Degradable defoaming agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of defoaming agents, and particularly relates to a degradable defoaming agent as well as a preparation method and application thereof. The degradable vegetable oil acid amide in the defoaming agent is easily dispersed in liquid, so that the surface tension of the liquid is reduced; the polyol fatty acid ester can form insoluble particles for defoaming; the nano-emulsion stabilizing aid physically and efficiently defoams by adsorbing gas, and has a thickening effect; fatty alcohol can be quickly diffused to a foam interface, so that the surface tension is reduced, and a quick defoaming effect is achieved. The prepared degradable defoaming agent is free of silicone oil residues, biodegradable in bio-based component and environmentally friendly, the fatty alcohol and the degradable vegetable oleic acid amide can conduct defoaming in time, the nano emulsion stabilizing additive and the fatty acid ester can inhibit the foam regeneration effect, the lauric acid diethanol amine and the Tween 80 can improve the compatibility and dispersity of all the components of the defoaming agent, and the defoaming effect is good. Through the synergistic effect of all the components, the foam inhibitor has excellent degradability, dispersibility and foam inhibition when being applied to paint and ink.

Description

Technical Field

[0001] The present invention belongs to the technical field of defoamers, and particularly relates to a degradable defoamer, a preparation method thereof, and an application thereof. Background Art

[0002] A defoamer refers to a type of additive that eliminates foam by reducing the surface tension of the system and inhibits the generation of foam. The basic characteristics of a defoamer are low surface tension, good defoaming performance, stable chemical properties, no reaction with the defoaming system, good storage stability, and being green, non-toxic, and pollution-free. To date, the commonly used types of defoamers are fatty acid ester defoamers, polyether defoamers, silicone defoamers, and mineral oil defoamers. Silicone defoamers usually have higher costs, and their high chemical stability leads to non-degradability; mineral oil defoamers take months to years to degrade and are prone to causing oil film pollution; polyether defoamers can be degraded by microorganisms, but the greater the degree of polymerization, the worse their biodegradability. Due to the continuous improvement of national environmental protection requirements, green, efficient, and degradable defoamers have become the future development trend.

[0003] The Chinese invention patent with publication number CN113577833B provides a green solid defoamer and a preparation method thereof. It is characterized in that the defoamer uses natural oils as the defoaming active ingredient, mineral compounds and biological compounds as carriers, and polyglycerol as a structurant, and a green solid defoamer product is prepared by means of an atom-economical process. The preparation steps of the green solid defoamer are as follows: (1) adding the carrier to mixer M1 and stirring evenly; (2) adding the defoaming active ingredient and the structurant to M2 simultaneously and stirring evenly; (3) adding the mixture in (2) to mixer M1 and stirring evenly; (4) crushing or granulating the mixture obtained in (3), and the obtained mixture is the prepared green solid defoamer. The green solid defoamer described in this invention is not only green and environmentally friendly, biodegradable, but also has strong defoaming and foam-inhibiting performance and anti-attenuation performance. The Chinese invention patent with publication number CN111790182B discloses a behenic acid-stearic acid-oleic acid polyol fatty acid ester, a preparation method thereof, and a defoamer formulation. The fatty acid ester of behenic acid-stearic acid-oleic acid is obtained by successively esterifying behenic acid, stearic acid, and oleic acid with polyol in stages, and a defoamer formulation is compounded based on this polyol fatty acid ester, which has good defoaming stability in a wide temperature range of 30 to 55°C. However, the prior art has the technical problem that the components of fatty acid ester defoamers are not further improved to improve the degradability, dispersibility, and foam-inhibiting properties of the defoamers. Summary of the Invention

[0004] The object of the present invention is to provide a degradable defoamer and its preparation method and application, which are used to solve the technical problem that in the prior art, the structure and components of fatty acid ester defoamers have not been further improved to achieve the improvement of the degradability, dispersibility and foam inhibition performance of the defoamer.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A degradable defoamer is prepared from the following components in parts by mass: 10 - 12 parts of degradable vegetable oil fatty acid amide, 1 - 3 parts of lauric acid diethanolamine, 13 - 15 parts of polyol fatty acid ester, 1 - 3 parts of nanoemulsion stabilizing agent, 2 - 5 parts of Tween 80, 20 - 30 parts of fatty alcohol and 20 - 50 parts of deionized water.

[0006] The fatty alcohol is any one of lauryl alcohol, n - octanol and n - decanol.

