阅读说明：本技术 一种乳液型环保涂料用消泡剂及制备方法 (Defoaming agent for emulsion type environment-friendly coating and preparation method thereof ) 是由 胡佳新 黄伟 曹添 苏芳 于 2020-04-30 设计创作，主要内容包括：本发明提供了一种乳液型环保涂料用消泡剂及制备方法,采用天然油代替传统矿物油制备乳液型消泡剂,更符合涂料行业绿色环保的要求,且本方法制备的乳液型环保涂料用消泡剂有更好的相容性和消抑泡性能,不影响涂料的漆膜光泽度。(The invention provides a defoaming agent for an emulsion type environment-friendly coating and a preparation method thereof, wherein natural oil is adopted to replace traditional mineral oil to prepare the emulsion type defoaming agent, so that the emulsion type defoaming agent is more in line with the requirement of environmental protection in the coating industry, and the defoaming agent for the emulsion type environment-friendly coating prepared by the method has better compatibility and defoaming and foam inhibition performance, and the glossiness of a paint film of the coating is not influenced.)

1. An emulsion type defoaming agent for environment-friendly coating and a preparation method thereof are characterized in that the defoaming agent comprises the following components:

A. carrier

The carrier is mainly selected from one or a mixture of two of vegetable oil and derivatives thereof, wherein the vegetable oil is selected from one or a mixture of more of castor oil, soybean oil, palm oil, rapeseed oil, linseed oil and peanut oil; the vegetable oil derivative is selected from one or more of epoxidized compounds of vegetable oil and amidated compounds of vegetable oil, and the using amount of the carrier accounts for 10-25% of the total mass of the defoaming agent;

B. white carbon black

The white carbon black is selected from hydrophobic fumed silica, and accounts for 0.5-3% of the total mass of the defoaming agent;

C. fatty acid metal soap

The fatty acid metal soap is selected from magnesium salt, aluminum salt and calcium salt of fatty acid, wherein the fatty acid refers to saturated or unsaturated fatty acid with 8-18 carbon atoms, and the dosage of the fatty acid metal soap is 1-15% of the total mass of the defoaming agent;

D. dispersing agent

The dispersant is selected from nonionic surfactant, anionic surfactant or amphoteric surfactant, and the specific nonionic surfactant is preferably alkyl glycoside (APG); the anionic surfactant is selected from carboxylate, sulfonate, sulfate ester salt and phosphate ester salt, the amphoteric surfactant is selected from amino acid type or betaine type, and the dispersant accounts for 0.1-1% of the total mass of the defoaming agent;

E. thickening agent

The thickener is selected from sodium carboxymethylcellulose, polyacrylate, carbomer, polyvinyl alcohol, xanthan gum and guar gum; the thickener accounts for 0.27 to 0.5 percent of the total mass of the defoamer;

F. emulsifier

The emulsifier is mainly selected from glyceryl monostearate, polyglycerol fatty acid ester, lecithin, monoglyceride and diglyceride, propylene glycol ester, polyoxyethylene (40) stearate, span 80, span 60, span 20, Tween 80, Tween 60 and Tween 20; one or two of the emulsifiers are selected and mixed for use, and the using amount of the emulsifiers accounts for 1-15% of the total mass of the defoaming agent;

G. preservative

The preservative is mainly selected from sodium benzoate, potassium sorbate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, dehydroacetic acid, sodium propionate and calcium propionate, and the consumption of the preservative accounts for 0.1-1% of the total mass of the defoaming agent;

H. water (W)

The water is deionized water, and the using amount of the water accounts for 45-75% of the total mass of the defoaming agent; the water is added in three parts, wherein the first part H1 accounts for 3/10 of the total mass of the water, the second part H2 accounts for 4/10 of the total mass of the water, and the third part H3 accounts for 3/10 of the total mass of the water;

the preparation method of the defoaming agent for the emulsion type environment-friendly coating comprises the following specific operation steps:

(1) preparation of the premix

Adding the white carbon black B into an A1 carrier heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a white carbon black/carrier dispersion liquid;

mixing C fatty acid metal soap, D dispersant and A2 carrier, heating to 100-150 deg.C, holding the temperature for 10-35min, mixing with white carbon black/carrier dispersion liquid at room temperature, grinding with colloid mill, homogenizing to obtain premix;

