric acid were added to a reactor, nitrogen was introduced, the temperature was raised to 130° C., tetrabutyl titanate was added and reacted for 2 hours, and then the temperature was raised to 190° C. and kept warm until the acid value was less than 10 mgKOH / g, and the unreacted matter was removed by distillation;

[0052] Preparation of modified 4A molecular sieve:

[0053] The commercially available LAT-FZS-4A spherical 4A molecular sieve (alkali metal aluminosilicate) was crushed by weight using a jet mill to obtain a molecular sieve powder with a particle size of 6-10 μm; a nonionic surfactant, glyceryl monooleate, and the molecular sieve powder were prepared and ball-milled in a weight ratio of 1:50, the ball milling speed was 500 r / min, the ball-to-material mass ratio was 80:1, and the ball milling time was 12 h; after ball milling, a modified 4A molecular sieve was obtained, and the modified 4A molecular sieve was placed in mineral oil and stirred at a high speed for homogenization and then set aside. The homogenization speed was 9000 r / min and the time was 20 min.

[0054] Preparation of modified aluminum silicate:

[0055] According to weight, 1 part of aluminum silicate raw material, 2 parts of magnesium stearate and 1 part of paraffin were put into a ball mill and mechanically ground at a speed of 100 r / min for 60 minutes to obtain modified aluminum silicate.

[0056] Preparation Example 3

[0057] Preparation of synthetic oil:

[0058] 16 parts by weight of 2,6-dihydroxymethyl-1,7-heptanediol and 84 parts by weight of 4-methyloctanoic acid were added to a reaction kettle, nitrogen was introduced, the temperature was raised to 180° C., tetraethoxyzirconium was added and reacted for 2 hours, then the temperature was raised to 200° C. and kept warm until the acid value was less than 10 mgKOH / g, and the unreacted matter was removed by distillation;

[0059] Preparation of modified 4A molecular sieve:

[0060] The commercially available LAT-FZS-4A spherical 4A molecular sieve (alkali metal aluminosilicate) was crushed by weight using a jet mill to obtain a molecular sieve powder with a particle size of 6-10 μm; a nonionic surfactant, glyceryl monooleate, and the molecular sieve powder were prepared and ball-milled at a weight ratio of 1:60, the ball milling speed was 550 r / min, the ball-to-material mass ratio was 80:1, and the ball milling time was 12 h; after ball milling, a modified 4A molecular sieve was obtained, and the modified 4A molecular sieve was placed in mineral oil and stirred at high speed for homogenization before use. The homogenization speed was 9500 r / min and the time was 20 min.

[0061] Preparation of modified aluminum silicate:

[0062] According to weight, 1 part of aluminum silicate raw material, 2 parts of magnesium stearate and 1 part of paraffin were put into a ball mill and mechanically ground at a speed of 100 r / min for 60 minutes to obtain modified aluminum silicate.

[0063] Comparative Preparation Example 1

[0064] The difference between this comparative preparation example and Preparation Example 1 lies in the preparation of the synthetic oil, and the specific differences are as follows:

[0065] Preparation of synthetic oil:

[0066] 44 parts by weight of 1,5-pentanediol and 56 parts by weight of 4-methyloctanoic acid were added to a reactor, nitrogen was introduced, the temperature was raised to 180°C, tetrabutyl titanate was added and the reaction was carried out for 2 hours, then the temperature was raised to 200°C and kept warm until the acid value was less than 10 mgKOH / g, and the unreacted matter was removed by distillation.

[0067] The remaining steps are the same as those in Preparation Example 1.

[0068] Comparative Preparation Example 2

[0069] The difference between this comparative preparation example and Preparation Example 2 lies in the preparation of the synthetic oil, and the specific differences are as follows:

[0070] Preparation of synthetic oil:

[0071] 32 parts by weight of 1,3-propylene glycol and 68 parts by weight of 2-methylbutyric acid were added to a reactor, nitrogen was introduced, the temperature was raised to 180°C, tetrabutyl titanate was added and the reaction was carried out for 2 hours, then the temperature was raised to 200°C and kept warm until the acid value was less than 10 mgKOH / g, and the unreacted matter was removed by distillation.

[0072] The remaining steps are the same as those in Preparation Example 2.

