Anti-corrosion defoaming agent and preparation method thereof

Abstract

The invention relates to an anti-corrosion defoaming agent and a preparation method thereof, and belongs to the technical field of high polymer materials. The corrosion-resistant defoaming agent is prepared from the following components in parts by weight: 90 to 120 parts of polyethylene glycol 6000 distearate, 120 to 150 parts of ethylenediamine polyoxyethylene polyoxypropylene ether, 2 to 5 parts of a high-temperature-resistant modifier, 1 to 4 parts of a dispersing agent, 1 to 4 parts of a penetrating agent, 20 to 35 parts of an emulsifier, 5 to 8 parts of a stabilizer, 2 to 5 parts of an antioxidant and 30 to 50 parts of water, the corrosion-resistant defoaming agent prepared by the preparation method disclosed by the invention not only has good high-temperature-resistant and defoaming effects, but also has excellent corrosion-resistant and aging-resistant effects.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an anti-corrosion defoamer and its preparation method. Background Technology

[0002] Defoamers can reduce the surface tension of water, solutions, suspensions, etc., eliminate and inhibit foam. They have excellent defoaming performance, chemical stability (does not react with the defoaming system), good storage stability, and are green, environmentally friendly, non-toxic, harmless and pollution-free. They are widely used in textiles, food processing, fermentation processes, building materials, papermaking industry, sewage treatment, petrochemicals and machinery processing.

[0003] However, traditional polyether defoamers are prone to thermal decomposition, oxidation, or volatilization at high temperatures, which weakens the intermolecular forces, reduces stability, and causes the active ingredients to become ineffective, greatly limiting their application. High temperatures also accelerate the volatilization and diffusion of polyether molecules, causing the effective ingredients to be lost rapidly and significantly shortening the service life of the defoamer. When high temperature and high pH environment work together, polyether molecules are prone to react with alkaline substances, destroying the hydrophilic group structure and further weakening the defoaming performance. In addition, although anti-corrosion defoamers themselves have a certain degree of corrosion resistance, with the continuous improvement of practical application requirements, their own corrosion resistance is no longer sufficient to meet current needs. Therefore, the development of anti-corrosion defoamers has important practical significance and application value. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an anti-corrosion defoamer and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions: An anti-corrosion defoamer and its preparation method, comprising the following raw materials in parts by weight: 90-120 parts of polyethylene glycol 6000 distearate, 120-150 parts of ethylenediamine polyoxyethylene polyoxypropylene ether, 2-5 parts of high-temperature resistant modifier, 1-4 parts of dispersant, 1-4 parts of penetrant, 20-35 parts of emulsifier, 5-8 parts of stabilizer, 2-5 parts of antioxidant, and 30-50 parts of water; The dispersant is sodium polyacrylate; The penetrant is sodium benzoate; The emulsifier is lecithin; The stabilizer is epoxy glycerol triester; The antioxidant mentioned is butylated hydroxyanisole.

[0006] The high-temperature resistant modifier is prepared by the following method: Step A1: Mix ethanol and 1,3-dimethyl-6-aminourea pyrimidine and stir for 30 min. Then add p-hydroxybenzaldehyde and anhydrous ethanol and mix. Stir at 75 °C for 10 h, cool to room temperature, filter, wash, and vacuum dry at 80 °C for 6 h to obtain the intermediate. Furthermore, the ratio of ethanol, 1,3-dimethyl-6-aminourea pyrimidine, p-hydroxybenzaldehyde, and anhydrous ethanol is 120-150 mL : 0.01-0.04 mol : 0.01-0.04 mol : 120-180 mL; Step A2: Mix allyltrimethoxysilane and ethanol-water solution at 35°C for 10 min, then add intermediate and mix well. React at 75°C for 4-5 h, wash, filter, and vacuum dry at 60°C to obtain the preproduct. Furthermore, the ratio of allyltrimethoxysilane, ethanol-water mixed solution, and intermediate is 0.01-0.04 mol: 120-150 mL: 0.01-0.04 mol, and the volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1. Step A3: Mix toluene, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 2-allyl-4-methylphenol and paraformaldehyde evenly, stir thoroughly, heat to 60°C, and react for 48 hours to obtain the compound. Furthermore, the ratio of toluene, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 2-allyl-4-methylphenol, and paraformaldehyde is 70-130 mL : 0.01-0.04 mol : 0.02-0.08 mol : 0.02-0.16 mol; Step A4: Mix the preproduct, compound and dodecafluoroheptyl methacrylate evenly, stir for 10 min, then add azobisisobutyronitrile, continue stirring for 30 min, react at 70℃ for 3 h, after the reaction is completed, rotary evaporate, vacuum dry at 50℃ for 12 h to obtain the high temperature resistant modifier. Furthermore, the ratio of the preproduct, compound, dodecafluoroheptyl methacrylate, and azobisisobutyronitrile is 0.01-0.04 mol: 0.01-0.04 mol: 0.01-0.04 mol: 2-18 g.