(2) preparation of thickening fluid

Heating H1 water to above 70 deg.C, slowly adding thickening agent E under stirring, stirring for 60min, and cooling to below 35 deg.C to obtain thickening solution;

(3) preparation of the antifoam

Heating H2 water, keeping the temperature at 60-80 deg.C, adding the emulsifier F into hot water, stirring for 5-15min, slowly adding the premixed solution under proper stirring, and keeping the temperature above 60 deg.C; mixing for 30-60min, cooling to 40-50 deg.C, grinding with colloid mill until particle diameter is below 10 μm, mixing with thickening liquid under high speed stirring for 20-30min, adding antiseptic G and H3 water, stirring, and homogenizing for 50-60min to obtain the final product.

2. The defoamer for emulsion type environment-friendly paint and the preparation method thereof as claimed in claim 1, characterized in that the white carbon black further preferably has a specific surface area of 50-200 m 2/g.

3. An emulsion type defoaming agent for environment-friendly paint and a preparation method thereof according to claim 1, characterized in that the dispersant anionic surfactant is preferably sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl diphenyl ether disulfonate, sodium dodecyl phosphate; .

4. An emulsion type environmental protection defoaming agent and its preparation method according to claim 1, characterized in that the dispersant amphoteric surfactant is preferably dodecyl dimethyl betaine, dodecyl amino propionic acid, decyl dimethyl hydroxypropyl sulfobetaine.

5. The defoamer for emulsion type environment-friendly paint and the preparation method thereof as claimed in claim 1, wherein said thickener is preferably polyacrylate.

6. The green solid antifoaming agent and the preparation method thereof according to claim 1, characterized in that the emulsifier is span 60, polyoxyethylene (40) stearate.

7. The green solid antifoaming agent and the preparation method thereof according to claim 1, characterized in that the preservative is preferably potassium sorbate.

Technical Field

The invention relates to a defoaming agent for an emulsion type environment-friendly coating and a preparation method thereof, and the defoaming agent belongs to a fine chemical preparation, so the invention belongs to the technical field of fine chemical preparations.

Background

Along with improvement of the living standard of people and improvement of policies, regulations and standards, the environment-friendly coating is more and more widely valued and applied, and higher requirements are also put forward on the emulsion type coating. Emulsion type coatings are heterogeneous systems of multiple phases that are prone to bubble formation. In order to reduce the influence caused by bubbles in the coating construction process and meet the current requirement on green and environment-friendly chemicals, a green and environment-friendly defoaming auxiliary agent needs to be added. Patents CN1672762A, CN1676544 and CN1751768 mainly describe mineral oil defoamers including stearic acid soap, amide, polyacrylate, white carbon black and the like as main defoaming substances, and the mineral oil defoamers are used in an aqueous system and are easy to float from water to the surface of ink mainly due to the low density of the mineral oil defoamers. In addition, white carbon black in this type of defoaming agent has no structural similarity with the main material mineral oil, and therefore easily precipitates from the defoaming agent. Further, the mineral oil type defoaming agent also affects the gloss of the ink. In CN101991975B, mineral oil is used as a carrier, and fatty acid metal soap and fatty acid amide are simultaneously added, so that the stability of the product is improved, the defoaming and foam inhibiting performance is further improved, the defoaming and foam inhibiting performance and the stability of the product are improved, but the product still selects mineral oil as the carrier, the VOC content of the final product is high, and the environmental protection performance is poor. The antifoaming agent for the coating mostly adopts mineral oil as a carrier, and the mineral is mostly composed of alkane, aromatic hydrocarbon, cyclane and part of olefin. Due to the structural characteristics, the content of VOC (volatile organic compounds) is higher, and the requirements of environmental protection development of the current industry are not met. The invention uses vegetable oil and the derivatives thereof to replace mineral oil as a carrier to prepare the green, high-efficiency and environment-friendly defoaming agent for the coating.