[0073] Comparative Preparation Example 3

[0074] The difference between this comparative preparation example and preparation example 1 lies in the preparation of the modified 4A molecular sieve in the repair additive. The specific differences are as follows:

[0075] Preparation of modified 4A molecular sieve:

[0076] The commercially available LAT-FZS-4A spherical 4A molecular sieve (alkali metal aluminosilicate) was crushed by weight using a jet mill to obtain a molecular sieve powder with a particle size of 6-10 μm; a 10% concentration of sodium hydroxide solution and the molecular sieve powder were ball-milled at a weight ratio of 1:55, the ball milling speed was 600 r / min, the ball-to-material mass ratio was 80:1, and the ball milling time was 12 h; after ball milling, a modified 4A molecular sieve was obtained, and the modified 4A molecular sieve was placed in mineral oil and stirred at high speed for homogenization and then set aside. The homogenization speed was 10000 r / min and the time was 20 min.

[0077] The remaining steps are the same as those in Preparation Example 1.

[0078] Comparative Preparation Example 4

[0079] The difference between this comparative preparation example and preparation example 1 is that 4A molecular sieve is not used. The specific differences are as follows:

[0080] Preparation of modified materials to replace 4A molecular sieve:

[0081] The activated carbon was crushed by weight using a jet mill to obtain activated carbon powder with a particle size of 3-10 μm; a nonionic surfactant, glyceryl monooleate, and activated carbon powder were prepared and ball-milled in a weight ratio of 1:55, the ball-milling speed was 600 r / min, the ball-to-material mass ratio was 80:1, and the ball-milling time was 12 h; after ball milling, modified activated carbon powder was obtained, and the modified activated carbon powder was placed in mineral oil and stirred at a high speed for homogenization, and then set aside. The homogenization speed was 10,000 r / min and the time was 20 min.

[0082] The remaining steps are the same as those in Preparation Example 1.

[0083] Example 1

[0084] Preparation of a refrigeration oil: The synthetic oil prepared in Preparation Example 1, modified 4A molecular sieve and modified aluminum silicate were added according to parts by weight to prepare the refrigeration oil.

[0085] The specific components of this embodiment are: 40 parts of mineral oil, 70 parts of synthetic oil and 5 parts of repair additive.

[0086] Based on 5 parts by weight of the repair additive, 1.5 parts of the modified molecular sieve are placed in mineral oil and homogenized in a ratio of 10 parts of mineral oil for every 1.5 parts of the modified molecular sieve, and then 3 parts of modified aluminum silicate and 0.5 parts of carbodiimide are mixed therein to finally obtain 15 parts by weight of the repair additive mixed oil.

[0087] By weight, 30 parts of mineral oil, 70 parts of synthetic oil and 15 parts of repair additive mixed oil were mixed, heated to 200 ° C, stirred for 50 minutes, cooled to room temperature and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 27mm 2 / s water-resistant refrigeration oil.

[0088] Example 2

[0089] Preparation of a refrigeration oil: The synthetic oil prepared in Preparation Example 2, modified 4A molecular sieve and modified aluminum silicate were added according to parts by weight to prepare the refrigeration oil.

[0090] The specific components of this embodiment are: 30 parts of mineral oil, 50 parts of synthetic oil and 4 parts of repair additive.

[0091] Based on 4 parts by weight of the repair additive, 1.1 parts of modified molecular sieves are placed in mineral oil for homogenization at a ratio of 10 parts of mineral oil for every 1.1 parts of modified molecular sieves. Then, 2.6 parts of modified aluminum silicate and 0.3 parts of carbodiimide are mixed therein to finally obtain 14 parts by weight of the repair additive mixed oil.

[0092] By weight, 20 parts of mineral oil, 50 parts of synthetic oil and 14 parts of repair additive mixed oil were mixed, heated to 170 ° C, stirred for 40 minutes, cooled to room temperature, and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 24mm 2 / s water-resistant refrigeration oil.

[0093] Example 3

[0094] Preparation of a refrigeration oil: The synthetic oil prepared in Preparation Example 3, modified 4A molecular sieve and modified aluminum silicate were used to prepare refrigeration oil according to parts by weight.

[0095] The specific components of this embodiment are: 50 parts of mineral oil, 80 parts of synthetic oil and 8 parts of repair additive.

[0096] Based on 8 parts by weight of the repair additive, 1.8 parts of modified molecular sieves are placed in mineral oil for homogenization at a ratio of 10 parts of mineral oil for every 1.8 parts of modified molecular sieves. Then, 4.5 parts of modified aluminum silicate and 1.7 parts of carbodiimide are mixed therein to finally obtain 18 parts by weight of the repair additive mixed oil.

