Intumescent water-based vinyl acetate-ethylene fireproof coating for steel structure and preparation method of intumescent water-based vinyl acetate-ethylene fireproof coating

Abstract

The invention relates to a fireproof coating, in particular to an intumescent water-based vinyl acetate-ethylene fireproof coating for a steel structure. The coating is prepared from the following substances in percentage by weight: 40 to 50 percent of water-based vinyl acetate-ethylene copolymer emulsion, 15 to 20 percent of ammonium polyphosphate, 8 to 10 percent of pentaerythritol, 11 to 13 percent of melamine, 2 to 3 percent of expansible graphite, 0.1 to 1 percent of titanium dioxide, 1 to 2 percent of hollow floating beads, 1 to 2 percent of basalt scales and the balance of water. By optimizing the types and proportions of the intumescent flame-retardant system and the heat-insulating filler, the thickness of an intumescent carbonized layer is increased and the structure of the intumescent carbonized layer is improved on the premise of ensuring the adhesive force of the intumescent carbonized layer and a steel substrate, so that the intumescent water-based vinyl acetate-ethylene fireproof coating for the steel structure, which is high in fire resistance, environment-friendly and single-component, is obtained.

Description

Technical Field

[0001] The invention relates to the field of fire retardant coatings, and in particular to an intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating and a preparation method thereof. Background Art

[0002] Intumescent water-based fire retardant coatings have become the focus of research and application of steel structure fire retardant coatings due to their good environmental protection. Intumescent water-based fire retardant coatings are usually composed of four parts: resin emulsion, intumescent flame retardant system, filler and additives. Among them, resin emulsions mainly include water-based polyurethane emulsions, water-based acrylic emulsions, water-based epoxy emulsions, water-based styrene-acrylic emulsions, water-based vinyl acetate-ethylene copolymer emulsions, water-based polyurea emulsions, etc. Compared with a single emulsion, the fire retardant coatings composed of copolymer emulsions and blended emulsions composed of two or more emulsions have better fire resistance. CN 105131745 A Chinese patent discloses a high-intumescent water-based vinyl acetate-ethylene fire retardant coating for steel structures. The invention uses ammonium metaphosphate as a curing agent, and the curing agent is added to other components during construction, and the construction needs to be completed in a short time, which has construction limitations. CN 111363427 A Chinese patent discloses a single-component intumescent water-based vinyl acetate-ethylene fire retardant coating. However, the invention is suitable for cable fire prevention, but not for steel structure fire prevention. Chinese patent CN 110903689A discloses a single-component intumescent water-based vinyl acetate-ethylene fire retardant coating for steel structure. The invention uses a silane-modified ammonium polyphosphate-pentaerythritol-melamine ternary flame retardant system to improve the water resistance of the fire retardant coating. However, the fire retardant coating of the invention contains 20-25% water, and the hydrophobic ternary intumescent flame retardant will reduce its compatibility with the hydrophilic water-based resin emulsion and water, which is not conducive to improving the fire resistance. Summary of the invention

[0003] Aiming at the problem that the existing intumescent water-based fire-retardant coating has poor comprehensive performance, the present invention provides an intumescent water-based vinyl acetate-ethylene steel structure fire-retardant coating, which is composed of the following substances in percentage by weight: 40-50% of water-based vinyl acetate-ethylene copolymer emulsion, 15-20% of ammonium polyphosphate, 8-10% of pentaerythritol, 11-13% of melamine, 2-3% of expandable graphite, 0.1-1% of titanium dioxide, 1-2% of hollow floating beads, 1-2% of basalt flakes, and the balance of water.

[0004] Specifically, the solid content of the aqueous vinyl acetate-ethylene copolymer emulsion is 40-60%, and the particle size is 0.1-0.5 μm; the degree of polymerization of ammonium polyphosphate is ≥1000; the solid content of pentaerythritol is ≥98%, and the particle size is 3-5 μm; the expandable graphite is a 300-400 mesh flaky powder with a thickness of 5-15 μm; the titanium dioxide is a spherical powder of 800-1200 mesh; the hollow floating beads are hollow spherical powders of 150-300 mesh; and the basalt flakes are 300-400 mesh.

