Polyether siloxane defoamer for water-based paint and method for preparing the same

Abstract

The present application relates to the technical field of paint, and proposes a polyether siloxane defoaming agent for water-based paint and a preparation method thereof.The components of the polyether siloxane defoaming agent include polyether modified silicone oil, silicone paste, emulsifier and additive, and the additive includes perfluoroalkyl alcohol polyoxyethylene ether.The perfluoroalkyl chain and the polyoxyethylene ether chain of the additive perfluoroalkyl alcohol polyoxyethylene ether in the defoaming agent respectively endow the material with extremely low surface energy, excellent chemical inertness and higher hydrophilicity, high compatibility with water-based paint, and can effectively reduce defects such as shrinkage and pinholes of paint film, and enhance the resistance of the defoaming agent to acid and alkali, and the chemical stability is high.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a polyether siloxane defoamer for water-based coatings and its preparation method. Background Technology

[0002] With rapid industrialization and increasingly stringent environmental requirements, water-based coatings are gradually replacing traditional oil-based coatings, becoming the mainstream choice in the market. This shift is not only due to the lower volatile organic compound (VOC) emissions of water-based coatings, making them more compliant with environmental regulations, but also because of their advantages in safety and ease of use. However, water-based coatings are prone to bubble formation during production and application. These bubbles can create defects in the paint film, affecting its appearance and final performance.

[0003] To address this challenge, defoamers (or antifoaming agents) are widely used in water-based coatings. Defoamers eliminate bubbles through the principle of incompatibility, utilizing their incompatibility with the coating system to disrupt the stability of the bubbles and cause them to burst rapidly. However, the carrier materials of traditional defoamers are not fully compatible with the coating system, leading to surface defects such as pinholes and craters in the paint film. These defects not only affect the appearance of the coating but may also weaken its protective properties and shorten its service life.

[0004] Patent CN110157232A discloses a defoamer specifically for water-based environmentally friendly coatings. However, this defoamer relies excessively on emulsifiers, which leads to decreased stability and affects its dispersion and long-term performance in coatings. Therefore, a defoamer with high compatibility and good stability with water-based coatings is needed. Summary of the Invention

[0005] In view of this, the present invention proposes a polyether siloxane defoamer for water-based coatings with high compatibility and good stability, and a method for preparing the same.

[0006] The technical solution of the present invention is implemented as follows: On the one hand, the present invention provides a polyether siloxane defoamer for water-based coatings, comprising polyether modified silicone oil, silicone paste, emulsifier and additives, wherein the additives include perfluoroalkyl ethanol polyoxyethylene ether.

[0007] Specifically, the perfluoroalkyl chains of perfluoroalkyl ethanol polyoxyethylene ethers endow the material with extremely low surface energy and excellent chemical inertness, making it highly effective in reducing surface tension. This significantly enhances the dispersibility of defoamers and effectively reduces defects such as pinholes and craters in the paint film. The polyoxyethylene ether chain is a hydrophilic part, typically composed of repeating ethoxy (-CH2CH2O-) units, giving it good solubility and dispersibility in waterborne coating systems, thus enhancing the high compatibility of waterborne coatings. Furthermore, perfluoroalkyl ethanol polyoxyethylene ethers exhibit excellent resistance to acids and alkalis and high chemical stability.

[0008] Based on the above technical solutions, the preferred formulation, calculated by weight, includes 65-70 parts of polyether-modified silicone oil, 4-6 parts of silicone paste, 8-12 parts of emulsifier, and 12-18 parts of additives.

[0009] Based on the above technical solutions, preferably, the additives also include polyethylene glycol phosphate.

[0010] Specifically, polyethylene glycol phosphate (PEG) possesses excellent hydrophilicity and emulsifying ability. As a surfactant, its hydrophilic groups enhance the solubility and compatibility of perfluoroalkyl ethanol polyoxyethylene ether (PFEE) in waterborne coatings, helping to form a more uniform dispersion. The stable structure of phosphate esters further improves the stability of defoamers under dynamic and different environmental conditions, prevents phase separation of PFEE, and improves the overall defoaming performance of the coating and the surface quality of the paint film.

