Polyether siloxane defoaming agent for water-based paint and preparation method of polyether siloxane defoaming agent

Abstract

The invention relates to the technical field of coatings, and provides a polyether siloxane defoaming agent for a water-based coating and a preparation method of the polyether siloxane defoaming agent, the polyether siloxane defoaming agent comprises polyether modified silicone oil, silicon paste, an emulsifier and an auxiliary agent, and the auxiliary agent comprises perfluoroalkyl ethanol polyoxyethylene ether. A perfluoroalkyl chain and a polyoxyethylene ether chain of the auxiliary perfluoroalkyl ethanol polyoxyethylene ether in the defoaming agent respectively endow a material with extremely low surface energy, excellent chemical inertness and relatively high hydrophilicity, have high compatibility with a water-based coating, can effectively reduce the defects of shrinkage cavities, needle holes and the like of a paint film, enhance the resistance of the defoaming agent to acid and alkali, and improve the corrosion resistance of the defoaming agent to the water-based coating. The chemical stability is high.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a polyether siloxane defoamer for water-based coatings and a preparation method thereof. Background Art

[0002] With the rapid development of industrialization and the improvement of environmental protection requirements, water-based paints have gradually replaced traditional oil-based paints and become the mainstream choice in the market. This shift is not only because water-based paints have lower volatile organic compound (VOC) emissions and are more in line with environmental regulations, but also because of their advantages in safety and ease of use. However, water-based paints are prone to bubbles during production and construction, which can form defects in the paint film, affecting its appearance and final performance.

[0003] To meet this challenge, defoamers (or anti-foaming agents) are widely used in water-based coatings. Defoamers eliminate bubbles through the incompatibility principle, that is, they use their incompatibility with the coating system to destroy the stability of bubbles and cause them to burst quickly. However, the carrier materials of traditional defoamers are not completely compatible with the coating system, resulting in surface defects such as shrinkage cavities and pinholes 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] The invention patent with patent number CN110157232A discloses a defoamer for water-based environmentally friendly coatings. The over-reliance on emulsifiers will lead to a decrease in the stability of the defoamer, affecting its dispersion effect and long-term performance in the coating. 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 provides a polyether siloxane defoamer for water-based coatings with high compatibility with water-based coatings and good stability, and a preparation method thereof.

[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, including polyether modified silicone oil, silicone paste, emulsifier and additives, wherein the additive includes perfluoroalkylethanol polyoxyethylene ether.

[0007] Specifically, the perfluoroalkyl chain of perfluoroalkylethanol polyoxyethylene ether gives the material extremely low surface energy and excellent chemical inertness, making it very effective in reducing surface tension, greatly enhancing the dispersibility of defoamers, and effectively reducing defects such as shrinkage holes and pinholes in paint films. The polyoxyethylene ether chain is a hydrophilic part, usually composed of ethoxy (-CH2CH2O-) repeating units, which makes it have good solubility and dispersibility in water-based coating systems, thereby enhancing the compatibility of water-based coatings. In addition, perfluoroalkylethanol polyoxyethylene ether has excellent resistance to acids and alkalis and high chemical stability.

[0008] On the basis of the above technical scheme, preferably, calculated by weight, it 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 auxiliary agent.

[0009] On the basis of the above technical solution, preferably, the auxiliary agent further comprises polyethylene glycol phosphate.

[0010] Specifically, polyethylene glycol phosphate has excellent hydrophilicity and emulsification ability. As a surfactant, the hydrophilic group in its structure can enhance the solubility and compatibility of perfluoroalkyl alcohol polyoxyethylene ether in water-based coatings, helping to form a more uniform dispersion. The stable structure of phosphate can further improve the stability of the defoamer under dynamic and different environmental conditions, prevent the phase separation of perfluoroalkyl alcohol polyoxyethylene ether, and improve the overall defoaming performance of the coating and the surface quality of the paint film.

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

[0012] On the basis of the above technical solution, preferably, the mass ratio of the perfluoroalkylethanol polyoxyethylene ether:polyethylene glycol phosphate is 3-5:1.

[0013] On the basis of the above technical scheme, preferably, the preparation method of the polyether-modified silicone oil comprises the following steps: putting allyl polyether and hydrogen-containing silicone oil into a reaction kettle, stirring and heating to 110°C, adding chloroplatinic acid catalyst, continuing to heat to 125-135°C for polymerization reaction for 4-5h, and ripening for 2h after the reaction to obtain the polyether-modified silicone oil.

