A method for preparing a wear-resistant and flame-retardant acrylic resin coating

Abstract

This invention relates to the field of polymer materials technology and discloses a method for preparing a wear-resistant and flame-retardant acrylic resin coating. The invention prepares an epoxy-based triphosphazene through esterification and click reactions. This triphosphazene, along with silica modified by a silane coupling agent, is added to an acrylic coating. During high-temperature curing, the epoxy groups contained therein react with the carboxyl groups in the matrix, which not only increases the exudation resistance of silica and small-molecule flame-retardant structures but also enhances the overall performance of the coating through the resulting cross-linked network structure. The coating prepared by this invention exhibits excellent flame-retardant properties, wear resistance, and impact resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing a wear-resistant and flame-retardant acrylic resin coating. Background Technology

[0002] Acrylic resin coatings, using acrylic resin as the main film-forming substance, possess excellent environmental and weather resistance properties and are widely used in building exteriors, furniture, and electronic products. However, due to structural limitations, acrylic resin coatings still have shortcomings in practical applications, such as less-than-ideal wear resistance and flame retardancy. Silica, with its high hardness and wear resistance, is widely used in construction, chemicals, plastics, and coatings; however, its compatibility with organic materials is poor.

[0003] For example, the patent with authorization announcement number CN 116716034 B discloses a flame-retardant superhydrophobic coating and its application method. The coating prepared by this method using modified epoxy acrylic resin and nano silica as raw materials has excellent flame-retardant properties, but does not improve the wear resistance of the coating. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a wear-resistant and flame-retardant acrylic resin coating. The prepared acrylic resin coating exhibits excellent wear resistance, flame retardancy, and mechanical properties.

[0006] (II) Technical Solution

[0007] A method for preparing a wear-resistant and flame-retardant acrylic resin coating, the method comprising the following steps:

[0008] Step 1: Add trimer O,O-2-hydroxypropanephosphazene, mercaptopropionic acid and catalyst to toluene solvent, heat under nitrogen protection and reflux for 8-12 h. After the reaction is completed, cool to room temperature, wash with deionized water and distill to obtain mercapto-cyclic triphosphazene.

[0009] Step 2: Under nitrogen protection, mercapto-cyclic triphosphazene, allyl glycidyl ether, and dimethyl benzoate (DMPA) were added to tetrahydrofuran solvent, stirred and dispersed, and irradiated with UV (λ=352nm, 40W) for 30 min. The mixture was then rotary evaporated to obtain epoxy-based triphosphazene.

[0010] Step 3: Add amino resin, epoxy triphosphazene, and silane coupling agent modified silica to the acrylic emulsion and stir for 5-10 minutes. Then add solvent, defoamer, and leveling agent, stir for 5 minutes, coat evenly on tinplate, let it dry naturally to form a film, and then place it in an oven at 170℃ for 15 minutes to cure, thus obtaining an acrylic resin coating.

[0011] Under high temperature conditions, the epoxy groups in silica modified by epoxy-cyclotriphosphazene and silane coupling agent undergo a cross-linking reaction with the carboxyl groups in acrylic resin, which not only improves the density of the coating, i.e., the cross-linking density, but also improves the exudation resistance of the small molecule flame retardant structure and the compatibility between silica and organic coatings.

[0012] Preferably, in step 1, the ratio of trimer O,O-2-hydroxypropanephosphazene to mercaptopropionic acid is 1g:(0.8-1.2)g.

[0013] Preferably, in step 1, the catalyst is p-toluenesulfonic acid, and its amount is 3-5% of the mass of trimer O,O-2-hydroxypropanephosphazene.

[0014] Preferably, in step 2, the ratio of mercaptocyclotriphosphazene to allyl glycidyl ether is 1g:(0.52-0.6)g.

[0015] Preferably, in step 3, the ratio of acrylic resin emulsion, amino resin, epoxy cyclotriphosphazene, and silane coupling agent modified silica is 100g:(20-40)g:(5-10)g:(1-5)g.