[0005] The preparation method of the intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating of the present invention comprises the following steps:

[0006] 1. Weigh ammonium polyphosphate, pentaerythritol, melamine, expandable graphite, titanium dioxide, hollow floating beads and basalt flakes according to proportion, and stir and mix at 100-300 rpm for 10-20 minutes to obtain a mixed powder;

[0007] 2. Weigh water and aqueous vinyl acetate-ethylene copolymer emulsion in proportion, stir mechanically at 500-600 rpm, add the mixed powder prepared in step 1 spoonful by spoonful during the stirring process, and after all the addition is completed, stir at 1000-1200 rpm for 20-40 minutes to prepare a mixed slurry;

[0008] 3. Apply the mixed slurry obtained in step 2 on the surface of the steel structure and cure it at room temperature for 1 week.

[0009] The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating of the present invention utilizes the intumescent carbonized layer formed by the fire retardant coating during a fire to delay the transmission of oxygen and heat to the steel structure, thereby protecting the steel structure. The expansion rate of the fire retardant coating and the structure of the intumescent carbonized layer are the core factors affecting the fire resistance. Generally speaking, the higher the expansion rate, the thicker the intumescent carbonized layer, the finer the pores inside the carbonized layer, the farther the transmission path of heat and oxygen, and the better the fireproof effect. Ammonium polyphosphate-pentaerythritol-melamine is a universal chemical intumescent flame retardant system, and expandable graphite is a universal physical intumescent system. During a fire, the ammonium polyphosphate-pentaerythritol-melamine ternary chemical intumescent flame retardant system reacts chemically to form a carbonized layer skeleton. At the same time, expandable graphite expands when heated and also forms a carbonized layer skeleton. Although the ammonium polyphosphate-pentaerythritol-melamine-expandable graphite quaternary intumescent flame retardant system can increase the expansion rate of the fire retardant coating and increase the thickness of the intumescent carbonized layer, it will also change the structure of the carbonized layer at the same time. If the carbonized layer structure shows phenomena such as falling off, cracks, and enlarged pores, it will not effectively delay the transmission of oxygen and heat, and cannot play a role in protecting the steel structure. The present invention reasonably designs the ratio of the four, so that the chemical expansion carbonization layer and the physical expansion carbonization layer are reasonably matched, and the expansion rate of the fire-retardant coating is increased without reducing the adhesion between the chemical carbonization layer and the steel substrate, and the pore size of the carbonization layer is adjusted, thereby increasing the transmission distance of oxygen and heat, and obtaining higher fire resistance. In addition, the technical solution uses hollow floating beads and basalt flakes as thermal insulation fillers. In the event of a fire, the hollow floating beads and basalt flakes can be dispersed into the carbonization layer to reduce the heat transmission rate. In summary, the present invention optimizes the expansion flame retardant system and the type and ratio of thermal insulation fillers, increases the thickness of the expansion carbonization layer, improves the structure of the expansion carbonization layer, and obtains a high fire resistance, environmentally friendly, single-component expansion type water-based vinyl acetate-ethylene steel structure fire retardant coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the macroscopic morphology of the carbonized layer of the intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating after flame combustion in Example 1.

[0011] Figure 2 This is the microscopic morphology of the carbonized layer of the intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating after flame combustion in Example 1. DETAILED DESCRIPTION

[0012] The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0013] Example 1

[0014] An expandable water-based vinyl acetate-ethylene steel structure fireproof coating comprises the following substances in percentage by weight: 50% water-based vinyl acetate-ethylene copolymer emulsion, 18% ammonium polyphosphate, 9% pentaerythritol, 11% melamine, 2% expandable graphite, 1% titanium dioxide, 1.5% hollow floating beads, 1.5% basalt flakes, and 6% water. Among them, the water-based vinyl acetate-ethylene copolymer emulsion has a solid content of 55% and a particle size of 0.3 μm; the degree of polymerization of ammonium polyphosphate is 1000; the solid content of pentaerythritol is 98.5% and the particle size is 3 μm; the purity of melamine is 99%; the expandable graphite is a 325-mesh flaky powder with a thickness of 10 μm; the titanium dioxide is a 1000-mesh spherical powder; the hollow floating beads are a 200-mesh hollow spherical powder; and the basalt flakes are a 325-mesh flaky powder.