[0007] Preferably, the preparation method of the degradable vegetable oil fatty acid amide includes the following steps: S11. By mass, add 80 - 120 parts of vegetable oil and 45 - 65 parts of anhydrous methanol into a reaction kettle, add 98wt% concentrated sulfuric acid, heat up to 80 - 90°C and reflux for 5 - 6h, wash with deionized water, let it stand for stratification, collect the organic phase, add 5 - 10 parts of anhydrous sodium sulfate for water removal, and obtain methyl vegetable oil fatty acid ester by low - pressure distillation; S12. By mass, add 80 - 100 parts of methyl vegetable oil fatty acid ester and 15 - 30 parts of 1,4 - butanediamine into a reaction kettle, add 0.5 - 1 part of alkali catalyst, heat up to 70 - 80°C and keep the temperature for reaction for 3 - 4h, obtain the crude product of N - (4 - aminobutyl) vegetable oil fatty acid amide by rotary evaporation under reduced pressure, add the crude product of N - (4 - aminobutyl) vegetable oil fatty acid amide into anhydrous ethanol, heat and recrystallize at 40 - 50°C, filter by suction, and obtain N - (4 - aminobutyl) vegetable oil fatty acid amide by rotary evaporation of the filtrate under reduced pressure; S13. By mass, add 50 - 80 parts of N - (4 - aminobutyl) vegetable oil fatty acid amide and 30 - 40 parts of aldose compound into a reaction kettle, add 200 - 300 parts of methanol, stir until the solid is completely dissolved, then heat up to 60 - 70°C and react for 2 - 3h, cool to room temperature, rotary evaporate to remove methanol, wash with methanol and 75 - 90wt% ethanol solution, and dry at 60 - 70°C to obtain the degradable vegetable oil fatty acid amide.

[0008] Preferably, the synthesis principle of the degradable vegetable oil fatty acid amide is as follows:

[0009] is vegetable oil, is aldose compound.

[0010] Preferably, the vegetable oil in S11 is any one of castor oil, soybean oil, and palm oil.

[0011] Preferably, the addition amount of 98wt% concentrated sulfuric acid in S11 is 1-2% of the mass of the vegetable oil.

[0012] Preferably, the base catalyst in S12 is any one of sodium hydroxide and potassium hydroxide.

[0013] Preferably, the aldose compound in S13 is any one of D-glucose, D-mannose, and D-galactose.

[0014] Preferably, the preparation method of the polyol fatty acid ester includes the following steps: S21. By mass, add 80-100 parts of polyol to the reaction kettle, add 0.5-0.8 parts of aluminum trifluoride, stir at a speed of 300-500 r / min for 0.5-1 h, evacuate the reaction kettle to vacuum with a vacuum pump, heat up to 150-170 °C and react for 3-4 h. After the hydroxyl value is qualified, cool to room temperature, collect the supernatant liquid to obtain the etherified polyol; S22. By mass, add fatty acid and acid catalyst to 80-100 parts of the etherified polyol, heat up to 50-60 °C and stir at a speed of 300-500 r / min for 0.5-1 h, evacuate the reaction kettle to vacuum with a vacuum pump, heat up to 190-230 °C and react until the acid value in the system is reduced to 7-10 KOH / g, cool to room temperature, collect the supernatant liquid to obtain the polyol fatty acid ester.

[0015] Preferably, the polyol in S21 is any one of sorbitol, mannitol, and xylitol.

[0016] Preferably, the fatty acid in S22 is any one of lauric acid, myristic acid, and oleic acid.

[0017] Preferably, the molar ratio of the fatty acid to the polyol in S22 is 1.4-1.6:0.9-1.1, and the addition amount of the acid catalyst is 0.5-0.8% of the total weight of the oleic acid and the etherified polyol.

[0018] Preferably, the acid catalyst in S22 is any one of 98wt% concentrated sulfuric acid, p-toluenesulfonic acid, and phosphoric acid.

[0019] Preferably, the preparation method of the nano-emulsion stabilizing agent includes the following steps: S31. By mass, add 7 - 10 parts of tetraethyl orthosilicate to 50 - 100 parts of absolute ethanol, add 1 - 2 parts of octadecyltrimethoxysilane and 0.5 - 1 part of methyltriethoxysilane, dropwise add 5 - 10 wt% dilute hydrochloric acid to adjust the pH to 3 - 4 to obtain a mixed solution. Heat the mixed solution to 70 - 80 °C, slowly dropwise add 3 - 6 parts of deionized water, complete the dropping within 0.5 - 1 h. After the dropping is completed, keep the temperature at 70 - 80 °C for heat preservation reaction for 4 - 6 h, filter by suction to collect the solid, wash it with deionized water, and dry it at 30 - 40 °C to obtain modified nano - silica; S32. By mass, put 10 - 20 parts of microcrystalline cellulose into 150 - 200 parts of sodium hydroxide solution for pretreatment for 2 - 3 h, wash it with deionized water, and dry it at 30 - 40 °C to obtain pretreated microcrystalline cellulose. Add 10 - 20 parts of pretreated microcrystalline cellulose to 200 - 300 parts of acid hydrolysis solution for acid hydrolysis for 2 - 3 h, centrifuge and filter to collect the colloid, dialyze it with a dialysis bag until the pH of the colloid is 5 - 6, and freeze - dry it at 0 - 5 °C and grind it to obtain spherical nano - cellulose; S33. By mass, mix 1 - 3 parts of modified nano - silica and 3 - 5 parts of spherical nano - cellulose to obtain a nano - emulsion stabilizing agent.