[0014] On the basis of the above technical scheme, preferably, the mass ratio of the allyl polyether to the 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 the allyl polyether and the hydrogen-containing silicone oil.

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

[0016] On the basis of the above technical solution, preferably, the molecular weight of the hydrogen-containing silicone oil is about 1000 Da, and the mass fraction of hydrogen groups is 0.18%.

[0017] On the basis of the above technical solution, 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, comprising mixing polyether modified silicone oil, silicone paste, emulsifier and additives in proportion, emulsifying for 20-30 minutes at 2700-2800 r / min using an emulsifying disperser, and then heating to 120-130° C. and stirring for reaction for 2-3 hours to obtain the defoamer.

[0019] The polyether siloxane defoamer for water-based coatings and the preparation method thereof of the present invention have the following beneficial effects compared with the prior art:

[0020] (1) In the defoamer of the present invention, perfluoroalkylethanol polyoxyethylene ether is used as an auxiliary agent. Its perfluoroalkyl chain and polyoxyethylene ether chain respectively give the material extremely low surface energy, excellent chemical inertness and high hydrophilicity, so that the compatibility of the defoamer with water-based coatings is improved, and defects such as shrinkage cavities and pinholes in the paint film can be effectively reduced. In addition, perfluoroalkylethanol polyoxyethylene ether can also enhance the resistance of the defoamer to acids and alkalis and improve the chemical stability of the defoamer.

[0021] (2) Polyethylene glycol phosphate is compounded with perfluoroalkyl alcohol polyoxyethylene ether. The hydrophilic groups in its structure can enhance the solubility and compatibility of perfluoroalkyl alcohol polyoxyethylene ether in water-based coatings and help form a more uniform dispersion. In addition, the stable structure of phosphate can further improve the stability of the defoamer under dynamic and different environmental conditions, prevent the phase separation of perfluoroalkyl alcohol polyoxyethylene ether, and improve the defoaming performance of the overall coating and the surface quality of the paint film. By improving compatibility and dispersibility, polyethylene glycol phosphate can help overcome the technical barriers of perfluoroalkyl alcohol polyoxyethylene ether in water-based coatings, thereby achieving a more lasting and effective defoaming effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a product picture of the polyether siloxane defoamer prepared by the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The allyl polyether of the present invention is FB1000, purchased from Yangzhou Chenhua New Materials Co., Ltd. The hydrogen-containing silicone oil is H518, purchased from Zhejiang Runhe Chemical New Materials Co., Ltd. Emulsifiers CJ-8000 and CJ-8100 are both self-made by our company (Wuhan Chenyuda Technology Co., Ltd.). The silicone paste is 855E 352, purchased from Shenzhen Longdi Chemical Co., Ltd. Perfluoroalkylethanol polyoxyethylene ether model PEO-300, purchased from Hubei Shineng Chemical Technology Co., Ltd. Polyethylene glycol phosphate was purchased from Hai'an Petrochemical Plant, Jiangsu Province.

[0026] Example 1

[0027] The components of the polyether siloxane defoamer for water-based coatings of this embodiment include 695 g of polyether-modified silicone oil, 55 g of silicone paste, 100 g of CJ-8100 emulsifier and 150 g of perfluoroalkylethanol polyoxyethylene ether.

[0028] The preparation method of polyether-modified silicone oil comprises the following steps: adding 723 g of allyl polyether and 277 g of hydrogen-containing silicone oil into a reaction kettle, closing the feed port, starting stirring, and heating to increase the temperature; when the temperature in the kettle reaches 110° C., closing the heating, opening the feed port, adding 0.01 g of chloroplatinic acid catalyst, continuing to increase the temperature to 130° C., then maintaining the temperature for a polymerization reaction for 4.5 hours, and ripening for 2 hours after the reaction to obtain the polyether-modified silicone oil.

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

[0030] Example 2

[0031] Compared with Example 1, Example 2 adds polyethylene glycol phosphate as the auxiliary agent, which is as follows:

[0032] The components of the polyether siloxane defoamer for water-based coatings of this embodiment include 695 g of polyether-modified silicone oil, 55 g of silicone paste, 100 g of CJ-8100 emulsifier, 150 g of perfluoroalkylethanol polyoxyethylene ether, and 30 g of polyethylene glycol phosphate.

