WO2023050314A1

WO2023050314A1 - Environmentally friendly structural water-based intumescent fire retardant coating and preparation method therefor

Info

Publication number: WO2023050314A1
Application number: PCT/CN2021/122190
Authority: WO
Inventors: 刘治田; 石遒; 王成
Original assignee: 武汉工程大学
Priority date: 2021-09-29
Filing date: 2021-09-30
Publication date: 2023-04-06
Also published as: CN114106647B; CN114106647A

Abstract

An environmentally friendly structural water-based intumescent fire retardant coating, comprising the following components in percentage by mass: 20-30% of an acrylate-based emulsion, 30-36% of melamine formaldehyde resin microencapsulated ammonium polyphosphate, 20-30% of expandable graphite, 1-10% of ascorbic acid, 1-10% of sepiolite powder, 0.5-1% of hydroxyethyl cellulose, 0.5-1% of a dispersing agent, 0.5-1% of a defoaming agent, 0.5-1% of n-octanol, and the balance of water. The ascorbic acid and the sepiolite powder are simultaneously introduced into an expandable graphite-based intumescent fire retardant coating, so that the gas-phase and solid-phase synergistic effect of the ascorbic acid and the sepiolite powder can remarkably improve the use performance of the obtained intumescent fire retardant coating, such as fire resistance, aging resistance, acid and alkali resistance, and stain resistance; moreover, construction and preparation involved are simple, the fire retardant effect is excellent, and the coating is environmentally friendly and is suitable for popularization and application.

Description

A kind of environmentally friendly structural water-based intumescent fireproof coating and preparation method thereof

technical field

The invention belongs to the technical field of fireproof coatings, and in particular relates to an environmentally friendly structured water-based swelling fireproof coating and a preparation method thereof.

Background technique

Structural fire-resistant coatings belong to a class of heat-insulating coatings that are coated on the surface of structural components and can protect structural components when a fire occurs or in a high-temperature environment similar to a fire scene; It is heat-insulating fire retardant coating and intumescent fire retardant coating.

Intumescent fireproof coatings are usually composed of ammonium polyphosphate, pentaerythritol, and melamine as the acid source (dehydrating agent), carbon source (char forming agent), and gas source (foaming agent) as the main body, supplemented by resin as the main body. The adhesive is composed of pigments, fillers and additives as auxiliary materials according to the actual situation. When a fire occurs, the intumescent fire protection system interacts. Dehydration carbonization forms a dense honeycomb coke layer, which insulates air and heat transfer, thereby achieving excellent fire and heat insulation effects.

Due to its unique interlayer structure and high-temperature expansion properties, expandable graphite is often used as a partial replacement of gas source and carbon source. When the temperature rises, the graphite intercalation compound (Graphite Intercalation on Compounds) between expandable graphite layers instantly It decomposes rapidly and produces a large amount of gas, which makes the graphite expand into a worm-like new substance along the axis, that is, expanded graphite. The acid radicals are released during expansion, which also promotes the carbonization of the binder, thereby achieving good results through various flame retardant methods.

The amount of fillers added in fire retardant coatings is small, which often only enhances or reduces costs, and often has limited contribution to the fire and flame retardancy of intumescent fire retardant coatings, such as commonly used titanium dioxide, montmorillonite, sepiolite etc., due to its low cost and strong functionality, it is widely used in various coatings and polymer products. In patent CN112745703A, graphene and sepiolite powder are simultaneously applied to fireproof coatings. In patent CN112708316A, modified carbon nanotubes and sepiolite powder are simultaneously applied to fireproof coatings. Due to the high cost of graphene and modified carbon nanotubes, Does not have practical application value. In patent CN109535889A, silicon carbide, sepiolite, and titanium dioxide are washed with a mixed acid composed of concentrated sulfuric acid and concentrated nitric acid. Although the fire resistance can be improved to a certain extent, it will be accompanied by the generation of a large amount of waste.

Therefore, it is of great practical application value and research significance to further explore fillers suitable for structural waterborne intumescent fireproof coatings and optimize their preparation process.

Contents of the invention

The main purpose of the present invention is to address the deficiencies in the prior art, to provide an environmentally friendly structural water-based intumescent fireproof coating, which has the advantages of long fire-resistant time, excellent adhesion, short drying time, and environmental friendliness, and The preparation process involved is simple, the cost is low, and it is suitable for popularization and application.