[0020] Preferably, in S32, the type of microcrystalline cellulose is any one of PH101, PH102, and PH105, and the acid hydrolysis solution is prepared by mixing 37 wt% hydrochloric acid, 98 wt% sulfuric acid and deionized water according to the mass ratio of 1:2.5 - 3:6 - 6.5.

[0021] Preferably, in S32, the cut - off molecular weight of dialysis is 2000 - 3500 Da.

[0022] A preparation method of a biodegradable defoamer includes the following steps: S1. Mix 10 - 12 parts of biodegradable oleic acid amide, 1 - 3 parts of lauric acid diethanolamine, 13 - 15 parts of polyol fatty acid ester and 0.5 - 1.5 parts of Tween 80, and ultrasonically disperse for 20 - 30 min to obtain an oil phase; S2. Add the remaining Tween 80 and 1 - 3 parts of nano - emulsion stabilizing agent to 20 - 50 parts of deionized water to obtain an aqueous phase. Add the aqueous phase to the oil phase at 30 - 40 °C and homogenize and emulsify at a rotation speed of 10000 - 12000 r / min for 5 - 10 min; S3. Cool the system to room temperature, add 20 - 30 parts of fatty alcohol, and adjust the pH of the system to 6 - 8 with 5 - 10 wt% sodium hydroxide solution or 5 - 10 wt% citric acid solution, and package to obtain a biodegradable defoamer.

[0023] The present invention also provides an application of a degradable defoamer for preparing coating inks, and the preparation method comprises the following steps: S41. By mass, 30 - 40 parts of acrylic resin, 7 - 8 parts of ethanol and 5 - 7 parts of deionized water are mixed to obtain a solvent. 5 - 10 parts of pigments and defoamer are added to the solvent, and stirred and dispersed at a speed of 800 - 1000 r / min for 5 - 10 min, and ground to a fineness of less than 10 - 15 μm to obtain base ink; S42. By mass, 40 - 50 parts of the base ink are poured into a dispersion kettle. The defoamer is added to 5 - 7 parts of deionized water and then added to the dispersion kettle. 8 - 13 parts of HR830 film-forming emulsion and 15 - 20 parts of 3,3-dimethyl methacrylate are added, and stirred evenly at a speed of 300 - 500 r / min to obtain coating ink.

[0024] Preferably, in S41, after the defoamer is stirred evenly, it is added to the solvent in 2 - 3 times, and the addition amount is 0.2 - 0.5% of the mass of the solvent.

[0025] Preferably, in S42, the addition amount of the defoamer is 0.2 - 0.5% of the mass of the base ink.

[0026] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: 1. The degradable vegetable oil fatty acid amide in the degradable defoamer of the present invention is easily dispersed in the liquid, reducing the surface tension of the liquid to achieve a defoaming effect; the polyol fatty acid ester can form insoluble particles to destroy the foam; the nano-emulsion stabilizing agent physically defoams efficiently by adsorbing gas and has a thickening effect; the fatty alcohol can quickly diffuse to the foam interface and briefly reduce the local surface tension to achieve a rapid defoaming effect. The degradable defoamer prepared by the present invention has no silicone oil residue, the contained bio-based components are degradable, environmentally friendly, the fatty alcohol and the degradable vegetable oil fatty acid amide can defoam immediately, the nano-emulsion stabilizing agent and the fatty acid ester can inhibit the foam regeneration effect, and the lauric acid diethanolamine and the Tween 80 can improve the compatibility and dispersibility of each component of the defoamer. Through the synergistic effect of each component, it has excellent degradability, dispersibility and foam inhibition.

[0027] 2. After the present invention prepares methyl oleate by reacting vegetable oil with anhydrous methanol, then reacts with 1,4-butanediamine to obtain N-(4-aminobutyl) oleic acid amide of vegetable oil, and finally reacts with an aldose compound to obtain a degradable vegetable oil fatty acid amide. Its raw materials are inexpensive and renewable. The degradable vegetable oil fatty acid amide has a long alkyl chain and multiple hydroxyl groups, making it easily dispersed in the liquid and having excellent defoaming performance and emulsifying performance.

[0028] 3. After the polyol is dehydrated and etherified, and then reacted with fatty alcohol, the obtained polyol fatty acid ester has low-cost and renewable raw materials, excellent emulsifying and dispersing properties. When applied to the defoamer, the hydrophilic and hydrophobic groups in its molecular structure can be evenly distributed on the foam surface, and the stability of the foam is destroyed by reducing the surface tension of the foam, preventing the regeneration of the foam and having the ability of persistent foam suppression.