[0011] By improving compatibility and dispersibility, polyethylene glycol phosphate can help overcome the technical barriers of perfluoroalkyl ethanol polyoxyethylene ethers in waterborne coatings, thereby achieving a more durable and effective defoaming effect.

[0012] Based on the above technical solutions, preferably, the mass ratio of the perfluoroalkyl ethanol polyoxyethylene ether to polyethylene glycol phosphate is 3-5:1.

[0013] Based on the above technical solutions, preferably, the preparation method of the polyether modified silicone oil includes the following steps: allyl polyether and hydrogen-containing silicone oil are put into a reaction vessel, stirred and heated to 110°C, chloroplatinic acid catalyst is added, and the temperature is further raised to 125-135°C for polymerization reaction for 4-5 hours. After the reaction is completed, it is aged for 2 hours to obtain polyether modified silicone oil.

[0014] Based on the above technical solutions, preferably, the mass ratio of allyl polyether to hydrogen-containing silicone oil is 70-80:20-30, and the amount of chloroplatinic acid is 0.001%-0.002% of the total amount of allyl polyether and hydrogen-containing silicone oil.

[0015] Based on the above technical solutions, preferably, the molecular weight of the allyl polyether is 1000 Da, and the molar ratio of EO to PO is 7:3.

[0016] Based on the above technical solutions, preferably, the molecular weight of the hydrogen-containing silicone oil is about 1000 Da, and the hydrogen mass fraction is 0.18%.

[0017] Based on the above technical solutions, preferably, the emulsifier is one or both of CJ-8100 emulsifier and CJ-8000 emulsifier.

[0018] On the other hand, the present invention also provides a method for preparing a polyether siloxane defoamer for water-based coatings, wherein polyether modified silicone oil, silicone paste, emulsifier and additives are mixed in proportion, emulsified in an emulsifying disperser at 2700-2800 r / min for 20-30 min, and then heated to 120-130℃ and stirred for 2-3 h to obtain the defoamer.

[0019] The polyether siloxane defoamer for water-based coatings and its preparation method of the present invention have the following advantages over the prior art:

[0020] (1) In the defoamer of the present invention, perfluoroalkyl ethanol polyoxyethylene ether is used as an additive. Its perfluoroalkyl chain and polyoxyethylene ether chain respectively endow the material with extremely low surface energy, excellent chemical inertness and high hydrophilicity, which improves the compatibility of the defoamer with water-based coatings and can also effectively reduce defects such as cratering and pinholes in the paint film. In addition, perfluoroalkyl ethanol polyoxyethylene ether can also enhance the defoamer's resistance to acids and alkalis and improve the chemical stability of the defoamer.

[0021] (2) Polyethylene glycol phosphate (PEG) is compounded with perfluoroalkyl ethanol polyoxyethylene ether (PFEE). The hydrophilic groups in PEG's structure enhance the solubility and compatibility of PFEE in waterborne coatings, helping to form a more uniform dispersion. Furthermore, the stable structure of the phosphate ester can further improve the stability of the defoamer under dynamic and different environmental conditions, preventing phase separation of PFEE and improving the overall defoaming performance and surface quality of the coating film. By improving compatibility and dispersibility, PEG can help overcome the technical barriers of PFEE in waterborne coatings, thereby achieving a more durable and effective defoaming effect. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The image shows a physical product of the polyether siloxane defoamer prepared according to the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not 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 effort are within the scope of protection of the present invention.

[0025] The allyl polyether of this invention, product number FB1000, was purchased from Yangzhou Chenhua New Materials Co., Ltd. The hydrogen-containing silicone oil, product number H518, was purchased from Zhejiang Runhe Chemical New Materials Co., Ltd. The emulsifiers CJ-8000 and CJ-8100 were both manufactured in-house by our company (Wuhan Chenyuda Technology Co., Ltd.). The silicone paste, product number 855E 352, was purchased from Shenzhen Longdi Chemical Co., Ltd. The perfluoroalkyl ethanol polyoxyethylene ether, model PEO-300, was purchased from Hubei Shineng Chemical Technology Co., Ltd. The polyethylene glycol phosphate was purchased from Jiangsu Haian Petrochemical Plant.