[0097] By weight, 40 parts of mineral oil, 80 parts of synthetic oil and 18 parts of repair additive mixed oil were mixed, heated to 220 ° C, stirred for 60 minutes, cooled to room temperature, and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 28mm 2 / s water-resistant refrigeration oil.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 1 is that the synthetic oil prepared in Comparative Preparation Example 1, the modified 4A molecular sieve and the modified aluminum silicate are used to prepare the refrigeration oil.

[0100] The specific components of this comparative example are: 40 parts of mineral oil, 70 parts of synthetic oil and 5 parts of repair additive.

[0101] Based on 5 parts by weight of the repair additive, 1.5 parts of modified molecular sieve are placed in mineral oil for homogeneous dispersion at a ratio of 10 parts of mineral oil for every 1.5 parts of modified molecular sieve, and then 3 parts of modified aluminum silicate and 0.5 parts of carbodiimide are mixed therein to finally obtain 15 parts by weight of the repair additive mixed oil.

[0102] By weight, 30 parts of mineral oil, 70 parts of synthetic oil and 15 parts of repair additive mixed oil were mixed, heated to 210 ° C, stirred for 45 minutes, cooled to room temperature and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 32mm 2 / s water-resistant refrigeration oil.

[0103] Comparative Example 2

[0104] The difference between this comparative example and Example 1 is that the synthetic oil prepared in Comparative Preparation Example 2, the modified 4A molecular sieve and the modified aluminum silicate are used to prepare the refrigeration oil.

[0105] The specific components of this comparative example are: 40 parts of mineral oil, 70 parts of synthetic oil and 5 parts of repair additive.

[0106] Based on 5 parts by weight of the repair additive, 1.5 parts of the modified molecular sieve are placed in mineral oil and homogenized in a ratio of 10 parts of mineral oil for every 1.5 parts of the modified molecular sieve, and then 3 parts of modified aluminum silicate and 0.5 parts of carbodiimide are mixed therein to finally obtain 15 parts by weight of the repair additive mixed oil.

[0107] By weight, 30 parts of mineral oil, 65 parts of synthetic oil and 15 parts of repair additive mixed oil were mixed, heated to 220 ° C, stirred for 40 minutes, cooled to room temperature, and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 35mm 2 / s water-resistant refrigeration oil.

[0108] Comparative Example 3

[0109] The difference between this comparative example and Example 1 is that the synthetic oil prepared in Comparative Preparation Example 3, the modified 4A molecular sieve and the modified aluminum silicate are used to prepare the refrigeration oil.

[0110] The specific components of this comparative example are: 40 parts of mineral oil, 70 parts of synthetic oil and 5 parts of repair additive.

[0111] Based on 5 parts by weight of the repair additive, 1.5 parts of the modified molecular sieve are placed in mineral oil and homogenized in a ratio of 10 parts of mineral oil for every 1.5 parts of the modified molecular sieve, and then 3 parts of modified aluminum silicate and 0.5 parts of carbodiimide are mixed therein to finally obtain 15 parts by weight of the repair additive mixed oil.

[0112] By weight, 30 parts of mineral oil, 65 parts of synthetic oil and 15 parts of repair additive mixed oil were mixed, heated to 200 ° C, stirred for 50 minutes, cooled to room temperature and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 35mm 2 / s water-resistant refrigeration oil.

[0113] Comparative Example 4

[0114] The difference between this comparative example and Example 1 is that the synthetic oil prepared in Comparative Preparation Example 3, the modified 4A molecular sieve and the modified aluminum silicate are used to prepare the refrigeration oil.

[0115] The specific components of this comparative example are: 40 parts of mineral oil, 70 parts of synthetic oil and 5 parts of repair additive.

[0116] Based on 5 parts by weight of the repair additive, 1.5 parts by weight of modified activated carbon powder are placed in mineral oil and homogenized in a ratio of 10 parts of mineral oil for every 1.5 parts of modified molecular sieve, and then 3 parts of modified aluminum silicate and 0.5 parts of carbodiimide are mixed therein to finally obtain 15 parts by weight of the repair additive mixed oil.