[0029] 4. In the present invention, nano-silica is precipitated by adding deionized water to tetraethyl orthosilicate in absolute ethanol, and then modified with octadecyltrimethoxysilane and methyltriethoxysilane. The prepared modified nano-silica and spherical nano-cellulose are mixed to obtain a nano-emulsion stabilizing agent with excellent dispersibility and emulsion stability. The modification with octadecyltrimethoxysilane endows the modified nano-silica with strong hydrophobic properties, which can be adsorbed on the oil phase side and has a thickening effect; spherical nano-cellulose has hydrophilic properties, can be adsorbed on the water phase side and can form a three-dimensional network structure through hydrogen bonds to stabilize the emulsion; the nano-emulsion stabilizing agent can improve the stability and retention time of the emulsion when applied to the defoamer. Specific embodiments

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] The types of acrylic resins involved in the embodiments of the present invention are any one of WH-560A and MR1741W. WH-560A is purchased from Jining Tangyi Chemical Co., Ltd., and MR1741W is purchased from Guangdong Ked ding Functional Materials Co., Ltd.; the pigment is prepared by mixing 85 wt% carbon black and 15 wt% phthalocyanine blue; the HR830 film-forming emulsion is purchased from Guangzhou Houhuan Chemical Auxiliary Co., Ltd.; 3,3-dimethyl methacrylate is purchased from Wuhan Karnos Technology Co., Ltd.

[0032] Example 1. A degradable defoamer in this example is prepared from the following components by mass: 10 g of degradable vegetable oleic acid amide, 1 g of lauric acid diethanolamine, 14 g of polyol fatty acid ester, 2 g of nano-emulsion stabilizing agent, 3 g of Tween 80, 20 g of fatty alcohol and 50 g of deionized water.

[0033] The fatty alcohol is lauryl alcohol.

[0034] The preparation method of a degradable defoamer in this example includes the following steps: S1. Mix 10 g of biodegradable oleic acid amide, 1 g of lauryl diethanolamide, 14 g of polyol fatty acid ester, and 1.5 g of Tween 80, and disperse them by ultrasonic for 30 min to obtain the oil phase; S2. Add the remaining Tween 80 and 2 g of nanoemulsion stabilizing agent to 50 g of deionized water to obtain the aqueous phase. Add the aqueous phase to the oil phase at 40 °C and homogenize and emulsify at a speed of 12,000 r / min for 5 min; S3. Cool the system to room temperature, add 20 g of fatty alcohol, adjust the pH of the system to 7 with 10 wt% citric acid solution, and package to obtain a biodegradable defoamer.

[0035] The preparation method of the biodegradable oleic acid amide in this example includes the following steps: S11. Add 100 g of castor oil and 63 g of anhydrous methanol to the reaction kettle by mass, add 1 g of 98 wt% concentrated sulfuric acid, heat up to 90 °C and reflux for 6 h, wash with deionized water, let it stand and separate layers, collect the organic phase, add 10 g of anhydrous sodium sulfate to remove water, and distill under low pressure to obtain methyl oleate; S12. Add 80 g of methyl oleate and 22 g of 1,4-diaminobutane to the reaction kettle by mass, add 1 g of sodium hydroxide, heat up to 80 °C and keep the temperature for 4 h, and obtain the crude product of N-(4-aminobutyl) oleic acid amide by rotary evaporation under reduced pressure. Add the crude product of N-(4-aminobutyl) oleic acid amide to anhydrous ethanol, heat and recrystallize at 50 °C, filter by suction, and rotary evaporate the filtrate under reduced pressure to obtain N-(4-aminobutyl) oleic acid amide; S13. Add 60 g of N-(4-aminobutyl) oleic acid amide and 33 g of D-glucose to the reaction kettle by mass, add 250 g of methanol, stir until the solid is completely dissolved, then heat up to 60 °C and react for 2 h, cool to room temperature, rotary evaporate to remove methanol, wash with methanol and 75 wt% ethanol solution, and dry at 60 °C to obtain the biodegradable oleic acid amide.

[0036] The preparation method of the polyol fatty acid ester in this example includes the following steps: S21. Add 91 g of sorbitol to the reaction kettle by mass, add 0.5 g of aluminum trifluoride, stir at a speed of 300 r / min for 0.5 h, evacuate the reaction kettle with a vacuum pump, heat up to 150 °C and react for 4 h, detect the hydroxyl value to be 1350 mgKOH / g, cool to room temperature, and collect the supernatant to obtain the etherified polyol; S22. By mass, add 230 g of oleic acid and 1.6 g of p-toluenesulfonic acid to 80 g of etherified polyol, heat up to 60 °C, stir at a speed of 500 r / min for 0.5 h, evacuate the reaction kettle to vacuum with a vacuum pump, heat up to 210 °C and react until the acid value in the system decreases to 8 KOH / g, cool to room temperature, collect the upper clear liquid to obtain polyol fatty acid ester.