Disclosure of Invention

The defoaming agent for the emulsion type environment-friendly coating is prepared by replacing the traditional mineral oil with natural oil, and better meets the requirement of environmental protection in the coating industry.

The invention relates to a defoaming agent for an emulsion type environment-friendly coating and a preparation method thereof, wherein the defoaming agent comprises the following substances:

a vector

The carrier is mainly selected from one or a mixture of two of vegetable oil and derivatives thereof, wherein the vegetable oil is selected from one or a mixture of more of castor oil, soybean oil, palm oil, rapeseed oil, linseed oil and peanut oil; the vegetable oil derivative is selected from one or more of epoxidized compounds of vegetable oil and amidated compounds of vegetable oil, and the carrier accounts for 10-25% of the total mass of the defoaming agent.

The carrier of the invention is added in two parts, the first part A1 accounts for 4/5 of the total mass of the carrier, and the second part accounts for 1/5 of the total mass of the carrier.

B white carbon black

The white carbon black is divided into two types of precipitated white carbon black and gas-phase white carbon black according to the manufacturing method, and is divided into hydrophilic white carbon black and hydrophobic white carbon black according to surface properties, and the white carbon black is selected from hydrophobic gas-phase white carbon black, and further preferably has the specific surface area of 50-200 m²Hydrophobic fumed silica/g; the white carbon black accounts for 0.5-3% of the total mass of the defoaming agent.

C fatty acid metal soap

The fatty acid metal soap is selected from magnesium salt, aluminum salt and calcium salt of fatty acid, wherein the fatty acid refers to saturated or unsaturated fatty acid with 8-18 carbon atoms, and the dosage of the fatty acid metal soap is 1-15% of the total mass of the defoaming agent.

D dispersing agent

The dispersant is selected from nonionic surfactants, anionic surfactants or amphoteric surfactants, and the specific nonionic surfactant is preferably alkyl glycoside (APG); the anionic surfactant is selected from carboxylate, sulfonate, sulfate ester salt and phosphate ester salt, and is preferably sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl diphenyl oxide disulfonate and sodium dodecyl phosphate; the amphoteric surfactant is selected from amino acid type or betaine type, and preferably dodecyl dimethyl betaine, dodecyl aminopropionic acid, and decyl dimethyl hydroxypropyl sulfobetaine.

The dispersant accounts for 0.1-1% of the total mass of the defoaming agent.

E thickening agent

The thickener comprises sodium carboxymethylcellulose, polyacrylate, carbomer, polyvinyl alcohol, xanthan gum and guar gum. Polyacrylates are preferred herein as thickeners. The thickening agent accounts for 0.27-0.5% of the total mass of the defoaming agent.

F emulsifier

The emulsifier is mainly selected from glyceryl monostearate, polyglycerol fatty acid ester, lecithin, mono-diglyceride, propylene glycol ester, polyoxyethylene (40) stearate, span 80, span 60, span 20, tween 80, tween 60 and tween 20; further preferably span 60 or polyoxyethylene (40) stearate. One or two of the emulsifiers are selected and mixed for use, and the using amount of the emulsifiers accounts for 1-15% of the total mass of the defoaming agent.

G preservative

The preservative is mainly selected from sodium benzoate, potassium sorbate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, dehydroacetic acid, sodium propionate and calcium propionate. Potassium sorbate is preferred as a preservative in the present invention. The consumption of the preservative accounts for 0.1-1% of the total mass of the defoaming agent.

H water

The water is deionized water, and the using amount of the water accounts for 45-75% of the total mass of the defoaming agent. The water of the invention is added in three parts, wherein the first part H1 accounts for 3/10 of the total mass of the water, the second part H2 accounts for 4/10 of the total mass of the water, and the third part H3 accounts for 3/10 of the total mass of the water.

The preparation method of the defoaming agent for the emulsion type environment-friendly coating comprises the following steps:

(1) preparation of the premix

Adding the white carbon black B into an A1 carrier heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a white carbon black/carrier dispersion liquid;

mixing C fatty acid metal soap, D dispersant and A2 carrier, heating to 100-150 deg.C, holding the temperature for 10-35min, mixing with the white carbon black/carrier dispersion liquid at room temperature, grinding with colloid mill, and homogenizing to obtain the premixed liquid.