[0007] A method for preparing an anti-corrosion defoamer specifically includes the following steps: S1. Mix polyethylene glycol 6000 distearate and ethylenediamine polyoxyethylene polyoxypropylene ether, heat to 80-95℃, stir for 30 minutes to obtain the mixture. S2. Pre-emulsify the emulsifier in a 70℃ water bath for 15 minutes, then add water, high-temperature modifier, penetrant, dispersant and mixture, mix evenly, adjust pH to 6-7, heat to 75-90℃, add stabilizer and antioxidant and stir for 15 minutes, dehydrate under reduced pressure, filter, and obtain anti-corrosion defoamer.

[0008] The beneficial effects of this invention are: The anti-corrosion defoamer of this invention has good high temperature resistance and defoaming effect, and also has excellent corrosion resistance and aging resistance, further extending its service life.

[0009] The high-temperature resistant modifier prepared in this invention exhibits superior high-temperature resistance performance compared to traditional small-molecule high-temperature resistant modifiers due to the advantages of its macromolecular polymer. First, an intermediate is prepared by reacting the aldehyde group of p-hydroxybenzaldehyde with the amino group of 1,3-dimethyl-6-aminouracil. Next, a preproduct is prepared by reacting the silanol groups generated from the hydrolysis of allyltrimethoxysilane with the hydroxyl groups of the intermediate. Then, under the action of paraformaldehyde, a compound containing a benzoxazine structure is prepared by reacting the hydroxyl groups of 2-allyl-4-methylphenol with the amino group of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane. Finally, the high-temperature resistant modifier is prepared by copolymerizing the preproduct, the compound, and the carbon-carbon double bond of dodecafluoroheptyl methacrylate. In this high-temperature modifier, the nitrogen atom in 1,3-dimethyl-6-aminoureapyrimidine captures alkyl and peroxy radicals generated by the thermal degradation of the defoamer with its lone pair electrons, terminating the chain reaction, delaying the thermo-oxidative aging process, and effectively improving the thermal stability and aging resistance of the defoamer. Furthermore, the benzoxazine structure is a benzohexacyclic compound containing a nitrogen- and oxygen-containing six-membered heterocycle. It has a high glass transition temperature and excellent heat resistance and chemical corrosion resistance. Synergistically, it works with dodecylfluoroheptyl methacrylate to improve the hydrophobicity and oleophobicity of the copolymer, extending its service life. Secondly, the dodecylfluoroheptyl methacrylate molecule contains a large number of fluorine atoms, which shield and protect the main chain, forming a dense fluoride protective layer, effectively reducing the impact of chemical substances on the polymerization process. The erosion of the chain enhances the stability of the defoamer in corrosive media such as acids and alkalis. At the same time, dodecyl fluoroheptyl methacrylate has high chemical stability and is not easily decomposed. The polyfluorine atoms and branched structure in its molecule can enhance the copolymer's resistance to ultraviolet rays and reduce the performance degradation caused by photo-oxidation. In addition, it synergizes with 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane to impart excellent hydrophobic and oleophobic properties. This not only reduces the contact area between the foam surface and the liquid, thus reducing the foam's stability and enhancing the defoaming efficiency of the defoamer, but also prevents corrosive media from adsorbing on the defoamer surface, improving its corrosion resistance, and reducing the adhesion of contaminants such as dust and oil, thus reducing the risk of performance degradation. Detailed Implementation