[0037] The preparation method of the nanoemulsion stabilizing agent in this example includes the following steps: S31. By mass, add 8 g of tetraethyl orthosilicate to 100 g of absolute ethanol, add 2 g of octadecyltrimethoxysilane and 1 g of methyltriethoxysilane, add 10 wt% dilute hydrochloric acid dropwise to adjust the pH to 4 to obtain a mixed solution, heat the mixed solution to 80 °C, slowly add 6 g of deionized water dropwise, finish dropping in 1 h, keep the temperature at 80 °C for heat preservation reaction for 4 h after dropping, filter by suction to collect the solid, wash with deionized water, and dry at 40 °C to obtain modified nano-silica. S32. By mass, put 10 g of PH101 microcrystalline cellulose into 150 g of 25 wt% sodium hydroxide solution for pretreatment for 2 h, wash with deionized water, dry at 30 °C to obtain pretreated microcrystalline cellulose, add 10 g of pretreated microcrystalline cellulose to 300 g of acidolysis solution for acidolysis for 2 h. The acidolysis solution is prepared by mixing 37 wt% hydrochloric acid, 98 wt% sulfuric acid and deionized water according to the mass ratio of 1:3:6. Centrifuge and filter to collect the colloid, the molecular weight cut-off of the dialysis bag is 3500 Da, dialyze with the dialysis bag until the pH of the colloid is 6, freeze-dry at 0 °C, and grind to obtain spherical nano-cellulose. S33. By mass, mix 1 g of modified nano-silica and 3 g of spherical nano-cellulose to obtain the nanoemulsion stabilizing agent.

[0038] This example also provides an application of a degradable defoamer for preparing coating inks, and the preparation method includes the following steps: S41. By mass, mix 300 g of WH-560A acrylic resin, 70 g of ethanol and 50 g of deionized water to obtain a solvent, add 80 g of pigment and 2 g of defoamer to the solvent, stir the defoamer evenly and add it to the solvent in 2 times, stir and disperse at a speed of 800 r / min for 5 min, and grind to a fineness of less than 15 μm to obtain base ink. S42. By mass, pour 500 g of base ink into a dispersion kettle, add 2.5 g of defoamer to 50 g of deionized water and then add it to the dispersion kettle, add 10 g of HR830 film-forming emulsion and 15 g of 3,3-dimethyl methacrylate, stir evenly at a speed of 500 r / min to obtain coating ink.

[0039] Example 2. A degradable defoamer of this example is prepared from components with the following masses: 10 g of degradable vegetable oil amide, 2 g of lauric acid diethanolamine, 15 g of polyol fatty acid ester, 1 g of nanoemulsion stabilizing aid, 2 g of Tween 80, 30 g of fatty alcohol, and 30 g of deionized water.

[0040] The fatty alcohol is n-decanol.

[0041] The preparation method of a degradable defoamer of this example includes the following steps: S1. Mix 10 g of degradable vegetable oil amide, 2 g of lauric acid diethanolamine, 15 g of polyol fatty acid ester, and 1 g of Tween 80, and ultrasonically disperse for 20 min to obtain an oil phase; S2. Add the remaining Tween 80 and 1 g of nanoemulsion stabilizing aid to 30 g of deionized water to obtain an aqueous phase. Add the aqueous phase to the oil phase at 30 °C and homogenize and emulsify at a speed of 10000 r / min for 10 min; S3. Cool the system to room temperature, add 30 g of fatty alcohol, adjust the pH of the system to 8 with 5 wt% sodium hydroxide solution, and package to obtain a degradable defoamer.

[0042] This example also provides the application of a degradable defoamer, which is used for preparing coating inks. The preparation method includes the following steps: S41. Mix 400 g of MR1741W acrylic resin, 75 g of ethanol, and 50 g of deionized water by mass to obtain a solvent. Add 50 g of pigment and 2 g of defoamer to the solvent. After stirring the defoamer evenly, add it to the solvent in 3 portions, stir and disperse at a speed of 1000 r / min for 5 min, and grind to a fineness of less than 10 μm to obtain base ink; S42. Pour 500 g of base ink into a dispersion kettle. Add 2 g of defoamer to 50 g of deionized water and then add it to the dispersion kettle. Add 80 g of HR830 film-forming emulsion and 150 g of 3,3-dimethyl methacrylate, and stir evenly at a speed of 500 r / min to obtain coating inks.

[0043] The difference between the degradable vegetable oil amide of this example and that of Example 1 is that the vegetable oil is replaced by palm oil and the aldose compound is replaced by D-mannose.

[0044] The preparation methods of the polyol fatty acid ester and the nanoemulsion stabilizing aid in this example are the same as those in Example 1.

[0045] Example 3. A degradable defoamer of this example is prepared from components with the following masses: 12 g of degradable vegetable oil oleamide, 3 g of lauric acid diethanolamine, 13 g of polyol fatty acid ester, 3 g of nano-emulsion stabilizing agent, 5 g of Tween 80, 30 g of fatty alcohol, and 40 g of deionized water.