[0117] By weight, 30 parts of mineral oil, 65 parts of synthetic oil and 15 parts of repair additive mixed oil were mixed, heated to 170 ° C, stirred for 60 minutes, cooled to room temperature, and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 32mm 2 / s water-resistant refrigeration oil.

[0118] Comparative Example 5

[0119] The difference between this comparative example and Example 1 is that no carbodiimide is added to the repair additive. The specific differences are as follows:

[0120] This comparative example uses the synthetic oil prepared in Preparation Example 1, modified 4A molecular sieve, and modified aluminum silicate.

[0121] The specific components are: 40 parts mineral oil, 70 parts synthetic oil and 5 parts repair additives.

[0122] Based on 5 parts by weight of the repair additive, 1.5 parts of the modified molecular sieve are placed in mineral oil for homogenization at a ratio of 10 parts of mineral oil for every 1.5 parts of the modified molecular sieve, and then 3.5 parts of modified aluminum silicate are mixed therein to finally obtain 15 parts by weight of the repair additive mixed oil.

[0123] By weight, 30 parts of mineral oil, 70 parts of synthetic oil and 15 parts of repair additive mixed oil were mixed, heated to 200 ° C, stirred for 50 minutes, cooled to room temperature and filtered using synthetic fiber filter cloth and activated carbon filter element to obtain a viscosity of 27mm 2 / s water-resistant refrigeration oil.

[0124] Experiments and data

[0125] The water-resistant cooling oils prepared in Examples 1, 2, and 3 and Comparative Examples 1, 2, 3, 4, and 5 were subjected to component wear resistance tests and water resistance tests, respectively. The test standards are as follows:

[0126] The wear resistance test method is carried out in accordance with the standard of SH / T0203;

[0127] The water resistance test method is tested in accordance with the standard of GB / T 3142--2019;

[0128] The test method is as follows:

[0129] Refrigeration oil was mixed with water for shear emulsification, with the water content adjusted to 2000ppm. The upper test piece was then subjected to friction against the blade in a sealed container at 120°C, a load of 1500N, and a rotation speed of 820rpm for 1 hour. The acid value and wear value were then measured.

[0130] The test data are shown in Table 1 and Table 2 below:

[0131] Table 1

[0132]

[0133] Table 2

[0134]

[0135]

[0136] The acid values ​​of the water-resistant engine oils of Examples 1-3 and Comparative Examples 1-4 are plotted as a line graph. Figure 1 shown.

[0137] analyze

[0138] According to the data in Table 1 and Table 2, the changes in the acid values ​​of Example 1, Example 2, and Example 3 before and after the test are all less than 0.15 mgKOH / g, which are relatively low acid values. In the presence of 2000 ppm of water, acidolysis is less, and the wear on the blade and the upper test piece is also low. The lubrication performance is good, and the wear spot diameter and maximum no-seizure load data of the steel ball are both good.

[0139] The experimental data of Comparative Examples 1 and 2 show that when 1,5-pentanediol and 1,3-propylene glycol are used to prepare water-resistant composite esters, there is no branching on the carbon atom closest to the ester group, and the acid value changes greatly before and after the test, both of which are higher than the safety value of 0.15, proving that the composite ester in the synthetic oil undergoes significant hydrolysis. A larger acid value easily causes mechanical corrosion. The refrigeration oils of Comparative Examples 1 and 2 have a smaller increase in the amount of wear on the blades and the upper test piece, and the steel ball wear spot diameter and the maximum no-seizure load are both lower than those of Examples 1, 2, and 3. Therefore, continued hydrolysis after long-term use will cause greater damage.

[0140] It can be seen from the experimental data of Comparative Example 3 that the surface hydroxyl group modification using sodium hydroxide has a low acid value variation, which proves that the water resistance is good and the degree of hydrolysis is low. The wear amount is the largest compared with Examples 1-3 and Comparative Examples 1 and 2, which proves that the lubrication effect on the damaged area in the wear test is poor and the wear damage is large. The molecular sieve as a hard particle has a greater effect on the scratching of the metal surface, and the steel ball wear spot diameter and the maximum no-seizure load are also the worst compared with Examples 1-3 and Comparative Examples 1 and 2, which proves that the monoolein modification of the molecular sieve has better lubrication and dispersion effects.

