Defoaming agent for water-based paint as well as preparation method and application of defoaming agent

Abstract

The invention discloses a defoaming agent for water-based paint as well as a preparation method and application of the defoaming agent. The defoaming agent is prepared from the following components in parts by weight: 100 to 200 parts of vegetable oil, 20 to 40 parts of expanded perlite powder, 0.6 to 1.5 parts of stannous octoate, 20 to 40 parts of polyether polyol, 5 to 10 parts of polyethylene glycol monooleate and 0.1 to 0.5 part of preservative. The preparation method comprises the following steps: reacting vegetable oil, expanded perlite powder and stannous octoate for 6 hours at 70 DEG C under the protection of nitrogen, so that the vegetable oil is grafted on the surface of the perlite powder; adding polyether polyol and an emulsifier, and stirring at 60 DEG C for 2 hours; and cooling, adding the preservative, and uniformly stirring to obtain the oil-based defoaming agent. According to the defoaming agent, the porous structure and the surface hydrophobic characteristic of the modified perlite powder are utilized, the foam inhibition effect of the polyether polyol is cooperated, rapid defoaming, lasting foam inhibition, high temperature resistance and adaptation to a high-viscosity system are achieved, compatibility with water-based paint is good, the appearance of a paint film is not affected, and the defoaming agent is particularly suitable for the high-speed dispersion and construction process of the water-based paint.

Description

Technical Field

[0001] This invention relates to the field of chemical additives technology, specifically to a defoamer for water-based coatings, its preparation method, and its application. Background Technology

[0002] Water-based coatings are widely used in construction, woodworking, and industrial coatings due to their advantages such as environmental friendliness and low VOC emissions. However, during the production, filling, and application of water-based coatings, the presence of surfactants and their high-speed dispersion make the system prone to foaming. If foam is not eliminated in time, it can lead to surface defects such as pinholes, craters, and fisheyes in the coating, affecting the appearance and protective performance of the coating film, and in severe cases, even causing production interruptions and material waste.

[0003] Currently, commonly used defoamers mainly include mineral oil-based, silicone-based, and polyether-based defoamers. Mineral oil-based defoamers are low in cost but lack sufficient high-temperature defoaming performance; silicone-based defoamers defoam quickly but have poor compatibility with aqueous systems and are prone to silicone spots; polyether-based defoamers have a long defoaming time but a slow initial defoaming speed and low defoaming efficiency in high-viscosity systems. Therefore, developing a novel defoamer that combines rapid defoaming, long-lasting defoaming, high-temperature resistance, suitability for high-viscosity systems, and good compatibility is of great significance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a defoamer for water-based coatings, its preparation method and application.

[0005] To solve the above-mentioned technical problems, the defoamer in this invention adopts the following technical solution: the raw materials of the defoamer are composed of the following components by weight: vegetable oil: 100-200 parts; expanded perlite powder: 20-40 parts; stannous octoate: 0.6-1.5 parts; polyether polyol: 20-40 parts; polyethylene glycol monooleate: 5-10 parts; preservative: 0.1-0.5 parts.

[0006] Furthermore, in the above-mentioned defoamer technical solution, the vegetable oil is at least one of soybean oil or flaxseed oil.

[0007] Furthermore, in the above-mentioned defoamer technical solution, the specific surface area of ​​the expanded perlite powder is greater than 200 m² / g, and the surface contains hydroxyl groups.

[0008] Furthermore, in the above-mentioned defoamer technical solution, the polyether polyol is a glycerol polyoxypropylene ether with a molecular weight of 3000.

[0009] Furthermore, in the above-mentioned defoamer technical solution, the preservative is sodium benzoate.

[0010] Furthermore, in the above-mentioned defoamer technical solution, the preparation method of the defoamer includes the following steps: Step (1) Add vegetable oil, expanded perlite powder and stannous octoate to the reaction vessel, and stir at 70°C for 6 hours under nitrogen protection; Step (2) Add polyether polyol and polyethylene glycol (400) monooleate under stirring, and stir at 60°C for 2 hours; Step (3) Cool to room temperature, add preservative, and continue stirring for 30 minutes to obtain the oil-based defoamer.

[0011] In application, the defoamer is added to the water-based coating system at a mass percentage of 0.05%-0.3% to control foam generated during high-speed dispersion and construction.