[0010] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] Example 1: A method for preparing an anti-corrosion defoamer, specifically including the following steps: S1. Weigh the raw materials according to the following parts by weight: 90 parts of polyethylene glycol 6000 distearate, 120 parts of ethylenediamine polyoxyethylene polyoxypropylene ether, 2 parts of high-temperature resistant modifier (prepared in this embodiment), 1 part of dispersant, 1 part of penetrant, 20 parts of emulsifier, 5 parts of stabilizer, 2 parts of antioxidant, and 30 parts of water; mix polyethylene glycol 6000 distearate and ethylenediamine polyoxyethylene polyoxypropylene ether, heat to 80°C, and stir for 30 minutes to obtain the mixture. S2. Lecithin was pre-emulsified in a 70℃ water bath for 15 minutes, then water, high-temperature modifier, sodium benzoate, sodium polyacrylate and other mixtures were added and mixed evenly. The pH was adjusted to 6, and the temperature was raised to 75℃. Then, epoxy glycerol triester and butylated hydroxyanisole were added and stirred for 15 minutes. The mixture was dehydrated under reduced pressure and filtered to obtain an anti-corrosion defoamer. The high-temperature resistant modifier is prepared by the following method: Step A1: Mix 120 mL of ethanol and 0.01 mol of 1,3-dimethyl-6-aminourea pyrimidine and stir for 30 min. Then add 0.01 mol of p-hydroxybenzaldehyde and 120 mL of anhydrous ethanol and mix. Stir at 80 °C for 10 h, cool to room temperature, filter, wash, and vacuum dry at 75 °C for 6 h to obtain the intermediate. Step A2: Mix 0.01 mol allyltrimethoxysilane and 120 mL ethanol-water mixed solution at 35 °C for 10 min, then add 0.01 mol intermediate and mix well. React at 75 °C for 4 h, wash, filter, and vacuum dry at 60 °C to obtain the preproduct. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1. Step A3: Mix 70 mL toluene, 0.01 mol 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 0.02 mol 2-allyl-4-methylphenol and 0.02 mol paraformaldehyde evenly, stir thoroughly, heat to 60 °C, and react for 48 h to obtain the compound; Step A4: Mix 0.01 mol of preproduct, 0.01 mol of compound and 0.01 mol of dodecafluoroheptyl methacrylate evenly, stir for 10 min, then add 2 g of azobisisobutyronitrile, continue stirring for 30 min, react at 70 °C for 3 h, after the reaction is completed, rotary evaporate, vacuum dry at 50 °C for 12 h to obtain the high temperature resistant modifier.