To achieve the above object, the technical solution adopted in the present invention is:

An environmentally friendly structural water-based intumescent fireproof coating, the components and their mass percentages include: 20-30% of acrylate-based emulsion, 30-36% of melamine-formaldehyde resin microencapsulated ammonium polyphosphate (MFAPP) , expandable graphite 20-30%, ascorbic acid 1-10%, sepiolite powder 1-10%, hydroxyethyl cellulose 0.5-1%, dispersant 0.5-1%, defoamer 0.5-1%, n-octane Alcohol 0.5-1%, the rest is water.

Preferably, the mass ratio of the ascorbic acid to the sepiolite powder is 2:1-1:2; the sum of the mass of the two accounts for 5-10% of the total amount of raw materials for the fireproof coating.

In the above solution, the particle diameter of the ammonium polyphosphate microencapsulated by the melamine formaldehyde resin is 50-200 microns.

In the above scheme, the particle size of the expandable graphite is 150-300 mesh

In the above solution, the particle size of the sepiolite powder is 800-1500 mesh.

In the above scheme, the acrylate-based emulsion can be selected from acrylate core-shell emulsion, methacrylate emulsion, styrene-acrylic emulsion or styrene-acrylic core-shell emulsion; its solid content is 30-55%, and the aggregation rate is 0.1-2 %.

Preferably, the acrylate core-shell emulsion is formed by core-shell emulsion polymerization with emulsifier, core monomer mixture, shell monomer mixture and crosslinking monomer as main raw materials. The specific preparation method includes the following steps:

1) Dissolve the emulsifier in water to prepare an emulsifier aqueous solution, and divide it into three parts, add the nucleus monomer mixture to one part of the emulsifier aqueous solution, pre-emulsify for 0.5-1 hour, and obtain the nucleus pre-emulsion, and think of another emulsifier Add the shell monomer mixture and cross-linking monomer to the aqueous solution, and pre-emulsify for 1-2 hours to obtain a shell pre-emulsion; dissolve the buffer in the remaining part of the emulsifier aqueous solution to obtain a buffer aqueous solution; dissolve the initiator in water , to obtain an aqueous initiator solution;

2) Preparation of seed emulsion: under agitation, sequentially add aqueous buffer solution, 1/4 to 1/3 volume of initiator aqueous solution and 2/5 to 1/2 volume of nuclear pre-emulsion to the reaction vessel, and then Raise the temperature to 65-70°C, when a large amount of blue light appears in the emulsion, keep it warm for 0.5-1 hour to obtain the seed emulsion;

3) Polymerization of the nuclear layer: Add the remaining nuclear pre-emulsion and 1/4 to 1/3 volume of the initiator aqueous solution to the obtained seed emulsion, and control the dropwise addition within 1.0 to 1.5 hours, and then control the temperature to 70 ~ 80 ℃, and keep warm for 0.5 ~ 1h to get the nucleus layer emulsion;

4) Shell layer polymerization: add the remaining initiator aqueous solution and shell pre-emulsion to the obtained core layer emulsion dropwise, and control the dropping within 1~2h, then raise the temperature to 80~85°C and keep it for 0.5~1h, and then cool naturally to 40-50°C, adjust the pH value to 7-9, and sieve to obtain the acrylate core-shell emulsion.

In the above scheme, the core monomer mixture and the shell monomer mixture are composed of soft monomer and hard monomer respectively; wherein, the soft monomer is n-butyl acrylate, and the hard monomer is methyl methacrylate; the core monomer The mass ratio of the soft and hard monomers in the mixture is 2:1 to 5:1, and the mass ratio of the soft and hard monomers in the shell monomer mixture is 3:1 to 1:3.

In the above scheme, the mass ratio of the core monomer mixture to the shell monomer mixture is 2:3˜3:2.

In the above solution, the cross-linking monomer is methacrylic acid, and the cross-linking monomer accounts for 1-10% of the total mass of the core monomer mixture and the shell monomer mixture.

