A kind of preparation method of EVA waterproof coating

Abstract

The present invention relates to the technical field of coatings and discloses a method for preparing an EVA waterproof coating. Activated montmorillonite reacts with toluene diisocyanate to obtain isocyanate-modified montmorillonite. EVA is hydrolyzed under the catalysis of potassium hydroxide to obtain hydroxylated EVA. An epoxy trisiloxane intermediate reacts with terephthalic acid under ring-opening esterification with benzyltriethylammonium chloride to obtain p-hydroxytrisiloxane benzoate. P-hydroxytrisiloxane benzoate, hydroxylated EVA, and isocyanate-modified montmorillonite are cross-linked with toluene diisocyanate under the catalysis of stannous octoate, and a defoamer and a dispersant are added thereto and stirred uniformly to obtain an EVA waterproof coating. The EVA waterproof coating prepared by the present invention has good mechanical properties and waterproof properties.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a method for preparing an EVA waterproof coating. Background Art

[0002] Water, chloride ions, and other harmful ions can penetrate concrete and other porous materials through their pores, affecting their durability and increasing maintenance costs. Therefore, waterproof coatings are needed to impart waterproof and wear-resistant properties to these materials, extending their useful life. Therefore, the research and development of new waterproof coatings is a key area of ​​research.

[0003] EVA is an ethylene-vinyl acetate copolymer material with excellent elasticity, flexibility, insulation, and chemical resistance. It is widely used in wires and cables, films, adhesives, coatings, and other fields. Montmorillonite is a natural silicate mineral with a negative surface charge, consisting of a layer of aluminum oxide octahedra sandwiched between two layers of silicon oxide tetrahedrons. It has good dispersibility and impact resistance. For example, patent application publication number CN113930169B discloses a heat-resistant EVA film and its preparation method. The film produced by this invention has good tensile strength, tear strength, and good resistance to moisture and heat, but its water resistance is poor. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a preparation method of an EVA waterproof coating, and the prepared EVA waterproof coating has good mechanical properties and waterproof properties.

[0005] The technical solution of the present invention is:

[0006] A preparation method of an EVA waterproof coating, the preparation method is as follows:

[0007] (1) placing an epoxy trisiloxane intermediate, terephthalic acid, and benzyltriethylammonium chloride in 1,2-dichloroethane, reacting at 75-90° C. for 2.5-4 hours, cooling to room temperature, filtering under reduced pressure, recrystallizing, and drying to obtain p-hydroxytrisiloxane benzoate;

[0008] (2) Place p-hydroxytrisiloxane benzoate, hydroxylated EVA, isocyanate-modified montmorillonite, stannous octoate, and tetrahydrofuran solvent in a flask, stir evenly, add toluene diisocyanate, heat to 60-70°C, react for 2-4 hours, cool to room temperature, add water, remove tetrahydrofuran by vacuum distillation, add defoamer and dispersant, stir evenly, and obtain EVA waterproof coating.

[0009] Furthermore, in step (1), the mass ratio of the epoxytrisiloxane intermediate to terephthalic acid is 1:0.2-0.3.

[0010] Furthermore, the amount of benzyltriethylammonium chloride used in step (1) is 1-1.5% of the total mass of the epoxytrisiloxane intermediate and terephthalic acid.

[0011] Furthermore, in the step (2), the mass ratio of p-hydroxytrisiloxane benzoate, hydroxylated EVA, isocyanate-modified montmorillonite, stannous octoate, and toluene diisocyanate is 5-30:100:0.5-8:0.02-0.12:3-20.

[0012] Furthermore, the preparation method of the hydroxylated EVA in step (2) is as follows:

[0013] (3) EVA is placed in a toluene solution, and an isopropanol solution of potassium hydroxide is added at 50-70°C, and the mixture is stirred for 5-8 hours. The mixture is precipitated with ethanol, filtered, washed with ethanol, and dried to obtain hydroxylated EVA.

[0014] Furthermore, in step (3), the mass ratio of EVA to potassium hydroxide is 100:5-7.

[0015] Furthermore, the preparation method of the isocyanate-modified montmorillonite in step (2) is as follows:

[0016] (4) Under nitrogen protection, activated montmorillonite and toluene diisocyanate are placed in a toluene solvent and stirred and dispersed for 20-40 minutes, the temperature is raised to react, cooled to room temperature, filtered, washed, and vacuum dried to obtain isocyanate-modified montmorillonite.

[0017] Furthermore, in step (4), the mass ratio of activated montmorillonite to toluene diisocyanate is 1:0.2-0.5.

