Epoxy modified waterborne alkyd resin emulsion as well as preparation method and application thereof

Abstract

The invention discloses an epoxy modified waterborne alkyd resin emulsion as well as a preparation method and application thereof. The epoxy modified waterborne alkyd resin emulsion is prepared from epoxy resin, vegetable oleic acid, hydroxypropyl-terminated polydimethylsiloxane, a phase transfer catalyst, a metal carboxylate catalyst, polyol, aromatic binary acid and / or aromatic anhydride, an emulsifier and water. The preparation method comprises the following steps: 1) mixing epoxy resin, vegetable oleic acid, hydroxypropyl-terminated polydimethylsiloxane, a phase transfer catalyst and a metal carboxylate catalyst for condensation reaction, and then adding polyol and binary acid for esterification reaction to obtain epoxy modified alkyd resin; and 2) mixing the epoxy modified alkyd resin and the emulsifier, and adding water for emulsification to obtain the target product. The epoxy modified waterborne alkyd resin emulsion disclosed by the invention is free of VOC (Volatile Organic Compounds), and a formed paint film is good in water resistance, low in gloss and strong in adhesive force, and is suitable for high-end application with delustering requirements and high performance requirements.

Description

Technical Field

[0001] This invention relates to the field of waterborne coatings technology, specifically to an epoxy-modified waterborne alkyd resin emulsion, its preparation method, and its application. Background Technology

[0002] Waterborne alkyd coatings refer to waterborne coatings with waterborne alkyd resin as the main film-forming substance. They offer advantages such as convenient application, high gloss and fullness of the film, and safety and environmental friendliness, making them widely used in architectural decoration (e.g., coating of interior and exterior doors, windows, railings, and metal components), industrial maintenance (e.g., corrosion protection of steel structures and bridges), and wood coatings. However, due to the presence of ester bonds in the molecular structure of waterborne alkyd resins, these coatings are prone to hydrolysis during storage, leading to performance degradation. Furthermore, the water resistance of existing waterborne alkyd resin-formed films is generally poor, and further improvement is needed. Additionally, the high gloss of existing waterborne alkyd resin-formed films makes them unsuitable for applications requiring matting (currently, this is mainly achieved by adding matting agents, but the poor compatibility between matting agents and the waterborne alkyd resin system significantly impacts the overall system stability). In conclusion, existing waterborne alkyd resins cannot fully meet practical application requirements, significantly limiting their practical application.

[0003] Therefore, it is of great significance to develop an epoxy-modified waterborne alkyd resin emulsion with good water resistance, low gloss, and good adhesion after film formation. Summary of the Invention

[0004] The purpose of this invention is to provide an epoxy-modified waterborne alkyd resin emulsion, its preparation method, and its application.

[0005] The technical solution adopted in this invention is: An epoxy-modified waterborne alkyd resin emulsion, which is made from the following raw materials in the following mass percentages: Epoxy resin: 10%–15%; Vegetable oleic acid: 25%–35%; Hydroxypropyl-terminated polydimethylsiloxane: 2%–4%; Phase transfer catalyst: 0.6%–1.2%; Metal carboxylate catalyst: 0.05%–0.15%; Polyols: 20%–30%; Dicarboxylic acid: 13%–25%; Emulsifier: 4%–10%; Water: Balance.

[0006] Preferably, the epoxy resin is at least one of epoxy resin E51, epoxy resin E44, and epoxy resin E20.

[0007] Preferably, the plant oleic acid is at least one of linolenic acid, dehydrated ricinoleic acid, and palmitic acid.

[0008] Preferably, the phase transfer catalyst is at least one of tetrabutylammonium bromide, hexadecyltrimethylammonium bromide, and tetrabutylammonium chloride.

[0009] Preferably, the metal carboxylate catalyst is at least one of dibutyltin dilaurate, stannous octoate, and bismuth isooctanoate.

[0010] Preferably, the polyol is at least one of trimethylolpropane, glycerol, and pentaerythritol.

[0011] Preferably, the dicarboxylic acid is at least one selected from terephthalic acid, phthalic anhydride, and maleic anhydride.