[0046] The fatty alcohol is n-octanol.

[0047] The preparation method of a degradable defoamer in this example includes the following steps: S1. Mix 12 g of degradable vegetable oil oleamide, 3 g of lauric acid diethanolamine, 13 g of polyol fatty acid ester, and 1.5 g of Tween 80, and ultrasonically disperse for 20 min to obtain an oil phase; S2. Add the remaining Tween 80 and 3 g of nano-emulsion stabilizing agent to 40 g of deionized water to obtain an aqueous phase. Add the aqueous phase to the oil phase at 35 °C and homogenize and emulsify at a speed of 11,000 r / min for 5 min; S3. Cool the system to room temperature, add 30 g of fatty alcohol, and adjust the pH of the system to 6 with 5 wt% citric acid solution, and package to obtain a degradable defoamer.

[0048] This example also provides an application of a degradable defoamer for preparing coating inks. The preparation method includes the following steps: S41. Mix 350 g of WH-560A acrylic resin, 80 g of ethanol, and 70 g of deionized water by mass to obtain a solvent. Add 100 g of pigment and 1 g of defoamer to the solvent. After stirring the defoamer evenly, add it to the solvent in 2 portions, and stir and disperse at a speed of 800 r / min for 5 min, and grind to a fineness of less than 15 μm to obtain base ink; S42. Pour 450 g of base ink into a dispersion kettle by mass. Add 0.9 g of defoamer to 50 g of deionized water and then add it to the dispersion kettle. Add 130 g of HR830 film-forming emulsion and 200 g of 3,3-dimethyl methacrylate, and stir evenly at a speed of 500 r / min to obtain coating ink.

[0049] The difference between the polyol fatty acid ester in this example and that in Example 1 is that the polyol is replaced by xylitol and the fatty acid is replaced by lauric acid.

[0050] The difference between the nano-emulsion stabilizing agent in this example and that in Example 1 is that the model of microcrystalline cellulose is replaced by PH105.

[0051] The preparation method of the degradable vegetable oil oleamide in this example is the same as that in Example 1.

[0052] Comparative Example 1. The difference between this comparative example and Example 1 is that the degradable vegetable oil oleamide is replaced by oleic acid diethanolamide.

[0053] Comparative Example 2. The difference between this comparative example and Example 1 is that polyol fatty acid ester is not added.

[0054] Comparative Example 3. The difference between this comparative example and Example 1 is that the nano-emulsion stabilizing agent is replaced with nano-silica, model HL-200, purchased from Hubei Huifu Nano Materials Co., Ltd.

[0055] Performance Test Add 2 g of sodium dodecyl sulfate and 2 g of polyoxyethylene lauryl ether to 1 L of deionized water, and stir evenly to prepare a foaming solution.

[0056] Take 50 mL of the foaming solution and shake it up and down 25 times at 25 °C, then let it stand until the foam height is stable. Record it as the initial foam height. Take 0.25 g of the defoamers prepared in Examples 1-3 and Comparative Examples 1-3 respectively and add them to 50 mL of the foaming solution and start timing. Record the time it takes for the foam in the foaming solution to disappear, that is, the defoaming time. Put the defoamed foaming solution into a shaker and oscillate it, and record the time it takes for the foam height to reach the initial foam height, that is, the foam suppression time.

[0057] Send the defoamers prepared in Examples 1-3 and Comparative Examples 1-3 to a testing agency to test the degradation rate. Bury 10 g of the defoamer in the soil 50 cm below the ground surface, and detect the mass after 3 months. The degradation rate is calculated by the following formula:

[0058] δ is the degradation rate, m 0 is the initial mass of the defoamer, in g, m is the mass of the defoamer after being buried in the soil for 3 months, in g.

[0059] The test results are shown in Table 1 below: Table 1 Test Results

[0060] After applying the defoamers of the examples and comparative examples to the preparation of coating inks, the viscosity of the inks was detected according to GB / T 2794-2013 "Determination of Viscosity of Adhesives - Single Cylinder Rotating Viscometer Method"; according to GB / T 6753.3-1986 "Test Method for Storage Stability of Coatings", it was sealed and stored at 50 °C for 30 d, and the layering situation of the inks was detected.

[0061] The coating inks prepared in the examples and comparative examples were applied to an iron plate. After natural air drying, they were placed in an oven and heated to 180 °C for drying for 30 min. According to GB / T 9286-2021 "Paints and varnishes - Cross-cut test", the adhesion grade of the ink was tested. According to GB / T 1733-1993 "Method for the determination of water resistance of films", they were soaked in deionized water at 100 °C for 2 h, and the adhesion of the ink coating was observed.