[0016] Preferably, in step 3, the amino resin is R717 amino resin, the solvent is one of dipropylene glycol methyl ether, propylene glycol phenyl ether, and ethylene glycol butyl ether; the defoamer is one of defoamer BYK015, defoamer DC-65, and defoamer DNE01; and the leveling agent is one of leveling agent BYK-333 and leveling agent BYK-3455.

[0017] Preferably, in step 3, the preparation method of silane coupling agent modified silica includes the following steps:

[0018] Glycidyl ether propyltrimethoxysilane was added to ethanol, and the pH was adjusted to 4-5 with 1 mol / L oxalic acid. After hydrolysis for 1 h, a silica ethanol solution was added, and the mixture was stirred and dispersed. The temperature was controlled at 70-80℃, and the reaction was carried out for 1-2 h. The mixture was washed with ethanol and dried to obtain silane coupling agent modified silica.

[0019] Preferably, the ratio of glycidyl ether propyltrimethoxysilane to silica is (1-2) mL:10 g.

[0020] (iii) Beneficial technical effects

[0021] This invention prepares an epoxy-based cyclotriphosphazene through esterification and click reactions. The novel structure has two main advantages: firstly, the presence of a flame-retardant cyclotriphosphazene structure enhances the flame-retardant properties of the coating; secondly, the presence of epoxy groups allows the coating to react with carboxyl groups in the matrix during high-temperature curing, forming a strong interfacial bond and significantly improving the overall performance of the coating. This invention also uses glycidyl ether propyltrimethoxysilane to modify silica. This modified silica contains epoxy groups that, during high-temperature curing, form a dense cross-linked network on the silica surface. This not only increases the compatibility between silica and the organic coating, thus increasing the coating's density, but also acts as a buffer structure, absorbing and dispersing stress under external pressure, thereby improving the overall performance of the coating. Attached Figure Description

[0022] Figure 1 It is the reaction route of epoxy-based triphosphazene. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments in order to better understand the technical solution. All raw materials used in the present invention are commercially available.

[0024] Preparation method of trimer O,O-2-hydroxypropanephosphazene: Under a nitrogen atmosphere, 21.78 g of N,N-dimethylaniline and 10.42 g of hexachlorocyclotriphosphazene were added to a dioxane solvent and stirred to dissolve. Then, 8.28 g of glycerol was added, the temperature was raised to 100 °C, and the reaction was maintained at this temperature for 18 h. The mixture was then cooled to room temperature, filtered, distilled under reduced pressure, washed with deionized water, and the organic phase was dried to obtain trimer O,O-2-hydroxypropanephosphazene.

[0025] Example 1

[0026] Step 1: Add 20g of trimer O,O-2-hydroxypropanephosphazene, 20g of mercaptopropionic acid, and 0.8g of p-toluenesulfonic acid to toluene solvent. Under nitrogen protection, heat and reflux for 12h. After the reaction is completed, cool to room temperature, wash with deionized water, and distill to obtain mercapto-cyclic triphosphazene.

[0027] Step 2: Under nitrogen protection, 15g of mercaptocyclotriphosphazene, 9g of allyl glycidyl ether, and 2.5wt% of DMPA were added to tetrahydrofuran solvent, stirred and dispersed, and then irradiated with UV (λ=352nm, 40W) for 30min. The mixture was then rotary evaporated to obtain epoxy cyclotriphosphazene.

[0028] Step 3: Add 1 mL of glycidyl ether propyltrimethoxysilane to ethanol, adjust the pH to 4 with 1 mol / L oxalic acid, hydrolyze for 1 h, add an ethanol solution containing 5 g of silica, stir and disperse, control the temperature at 80℃, react for 1 h, wash with ethanol, dry, and obtain silane coupling agent modified silica.

[0029] Step 4: Add 20g of R717 amino resin, 5g of epoxy triphosphazene, and 1g of silane coupling agent modified silica to 100g of acrylic emulsion L-631 and stir for 5 minutes. Then add 10g of dipropylene glycol methyl ether, 0.3g of defoamer BYK-015, and 0.3g of leveling agent BYK-3455, stir for 5 minutes, coat evenly on tinplate, let it dry naturally to form a film, and then place it in an oven at 170℃ to cure for 15 minutes to obtain an acrylic resin coating.