[0012] Example 2: A method for preparing an anti-corrosion defoamer, specifically including the following steps: S1. Weigh the raw materials according to the following parts by weight: 100 parts of polyethylene glycol 6000 distearate, 130 parts of ethylenediamine polyoxyethylene polyoxypropylene ether, 3 parts of high-temperature resistant modifier (prepared in this embodiment), 2 parts of dispersant, 2 parts of penetrant, 25 parts of emulsifier, 6 parts of stabilizer, 3 parts of antioxidant, and 37 parts of water; mix polyethylene glycol 6000 distearate and ethylenediamine polyoxyethylene polyoxypropylene ether, heat to 85°C, and stir for 30 minutes to obtain the mixture. S2. Lecithin was pre-emulsified in a 70℃ water bath for 15 minutes, then water, high-temperature modifier, sodium benzoate, sodium polyacrylate and other mixtures were added and mixed evenly. The pH was adjusted to 6.3, and the temperature was raised to 80℃. Then, epoxy glyceryl triester and butylated hydroxyanisole were added and stirred for 15 minutes. The mixture was dehydrated under reduced pressure and filtered to obtain an anti-corrosion defoamer. The high-temperature resistant modifier is prepared by the following method: Step A1: Mix 130 mL of ethanol and 0.02 mol of 1,3-dimethyl-6-aminourea pyrimidine and stir for 30 min. Then add 0.02 mol of p-hydroxybenzaldehyde and 140 mL of anhydrous ethanol and mix. Stir at 80 °C for 10 h, cool to room temperature, filter, wash, and vacuum dry at 75 °C for 6 h to obtain the intermediate. Step A2: Mix 0.02 mol allyltrimethoxysilane and 130 mL ethanol-water mixed solution at 35 °C for 10 min, then add 0.02 mol intermediate and mix well. React at 75 °C for 4.3 h, wash, filter, and vacuum dry at 60 °C to obtain the preproduct. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1. Step A3: Mix 90 mL of toluene, 0.02 mol of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 0.04 mol of 2-allyl-4-methylphenol and 0.07 mol of paraformaldehyde evenly, stir thoroughly, heat to 60 °C, and react for 48 h to obtain the compound; Step A4: Mix 0.02 mol of preproduct, 0.02 mol of compound and 0.02 mol of dodecafluoroheptyl methacrylate evenly, stir for 10 min, then add 7 g of azobisisobutyronitrile, continue stirring for 30 min, react at 70 °C for 3 h, after the reaction is completed, rotary evaporate, and vacuum dry at 50 °C for 12 h to obtain the high temperature resistant modifier.

[0013] Example 3: A method for preparing an anti-corrosion defoamer, specifically including the following steps: S1. Weigh the raw materials according to the following parts by weight: 110 parts of polyethylene glycol 6000 distearate, 140 parts of ethylenediamine polyoxyethylene polyoxypropylene ether, 4 parts of high-temperature resistant modifier (prepared in this example), 3 parts of dispersant, 3 parts of penetrant, 30 parts of emulsifier, 7 parts of stabilizer, 4 parts of antioxidant, and 44 parts of water; mix polyethylene glycol 6000 distearate and ethylenediamine polyoxyethylene polyoxypropylene ether, heat to 90°C, and stir for 30 minutes to obtain the mixture. S2. Lecithin was pre-emulsified in a 70℃ water bath for 15 minutes, then water, high-temperature modifier, sodium benzoate, sodium polyacrylate and other mixtures were added and mixed evenly. The pH was adjusted to 6.7, and the temperature was raised to 85℃. Then, epoxy glyceryl triester and butylated hydroxyanisole were added and stirred for 15 minutes. The mixture was dehydrated under reduced pressure and filtered to obtain an anti-corrosion defoamer. The high-temperature resistant modifier is prepared by the following method: Step A1: Mix 140 mL of ethanol and 0.03 mol of 1,3-dimethyl-6-aminourea pyrimidine and stir for 30 min. Then add 0.03 mol of p-hydroxybenzaldehyde and 160 mL of anhydrous ethanol and mix. Stir at 80 °C for 10 h, cool to room temperature, filter, wash, and vacuum dry at 75 °C for 6 h to obtain the intermediate. Step A2: Mix 0.03 mol allyltrimethoxysilane and 140 mL ethanol-water mixed solution at 35 °C for 10 min, then add 0.03 mol intermediate and mix well. React at 75 °C for 4.6 h, wash, filter, and vacuum dry at 60 °C to obtain the preproduct. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1. Step A3: Mix 110 mL toluene, 0.03 mol 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 0.06 mol 2-allyl-4-methylphenol and 0.12 mol paraformaldehyde evenly, stir thoroughly, heat to 60 °C, and react for 48 h to obtain the compound; Step A4: Mix 0.03 mol of preproduct, 0.03 mol of compound and 0.03 mol of dodecafluoroheptyl methacrylate evenly, stir for 10 min, then add 12 g of azobisisobutyronitrile, continue stirring for 30 min, react at 70 °C for 3 h, after the reaction is completed, rotary evaporate, and vacuum dry at 50 °C for 12 h to obtain the high temperature resistant modifier.