[0062] The test results are shown in Table 2 below: Table 2 Ink properties

[0063] From the data in Table 1, it can be seen that the defoaming time of the defoamers prepared in Examples 1 to 3 was 12 - 15 s, and the foam suppression time was 35 - 39 s. In Comparative Example 1, the biodegradable vegetable oil amide was replaced with diethanolamide oleate, resulting in a decrease in its diffusion rate. Therefore, the defoaming time of Comparative Example 1 was 21 s, and the foam suppression time was 27 s. In Comparative Example 2, the polyol fatty acid ester was not added, resulting in a decrease in defoaming and foam suppression performance. The defoaming time of Comparative Example 2 was 28 s, and the foam suppression time was 24 s. This shows that the defoamer prepared by the present invention has excellent defoaming and foam suppression performance; the degradation rate of the defoamer prepared in Examples 1 to 3 was 71.6 - 74.3%, indicating that the defoamer prepared by the present invention has excellent degradation performance.

[0064] From the data in Table 2, it can be seen that after the defoamers of Examples 1 to 3 were applied to prepare coating inks, the viscosity of the inks was between 1.76 - 1.81 Pa·s and did not delaminate after being sealed and stored at 50 °C for 30 d. This shows that the defoamer prepared by the present invention can improve the storage stability of coating inks when applied to the preparation of coating inks. In Comparative Example 3, the nanoemulsion stabilizing agent was replaced with nano-silica, resulting in a decrease in the stability and viscosity of the oil phase. Therefore, its viscosity was 1.54 Pa·s and it delaminated after being sealed and stored at 50 °C for 30 d; the adhesion grade of the coatings prepared by applying the defoamers of Examples 1 to 3 to prepare coating inks was all Grade 1, and there were no bubbles and no peeling of the coatings after being soaked in deionized water at 100 °C for 2 h. This shows that the defoamer prepared by the present invention has excellent defoaming and foam suppression performance and has excellent adhesion and water resistance when applied to coating inks.

[0065] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

[0066] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments only. Obviously, according to the content of this specification, many modifications and variations can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A degradable defoamer, characterized in that: It is prepared from the following components in parts by weight: 10-12 parts of degradable vegetable oleic acid amide, 1-3 parts of diethanolamine laurate, 13-15 parts of polyol fatty acid ester, 1-3 parts of nanoemulsion stabilizing agent, 2-5 parts of Tween 80, 20-30 parts of fatty alcohol and 20-50 parts of deionized water; The fatty alcohol is any one of lauryl alcohol, n-octanol and n-decanol; The preparation method of the degradable vegetable oleic acid amide comprises the following steps: S11, by mass, add 80-120 parts of vegetable oil and 45-65 parts of anhydrous methanol into a reactor, add 98wt% concentrated sulfuric acid, heat to 80-90°C and reflux for reaction for 5-6h, wash with deionized water, stand for stratification, collect the organic phase, add 5-10 parts of anhydrous sodium sulfate to remove water, and distill at low pressure to obtain vegetable oil methyl ester; S12, by mass, add 80-100 parts of vegetable oleic acid methyl ester and 15-30 parts of 1,4-diamine into a reaction kettle, add 0.5-1 parts of an alkali catalyst, heat to 70-80°C and keep the reaction for 3-4 hours, and evaporate under reduced pressure to obtain a crude product of N-(4-aminobutyl) vegetable oleic acid amide, add the crude product of N-(4-aminobutyl) vegetable oleic acid amide to anhydrous ethanol, heat at 40-50°C for recrystallization, filter, and evaporate the filtrate under reduced pressure to obtain N-(4-aminobutyl) vegetable oleic acid amide; S13. Add 50-80 parts of N-(4-aminobutyl) vegetable oleic acid amide and 30-40 parts of aldose compounds into a reactor, add 200-300 parts of methanol, stir until the solid is completely dissolved, heat to 60-70°C and react for 2-3 hours, cool to room temperature, remove methanol by rotary evaporation, wash with methanol and 75-90wt% ethanol solution, and dry at 60-70°C to obtain degradable vegetable oleic acid amide.

2. A degradable defoamer according to claim 1, characterized in that: The vegetable oil in S11 is any one of castor oil, soybean oil and palm oil, and the amount of 98wt% concentrated sulfuric acid added is 1-2% of the mass of the vegetable oil; the alkaline catalyst in S12 is any one of sodium hydroxide and potassium hydroxide; the aldose compound in S13 is any one of D-glucose, D-mannose and D-galactose.

3. A degradable defoamer according to claim 1, characterized in that: The preparation method of the polyol fatty acid ester comprises the following steps: S21. Add 80-100 parts of polyol by mass into a reactor, add 0.5-0.8 parts of aluminum trifluoride, stir at a speed of 300-500 r / min for 0.5-1 h, evacuate the reactor to vacuum with a vacuum pump, heat to 150-170° C. and react for 3-4 h. After the hydroxyl value is tested to be qualified, cool to room temperature, collect the supernatant, and obtain an etherified polyol. S22. Add fatty acid and acid catalyst to 80-100 parts of etherified polyol by mass, raise the temperature to 50-60°C and stir at 300-500 r / min for 0.5-1 h, evacuate the reactor with a vacuum pump, raise the temperature to 190-230°C and react until the acid value in the system decreases to 7-10KOH / g, cool to room temperature, collect the supernatant, and obtain polyol fatty acid ester.