[0012] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages:

[0013] 1. By grafting expanded perlite powder with vegetable oil, a hydrophobic porous structure is formed, which can quickly puncture foam and continuously inhibit foam regeneration.

[0014] 2. The modified perlite powder and polyether polyol work synergistically to maintain excellent defoaming performance in high-temperature and high-viscosity water-based coatings.

[0015] 3. The modified particles have good compatibility with the oil phase. When used with emulsifiers, they are evenly dispersed in water-based systems and do not cause paint film defects such as pinholes and fisheyes.

[0016] 4. The preparation process is simple, the raw materials are readily available, the cost is controllable, the reaction conditions are mild, and it is suitable for industrial production. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] This invention provides a defoamer for water-based coatings, which is composed of the following raw materials in parts by weight:

[0019] Vegetable oil: 100-200 parts;

[0020] Expanded perlite powder: 20-40 parts;

[0021] Stannous octoate: 0.6-1.5 parts;

[0022] Polyether polyol: 20-40 parts;

[0023] Polyethylene glycol monooleate: 5-10 parts;

[0024] Preservative: 0.1-0.5 parts.

[0025] The vegetable oil serves as the continuous phase of the entire defoamer, carrying other components and facilitating addition and dispersion. Under the catalysis of stannous octoate, the double bonds of unsaturated fatty acids in the vegetable oil can undergo a grafting reaction with the hydroxyl groups on the surface of expanded perlite powder, changing the surface of the perlite powder from hydrophilic to hydrophobic.

[0026] Vegetable oils have a certain defoaming ability, which can reduce the surface tension of the gas-liquid interface and promote foam breakage.

[0027] The preferred vegetable oil is soybean oil or flaxseed oil, which contains a high proportion of unsaturated fatty acids (such as linoleic acid and linolenic acid), has high double bond activity, and is easy to chemically graft onto the surface of perlite powder, thereby enhancing the modification effect.

[0028] The expanded perlite powder has a porous structure, preferably with a specific surface area >200 m² / g, and its surface is rich in hydroxyl-rich expanded perlite powder. It can physically adsorb onto the surface of air bubbles, utilizing its porous structure to puncture the foam film and achieve rapid defoaming. Under the catalysis of stannous octoate, vegetable oil is grafted onto its surface, changing it from hydrophilic to hydrophobic, enhancing its compatibility with the oil phase while maintaining its porous structure. The modified hydrophobic porous particles can exist stably in the system, continuously adsorbing onto the surface of newly formed air bubbles, preventing foam regeneration, and achieving long-term foam suppression.

[0029] The stannous octoate is used as a catalyst for esterification / grafting reactions to improve modification efficiency.

[0030] The polyether polyol (preferably glycerol polyoxypropylene ether, molecular weight 3000) acts as a defoamer, exhibiting excellent defoaming properties. It can continuously suppress foam formation in the system, extending the effective time of the defoamer. Simultaneously, the polyether polyol possesses high-temperature resistance, maintaining its activity at high temperatures, making it suitable for high-speed dispersion processes in water-based coatings.

[0031] The polyethylene glycol monooleate is used as an emulsifier, preferably polyethylene glycol (400) monooleate, which can reduce the interfacial tension between oil and water, allowing the oil-based defoamer to be uniformly dispersed in the waterborne coating, preventing oil droplet aggregation, and effectively introducing modified perlite powder and polyether polyol into the waterborne system stably. As a nonionic emulsifier, polyethylene glycol (400) monooleate is insensitive to changes in electrolytes and pH, making it suitable for the variable environment of waterborne coatings.

[0032] The preservative is sodium benzoate, which prevents the defoamer from deteriorating due to microbial contamination during storage and extends the product's shelf life.

[0033] The following are specific embodiments of the present invention.

[0034] Example 1

[0035] Weigh 100 parts of soybean oil (soybean oil with a high content of unsaturated fatty acids), 20 parts of expanded perlite powder (specific surface area >200 m² / g), and 0.6 parts of stannous octoate. Add them to a reaction vessel, purge with nitrogen, and stir at 70°C for 6 hours. Then add 20 parts of glycerol polyoxypropylene ether (molecular weight 3000) and 5 parts of polyethylene glycol (400) monooleate, and stir at 60°C for 2 hours. After cooling to room temperature, add 0.3 parts of sodium benzoate and continue stirring for 30 minutes to obtain defoamer sample A.