[0015] The preparation method of the intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating of this embodiment comprises the following steps:

[0016] 1. Weigh ammonium polyphosphate, pentaerythritol, melamine, expandable graphite, titanium dioxide, hollow floating beads and basalt flakes according to proportion, and stir and mix at 100 rpm for 15 minutes to obtain a mixed powder;

[0017] 2. Weigh water and aqueous vinyl acetate-ethylene copolymer emulsion in proportion, stir mechanically at 600 rpm, add the mixed powder prepared in step 1 spoonful by spoonful during the stirring process, and after all the addition is completed, stir at 1000 rpm for 30 minutes to prepare a mixed slurry;

[0018] 3. Apply the mixed slurry obtained in step 2 to the surface of the steel structure and obtain a fire-retardant coating with a thickness of 3 mm after curing at room temperature for 1 week.

[0019] Example 2

[0020] An expandable water-based vinyl acetate-ethylene steel structure fireproof coating includes the following substances in percentage by weight: 40% water-based vinyl acetate-ethylene copolymer emulsion, 15% ammonium polyphosphate, 10% pentaerythritol, 13% melamine, 3% expandable graphite, 0.5% titanium dioxide, 1% hollow floating beads, 1% basalt flakes, and 16.5% water. Among them, the water-based vinyl acetate-ethylene copolymer emulsion has a solid content of 60% and a particle size of 0.5 μm; the degree of polymerization of ammonium polyphosphate is 1500; the solid content of pentaerythritol is 98% and the particle size is 5 μm; the purity of melamine is 99%; the expandable graphite is a 300-mesh flaky powder with a thickness of 15 μm; the titanium dioxide is a 1200-mesh spherical powder; the hollow floating beads are 300-mesh hollow spherical powder; and the basalt flakes are 400-mesh flaky powder.

[0021] The preparation method of the intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating of this embodiment comprises the following steps:

[0022] 1. Weigh ammonium polyphosphate, pentaerythritol, melamine, expandable graphite, titanium dioxide, hollow floating beads and basalt flakes according to proportion, and stir and mix at 300 rpm for 20 minutes to obtain a mixed powder;

[0023] 2. Weigh water and aqueous vinyl acetate-ethylene copolymer emulsion in proportion, stir mechanically at 500 rpm, add the mixed powder prepared in step 1 spoonful by spoonful during the stirring process, and after all the addition is completed, stir at 1200 rpm for 20 minutes to prepare a mixed slurry;

[0024] 3. Apply the mixed slurry obtained in step 2 to the surface of the steel structure and obtain a fire-retardant coating with a thickness of 3 mm after curing at room temperature for 1 week.

[0025] Example 3

[0026] An expandable water-based vinyl acetate-ethylene steel structure fireproof coating comprises the following substances in percentage by weight: 45% water-based vinyl acetate-ethylene copolymer emulsion, 20% ammonium polyphosphate, 8% pentaerythritol, 12% melamine, 2.5% expandable graphite, 0.1% titanium dioxide, 2% hollow floating beads, 2% basalt flakes, and 8.4% water. Among them, the water-based vinyl acetate-ethylene copolymer emulsion has a solid content of 55% and a particle size of 0.3 μm; the degree of polymerization of ammonium polyphosphate is 1200; the solid content of pentaerythritol is 98% and the particle size is 4 μm; the purity of melamine is 99%; the expandable graphite is a 400-mesh flaky powder with a thickness of 5 μm; the titanium dioxide is a spherical powder with a mesh size of 800; the hollow floating beads are hollow spherical powders with mesh sizes of 150; and the basalt flakes are 300-mesh flaky powders.

[0027] The preparation method of the intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating of this embodiment comprises the following steps:

[0028] 1. Weigh ammonium polyphosphate, pentaerythritol, melamine, expandable graphite, titanium dioxide, hollow floating beads and basalt flakes according to proportion, and stir and mix at 200 rpm for 10 minutes to obtain a mixed powder;

[0029] 2. Weigh water and aqueous vinyl acetate-ethylene copolymer emulsion in proportion, stir mechanically at 600 rpm, add the mixed powder prepared in step 1 spoonful by spoonful during the stirring process, and after all the addition is completed, stir at 1000 rpm for 40 minutes to prepare a mixed slurry;

[0030] 3. Apply the mixed slurry obtained in step 2 to the surface of the steel structure and obtain a fire-retardant coating with a thickness of 3 mm after curing at room temperature for 1 week.