[0018] Furthermore, the heating reaction time in step (4) is 60-100 minutes and the temperature is 70-90°C.

[0019] The beneficial technical effects of the present invention are:

[0020] Activated montmorillonite reacts with toluene diisocyanate to produce isocyanate-modified montmorillonite. EVA is hydrolyzed under the catalysis of potassium hydroxide to produce hydroxylated EVA. The epoxy trisiloxane intermediate reacts with terephthalic acid under ring-opening esterification with benzyltriethylammonium chloride to produce p-hydroxytrisiloxane benzoate. P-hydroxytrisiloxane benzoate, hydroxylated EVA, and isocyanate-modified montmorillonite are then cross-linked with toluene diisocyanate under the catalysis of stannous octoate. A defoamer and dispersant are then added and stirred to produce an EVA waterproof coating.

[0021] The coating prepared by the present invention has a large cross-linked network structure, high density, low surface tension, and is distributed on the surface of the material. Water molecules and other ions cannot enter the interior of the material, and the coating has a good waterproof effect. Moreover, when impacted, the large network structure can also absorb more impact force, transfer the impact force received by the material, reduce stress concentration, delay the fracture process, and improve the mechanical properties of the material. In addition, the siloxane structure therein can produce a cross-linked structure through hydrolysis and gelation, restricting the entry of water molecules and improving the waterproof performance of the material. The montmorillonite used in the present invention has good mechanical properties, but its surface has active groups such as hydroxyl groups. It is first subjected to surface modification to reduce the surface free energy, and then used as a reactant to undergo a chemical reaction and applied to the EVA waterproof coating, thereby improving the mechanical properties of the coating. The EVA waterproof coating prepared by the present invention has good mechanical properties and waterproof performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the preparation route of 4-hydroxytrisiloxane benzoate. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of this application more clear, the present application is further described in detail below with reference to the embodiments. It should be understood that the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] Preparation method of epoxy trisiloxane intermediate: 1,1,1,3,5,5,5-heptamethyltrisiloxane and allyl glycidyl ether in a molar ratio of 1:1.05 are placed in an isopropanol solution, and an alcohol solution of chloroplatinic acid is added thereto under a nitrogen atmosphere. The reaction is carried out at 90°C for 5 hours, the solvent is evaporated, and low-boiling substances are removed in vacuo at 85°C and 60 kPa for 30 minutes. The mixture is cooled to room temperature to obtain the epoxy trisiloxane intermediate.

[0025] Preparation method of activated montmorillonite: Place montmorillonite in a flask under a nitrogen atmosphere and activate it at 250°C for 2 hours to obtain activated montmorillonite.

[0026] Example 1

[0027] (1) Under nitrogen protection, 60 g of activated montmorillonite and 15 g of toluene diisocyanate were placed in a toluene solvent and stirred for 30 min. The mixture was heated to 80 °C and reacted for 80 min. The mixture was cooled to room temperature, filtered, washed, and vacuum dried to obtain isocyanate-modified montmorillonite.

[0028] (2) 80 g of EVA was placed in a toluene solution, and 5 g of potassium hydroxide was added to an isopropanol solution, stirred to dissolve, and the two solutions were mixed. The mixture was stirred and reacted at 60° C. for 7 h, and ethanol was used for precipitation, filtration, ethanol washing, and drying to obtain hydroxylated EVA.

[0029] (3) 12 g of epoxy trisiloxane intermediate, 3-terephthalic acid, and 0.2 g of benzyltriethylammonium chloride were placed in 1,2-dichloroethane, reacted at 80° C. for 4 h, cooled to room temperature, filtered under reduced pressure, recrystallized, and dried to obtain p-hydroxytrisiloxane benzoate.

[0030] (4) 10 g of p-hydroxytrisiloxane benzoate, 200 g of hydroxylated EVA, 1 g of isocyanate-modified montmorillonite, 0.1 g of stannous octoate, and tetrahydrofuran solvent were placed in a flask, stirred evenly, and 20 g of toluene diisocyanate was added thereto. The temperature was raised to 65 ° C. and the reaction was carried out for 4 h. The temperature was lowered to room temperature, water was added thereto, and tetrahydrofuran was removed by vacuum distillation. 1.5 g of defoaming agent BKY-141 and 0.8 g of titanate dispersant NXH-1242 were added thereto, and the mixture was stirred evenly to obtain an EVA waterproof coating.