[0033] The preparation method of polyether-modified silicone oil comprises the following steps: adding 723 g of allyl polyether and 277 g of hydrogen-containing silicone oil into a reaction kettle, closing the feed port, starting stirring, and heating to increase the temperature; when the temperature in the kettle reaches 110° C., closing the heating, opening the feed port, adding 0.01 g of chloroplatinic acid catalyst, continuing to increase the temperature to 130° C., then maintaining the temperature for a polymerization reaction for 4.5 hours, and ripening for 2 hours after the reaction to obtain the polyether-modified silicone oil.

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

[0035] Example 3

[0036] The components of the polyether siloxane defoamer for water-based coatings of this embodiment include 650 g of polyether-modified silicone oil, 40 g of silicone paste, 80 g of CJ-8000 emulsifier, 90 g of perfluoroalkylethanol polyoxyethylene ether and 30 g of polyethylene glycol phosphate.

[0037] The preparation method of polyether-modified silicone oil comprises the following steps: putting 700g of allyl polyether and 300g of hydrogen-containing silicone oil into a reaction kettle, closing the feeding port, starting stirring, and heating to increase the temperature; when the temperature in the kettle reaches 110°C, closing the heating, opening the feeding port, adding 0.02g of chloroplatinic acid catalyst, continuing to increase the temperature to 125°C, and then keeping the temperature to carry out polymerization reaction for 4h, and ripening for 2h after the reaction to obtain polyether-modified silicone oil.

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

[0039] Example 4

[0040] The components of the polyether siloxane defoamer for water-based coatings of this embodiment include 700 g of polyether-modified silicone oil, 60 g of silicone paste, 120 g of CJ-8100 emulsifier, 120 g of perfluoroalkylethanol polyoxyethylene ether and 30 g of polyethylene glycol phosphate.

[0041] The preparation method of polyether-modified silicone oil comprises the following steps: putting 800g of allyl polyether and 200g of hydrogen-containing silicone oil into a reaction kettle, closing the feeding port, starting stirring, and heating to increase the temperature; when the temperature in the kettle reaches 110°C, closing the heating, opening the feeding port, adding 0.0015g of chloroplatinic acid catalyst, continuing to heat to 135°C, and then keeping the temperature to carry out polymerization reaction for 5h, and ripening for 2h after the reaction to obtain polyether-modified silicone oil.

[0042] The preparation method of the polyether siloxane defoamer for water-based coatings in this embodiment is as follows: polyether modified silicone oil, silicone paste, CJ-8100 emulsifier, perfluoroalkylethanol 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° C. and stirred for reaction for 2.5 h to obtain the defoamer.

[0043] Comparative Example 1

[0044] Compared with Example 1, Comparative Example 1 lacks the auxiliary agent perfluoroalkylethanol polyoxyethylene ether, and the rest of the contents are the same.

[0045] Comparative Example 2

[0046] Compared with Example 1, in Comparative Example 2, the auxiliary agent is replaced by sorbitan monostearate polyoxyethylene ether ester, and the rest of the contents are the same.

[0047] Comparative Example 3

[0048] Compared with Example 1, the amount of the auxiliary agent perfluoroalkylethanol polyoxyethylene ether used in Comparative Example 3 exceeds the specified range, specifically 250 g, and the rest of the contents are the same.

[0049] The polyether siloxane defoamers prepared in the examples and comparative examples were tested for performance, and the test methods and results are as follows:

[0050] Stability test: Centrifuge at 3000r / min for 30min in a high-speed centrifuge to observe whether there is floating oil stratification.

[0051] Dispersibility test: dilute the defoamer with water to form 10%, 20%, and 30% solutions, store at (70±5)℃ for 48h, and observe whether the emulsion has precipitation or oil floating phenomenon.

[0052] Defoaming test: In a 1L measuring cylinder, add 100mL of 0.2% sodium dodecylbenzene sulfonate aqueous solution as the foaming liquid, heat it to the required temperature in a water bath, and introduce N2 at a gas velocity of 2L / min to bubble; when the foam volume reaches 500mL, add 1ml of 10% polyether siloxane defoamer prepared in the embodiment and comparative example, and start timing at the same time to record the time when all the foam is eliminated. The shorter the time, the better the defoaming effect. Continue bubbling and record the time when the foam height reaches 500mL again. The longer the time, the better the anti-foaming property of the defoamer.