(2) Preparation of thickening fluid

Heating H1 water to above 70 deg.C, slowly adding thickening agent E under stirring, stirring for 60min, and cooling to below 35 deg.C to obtain thickening solution.

(3) Preparation of the antifoam

Heating H2 water and keeping the temperature at 60-80 deg.C, adding the F emulsifier into the hot water, stirring for 5-15min, and slowly adding the premix under proper stirring while keeping the temperature above 60 deg.C. Mixing for 30-60min, cooling to 40-50 deg.C, grinding with colloid mill until particle diameter is below 10 μm, mixing with thickening liquid under high speed stirring for 20-30min, adding antiseptic G and H3 water, stirring, and homogenizing for 50-60min to obtain the final product.

Detailed Description

Example 1

(1) Preparation of the premix

20g of a specific surface area of 80m²Adding hydrophobic fumed silica/g into 100g of castor oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 121g of fatty acid aluminum, 3g of alkyl glycoside and 30g of amidated castor oil, heating to 100 ℃, preserving heat for 20min, mixing with white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 198.3g water to above 70 deg.C, slowly adding 2.7g carbomer under stirring, stirring for 60min, and cooling to below 35 deg.C to obtain thickening solution.

(3) Preparation of the antifoam

200g of water are heated and kept at 70 ℃ and 120g of glyceryl monostearate are added to the hot water, stirred for 5min and then slowly added to the premix with appropriate stirring, while the temperature is maintained above 60 ℃. And continuously mixing for 30min, cooling to 40 ℃ after uniform mixing, grinding by a colloid mill until the particle size of the particles is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 20min, adding 5g of sodium benzoate and 200g of water, stirring and homogenizing for 50min to obtain the finished product of the defoaming agent.

Example 2

(1) Preparation of the premix

30g of a specific surface area of 60m²Adding the hydrophobic fumed silica per gram into 150 grams of soybean oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 87g of fatty acid magnesium, 4g of sodium dodecyl sulfate and 40g of peanut oil, heating to 110 ℃, preserving heat for 15min, mixing with white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix liquid.

(2) Preparation of thickening fluid

Heating 180g of water to above 70 ℃, slowly adding 3g of xanthan gum under stirring, keeping the temperature and stirring for about 60min, and cooling to below 35 ℃ to obtain thickening fluid.

(3) Preparation of the antifoam

250g of water are heated and maintained at 75 ℃ and 80g of lecithin are added to the hot water, stirred for 8min and then slowly added to the premix with appropriate stirring, while maintaining the temperature above 60 ℃. And continuously mixing for 60min, cooling to 42 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 30min, adding 6g of potassium sorbate and 170g of water, stirring and homogenizing for 60min to obtain the finished product of the defoaming agent.

Example 3

(1) Preparation of the premix

10g of a specific surface area of 50m²Adding hydrophobic fumed silica/g into 200g of peanut oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 80g of fatty acid calcium, 8g of sodium dodecyl benzene sulfonate and 20g of epoxy peanut oil, heating to 120 ℃, preserving heat for 30min, mixing with white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix liquid.

(2) Preparation of thickening fluid

Heating 120g of water to above 70 ℃, slowly adding 5g of sodium carboxymethylcellulose while stirring, keeping the temperature and stirring for about 60min, and cooling to below 35 ℃ to obtain the thickening solution.

(3) Preparation of the antifoam

220g of water are heated and kept at 80 ℃ and 150g of propylene glycol ester are added to the hot water, stirred for 10min and then slowly added to the premix with appropriate stirring, while the temperature is kept above 60 ℃. And continuously mixing for 50min, cooling to 47 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 25min, adding 7g of sodium propionate and 180g of water, stirring and homogenizing for 52min, and thus obtaining the finished product of the defoaming agent.