The emulsifier described in the above scheme is composed of anionic emulsifier and nonionic emulsifier in a mass ratio of 1:3 to 3:1; the anionic emulsifier is a kind of sodium dodecylbenzoate or sodium lauryl sulfate, not The ionic emulsifier is alkylphenol polyoxyethylene ether, and the dosage of the emulsifier is 3-4% of the total mass of soft and hard monomers in the raw material.

In the above scheme, the aqueous buffer solution is one of sodium bicarbonate and sodium dihydrogen phosphate, and the amount of the buffer is 0.2 to 0.5% of the total mass of the core monomer mixture and the shell monomer mixture; the concentration of the buffer aqueous solution is 5~10wt%.

In the above scheme, the dispersant is wetting and dispersing agent 5040 and the like.

In the above solution, the defoamer is silicone defoamer 470 and the like.

In the above scheme, the water is deionized water.

The preparation method of above-mentioned a kind of environmentally friendly structural type water-based intumescent fireproof coating comprises the following steps:

1) The raw materials are weighed according to the proportion, each raw material and its mass percentage include: acrylate-based emulsion 20-30%, MFAPP 30-36%, expandable graphite 20-30%, ascorbic acid 1-5%, sepiolite powder 1-5%, hydroxyethyl cellulose 0.5-1%, dispersant 0.5-1%, defoamer 0.5-1%, n-octanol 0.5-1%, the rest is water;

2) Evenly mix the weighed acrylate-based emulsion, MFAPP, expandable graphite, ascorbic acid, sepiolite powder, and hydroxyethyl cellulose, grind to a particle-free powder, then add water, stir and grind until uniform, without obvious particles; Then add defoamer and dispersant, continue to stir and grind evenly;

3) Finally, add acrylate-based emulsion and n-octanol to grind and mix evenly to obtain the fire-resistant coating.

Principle of the present invention is:

The present invention introduces environment-friendly fillers into the water-based novel intumescent fireproof paint, and the introduction of ascorbic acid improves the cleaning effect of the paint on structural parts (especially the rust on the surface of steel structure buildings), and simultaneously the ascorbic acid and sepiolite surface Silica-alumina hydroxyl reaction, combined with dehydration, ascorbic acid gathers on the surface of sepiolite powder, which can effectively prevent ascorbic acid from being oxidized and improve its stability; The quenching effect of free radicals can promote the coking of the substrate, and at the same time, the two-dimensional nano-material sepiolite can further reduce the heat and oxygen transfer at the fire scene, protect the coke, and reduce the oxidation rate of ascorbic acid, thereby affecting the steel structure. to a good protective effect.

Compared with prior art, the beneficial effect of the present invention is:

1) The present invention proposes for the first time that ascorbic acid and sepiolite powder are simultaneously introduced into the expandable graphite-based intumescent fireproof coating. Adjacent hydroxyl groups and the unique layered structure and nano-sized properties of sepiolite can further improve the aging resistance, acid and alkali resistance and stain resistance of the obtained fireproof coating;

2) The fireproof coating obtained in the present invention has the advantages of long fireproof time, long service life, good weather resistance, good decoration, water-based environmental protection, etc.; and the involved construction preparation is simple, the fireproof effect is excellent, and is suitable for popularization and application;

3) Compared with conventional nanomaterials such as carbon nanotube graphene and ascorbic acid, sepiolite has the advantages of lower cost and less dosage, which can provide a new idea for the preparation of high-performance and low-cost fireproof coatings;

4) Ascorbic acid, as a biomass material, is easy to obtain, low in price, and environmentally friendly; compared with pentaerythritol, expandable graphite does not require petrochemical products in the synthesis process; at the same time, the coating uses water as a solvent, which is green and environmentally friendly .

Description of drawings

Fig. 1 is the back temperature curve of the slab combustion method of the intumescent fireproof coating obtained in Examples 1-3 and Comparative Examples 1-2.

Fig. 2 is successively the charcoal layer topography diagram of the intumescent fireproof coating obtained in Example 2 and Comparative Examples 1-2 after the slab combustion method.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In the following examples, the dispersant used is wetting and dispersing agent 5040; the defoamer is silicone defoamer 470.

The origin of the sepiolite used is Shijiazhuang, Hebei, and its particle size is 800-1000 mesh.

The expanded graphite mesh used is 150-300 mesh.