[0031] Example 2

[0032] (1) Under nitrogen protection, 60 g of activated montmorillonite and 20 g of toluene diisocyanate were placed in a toluene solvent and stirred for 30 min. The mixture was heated to 90 °C and reacted for 100 min. The mixture was cooled to room temperature, filtered, washed, and vacuum dried to obtain isocyanate-modified montmorillonite.

[0033] (2) 80 g of EVA was placed in a toluene solution, and 5.6 g of potassium hydroxide was added to an isopropanol solution, stirred to dissolve, and the two solutions were mixed. The mixture was stirred and reacted at 50° C. for 7 h, ethanol precipitation was performed, suction filtration was performed, ethanol washing was performed, and drying was performed to obtain hydroxylated EVA.

[0034] (3) 12 g of epoxy trisiloxane intermediate, 3.5 g of terephthalic acid, and 0.23 g of benzyltriethylammonium chloride were placed in 1,2-dichloroethane, reacted at 90° C. for 3 h, cooled to room temperature, filtered under reduced pressure, recrystallized, and dried to obtain p-hydroxytrisiloxane benzoate.

[0035] (4) 26 g of p-hydroxytrisiloxane benzoate, 200 g of hydroxylated EVA, 6 g of isocyanate-modified montmorillonite, 0.24 g of stannous octoate, and tetrahydrofuran solvent were placed in a flask, stirred evenly, and 25 g of toluene diisocyanate was added thereto. The temperature was raised to 70 ° C. and the reaction was carried out for 3 h. The temperature was lowered to room temperature, water was added thereto, and tetrahydrofuran was removed by vacuum distillation. 1.5 g of defoaming agent BKY-141 and 0.8 g of titanate dispersant NXH-1242 were added thereto, and the mixture was stirred evenly to obtain an EVA waterproof coating.

[0036] Example 3

[0037] (1) Under nitrogen protection, 60 g of activated montmorillonite and 20 g of toluene diisocyanate were placed in a toluene solvent and stirred for 20 min. The mixture was heated to 80 °C and reacted for 70 min. The mixture was cooled to room temperature, filtered, washed, and vacuum dried to obtain isocyanate-modified montmorillonite.

[0038] (2) 80 g of EVA was placed in a toluene solution, and 5 g of potassium hydroxide was added to an isopropanol solution, stirred to dissolve, and the two solutions were mixed. The mixture was stirred and reacted at 60° C. for 6 h, ethanol precipitation was performed, suction filtration was performed, ethanol washing was performed, and drying was performed to obtain hydroxylated EVA.

[0039] (3) 12 g of epoxy trisiloxane intermediate, 3.5 g of terephthalic acid, and 0.15 g of benzyltriethylammonium chloride were placed in 1,2-dichloroethane, reacted at 80° C. for 3 h, cooled to room temperature, filtered under reduced pressure, recrystallized, and dried to obtain p-hydroxytrisiloxane benzoate.

[0040] (4) 42 g of p-hydroxytrisiloxane benzoate, 200 g of hydroxylated EVA, 11 g of isocyanate-modified montmorillonite, 0.15 g of stannous octoate, and tetrahydrofuran solvent were placed in a flask, stirred evenly, and 20 g of toluene diisocyanate was added thereto. The temperature was raised to 65 ° C. and the reaction was carried out for 4 h. The temperature was lowered to room temperature, water was added thereto, and tetrahydrofuran was removed by vacuum distillation. 1.5 g of defoaming agent BKY-141 and 0.8 g of titanate dispersant NXH-1242 were added thereto, and the mixture was stirred evenly to obtain an EVA waterproof coating.

[0041] Example 4

[0042] (1) Under nitrogen protection, 60 g of activated montmorillonite and 20 g of toluene diisocyanate were placed in a toluene solvent and stirred for 30 min. The mixture was heated to 80 °C and reacted for 80 min. The mixture was cooled to room temperature, filtered, washed, and vacuum dried to obtain isocyanate-modified montmorillonite.

[0043] (2) 80 g of EVA was placed in a toluene solution, and 5.6 g of potassium hydroxide was added to an isopropanol solution, stirred to dissolve, and the two solutions were mixed. The mixture was stirred and reacted at 60° C. for 7 h, ethanol precipitation was performed, suction filtration was performed, ethanol washing was performed, and drying was performed to obtain hydroxylated EVA.

[0044] (3) 12 g of epoxy trisiloxane intermediate, 3-terephthalic acid, and 0.2 g of benzyltriethylammonium chloride were placed in 1,2-dichloroethane, reacted at 80° C. for 3 h, cooled to room temperature, filtered under reduced pressure, recrystallized, and dried to obtain p-hydroxytrisiloxane benzoate.