[0014] Example 4: A method for preparing an anti-corrosion defoamer, specifically including the following steps: S1. Weigh the raw materials according to the following parts by weight: 120 parts of polyethylene glycol 6000 distearate, 150 parts of ethylenediamine polyoxyethylene polyoxypropylene ether, 5 parts of high-temperature resistant modifier (prepared in this example), 4 parts of dispersant, 4 parts of penetrant, 35 parts of emulsifier, 8 parts of stabilizer, 5 parts of antioxidant, and 50 parts of water; mix polyethylene glycol 6000 distearate and ethylenediamine polyoxyethylene polyoxypropylene ether, heat to 95°C, and stir for 30 minutes to obtain the mixture. S2. Lecithin was pre-emulsified in a 70℃ water bath for 15 minutes, then water, high-temperature modifier, sodium benzoate, sodium polyacrylate and other mixtures were added and mixed evenly. The pH was adjusted to 7, and the temperature was raised to 90℃. Then, epoxy glycerol triester and butylated hydroxyanisole were added and stirred for 15 minutes. The mixture was dehydrated under reduced pressure and filtered to obtain an anti-corrosion defoamer. The high-temperature resistant modifier is prepared by the following method: Step A1: Mix 150 mL of ethanol and 0.04 mol of 1,3-dimethyl-6-aminourea pyrimidine and stir for 30 min. Then add 0.04 mol of p-hydroxybenzaldehyde and 180 mL of anhydrous ethanol and mix. Stir at 80 °C for 10 h, cool to room temperature, filter, wash, and vacuum dry at 75 °C for 6 h to obtain the intermediate. Step A2: Mix 0.04 mol allyltrimethoxysilane and 150 mL ethanol-water mixed solution at 35 °C for 10 min, then add 0.04 mol intermediate and mix well. React at 75 °C for 5 h, wash, filter, and vacuum dry at 60 °C to obtain the preproduct. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1. Step A3: Mix 130 mL toluene, 0.04 mol 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 0.08 mol 2-allyl-4-methylphenol and 0.16 mol paraformaldehyde evenly, stir thoroughly, heat to 60 °C, and react for 48 h to obtain the compound; Step A4: Mix 0.04 mol of preproduct, 0.04 mol of compound and 0.04 mol of dodecafluoroheptyl methacrylate evenly, stir for 10 min, then add 18 g of azobisisobutyronitrile, continue stirring for 30 min, react at 70 °C for 3 h, after the reaction is completed, rotary evaporate, vacuum dry at 50 °C for 12 h to obtain the high temperature resistant modifier.

[0015] Comparative Example: This comparative example is an anti-corrosion defoamer. The difference between this example and Example 3 is that an equal amount of alumina is used instead of the high-temperature resistant modifier prepared in Example 3. All other aspects are the same.

[0016] Performance Testing: 20 mL of foaming solution was poured into a 100 mL graduated cylinder and shaken up and down until the foam reached 50 mL. Shaking was stopped, and 20 mg of the anti-corrosion defoamer prepared in Examples 1-4 and the comparative example was added. The time it took for the foam to disappear was recorded, and this time was defined as the defoaming time. Shaking continued, and the time it took for the foam to reach the 25 mL mark was recorded, which was defined as the foam suppression time. The highest temperature that the solution could withstand was also recorded. The defoaming rate was tested under acidic and alkaline working environments. The test results are shown in Table 1 below. Table 1

[0017] As can be seen from the test data in Table 1, the anti-corrosion defoamer prepared by the present invention has good high temperature resistance and defoaming effect. Table 1 also shows that the anti-corrosion defoamer prepared by the present invention has good corrosion resistance and aging resistance, thus extending its service life.