In the following examples, the acrylate-based emulsion used is an acrylate core-shell emulsion, and its preparation method comprises the following steps:

1) Dissolve 1.0g alkylphenol polyoxyethylene ether and 2.0g sodium lauryl sulfate in 90ml deionized water to prepare emulsifier aqueous solution, and divide it into three parts: 35ml, 30ml, and 25ml; Add butyl ester and 10g methyl methacrylate to 30ml emulsifier aqueous solution, stir and mix at room temperature, and pre-emulsify for 1h to obtain a nuclear pre-emulsion; mix 10g n-butyl acrylate, 30g methyl methacrylate and 2.4g Add methacrylic acid to 30ml of emulsifier aqueous solution, stir and mix at room temperature, and pre-emulsify for 2 hours to obtain a shell pre-emulsion; dissolve 0.3g of sodium bicarbonate in 25ml of emulsifier aqueous solution and stir to dissolve to obtain a buffer aqueous solution; 0.5g potassium persulfate was added into 30ml deionized water and stirred and dissolved to obtain an aqueous initiator solution;

2) Preparation of seed emulsion: In the reaction vessel, add buffer aqueous solution, 1/3 volume of initiator aqueous solution and 1/2 volume of nuclear pre-emulsion in turn while stirring, and heat up to 70 ° C. When a large amount of blue light appears in the emulsion time, keep warm for 0.5h to obtain seed emulsion;

3) Polymerization of the core layer: At the end of the heat preservation of the seed emulsion, slowly drop the remaining nuclear pre-emulsion and 1/3 initiator aqueous solution into the seed emulsion, and complete the dropwise addition within 1 hour, control the temperature to 80 ° C, and keep the temperature for 0.5 hours , to obtain the nuclear layer emulsion;

4) shell polymerization: when the core emulsion heat preservation is finished, add the remaining initiator aqueous solution and shell pre-emulsion dropwise, drop it in 1.5h, then raise the temperature to 85°C for 0.5h, then cool naturally to 40°C, Adjust the pH value to 8, and pass through a 200-mesh sieve to obtain an acrylic acid core-shell emulsion; its solid content is 41%, and its aggregation rate is 0.34%.

In the following examples, the melamine-formaldehyde resin microencapsulated ammonium polyphosphate (MFAPP) used is provided by Hangzhou Jieersi Flame Retardant Chemical Co., Ltd., and its particle size is 50-200 microns.

Example 1

An environmentally friendly structural water-based intumescent fireproof coating, the components and their mass percentages are: acrylate core-shell emulsion 20%, MFAPP 32%, expandable graphite 24%, ascorbic acid 3.5%, sepiolite powder 6.5% %, hydroxyethyl cellulose 0.5%, dispersant 0.5%, defoamer 0.5%, n-octanol 0.5%, water 12%; Its preparation method comprises the following steps:

1) Weigh the raw materials according to the above proportioning requirements;

2) Grind the weighed MFAPP, expandable graphite, ascorbic acid, hydroxyethyl cellulose, and sepiolite powder until there are no particles, then add water to fully grind and mix evenly; then add defoamer and dispersant, and continue to grind fully;

3) Finally, the acrylate core-shell emulsion and n-octanol are added and thoroughly ground and mixed to obtain the fireproof coating.

Example 2

A water-based intumescent fireproof coating, its preparation method is roughly the same as in Example 1, the difference is that each component and its mass percentage are: acrylate core-shell emulsion 20%, MFAPP 32%, expandable graphite 24% , ascorbic acid 5%, sepiolite powder 5%, hydroxyethyl cellulose 0.5%, dispersant 0.5%, defoamer 0.5%, n-octanol 0.5%, water 12%.

Example 3

A water-based intumescent fireproof coating, its preparation method is roughly the same as in Example 1, the difference is that each component and its mass percentage are: acrylate core-shell emulsion 20%, MFAPP 32%, expandable graphite 24% , ascorbic acid 6.5%, sepiolite powder 3.5%, hydroxyethyl cellulose 0.5%, dispersant 0.5%, defoamer 0.5%, n-octanol 0.5%, water 12%.