Example 4

(1) Preparation of the premix

5g of a specific surface area of 100m²Adding hydrophobic fumed silica/g into 200g palm oil heated to 100 deg.C, stirring, and mixingMixing, cooling the mixture to room temperature to obtain white carbon black/carrier dispersion liquid;

mixing 10g of fatty acid aluminum, 9g of sodium dodecyl phosphate and 50g of rapeseed oil, heating to 140 ℃, preserving heat for 35min, mixing with the white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 225g water to above 70 deg.C, slowly adding 5g polyacrylate under stirring, stirring for 60min, and cooling to below 35 deg.C to obtain thickening solution.

(3) Preparation of the antifoam

215g of water are heated and kept at 60 ℃ and 140g of span 60 are added to the hot water, stirred for 13min and then slowly added to the premix with appropriate stirring, while the temperature is kept above 60 ℃. And continuously mixing for 40min, cooling to 46 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 24min, adding 6g of propyl p-hydroxybenzoate and 135g of water, stirring and homogenizing for 55min, and thus obtaining the finished product of the defoaming agent.

Example 5

(1) Preparation of the premix

29g of a specific surface area of 140m²Adding the hydrophobic fumed silica/g into 80g of rapeseed oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 130g of magnesium fatty acid, 5g of dodecyl amino propionic acid and 50g of epoxy rapeseed oil, heating to 150 ℃, preserving heat for 10min, mixing with white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 227g of water to above 70 ℃, slowly adding 4g of polyvinyl alcohol while stirring, keeping the temperature and stirring for about 60min, and cooling to below 35 ℃ to obtain thickening fluid.

(3) Preparation of the antifoam

180g of water are heated and maintained at 75 ℃ and 70g of tween 80 are added to the hot water, stirred for 15min and then slowly added to the premix with appropriate stirring, while maintaining the temperature above 60 ℃. And continuously mixing for 45min, cooling to 45 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 23min, adding 5g of dehydroacetic acid and 220g of water, stirring and homogenizing for 53min to obtain the finished product of the defoaming agent.

Example 6

(1) Preparation of the premix

The specific surface area of 12g was set to 200m²Adding the hydrophobic fumed silica/g into 140g of amidated rapeseed oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 150g of fatty acid calcium, 6g of alkyl glycoside and 30g of rapeseed oil, heating to 130 ℃, preserving heat for 15min, mixing with white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 176g of water to above 70 ℃, slowly adding 3g of guar gum under stirring, keeping the temperature and stirring for about 60min, and cooling to below 35 ℃ to obtain thickening fluid.

(3) Preparation of the antifoam

270g of water are heated and maintained at 80 ℃ and 60g of polyoxyethylene (40) stearate are added to the hot water, stirred for 12min and then the premix is added slowly with appropriate stirring, while maintaining the temperature above 60 ℃. And continuously mixing for 55min, cooling to 50 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 22min, adding 3g of calcium propionate and 150g of water, stirring and homogenizing for 52min to obtain the finished product of the defoaming agent.

Example 7

(1) Preparation of the premix

26g of a specific surface area of 180m²Adding the hydrophobic fumed silica/g into 190g of soybean oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 84g of aluminum stearate, 1g of dodecyl dimethyl betaine and 26g of rapeseed oil, heating to 120 ℃, preserving heat for 20min, mixing with the white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 135g of water to above 70 ℃, slowly adding 2g of sodium carboxymethylcellulose while stirring, keeping the temperature and stirring for about 60min, and cooling to below 35 ℃ to obtain the thickening solution.

(3) Preparation of the antifoam

Heating 300g of water and keeping the temperature at 70 ℃, adding 10g of polyglycerol fatty acid ester into the hot water, stirring for 14min, and slowly adding the premixed solution under proper stirring while keeping the temperature above 60 ℃. And continuously mixing for 30min, cooling to 49 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 22min, adding 1g of potassium sorbate and 225g of water, stirring and homogenizing for 56min to obtain the finished product of the defoaming agent.

Example 8

(1) Preparation of the premix

28g of a specific surface area of 160m²Adding hydrophobic fumed silica/g into 120g of linseed oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 90g of fatty acid calcium, 10g of decyl dimethyl hydroxypropyl sulfobetaine and 40g of epoxy linseed oil, heating to 110 ℃, keeping the temperature for 25min, mixing with white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 205g water to above 70 deg.C, slowly adding 4g polyacrylate under stirring, stirring for 60min, and cooling to below 35 deg.C to obtain thickening solution.