[0030] Example 2

[0031] Step 1: Add 20g of trimer O,O-2-hydroxypropanephosphazene, 16g of mercaptopropionic acid and 0.6g of p-toluenesulfonic acid to toluene solvent. Under nitrogen protection, heat and reflux for 8h. After the reaction is completed, cool to room temperature, wash with deionized water and distill to obtain mercapto-cyclic triphosphazene.

[0032] Step 2: Under nitrogen protection, 15g of mercaptocyclotriphosphazene, 8g of allyl glycidyl ether, and 2.5wt% of DMPA were added to tetrahydrofuran solvent, stirred and dispersed, and then irradiated with UV (λ=352nm, 40W) for 30min. The mixture was then rotary evaporated to obtain epoxy cyclotriphosphazene.

[0033] Step 3: Add 1 mL of glycidyl ether propyltrimethoxysilane to ethanol, adjust the pH to 5 with 1 mol / L oxalic acid, hydrolyze for 1 h, add an ethanol solution containing 5 g of silica, stir and disperse, control the temperature at 70 °C, react for 2 h, wash with ethanol, dry, and obtain silane coupling agent modified silica.

[0034] Step 4: Add 30g of R717 amino resin, 8g of epoxy triphosphazene, and 3g of silane coupling agent modified silica to 100g of acrylic emulsion L-631 and stir for 10 minutes. Then add 10g of dipropylene glycol methyl ether, 0.3g of defoamer BYK-015, and 0.3g of leveling agent BYK-3455, stir for 5 minutes, coat evenly on tinplate, let it dry naturally to form a film, and then place it in an oven at 170℃ to cure for 15 minutes to obtain an acrylic resin coating.

[0035] Example 3

[0036] Step 1: Add 20g of trimer O,O-2-hydroxypropanephosphazene, 24g of mercaptopropionic acid and 1g of p-toluenesulfonic acid to toluene solvent. Under nitrogen protection, heat and reflux for 10h. After the reaction is completed, cool to room temperature, wash with deionized water and distill to obtain mercapto-cyclic triphosphazene.

[0037] Step 2: Under nitrogen protection, 15g of mercaptocyclotriphosphazene, 7.8g of allyl glycidyl ether, and 2.5wt% of DMPA were added to tetrahydrofuran solvent, stirred and dispersed, and then irradiated with UV (λ=352nm, 40W) for 30min. The mixture was then rotary evaporated to obtain epoxy cyclotriphosphazene.

[0038] Step 3: Add 1 mL of glycidyl ether propyltrimethoxysilane to ethanol, adjust the pH to 4 with 1 mol / L oxalic acid, hydrolyze for 1 h, add an ethanol solution containing 5 g of silica, stir and disperse, control the temperature at 75 °C, react for 2 h, wash with ethanol, dry, and obtain silane coupling agent modified silica.

[0039] Step 4: Add 40g of R717 amino resin, 10g of epoxy cyclotriphosphazene, and 5g of silane coupling agent modified silica to 100g of acrylic emulsion L-631 and stir for 10 minutes. Then add 10g of dipropylene glycol methyl ether, 0.3g of defoamer BYK-015, and 0.3g of leveling agent BYK-3455, stir for 5 minutes, coat evenly on tinplate, let it dry naturally to form a film, and then place it in an oven at 170℃ to cure for 15 minutes to obtain an acrylic resin coating.

[0040] Comparative Example 1

[0041] The difference between this comparative example and Example 1 is that chloropropyltriethoxysilane is used instead of glycidyl ether propyltrimethoxysilane in step 3, while the remaining steps are the same as in Example 1.

[0042] Comparative Example 2

[0043] The difference between this comparative example and Example 1 is that in step 4, mercapto-cyclic triphosphazene is used instead of epoxy-based cyclic triphosphazene; the remaining steps are the same as in Example 1.