4. A degradable defoamer according to claim 3, characterized in that: The polyol in S21 is any one of sorbitol, mannitol, and xylitol; the fatty acid in S22 is any one of lauric acid, myristic acid, and oleic acid; the molar ratio of fatty acid to polyol is 1.4~1.6:0.9~1.1, and the amount of acid catalyst added is 0.5~0.8% of the total weight of oleic acid and etherified polyol; the acid catalyst is any one of 98wt% concentrated sulfuric acid, p-toluenesulfonic acid, and phosphoric acid.

5. A degradable defoamer according to claim 1, characterized in that: The preparation method of the nanoemulsion stabilizing agent comprises the following steps: S31. Add 7-10 parts of ethyl orthosilicate to 50-100 parts of anhydrous ethanol by mass, add 1-2 parts of octadecyltrimethoxysilane and 0.5-1 part of methyltriethoxysilane, add 5-10wt% of dilute hydrochloric acid to adjust the pH to 3-4 to obtain a mixed solution, heat the mixed solution to 70-80°C, slowly add 3-6 parts of deionized water, and complete the addition in 0.5-1h. After the addition is completed, keep the mixture at 70-80°C for 4-6h, collect the solid by suction, wash it with deionized water, and dry it at 30-40°C to obtain modified nano-silica. S32, by mass, placing 10-20 parts of microcrystalline cellulose in 150-200 parts of sodium hydroxide solution for pretreatment for 2-3 hours, washing with deionized water, drying at 30-40° C. to obtain pretreated microcrystalline cellulose, adding 10-20 parts of pretreated microcrystalline cellulose to 200-300 parts of acid hydrolysis solution for acid hydrolysis for 2-3 hours, collecting the colloid by centrifugal filtration, dialyzing with a dialysis bag until the colloid pH is 5-6, freeze-drying at 0-5° C., and grinding to obtain spherical nanocellulose; S33. Mix 1 to 3 parts of modified nano-silicon dioxide and 3 to 5 parts of spherical nano-cellulose by mass to obtain a nano-emulsion stabilizing agent.

6. A degradable defoamer according to claim 5, characterized in that: The model of the microcrystalline cellulose in the S32 is any one of PH101, PH102, and PH105. The acid hydrolysis solution is prepared by mixing 37wt% hydrochloric acid, 98wt% sulfuric acid and deionized water in a mass ratio of 1:2.5~3:6~6.5, and the dialysis molecular weight cutoff is 2000~3500Da.

7. A method for preparing a degradable defoamer according to any one of claims 1 to 6, characterized in that: The steps include: S1, mixing 10-12 parts of degradable vegetable oleic acid amide, 1-3 parts of diethanolamine laurate, 13-15 parts of polyol fatty acid ester and 0.5-1.5 parts of Tween 80, and ultrasonically dispersing for 20-30 minutes to obtain an oil phase; S2, adding the remaining amount of Tween 80 and 1-3 parts of nanoemulsion stabilizing aid into 20-50 parts of deionized water to prepare an aqueous phase, adding the aqueous phase into the oil phase at 30-40° C., and homogenizing and emulsifying at a speed of 10000-12000 r / min for 5-10 min; S3. Cool the system to room temperature, add 20-30 parts of fatty alcohol, adjust the pH of the system to 6-8 with 5-10wt% sodium hydroxide solution or 5-10wt% citric acid solution, and package to obtain a biodegradable defoaming agent.

8. Use of a degradable defoaming agent according to any one of claims 1 to 6, characterized in that: For preparing coating ink, comprising the following steps: S41. Mix 30-40 parts of acrylic resin, 7-8 parts of ethanol and 5-7 parts of deionized water by mass to prepare a solvent, add 5-10 parts of pigment and defoamer to the solvent, stir and disperse at a speed of 800-1000 r / min for 5-10 min, and grind to a fineness of less than 10-15 μm to prepare a base ink; S42. Pour 40-50 parts of base ink into a dispersion kettle by mass, add a defoamer into 5-7 parts of deionized water and then add them into the dispersion kettle, add 8-13 parts of HR830 film-forming emulsion and 15-20 parts of 3,3-dimethylmethacrylate, stir evenly at a speed of 300-500 r / min to prepare a coating ink.

9. The use of a degradable defoaming agent according to claim 8, characterized in that: The defoamer in S41 is stirred evenly and then added to the solvent in 2-3 portions, with the added amount being 0.2-0.5% of the mass of the solvent; the added amount of the defoamer in S42 is 0.2-0.5% of the mass of the base ink.

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