[0045] (4) 60 g of p-hydroxytrisiloxane benzoate, 200 g of hydroxylated EVA, 16 g of isocyanate-modified montmorillonite, 0.24 g of stannous octoate, and tetrahydrofuran solvent were placed in a flask, stirred evenly, and 30 g of toluene diisocyanate was added thereto. The temperature was raised to 65 ° C. and the reaction was carried out for 3 h. The temperature was lowered to room temperature, water was added thereto, and tetrahydrofuran was removed by vacuum distillation. 1.5 g of defoaming agent BKY-141 and 0.8 g of titanate dispersant NXH-1242 were added thereto, and the mixture was stirred evenly to obtain an EVA waterproof coating.

[0046] Comparative Example 1

[0047] (1) 80 g of EVA was placed in a toluene solution, and 5 g of potassium hydroxide was added to an isopropanol solution, stirred to dissolve, and the two solutions were mixed. The mixture was stirred and reacted at 60° C. for 7 h, and ethanol precipitation was performed. The mixture was filtered, washed with ethanol, and dried to obtain hydroxylated EVA.

[0048] (2) 12 g of epoxy trisiloxane intermediate, 3-terephthalic acid, and 0.2 g of benzyltriethylammonium chloride were placed in 1,2-dichloroethane, reacted at 80° C. for 4 h, cooled to room temperature, filtered under reduced pressure, recrystallized, and dried to obtain p-hydroxytrisiloxane benzoate.

[0049] (3) 10 g of p-hydroxytrisiloxane benzoate, 200 g of hydroxylated EVA, 0.1 g of stannous octoate and tetrahydrofuran solvent were placed in a flask, stirred evenly and 20 g of toluene diisocyanate was added thereto, the temperature was raised to 65 ° C, the reaction was carried out for 4 h, the temperature was lowered to room temperature, water was added thereto, tetrahydrofuran was removed by vacuum distillation, 1.5 g of defoaming agent BKY-141 and 0.8 g of titanate dispersant NXH-1242 were added thereto, and the mixture was stirred evenly to obtain an EVA waterproof coating.

[0050] Comparative Example 2

[0051] (1) Under nitrogen protection, 60 g of activated montmorillonite and 15 g of toluene diisocyanate were placed in a toluene solvent and stirred for 30 min. The mixture was heated to 80 °C and reacted for 80 min. The mixture was cooled to room temperature, filtered, washed, and vacuum dried to obtain isocyanate-modified montmorillonite.

[0052] (2) 200 g of hydroxylated EVA, 1 g of isocyanate-modified montmorillonite, 0.1 g of stannous octoate, and tetrahydrofuran solvent were placed in a flask, stirred evenly, and 20 g of toluene diisocyanate was added thereto. The temperature was raised to 65 ° C. and the reaction was carried out for 4 h. The temperature was lowered to room temperature. Water was added thereto, and tetrahydrofuran was removed by vacuum distillation. 1.5 g of defoaming agent BKY-141 and 0.8 g of titanate dispersant NXH-1242 were added thereto, and the mixture was stirred evenly to obtain an EVA waterproof coating.

[0053] The prepared waterproof coating was applied to a polytetrafluoroethylene plate to form a 1.5 mm thick film, which was cured for one week under standard test conditions (23 ± 2°C and 50 ± 10% relative humidity) before performance testing.

[0054] The mechanical properties of the samples were tested using an electronic tensile testing machine.

[0055] Tensile strength / MPa Elongation at break / % Example 1 10.31 117.0 Example 2 15.96 146.3 Example 3 18.60 163.4 Example 4 16.12 156.9 Comparative Example 1 9.21 104.3 Comparative Example 2 10.13 116.4

[0056] The tensile strength and elongation at break of Example 3 are relatively large, which are 11.60 MPa and 124.1% respectively. The tensile strength and elongation at break of Comparative Example 1 are the smallest. This is because montmorillonite is added to Examples 1-5 and Comparative Example 2, and montmorillonite has good mechanical properties. In addition, since Examples 1-5 and Comparative Example 1-2 both contain relatively excellent cross-linked network structures, they can transfer the impact force exerted on the material when impacted, thereby enhancing the mechanical properties of the coating.

[0057] The water resistance of the paint coating is tested with reference to GB / T 16777-2008 "Test methods for building waterproof coatings" and GB / T1733-1993 "Determination of water resistance of paint films".