[0044] Comparative Example 3

[0045] The difference between this comparative example and Example 1 is that 5625A amino resin is used instead of R717 amino resin in step 4, while the remaining steps are the same as in Example 1.

[0046] Comparative Example 4

[0047] The difference between this comparative example and Example 1 is that step 4 does not contain epoxy triphosphazene, while the remaining steps are the same as in Example 1.

[0048] According to GB / T1732-2020, the impact resistance is tested by dropping a 1kg weight onto the tinplate surface in a free-fall manner, and the test is carried out sequentially from low to high. The impact resistance is represented by the height at which the paint film breaks just before the impact.

[0049] Adhesion was tested in accordance with GB / T 9286-2021.

[0050] Table 1:

[0051] Impact resistance / kg·cm Adhesion / Grade Example 1 65 0 Example 2 70 0 Example 3 70 0 Comparative Example 1 50 1 Comparative Example 2 60 1 Comparative Example 3 55 0 Comparative Example 4 40 2

[0052] As shown in Table 1, the coatings prepared in the embodiments of the present invention have better impact resistance. In Comparative Example 1, chloropropyltriethoxysilane was used instead of glycidyl ether propyltrimethoxysilane, which does not contain epoxy groups. When the coating is cured at high temperature, the epoxy groups can react with the carboxyl groups in the resin matrix and form a dense cross-linked network structure on the silica surface, i.e., an organic buffer layer. This increases the tightness of the coating and the compatibility between silica and organic coating. When subjected to external force, the large organic buffer layer can absorb and disperse the impact force, thereby improving the impact resistance of the coating. However, the silane coupling agent modified silica in Comparative Example 1 does not contain epoxy groups, so it cannot form a dense cross-linked network structure on the silica surface, and cannot improve the further "fusion" between silica and organic coating. Therefore, its impact resistance is poor.

[0053] In Comparative Example 2, mercaptocyclotriphosphazene was used instead of epoxy-based cyclotriphosphazene. Its impact resistance was not as good as that of the embodiments of the present invention. The possible reasons are: (1) it does not contain epoxy groups and cannot form a dense cross-linked network structure with acrylic acid during high-temperature curing; (2) its chain length is shorter. The epoxy-based cyclotriphosphazene of the present invention has a longer chain length and can entangle with other molecular chains to form more physical cross-linking sites, thereby improving the impact resistance.

[0054] Comparative Example 3 uses 5625A amino resin instead of R717 amino resin, and its mechanical properties are not as good as those of the Example. This is because the R717 amino resin selected in this invention contains more secondary amino groups, which can not only undergo cross-linking reaction with acrylic resin, but also self-cross-link between amino resins, thereby increasing the cross-linking density of the coating and improving the impact resistance of the coating.

[0055] As can be seen from the adhesion level test structure, the adhesion performance test structure of the Examples and Comparative Example 3 is better than that of Comparative Examples 1-2. This is because the Examples and Comparative Example 3 contain silane coupling agent modified silica and epoxy triphosphazene prepared in this invention. Both contain epoxy groups. The epoxy groups can generate hydroxyl groups during the curing process. The hydroxyl groups can form hydrogen bonds or coordination bonds with the oxide layer or metal atoms on the metal surface, thereby enhancing the adhesion of the coating.

[0056] Comparative Example 4 does not contain the epoxy triphosphazene of the present invention, therefore it has the worst impact resistance and adhesion properties.

[0057] The abrasion resistance was tested using an abrasion tester. Specifically, the abrasion resistance of the coating was measured on a circular abrasion plate using a grinding wheel. After the coating was ground smooth, the initial weight was recorded. The weight was recorded every 50 revolutions, and the grinding wheel was re-ground. The abrasion resistance of the coating was judged by the average weight loss of the coating every 50 revolutions.

[0058] The flame retardant properties of the coating were tested using a horizontal-vertical burner.