[0053] High temperature resistance and alkali performance determination: In a 250mL three-necked flask equipped with a thermometer, a stirrer and a reflux condenser, 100mL of a 4% sodium dodecylbenzene sulfonate aqueous solution and 0.05mL of the polyether siloxane defoamer emulsion prepared in the examples and comparative examples were evenly dispersed, and KOH was added to make its pH = 14, and the mixture was stirred and heated in an oil bath to 100°C, the stirring speed was increased, and observation was made as to whether there was foam.

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

[0055] Mix the above components and stir evenly to obtain a water-based paint. Then place the paint at a constant temperature of 25°C for 24 hours, scrape the paint on a glass plate, and observe whether there are shrinkage cavities and pinholes after the paint film is dry (5 represents the best, 1 represents the worst).

[0056] Table 1 Performance of polyether silicone defoamer

[0057]

[0058]

[0059] As shown in Table 1, compared with the comparative example, the polyether siloxane defoamers prepared in Examples 1-4 of the present invention have better defoaming properties and no shrinkage cavities or pinholes, among which Example 4 has the best effect.

[0060] Compared with Example 1 and Example 2, after adding polyethylene glycol phosphate,

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

[0062] Compared with Example 1 and Comparative Example 2, the performance of perfluoroalkylethanol polyoxyethylene ether is better than that of sorbitan monostearate polyoxyethylene ether ester in terms of stability, dispersibility, defoaming rate, etc. This is because the inertness and durability of the perfluoroalkyl structure improve the stability and durability of the defoaming agent.

[0063] It can be seen from Example 1 and Comparative Example 3 that excessive perfluoroalkylethanol polyoxyethylene ether will reduce the compatibility of different components in the system, increase the risk of phase separation, and further affect the uniformity and long-term stability of the defoamer. Therefore, perfluoroalkylethanol polyoxyethylene ether should be added with caution, because its excessive amount will cause the performance of the defoamer to decrease.

[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 in the protection scope of the present invention.

Claims

1. A polyether siloxane defoamer for water-based coatings, characterized in that: The invention comprises polyether modified silicone oil, silicone paste, emulsifier and auxiliary agent, wherein the auxiliary agent comprises perfluoroalkylethanol polyoxyethylene ether.

2. A polyether siloxane defoamer for water-based coatings as claimed in claim 1, characterized in that: Calculated by weight, the composition 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 auxiliary agent.

3. A polyether siloxane defoamer for water-based coatings as claimed in claim 1, characterized in that: The auxiliary agent also includes polyethylene glycol phosphate.

4. A polyether siloxane defoamer for water-based coatings as claimed in claim 3, characterized in that: The mass ratio of the perfluoroalkylethanol polyoxyethylene ether to polyethylene glycol phosphate is 3-5:

1.

5. A polyether siloxane defoamer for water-based coatings as claimed in claim 1, characterized in that: The preparation method of the polyether-modified silicone oil comprises the following steps: putting allyl polyether and hydrogen-containing silicone oil into a reaction kettle, stirring and heating to 110° C., adding chloroplatinic acid catalyst, continuing to heat to 125-135° C. for polymerization reaction for 4-5 hours, and ripening for 2 hours after the reaction to obtain the polyether-modified silicone oil.

6. A polyether siloxane defoamer for water-based coatings as claimed in claim 5, characterized in that: The mass ratio of the allyl polyether to the hydrogen-containing silicone oil is 70-80:20-30, and the amount of chloroplatinic acid used is 0.001%-0.002% of the total amount of the allyl polyether and the hydrogen-containing silicone oil.

7. A polyether siloxane defoamer for water-based coatings as claimed in claim 5, characterized in that: The molecular weight of the allyl polyether is 1000 Da, and the molar ratio of EO to PO is 7:

3.

8. A polyether siloxane defoamer for water-based coatings as claimed in claim 5, characterized in that: The molecular weight of the hydrogen-containing silicone oil is about 1000 Da, and the mass fraction of hydrogen groups is 0.18%.

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

10. A method for preparing a polyether siloxane defoamer for water-based coatings according to any one of claims 1 to 9, characterized in that: The polyether modified silicone oil, silicone paste, emulsifier and auxiliary agent are mixed in proportion, emulsified at 2700-2800r / min for 20-30min using an emulsifying disperser, and then heated to 120-130°C and stirred for reaction for 2-3h to obtain a defoaming agent.

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