[0058] Water impermeability (0.3MPa, 120min) Water resistance Example 1 impermeable No peeling, no blistering, qualified Example 2 impermeable No peeling, no blistering, qualified Example 3 impermeable No peeling, no blistering, qualified Example 4 impermeable No peeling, no blistering, qualified Comparative Example 1 impermeable Peeling, no blistering, unqualified Comparative Example 2 permeable Peeling, blistering, unqualified

[0059] Examples 1-5 and Comparative Example 1 are all impermeable to water, but Comparative Example 2 is permeable to water. The water resistance of Examples 1-5 is acceptable, with no peeling or blistering. This is because the siloxane structures in Examples 1-5 and Comparative Example 1 can produce cross-linked structures through hydrolysis and gelation, restricting the entry of water molecules and improving the waterproof performance of the material. Furthermore, the structure prepared by the present invention has a low surface energy and good hydrophobic and waterproof properties. Therefore, Comparative Example 2 has the worst waterproof effect.

[0060] The present application has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art will appreciate that, without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present application, all of which fall within the scope of the present application. The scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for preparing an EVA waterproof coating, characterized in that: The preparation method is as follows: (1) placing an epoxy trisiloxane intermediate, terephthalic acid, and benzyltriethylammonium chloride in 1,2-dichloroethane, reacting at 75-90° C. for 2.5-4 hours, cooling to room temperature, filtering under reduced pressure, recrystallizing, and drying to obtain p-hydroxytrisiloxane benzoate; (2) placing p-hydroxytrisiloxane benzoate, hydroxylated EVA, isocyanate-modified montmorillonite, stannous octoate, and tetrahydrofuran solvent in a flask, stirring evenly, adding toluene diisocyanate thereto, heating to 60-70° C., reacting for 2-4 hours, cooling to room temperature, adding water thereto, removing tetrahydrofuran by vacuum distillation, adding a defoamer and a dispersant, stirring evenly, and obtaining an EVA waterproof coating; The preparation method of the epoxy trisiloxane intermediate comprises the following steps: 1,1,1,3,5,5,5-heptamethyltrisiloxane and allyl glycidyl ether in a molar ratio of 1:1.05 were placed in an isopropanol solution. Under a nitrogen atmosphere, an alcoholic solution of chloroplatinic acid was added thereto. The reaction was carried out at 90°C for 5 hours. The solvent was evaporated and low-boiling substances were removed in vacuo at 85°C and 60 kPa for 30 minutes. The mixture was cooled to room temperature to obtain an epoxytrisiloxane intermediate.

2. The preparation method of the EVA waterproof coating according to claim 1, wherein: In the step (1), the mass ratio of the epoxytrisiloxane intermediate to terephthalic acid is 1:0.2-0.

3.

3. The preparation method of the EVA waterproof coating according to claim 1, wherein: The amount of benzyltriethylammonium chloride used in step (1) is 1-1.5% of the total mass of the epoxytrisiloxane intermediate and terephthalic acid.

4. The preparation method of the EVA waterproof coating according to claim 1, wherein: In the step (2), the mass ratio of p-hydroxytrisiloxane benzoate, hydroxylated EVA, isocyanate-modified montmorillonite, stannous octoate, and toluene diisocyanate is 5-30:100:0.5-8:0.02-0.12:3-20.

5. The preparation method of the EVA waterproof coating according to claim 1, wherein: The preparation method of hydroxylated EVA in step (2) is as follows: (3) EVA is placed in a toluene solution, and an isopropanol solution of potassium hydroxide is added at 50-70°C, and the mixture is stirred for 5-8 hours. The mixture is precipitated with ethanol, filtered, washed with ethanol, and dried to obtain hydroxylated EVA.

6. The preparation method of the EVA waterproof coating according to claim 5, characterized in that: The mass ratio of EVA to potassium hydroxide in step (3) is 100:5-7.

7. The preparation method of the EVA waterproof coating according to claim 1, wherein: The preparation method of the isocyanate-modified montmorillonite in step (2) is as follows: (4) Under nitrogen protection, activated montmorillonite and toluene diisocyanate are placed in a toluene solvent and stirred and dispersed for 20-40 minutes, the temperature is raised to react, cooled to room temperature, filtered, washed, and vacuum dried to obtain isocyanate-modified montmorillonite.

8. The preparation method of the EVA waterproof coating according to claim 7, wherein: In the step (4), the mass ratio of activated montmorillonite to toluene diisocyanate is 1:0.2-0.

5.

9. The preparation method of the EVA waterproof coating according to claim 7, characterized in that: The heating reaction time in step (4) is 60-100 minutes, and the temperature is 70-90°C.

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