[0059] Table 2:

[0060]

[0061] As shown in Table 2, the coating prepared by this invention has good flame retardancy and wear resistance. The lower the wear amount, the better the wear resistance. In Comparative Example 1, chloropropyltriethoxysilane was used instead of glycidyl ether propyltrimethoxysilane, which does not contain epoxy groups. Epoxy groups can react with carboxyl groups in the resin matrix during high-temperature curing of the coating, forming a dense cross-linked network structure on the silica surface, thereby increasing the compatibility between silica and the organic coating and further improving the coating's tightness. Comparative Example 1 does not contain epoxy groups, therefore, during wear, the bonding force between silica and the coating matrix is ​​insufficient, failing to resist the external force brought by friction, causing the coating surface to peel off. Therefore, Comparative Example 1 has poor wear resistance. Comparative Example 4, because it does not contain the epoxy triphosphazene of this invention, has the worst wear resistance and flame retardancy.

[0062] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a wear-resistant and flame-retardant acrylic resin coating, characterized in that, The preparation method includes the following steps: Step 1: Add trimer O,O-2-hydroxypropanephosphazene, mercaptopropionic acid and catalyst to toluene solvent, heat under nitrogen protection and reflux for 8-12 h. After the reaction is completed, cool to room temperature, wash with deionized water and distill to obtain mercapto-cyclic triphosphazene. Step 2: Under nitrogen protection, mercapto-cyclic triphosphazene, allyl glycidyl ether, and benzoin dimethyl ether were added to tetrahydrofuran solvent, stirred and dispersed, irradiated with UV light for 30 min, and rotary evaporated to obtain epoxy-based triphosphazene. Step 3: Add amino resin, epoxy triphosphazene, and silane coupling agent modified silica to the acrylic emulsion and stir for 5-10 minutes. Then add solvent, defoamer, and leveling agent, stir for 5 minutes, and coat evenly on tinplate. Let it dry naturally to form a film, and cure in an oven at 170°C for 15 minutes to obtain an acrylic resin coating.

2. The method for preparing the wear-resistant and flame-retardant acrylic resin coating according to claim 1, characterized in that, In step 1, the ratio of trimer O,O-2-hydroxypropanephosphazene to mercaptopropionic acid is 1g:(0.8-1.2)g.

3. The method for preparing the wear-resistant and flame-retardant acrylic resin coating according to claim 1, characterized in that, In step 1, the catalyst is p-toluenesulfonic acid, and its dosage is 3-5% of the mass of trimero-O,O-2-hydroxypropanephosphazene.

4. The method for preparing the wear-resistant and flame-retardant acrylic resin coating according to claim 1, characterized in that, In step 2, the ratio of mercaptocyclotriphosphazene to allyl glycidyl ether is 1g:(0.52-0.6)g.

5. The method for preparing the wear-resistant and flame-retardant acrylic resin coating according to claim 1, characterized in that, In step 3, the ratio of acrylic resin emulsion, amino resin, epoxy cyclotriphosphazene, and silane coupling agent modified silica is 100g:(20-40)g:(5-10)g:(1-5)g.

6. The method for preparing the wear-resistant and flame-retardant acrylic resin coating according to claim 1, characterized in that, In step 3, the amino resin is R717 amino resin, the solvent is one of dipropylene glycol methyl ether, propylene glycol phenyl ether, and ethylene glycol butyl ether; the defoamer is one of defoamer BYK015, defoamer DC-65, and defoamer DNE01; and the leveling agent is one of leveling agent BYK-333 and leveling agent BYK-3455.

7. The method for preparing the wear-resistant and flame-retardant acrylic resin coating according to claim 1, characterized in that, In step 3, the preparation method of silane coupling agent modified silica includes the following steps: Glycidyl ether propyltrimethoxysilane was added to ethanol, and the pH was adjusted to 4-5 with 1 mol / L oxalic acid. After hydrolysis for 1 h, a silica ethanol solution was added, and the mixture was stirred and dispersed. The temperature was controlled at 70-80℃, and the reaction was carried out for 1-2 h. The mixture was washed with ethanol and dried to obtain silane coupling agent modified silica.

8. The method for preparing the wear-resistant and flame-retardant acrylic resin coating according to claim 7, characterized in that, The ratio of glycidyl ether propyltrimethoxysilane to silica is (1-2) mL: 10 g.

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