[0012] Preferably, the emulsifier is at least one of alkylphenol polyoxyethylene ether, sodium dodecyl sulfate, and sodium fatty alcohol polyoxyethylene ether sulfate.

[0013] A method for preparing the epoxy-modified waterborne alkyd resin emulsion as described above includes the following steps: 1) Epoxy resin, vegetable oleic acid, hydroxypropyl-terminated polydimethylsiloxane, phase transfer catalyst and metal carboxylate catalyst are mixed and subjected to condensation reaction, and then polyol and diacid are added to carry out esterification reaction to obtain epoxy modified alkyd resin. 2) Mix the epoxy-modified alkyd resin and emulsifier, then add water to emulsify, to obtain an epoxy-modified waterborne alkyd resin emulsion.

[0014] Preferably, the condensation reaction in step 1) is carried out at a temperature of 100℃ to 120℃ for a reaction time of 3h to 5h.

[0015] Preferably, the condensation reaction in step 1) is carried out in a protective atmosphere.

[0016] Preferably, the protective atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0017] Preferably, the esterification reaction in step 1) is carried out at a temperature of 200℃~220℃ until the acid value of the system is less than 10mg KOH / g.

[0018] A waterborne alkyd coating comprising the above-mentioned epoxy-modified waterborne alkyd resin emulsion.

[0019] The principle of this invention: This invention utilizes the good chemical resistance and excellent adhesion of epoxy resin. By modifying alkyd resin with epoxy resin, the water resistance of alkyd resin is improved. At the same time, an organosilicon polymer (hydroxypropyl-terminated polydimethylsiloxane) is introduced. The organosilicon polymer forms a rough surface after the emulsion is film-formed, thereby achieving a matte effect.

[0020] The beneficial effects of this invention are: the epoxy-modified waterborne alkyd resin emulsion of this invention is VOC-free, and the film formed has good water resistance, low gloss, and strong adhesion, making it suitable for high-end applications with matte finish and high performance requirements. Detailed Implementation

[0021] The present invention will be further explained and described below with reference to specific embodiments.

[0022] Example 1: An epoxy-modified waterborne alkyd resin emulsion is prepared as follows: 1) Mix 100g of epoxy resin E51, 300g of linoleic acid, 30g of hydroxypropyl-terminated polydimethylsiloxane, 8g of tetrabutylammonium bromide and 0.8g of dibutyltin dilaurate evenly, then heat to 110℃ in a nitrogen atmosphere and stir for 5h. Then add 235g of trimethylolpropane and 160g of phthalic anhydride, and heat to 210℃ and stir until the acid value of the reaction system drops below 10mgKOH / g. Cool to room temperature to obtain epoxy-modified alkyd resin. 2) Stir the epoxy-modified alkyd resin and 65g of alkylphenol polyoxyethylene ether until uniform, then add 99g of deionized water dropwise while stirring to emulsify and obtain an epoxy-modified waterborne alkyd resin emulsion.

[0023] Example 2: An epoxy-modified waterborne alkyd resin emulsion is prepared as follows: 1) Mix 130g of epoxy resin E20, 310g of linoleic acid, 35g of hydroxypropyl-terminated polydimethylsiloxane, 12g of hexadecyltrimethylammonium bromide and 0.9g of bismuth isooctanoate evenly, then heat to 120℃ in a nitrogen atmosphere and stir for 4h. Then add 260g of glycerol and 145g of maleic anhydride, and heat to 220℃ and stir until the acid value of the reaction system drops below 10mgKOH / g. Cool to room temperature to obtain epoxy-modified alkyd resin. 2) Stir the epoxy-modified alkyd resin and 50g of sodium dodecyl sulfate until they are evenly mixed, and then add 110g of deionized water dropwise while stirring to emulsify, so as to obtain an epoxy-modified waterborne alkyd resin emulsion.