[0036] Example 2

[0037] Weigh 150 parts of linseed oil, 30 parts of expanded perlite powder (specific surface area >200 m² / g), and 1.0 part of stannous octoate, add them to a reaction vessel, purge with nitrogen, and stir at 70℃ for 6 hours. Then add 30 parts of glycerol polyoxypropylene ether (molecular weight 3000) and 8 parts of polyethylene glycol (400) monooleate, and stir at 60℃ for 2 hours. After cooling to room temperature, add 0.3 parts of sodium benzoate, and continue stirring for 30 minutes to obtain defoamer sample B.

[0038] Example 3

[0039] Weigh 200 parts of soybean oil, 40 parts of expanded perlite powder (specific surface area >200 m² / g), and 1.5 parts of stannous octoate, add them to a reaction vessel, purge with nitrogen, and stir at 70℃ for 6 hours. Then add 40 parts of glycerol polyoxypropylene ether (molecular weight 3000) and 10 parts of polyethylene glycol (400) monooleate, and stir at 60℃ for 2 hours. After cooling to room temperature, add 0.5 parts of sodium benzoate, and continue stirring for 30 minutes to obtain defoamer sample C.

[0040] Application examples

[0041] The defoamer sample A obtained in Example 1 was added to the water-based acrylic emulsion coating at a mass percentage of 0.1%. After stirring for 10 minutes using a high-speed disperser (3000 rpm), the foam was observed to break down rapidly, and no obvious foam regeneration was observed within 30 minutes of standing. The coating was applied to a glass plate, and after drying, the paint film was smooth and free of defects such as pinholes, craters, and fisheyes.

[0042] The defoamer sample B obtained in Example 2 was added to the waterborne polyurethane coating at an addition amount of 0.2%. Under the same conditions, the defoaming effect was comparable to that of sample A, and the paint film had a good appearance.

[0043] The defoamer sample C obtained in Example 3 was added to the waterborne epoxy coating at an addition amount of 0.15%, and the test results also showed excellent defoaming performance and compatibility.

[0044] The defoamer provided by this invention is suitable for various water-based coating systems, and performs particularly well under harsh conditions such as high viscosity, high temperature, and high speed dispersion. It can be widely used in architectural coatings, wood coatings, industrial anti-corrosion coatings and other fields, and has good industrial application prospects.

[0045] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A defoamer for water-based coatings, characterized in that, The components of the defoamer raw material by weight are: Vegetable oil: 100-200 parts; Expanded perlite powder: 20-40 parts; Stannous octoate: 0.6-1.5 parts; Polyether polyol: 20-40 parts; Polyethylene glycol monooleate: 5-10 parts; Preservative: 0.1-0.5 parts.

2. The defoamer for water-based coatings according to claim 1, characterized in that: The vegetable oil is at least one of soybean oil or flaxseed oil.

3. The defoamer for water-based coatings according to claim 1, characterized in that: The expanded perlite powder has a specific surface area greater than 200 m² / g and contains hydroxyl groups on its surface.

4. The defoamer for water-based coatings according to claim 1, characterized in that: The polyether polyol is a glycerol polyoxypropylene ether with a molecular weight of 3000.

5. The defoamer for water-based coatings according to claim 1, characterized in that: The preservative is sodium benzoate.

6. A defoamer for water-based coatings according to any one of claims 1-5, characterized in that: The preparation method of this defoamer includes the following steps: Step (1) Add vegetable oil, expanded perlite powder and stannous octoate to the reaction vessel and stir at a constant temperature of 70°C for 6 hours under nitrogen protection; Step (2) Add polyether polyol and polyethylene glycol (400) monooleate under stirring, and keep warm at 60°C and stir for 2 hours; Step (3) Cool to room temperature, add preservative, and continue stirring for 30 minutes to obtain oil-based defoamer.

7. The defoamer for water-based coatings according to claim 6, characterized in that: This defoamer is added to water-based coating systems at a mass percentage of 0.05%-0.3% to control foam generated during high-speed dispersion and application.