(3) Preparation of the antifoam

295g of water is heated and kept at 65 ℃, 300g of span 60 and tween 80 are added into the hot water, stirred for 9min, and then the premixed solution is slowly added under proper stirring while keeping the temperature above 60 ℃. And continuously mixing for 35min, cooling to 48 ℃ after uniform mixing, grinding by a colloid mill until the particle size of the particles is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 20min, adding 8g of sodium benzoate and 170g of water, stirring and homogenizing for 60min to obtain the finished product of the defoaming agent.

Example 9

(1) Preparation of the premix

18g of a specific surface area of 110m²Adding hydrophobic fumed silica/g into 110g of linseed oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 130g of fatty acid aluminum, 2g of sodium dodecyl sulfate and 20g of peanut oil, heating to 120 ℃, preserving heat for 30min, mixing with white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 147g of water to above 70 ℃, slowly adding 5g of sodium carboxymethylcellulose while stirring, keeping the temperature and stirring for about 60min, and cooling to below 35 ℃ to obtain the thickening solution.

(3) Preparation of the antifoam

260g of water was heated and kept at 65 ℃ and 94g of tween 60 was added to the hot water, stirred for 10min and then slowly added to the premix with appropriate stirring, while keeping the temperature above 60 ℃. And continuously mixing for 45min, cooling to 41 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 25min, adding 9g of propyl p-hydroxybenzoate and 205g of water, stirring and homogenizing for 58min to obtain the finished product of the defoaming agent.

Example 10

(1) Preparation of the premix

22g of a specific surface area of 120m²Adding the hydrophobic fumed silica/g into 180g of rapeseed oil heated to 100 ℃, stirring and mixing, and cooling the mixture to room temperature to obtain a silica/carrier dispersion liquid;

mixing 100g of aluminum stearate, 7g of sodium dodecyl benzene sulfonate and 30g of soybean oil, heating to 150 ℃, preserving heat for 25min, mixing with the white carbon black/carrier dispersion liquid at room temperature, and grinding and homogenizing by a colloid mill to obtain the premix.

(2) Preparation of thickening fluid

Heating 165g of water to above 70 ℃, slowly adding 2g of sodium carboxymethylcellulose while stirring, keeping the temperature and stirring for about 60min, and cooling to below 35 ℃ to obtain thickening fluid.

(3) Preparation of the antifoam

189g of water are heated and maintained at 75 ℃ and 130g of span 80 are added to the hot water, stirred for 7min and then slowly added to the premix with appropriate stirring, while maintaining the temperature above 60 ℃. And continuously mixing for 50min, cooling to 43 ℃ after uniform mixing, grinding by a colloid mill until the particle size is below 10 mu m, stirring and mixing with the thickening liquid at a high speed for 28min, adding 10g of potassium sorbate and 165g of water, stirring and homogenizing for 55min to obtain the finished product of the defoaming agent.

Comparative example 1

An antifoam agent prepared according to example 1 of patent CN 106621478A.

Comparative example 2

Preparation of antifoam agent according to example 1 of patent CN105983252A

Defoaming and foam suppressing performance test

The test method comprises the following steps: adding 135g of prepared paint into a 1000ml stainless steel cup, then adding 15g of styrene-acrylic emulsion, stirring for 1min at a stirring speed of 600rpm under a high-speed dispersion machine to uniformly mix the paint and the styrene-acrylic emulsion, then adding 1% of thickening agent, 0.2% of 2-amino-2-methyl-1-propanol, continuously stirring for 1min at 600rpm, finally adding 0.3% of defoaming agent, stirring for 6min at a stirring speed of 600rpm, recording apparent bubbles after stopping stirring, immediately pouring the mixture into a 100ml measuring cylinder, recording the calculated specific gravity of the volume V, and indicating that the defoaming agent has good defoaming performance when the numerical value is large. The test results were as follows:

TABLE 1 comparison of defoaming agent defoaming and foam suppressing Properties