[0024] Example 3: An epoxy-modified waterborne alkyd resin emulsion is prepared as follows: 1) Mix 110g of epoxy resin E44, 290g of dehydrated ricinoleic acid, 33g of hydroxypropyl-terminated polydimethylsiloxane, 10g of tetrabutylammonium chloride and 1g of stannous octoate evenly, then heat to 100℃ in a nitrogen atmosphere and stir for 5h. Then add 250g of pentaerythritol and 170g of terephthalic acid, and heat to 200℃ and stir until the acid value of the reaction system drops below 10mgKOH / g. Cool to room temperature to obtain epoxy-modified alkyd resin. 2) Stir the epoxy-modified alkyd resin and 55g of fatty alcohol polyoxyethylene ether sodium sulfate evenly, and then add 105g of deionized water dropwise while stirring to emulsify, thus obtaining an epoxy-modified waterborne alkyd resin emulsion.

[0025] Example 4: An epoxy-modified waterborne alkyd resin emulsion is prepared as follows: 1) Mix 120g of epoxy resin E51, 320g of palmitoleic acid, 28g of hydroxypropyl-terminated polydimethylsiloxane, 11g of tetrabutylammonium bromide and 1.2g of bismuth isooctanoate evenly, then heat to 120℃ in a nitrogen atmosphere and stir for 3h. Then add 255g of trimethylolpropane and 175g of maleic anhydride, and heat to 220℃ and stir until the acid value of the reaction system drops below 10mgKOH / g. Cool to room temperature to obtain epoxy-modified alkyd resin. 2) Stir the epoxy-modified alkyd resin and 70g of alkylphenol polyoxyethylene ether until uniform, then add 85g of deionized water dropwise while stirring to emulsify and obtain an epoxy-modified waterborne alkyd resin emulsion.

[0026] Comparative Example 1: An epoxy-modified waterborne alkyd resin emulsion is identical to that in Example 1, except that hydroxypropyl-terminated polydimethylsiloxane and dibutyltin dilaurate were not added in step 1) of its preparation.

[0027] Comparative Example 2: An aqueous alkyd resin emulsion is identical to that in Example 1, except that epoxy resin E51 and tetrabutylammonium bromide are not added in step 1) during preparation.

[0028] Comparative Example 3: An epoxy-modified waterborne alkyd resin emulsion is prepared as follows: 100g of epoxy resin E51, 300g of linoleic acid, 30g of hydroxypropyl-terminated polydimethylsiloxane, 8g of tetrabutylammonium bromide, and 0.8g of dibutyltin dilaurate were stirred and mixed evenly. The mixture was then placed in a nitrogen atmosphere and heated to 110℃ with stirring for 5 hours. 235g of trimethylolpropane, 160g of phthalic anhydride, and 30g of 2,2-dimethylolpropionic acid were then added. The mixture was then heated to 210℃ with stirring until the acid value of the reaction system decreased to below 10mgKOH / g. The temperature was then lowered to 100℃, and 125g of propylene glycol monobutyl ether was added. Finally, 175mL of 25% ammonia water was added to neutralize the system, resulting in an epoxy-modified waterborne alkyd resin emulsion.

[0029] Performance testing: Gas chromatography was used to detect whether the emulsions of Examples 1-4 and Comparative Examples 1-3 contained VOCs. The emulsions of Examples 1-4 and Comparative Examples 1-3 were then coated onto glass plates and polished tinplate sheets using a coater to form films. The gloss, adhesion, and water resistance of the coating films were then tested. The test results are shown in the table below. Table 1 Performance test data of emulsions from Examples 1-4 and Comparative Examples 1-3

[0030] Note: Gloss: Tested according to "GB / T 9754-2025 Determination of gloss of paints and varnishes at 20°, 60° and 85°".

[0031] Adhesion: Tested according to "GB / T 1720-2020 Coating film cross-cut test".

[0032] Water resistance: Tested according to "GB / T 1733-1993 Test method for water resistance of paint film".

[0033] VOC: The test shall be conducted in accordance with “GB / T 23986.2-2023 Determination of volatile organic compounds (VOC) and / or semi-volatile organic compounds (SVOC) in paints and varnishes - Part 2: Gas chromatography”.