[0026] Example 1

[0027] The components of the waterborne coating polyether siloxane defoamer in this embodiment include 695g of polyether modified silicone oil, 55g of silicone paste, 100g of CJ-8100 emulsifier, and 150g of perfluoroalkyl ethanol polyoxyethylene ether.

[0028] The preparation method of polyether modified silicone oil includes the following steps: 723g of allyl polyether and 277g of hydrogen-containing silicone oil are put into a reaction vessel, the feed port is closed, stirring is started, and the temperature is raised; when the temperature inside the vessel reaches 110℃, the heating is stopped, the feed port is opened, 0.01g of chloroplatinic acid catalyst is added, the temperature is raised to 130℃, and then the polymerization reaction is carried out at the temperature for 4.5h. After the reaction is completed, the product is aged for 2h to obtain polyether modified silicone oil.

[0029] The preparation method of the waterborne coating polyether siloxane defoamer in this embodiment is as follows: polyether modified silicone oil, silicone paste, CJ-8100 emulsifier and perfluoroalkyl ethanol polyoxyethylene ether are mixed in proportion, emulsified at 2750 r / min for 30 min using an emulsifying disperser, and then heated to 125℃ and stirred for 3 h to obtain the defoamer.

[0030] Example 2

[0031] Compared with Example 1, Example 2 added polyethylene glycol phosphate as an additive, as detailed below:

[0032] The components of the waterborne coating polyether siloxane defoamer in this embodiment include 695g of polyether modified silicone oil, 55g of silicone paste, 100g of CJ-8100 emulsifier, 150g of perfluoroalkyl ethanol polyoxyethylene ether, and 30g of polyethylene glycol phosphate.

[0033] The preparation method of polyether modified silicone oil includes the following steps: 723g of allyl polyether and 277g of hydrogen-containing silicone oil are put into a reaction vessel, the feed port is closed, stirring is started, and the temperature is raised; when the temperature inside the vessel reaches 110℃, the heating is stopped, the feed port is opened, 0.01g of chloroplatinic acid catalyst is added, the temperature is raised to 130℃, and then the polymerization reaction is carried out at the temperature for 4.5h. After the reaction is completed, the product is aged for 2h to obtain polyether modified silicone oil.

[0034] The preparation method of the waterborne coating polyether siloxane defoamer in this embodiment is as follows: polyether modified silicone oil, silicone paste, CJ-8100 emulsifier, perfluoroalkyl ethanol polyoxyethylene ether and polyethylene glycol phosphate are mixed in proportion, emulsified at 2750 r / min for 30 min using an emulsifying disperser, and then heated to 125℃ and stirred for 3 h to obtain the defoamer.

[0035] Example 3

[0036] The components of the waterborne coating polyether siloxane defoamer in this embodiment include 650g of polyether modified silicone oil, 40g of silicone paste, 80g of CJ-8000 emulsifier, 90g of perfluoroalkyl ethanol polyoxyethylene ether, and 30g of polyethylene glycol phosphate.

[0037] The preparation method of polyether modified silicone oil includes the following steps: 700g of allyl polyether and 300g of hydrogen-containing silicone oil are put into a reaction vessel, the feed port is closed, stirring is started, and the temperature is raised; when the temperature inside the vessel reaches 110℃, the heating is stopped, the feed port is opened, 0.02g of chloroplatinic acid catalyst is added, the temperature is raised to 125℃, and then the polymerization reaction is carried out at the temperature for 4h. After the reaction is completed, the product is aged for 2h to obtain polyether modified silicone oil.