[0018] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing an anti-corrosion defoamer, characterized in that, Specifically, the following steps are included: S1. Weigh the raw materials according to the following parts by weight: 90-120 parts of polyethylene glycol 6000 distearate, 120-150 parts of ethylenediamine polyoxyethylene polyoxypropylene ether, 2-5 parts of high-temperature modifier, 1-4 parts of dispersant, 1-4 parts of penetrant, 20-35 parts of emulsifier, 5-8 parts of stabilizer, 2-5 parts of antioxidant, and 30-50 parts of water; mix polyethylene glycol 6000 distearate and ethylenediamine polyoxyethylene polyoxypropylene ether, heat to 80-95℃, stir for 30 minutes to obtain the mixture. S2. Pre-emulsify the emulsifier in a 70℃ water bath for 15 minutes, then add water, high-temperature resistant modifier, penetrant, dispersant and mixture, mix evenly, adjust pH=6-7, heat to 75-90℃, add stabilizer and antioxidant and stir for 15 minutes, dehydrate under reduced pressure, filter, and obtain anti-corrosion defoamer. The high-temperature resistant modifier is prepared by the following method: Step A1: Mix ethanol and 1,3-dimethyl-6-aminourea pyrimidine and stir for 30 min. Then add p-hydroxybenzaldehyde and anhydrous ethanol and mix. Stir at 75 °C for 10 h, cool to room temperature, filter, wash, and vacuum dry at 80 °C for 6 h to obtain the intermediate. Step A2: Mix allyltrimethoxysilane and ethanol-water solution at 35°C for 10 min, then add intermediate and mix well. React at 75°C for 4-5 h, wash, filter, and vacuum dry at 60°C to obtain the preproduct. Step A3: Mix toluene, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 2-allyl-4-methylphenol and paraformaldehyde evenly, stir thoroughly, heat to 60°C, and react for 48 hours to obtain the compound. Step A4: Mix the preproduct, compound and dodecafluoroheptyl methacrylate evenly, stir for 10 min, then add azobisisobutyronitrile, continue stirring for 30 min, react at 70℃ for 3 h, after the reaction is completed, rotary evaporate, vacuum dry at 50℃ for 12 h to obtain the high temperature resistant modifier.

2. The method for preparing an anti-corrosion defoamer according to claim 1, characterized in that, In step A1, the ratio of ethanol, 1,3-dimethyl-6-aminourea pyrimidine, p-hydroxybenzaldehyde, and anhydrous ethanol is 120-150 mL: 0.01-0.04 mol: 0.01-0.04 mol: 120-180 mL.

3. The method for preparing an anti-corrosion defoamer according to claim 1, characterized in that, In step A2, the ratio of allyltrimethoxysilane, ethanol-water mixed solution, and intermediate is 0.01-0.04 mol: 120-150 mL: 0.01-0.04 mol, and the volume ratio of ethanol to water in the ethanol-water mixed solution is 4:

1.

4. The method for preparing an anti-corrosion defoamer according to claim 1, characterized in that, In step A3, the ratio of toluene, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 2-allyl-4-methylphenol, and paraformaldehyde is 70-130 mL: 0.01-0.04 mol: 0.02-0.08 mol: 0.02-0.16 mol.

5. The method for preparing an anti-corrosion defoamer according to claim 1, characterized in that, In step A4, the ratio of the preproduct, compound, dodecafluoroheptyl methacrylate, and azobisisobutyronitrile is 0.01-0.04 mol: 0.01-0.04 mol: 0.01-0.04 mol: 2-18 g.

6. The method for preparing an anti-corrosion defoamer according to claim 1, characterized in that, The dispersant is sodium polyacrylate, the penetrant is sodium benzoate, the emulsifier is lecithin, the stabilizer is glycidyl triglyceride, and the antioxidant is butylated hydroxyanisole.

7. A corrosion-resistant defoamer, characterized in that, Prepared by the preparation method according to any one of claims 1-6.

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