[0031] Comparative Example 1

[0032] A fireproof coating comprises the following substances in weight percentage: 25% aqueous vinyl acetate-ethylene copolymer emulsion, 25% ammonium polyphosphate, 10% pentaerythritol, 7.5% melamine, and the balance is water. The preparation method is as follows: weigh the components in proportion, grind the powder and water for 40 to 50 minutes, then add the emulsion and stir for 15 to 20 minutes to obtain the fireproof coating. Apply the fireproof coating on the surface of the steel structure, and obtain a fireproof coating with a thickness of 3 mm after curing at room temperature for 1 week.

[0033] Table 1 shows the flame test performance of the fire retardant coatings of Examples 1 to 3 and Comparative Example 1. From the data in the table, it can be seen that the expandable water-based vinyl acetate-ethylene steel structure fire retardant coatings of Examples 1 to 3 of the present invention have higher expansion rates and better fire resistance.

[0034] Table 1. Flame test performance of fire retardant coatings in Examples 1 to 3 and Comparative Example 1

[0035] Expansion rate / % Temperature of the back-fired surface after heating for 30 minutes Example 1 14.5 149℃ Comparative Example 1 10.3 202℃ Example 2 13.8 156℃ Example 3 13.4 153℃

[0036] Referring to the large plate combustion method (GB12441), the fire resistance of the intumescent waterborne vinyl acetate-ethylene steel structure fire retardant coating of Example 1 was tested with an alcohol burner. The macroscopic morphology of the intumescent carbonized layer is as follows: Figure 1 As shown, the microscopic morphology is Figure 2 As shown, from Figure 1 It can be seen that the expanded carbonized layer of the intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating of Example 1 expands evenly and has good adhesion to the steel structure; Figure 2 It can be seen that the expanded carbonized layer of the expandable water-based vinyl acetate-ethylene steel structure fire retardant coating of Example 1 has no peeling and cracking, and the pores are small and evenly distributed.

[0037] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating, characterized in that: The invention is composed of the following substances in percentage by weight: 40-50% aqueous vinyl acetate-ethylene copolymer emulsion, 15-20% ammonium polyphosphate, 8-10% pentaerythritol, 11-13% melamine, 2-3% expandable graphite, 0.1-1% titanium dioxide, 1-2% hollow floating beads, 1-2% basalt flakes, and the balance water.

2. The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating according to claim 1, characterized in that: The solid content of the aqueous vinyl acetate-ethylene copolymer emulsion is 40-60%, and the particle size is 0.1-0.5 μm.

3. The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating according to claim 1, characterized in that: The degree of polymerization of the ammonium polyphosphate is ≥1000.

4. The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating according to claim 1, characterized in that: The pentaerythritol has a solid content of ≥98% and a particle size of 3 to 5 μm.

5. The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating according to claim 1, characterized in that: The expandable graphite is 300-400 mesh flake powder with a thickness of 5-15 μm.

6. The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating according to claim 1, characterized in that: The titanium dioxide is in the form of spherical powder with a mesh size of 800 to 1200.

7. The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating according to claim 1, characterized in that: The hollow floating beads are hollow spherical powders with mesh sizes of 150 to 300.

8. The intumescent water-based vinyl acetate-ethylene steel structure fire retardant coating according to claim 1, characterized in that: The basalt scales are 300 to 400 meshes.

9. A method for preparing an intumescent waterborne vinyl acetate-ethylene steel structure fire retardant coating as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved:

1. Weigh ammonium polyphosphate, pentaerythritol, melamine, expandable graphite, titanium dioxide, hollow floating beads and basalt flakes according to proportion, and stir and mix at 100-300 rpm for 10-20 minutes to obtain a mixed powder; 2. Weigh water and aqueous vinyl acetate-ethylene copolymer emulsion in proportion, stir mechanically at 500-600 rpm, add the mixed powder prepared in step 1 spoonful by spoonful during the stirring process, and after all the addition is completed, stir at 1000-1200 rpm for 20-40 minutes to prepare a mixed slurry; 3. Apply the mixed slurry obtained in step 2 on the surface of the steel structure and cure it at room temperature for 1 week.

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