[0038] The preparation method of polyether siloxane defoamer for water-based coatings is as follows: polyether modified silicone oil, silicone paste, CJ-8000 emulsifier, perfluoroalkyl ethanol polyoxyethylene ether and polyethylene glycol phosphate are mixed in proportion, emulsified at 2700 r / min for 20 min using an emulsifying disperser, and then heated to 120℃ and stirred for 2 h to obtain the defoamer.

[0039] Example 4

[0040] The components of the waterborne coating polyether siloxane defoamer in this embodiment include 700g of polyether modified silicone oil, 60g of silicone paste, 120g of CJ-8100 emulsifier, 120g of perfluoroalkyl ethanol polyoxyethylene ether, and 30g of polyethylene glycol phosphate.

[0041] The preparation method of polyether modified silicone oil includes the following steps: 800g of allyl polyether and 200g of hydrogen-containing silicone oil are put into a reaction vessel, the feed port is closed, stirring is started, and the temperature is raised; when the temperature inside the vessel reaches 110℃, the heating is stopped, the feed port is opened, 0.0015g of chloroplatinic acid catalyst is added, the temperature is raised to 135℃, and then the polymerization reaction is carried out at the temperature for 5h. After the reaction is completed, the product is aged for 2h to obtain polyether modified silicone oil.

[0042] The preparation method of the waterborne coating polyether siloxane defoamer in this embodiment is as follows: polyether modified silicone oil, silicone paste, CJ-8100 emulsifier, perfluoroalkyl ethanol polyoxyethylene ether and polyethylene glycol phosphate are mixed in proportion, emulsified at 2800 r / min for 25 min using an emulsifying disperser, and then heated to 130℃ and stirred for 2.5 h to obtain the defoamer.

[0043] Comparative Example 1

[0044] Comparative Example 1 is identical to Example 1 except for the absence of the additive perfluoroalkyl ethanol polyoxyethylene ether.

[0045] Comparative Example 2

[0046] Compared with Example 1, Comparative Example 2 uses sorbitan monostearate polyoxyethylene ether ester as the additive, while the rest are the same.

[0047] Comparative Example 3

[0048] Compared with Example 1, Comparative Example 3 uses 250g of perfluoroalkyl ethanol polyoxyethylene ether, an additive, which exceeds the specified range. The rest of the contents are the same.

[0049] The performance of the polyether siloxane defoamers prepared in the examples and comparative examples was tested. The test methods and results are as follows:

[0050] Stability test: Centrifuge at 3000 r / min for 30 min in a high-speed centrifuge and observe whether there is any oil separation phenomenon.

[0051] Dispersibility test: The defoamer was diluted with water to form 10%, 20%, and 30% solutions. The solutions were stored at (70±5)℃ for 48 hours, and the presence of precipitation or oil floating in the emulsion was observed.

[0052] Defoaming test: 100 mL of a 0.2% sodium dodecylbenzenesulfonate aqueous solution was added to a 1 L graduated cylinder as the foaming liquid. The mixture was heated to the desired temperature in a water bath, and N2 was introduced at a gas flow rate of 2 L / min for bubbling. When the foam volume reached 500 mL, 1 mL of the polyether siloxane defoamer prepared in the examples and comparative examples (10% by mass) was added, and timing was started simultaneously. The time taken for all the foam to dissipate was recorded. The shorter the time, the better the defoaming effect. Bubbling continued, and the time taken for the foam height to reach 500 mL again was recorded. The longer the time, the better the foam suppression effect of the defoamer.

[0053] High temperature and alkali resistance test: Add 100 mL of 4% sodium dodecylbenzenesulfonate aqueous solution and 0.05 mL of polyether siloxane defoamer emulsion prepared in the examples and comparative examples to a 250 mL three-necked flask equipped with a thermometer, stirrer and reflux condenser. Add KOH to make the pH=14. Stir and heat in an oil bath to 100°C, increase the stirring speed and observe whether there is foam.

[0054] Water-based coating components: 062688.3g, polyether siloxane defoamer 0.1g, texanol film-forming aid 6.6g, DPM film-forming aid 4.6g, FA-179 anti-flash rust aid 0.4g.