Comparative example 1

A water-based intumescent fireproof coating, its preparation method is roughly the same as in Example 1, the difference is that each component and its mass percentage are: acrylate core-shell emulsion 20%, MFAPP 32%, expandable graphite 24% , ascorbic acid 10%, hydroxyethyl cellulose 0.5%, dispersant 0.5%, defoamer 0.5%, n-octanol 0.5%, water 12%.

Comparative example 2

A water-based intumescent fireproof coating, its preparation method is roughly the same as in Example 1, the difference is that each component and its mass percentage are: acrylate core-shell emulsion 20%, MFAPP 32%, expandable graphite 24% , sepiolite powder 10%, hydroxyethyl cellulose 0.5%, dispersant 0.5%, defoamer 0.5%, n-octanol 0.5%, water 12%.

The intumescent fireproof coatings obtained in Examples 1-3 and Comparative Examples 1-2 were tested for their fire resistance performance, and the results are shown in Table 1.

Table 1 embodiment 1～3 and the performance test result of comparative example 1～2 gained intumescent fireproof coating

Fig. 1 is the back temperature curve of the large plate combustion method of the intumescent fireproof coating obtained in Examples 1 to 3 and Comparative Examples 1 to 2; Topography of charcoal layer after paint slab combustion method.

The above results show that: an environmentally friendly structural water-based intumescent fireproof coating obtained in the present invention has a good flame retardant effect, is environmentally friendly and pollution-free, has good durability, has good compatibility with the substrate, and has good adsorption, and can effectively take into account Other properties of the base material. The preparation method involved in the invention is simple and effective, and has wide application fields.

Apparently, the above-mentioned embodiments are only examples for clear illustration, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And therefore the obvious changes or changes extended are still within the scope of protection of the present invention.

Claims

An environmentally friendly structural water-based intumescent fireproof coating, characterized in that the components and their mass percentages include: 20-30% of acrylate-based emulsion, 30-36% of melamine-formaldehyde resin microencapsulated ammonium polyphosphate %, expandable graphite 20-30%, ascorbic acid 1-10%, sepiolite powder 1-10%, hydroxyethyl cellulose 0.5-1%, dispersant 0.5-1%, defoamer 0.5-1%, positive Octanol 0.5-1%, the rest is water.
The structural water-based intumescent fireproof coating according to claim 1, characterized in that the mass ratio of ascorbic acid to sepiolite powder is 2:1-1:2.
The structural water-based intumescent fireproof coating according to claim 1, characterized in that the sum of the mass of ascorbic acid and sepiolite powder accounts for 5-10% of the total amount of fireproof coating raw materials.
The structural water-based intumescent fireproof coating according to claim 1, characterized in that the particle diameter of the melamine-formaldehyde resin microencapsulated ammonium polyphosphate is 50-200 microns.
The structural water-based intumescent fireproof coating according to claim 1, characterized in that the particle size of the expandable graphite is 150-300 mesh
The structural water-based intumescent fireproof coating according to claim 1, characterized in that the particle size of the sepiolite powder is 800-1500 mesh.
The structural water-based intumescent fireproof coating according to claim 1, wherein the acrylate-based emulsion can be selected from acrylate core-shell emulsion, methacrylate emulsion, styrene-acrylic emulsion or styrene-acrylic core-shell emulsion, etc.; Its solid content is 30-55%, and the aggregation rate is 0.1-2%.
The preparation method of the environmentally friendly structural water-based intumescent fireproof coating according to any one of claims 1 to 7, characterized in that it comprises the following steps:

1) The raw materials are weighed according to the proportion, each raw material and its mass percentage include: acrylate-based emulsion 20-30%, MFAPP 30-36%, expandable graphite 20-30%, ascorbic acid 1-5%, sepiolite powder 1 ~5%, hydroxyethyl cellulose 0.5~1%, dispersant 0.5~1%, defoamer 0.5~1%, n-octanol 0.5~1%, the rest is water;

2) Evenly mix the weighed acrylate-based emulsion, MFAPP, expandable graphite, ascorbic acid, sepiolite powder, and hydroxyethyl cellulose, grind to a particle-free powder, then add water, stir and grind until uniform, without obvious particles; Then add defoamer and dispersant, continue to stir and grind evenly;

3) Finally, add acrylate-based emulsion and n-octanol to grind and mix evenly to obtain the fire-resistant coating.