[0141] From the experimental data of Comparative Example 4, it can be seen that the use of activated carbon to replace the molecular sieve has little effect on the acid value, but its wear amount is large, second only to Comparative Example 3, which proves that the damage at the damaged part in the wear test is large, and the diameter of the steel ball wear spot is larger than that of Comparative Example 3, which proves that its wear effect is poor but not as great as the damage of aluminum silicate. Its maximum no-seizure load is better than that of Comparative Example 3, which proves that the lubrication effect of activated carbon is better than that of hydroxyl-modified molecular sieve, but its lubricity is poorer than that of the embodiment.

[0142] The experimental data of Comparative Example 5 shows that its wear amount is low, and the diameter of the steel ball wear spot and the maximum no-seizure load are also greatly improved, which proves that its lubrication effect and repair effect have been improved to a certain extent. However, after testing, its acid value increase is greater than that of Comparative Example 3 and Comparative Example 4, and exceeds the safety value of 0.15 mgKOH / g. Long-term use may damage the mechanical surface. Therefore, adding a small amount of carbodiimide can effectively improve the problem of excessive acid value of the repair additive itself due to repair cross-linking, and has a strong improvement effect, preventing unreacted organic acid radicals from further damaging the metal surface.

[0143] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A water-resistant refrigeration oil, characterized in that: The refrigeration oil comprises, by weight, 30-50 parts of mineral oil, 50-80 parts of synthetic oil and 4-8 parts of repair additives; The synthetic oil comprises: a water-resistant composite ester prepared by esterification reaction of a C4-C9 straight-chain or branched fatty acid and a polyol with site-symmetrical branches; The repair additive is composed of 2-3 parts of modified 4A molecular sieve, 5-8 parts of modified aluminum silicate and 0.5-3 parts of carbodiimide in parts by weight; The preparation method of the modified 4A molecular sieve is as follows: S1, pulverizing the spherical 4A molecular sieve using a jet mill to obtain 4A molecular sieve powder; S2, preparing nonionic surfactant glyceryl monooleate and 4A molecular sieve powder for mechanical ball milling and mixing; S3, after ball milling, a modified 4A molecular sieve is obtained, and the modified 4A molecular sieve is placed in mineral oil and stirred at a high speed for use, wherein the speed of the homogenization is 9000-10000 r / min, and the time is 20 min; The modification method steps of the modified aluminum silicate are as follows: 1 part of aluminum silicate raw material, 2 parts of magnesium stearate and 1 part of paraffin wax were put into a ball mill by weight, and mechanically ground at a speed of 100 r / min for 60 min to obtain modified aluminum silicate; The polyol with site-symmetrical branching is one of 2,2-dimethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol and 2,6-dihydroxymethyl-1,7-heptanediol.

2. A water-resistant refrigeration oil according to claim 1, characterized in that: The C4-C9 straight-chain or branched fatty acid is one of succinic acid, 2-methylbutyric acid, 3-methylbutyric acid, 2,2,6,6-tetramethylpimelic acid, 3-ethylheptanoic acid, octanoic acid, 3-methyloctanoic acid, 4-methyloctanoic acid, 5-methyloctanoic acid, 6-methyloctanoic acid, adipic acid, and suberic acid.

3. The water-resistant refrigeration oil according to claim 1, characterized in that: The particle size of the modified 4A molecular sieve is ≤10 μm.

4. The water-resistant refrigeration oil according to claim 1, characterized in that: The mass ratio of monoolein and 4A molecular sieve powder in S2 is 1:50-60, the ball milling speed is 500-700r / min, the ball-to-material mass ratio of the ball mill is 80:1, and the ball milling time is 12h.

5. The water-resistant refrigeration oil according to claim 1, characterized in that: The ratio of the total molar number of carboxyl groups of the fatty acid to the total molar number of hydroxyl groups of the polyol is 1.15-1.35:

1.

6. Use of the water-resistant refrigeration oil according to any one of claims 1 to 5 in a refrigeration compression device.

7. The method for preparing a water-resistant refrigeration oil according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: Step 1: Preparation of synthetic oil: placing fatty acids and corresponding alcohols in a reaction kettle, stirring and heating to 130-180°C; adding a catalyst, and continuing to heat to 180-200°C until the acid value is less than 10 mgKOH / g to obtain synthetic oil; Step 2: Mix and stir the synthetic oil, mineral oil and repair additive at a temperature of 170-220°C for 40-60 minutes, and filter to obtain a water-resistant refrigeration oil. The viscosity of the refrigeration oil composition is 20-30 mm 2 / s.

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