[0055] After mixing the above components and stirring evenly, a water-based coating is obtained. The coating is then placed at a constant temperature of 25°C for 24 hours. A film is then scraped onto a glass plate, and after the film dries, it is observed whether there are any pinholes or craters (5 represents the best, 1 represents the worst).

[0056] Table 1 Performance of Polyether Siloxane Defoamers

[0057]

[0058]

[0059] As shown in Table 1, the polyether siloxane defoamers prepared in Examples 1-4 of the present invention have better defoaming properties and no pinholes or pores compared with the comparative examples, with Example 4 showing the best effect.

[0060] Compared to Example 2, after adding polyethylene glycol phosphate,

[0061] Compared with Comparative Example 1, the perfluoroalkyl chain and polyoxyethylene ether of the additive perfluoroalkyl ethanol polyoxyethylene ether endow the defoamer with extremely low surface energy, excellent chemical inertness and high hydrophilicity, thereby improving the stability, dispersibility and defoaming rate of the defoamer.

[0062] Compared with Comparative Example 2, perfluoroalkyl ethanol polyoxyethylene ether showed better performance than dehydrated sorbitan monostearate polyoxyethylene ether ester in terms of stability, dispersibility, and defoaming rate. This is because the inertness and durability of the perfluoroalkyl structure improve the stability and durability of the defoamer.

[0063] As shown in Example 1 and Comparative Example 3, excessive perfluoroalkyl ethanol polyoxyethylene ether can lead to decreased compatibility among different components in the system, increasing the risk of phase separation and consequently affecting the uniformity and long-term stability of the defoamer. Therefore, perfluoroalkyl ethanol polyoxyethylene ether should be added with caution, as excessive amounts can lead to a decrease in the performance of the defoamer.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polyether siloxane defoamer for water-based coatings, characterized in that: The product, calculated by weight, includes 65-70 parts of polyether-modified silicone oil, 4-6 parts of silicone paste, 8-12 parts of emulsifier, and 12-18 parts of additives. The additives include perfluoroalkyl ethanol polyoxyethylene ether and polyethylene glycol phosphate, wherein the mass ratio of perfluoroalkyl ethanol polyoxyethylene ether to polyethylene glycol phosphate is 3-5:

1.

2. The polyether siloxane defoamer for water-based coatings as described in claim 1, characterized in that: The preparation method of the polyether modified silicone oil includes the following steps: allyl polyether and hydrogen-containing silicone oil are put into a reaction vessel, stirred and heated to 110°C, chloroplatinic acid catalyst is added, and the temperature is further raised to 125-135°C for polymerization reaction for 4-5 hours. After the reaction is completed, it is aged for 2 hours to obtain polyether modified silicone oil.

3. The polyether siloxane defoamer for water-based coatings as described in claim 2, characterized in that: The mass ratio of allyl polyether to hydrogen-containing silicone oil is 70-80:20-30, and the amount of chloroplatinic acid is 0.001%-0.002% of the total amount of allyl polyether and hydrogen-containing silicone oil.

4. The polyether siloxane defoamer for water-based coatings as described in claim 2, characterized in that: The allyl polyether has a molecular weight of 1000 Da and a molar ratio of EO to PO of 7:

3.

5. The polyether siloxane defoamer for water-based coatings as described in claim 2, characterized in that: The hydrogen-containing silicone oil has a molecular weight of approximately 1000 Da and a hydrogen mass fraction of 0.18%.

6. The polyether siloxane defoamer for water-based coatings as described in claim 1, characterized in that: The emulsifier is one or both of CJ-8100 emulsifier and CJ-8000 emulsifier.

7. A method for preparing a polyether siloxane defoamer for water-based coatings as described in any one of claims 1-6, characterized in that: Polyether-modified silicone oil, silicone paste, emulsifier and additives are mixed in proportion and emulsified in an emulsifying disperser at 2700-2800 r / min for 20-30 min. Then the mixture is heated to 120-130℃ and stirred for 2-3 h to obtain the defoamer.

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