[0034] As shown in Table 1: 1) The epoxy-modified waterborne alkyd resin emulsions of Examples 1-4, without the addition of matting agent, were modified by adding terminal hydroxypropyl polydimethylsiloxane. The resulting coating film had a gloss of ≤5.0°, which was significantly reduced compared with Comparative Example 1. It is suitable for high-end applications with matting requirements. 2) The epoxy-modified waterborne alkyd resin emulsions in Examples 1 to 4 were all epoxy modified. The adhesion of the resulting paint film did not change significantly. This is because alkyd resin itself has good adhesion to the substrate. However, compared with the waterborne alkyd resin emulsion in Comparative Example 2, the water resistance of the resulting paint film was significantly enhanced, indicating that epoxy modification can significantly improve the water resistance of the paint film formed by alkyd resin. 3) The epoxy-modified waterborne alkyd resin emulsions in Examples 1-4 were prepared by external emulsification, and the raw material formulations contained no organic solvents, so no VOCs were detected. However, the epoxy-modified waterborne alkyd resin emulsion in Comparative Example 3 was prepared by internal emulsification, which required the use of hydrophilic monomers for modification. It was used in a water-dispersed form, and the resin viscosity was relatively high, so it generally needed to be diluted with organic solvents before use, thus containing VOCs. In summary, the epoxy-modified waterborne alkyd resin emulsion of the present invention is VOC-free, and the film formed has good water resistance, low gloss, and strong adhesion, making it suitable for high-end applications with matte finish and high performance requirements.

[0035] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An epoxy-modified waterborne alkyd resin emulsion, characterized in that, Made from the following raw materials by weight percentage: Epoxy resin: 10%–15%; Vegetable oleic acid: 25%–35%; Hydroxypropyl-terminated polydimethylsiloxane: 2%–4%; Phase transfer catalyst: 0.6%–1.2%; Metal carboxylate catalyst: 0.05%–0.15%; Polyols: 20%–30%; Dicarboxylic acid: 13%–25%; Emulsifier: 4%–10%; Water: Balance.

2. The epoxy-modified waterborne alkyd resin emulsion according to claim 1, characterized in that: The epoxy resin is at least one of epoxy resin E51, epoxy resin E44, and epoxy resin E20.

3. The epoxy-modified waterborne alkyd resin emulsion according to claim 1, characterized in that: The plant oleic acid is at least one of linolenic acid, dehydrated castor oil acid, and palmitoleic acid.

4. The epoxy-modified waterborne alkyd resin emulsion according to any one of claims 1 to 3, characterized in that: The phase transfer catalyst is at least one of tetrabutylammonium bromide, hexadecyltrimethylammonium bromide, and tetrabutylammonium chloride.

5. The epoxy-modified waterborne alkyd resin emulsion according to any one of claims 1 to 3, characterized in that: The metal carboxylate catalyst is at least one of dibutyltin dilaurate, stannous octoate, and bismuth isooctanoate.

6. The epoxy-modified waterborne alkyd resin emulsion according to any one of claims 1 to 3, characterized in that: The polyol is at least one of trimethylolpropane, glycerol, and pentaerythritol.

7. The epoxy-modified waterborne alkyd resin emulsion according to any one of claims 1 to 3, characterized in that: The dicarboxylic acid is at least one of terephthalic acid, phthalic anhydride, and maleic anhydride.

8. The epoxy-modified waterborne alkyd resin emulsion according to any one of claims 1 to 3, characterized in that: The emulsifier is at least one of alkylphenol polyoxyethylene ether, sodium dodecyl sulfate, and sodium fatty alcohol polyoxyethylene ether sulfate.

9. A method for preparing an epoxy-modified waterborne alkyd resin emulsion as described in any one of claims 1 to 8, characterized in that, Includes the following steps: 1) Epoxy resin, vegetable oleic acid, hydroxypropyl-terminated polydimethylsiloxane, phase transfer catalyst and metal carboxylate catalyst are mixed and subjected to condensation reaction, and then polyol and diacid are added to carry out esterification reaction to obtain epoxy modified alkyd resin. 2) Mix the epoxy-modified alkyd resin and emulsifier, then add water to emulsify, to obtain an epoxy-modified waterborne alkyd resin emulsion.

10. A water-based alkyd coating, characterized in that, It comprises the epoxy-modified waterborne alkyd resin emulsion according to any one of claims 1 to 8.

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