Core-shell structured hydrophobic flame-retardant dual-functional polymer coating material and method for preparing the same

Abstract

This invention relates to a core-shell structured hydrophobic and flame-retardant dual-functional polymer coating material and its preparation method, belonging to the technical field of flame-retardant and hydrophobic functional polymer materials. The technical problem solved by this invention is to provide a core-shell polymer coating material with both hydrophobic and flame-retardant functions. This material has a core-shell structure, with the core polymer monomers including phosphorus-containing flame-retardant monomers and the shell polymer monomers including fluorine-containing monomers, and the core and shell are connected by covalent bonds. The material contains elements such as phosphorus (P) and phosphorus (F), and the flame-retardant and hydrophobic functional groups are linked by stable chemical bonds, exhibiting good flame-retardant effect and hydrophobic properties. Its raw materials are readily available, the process is simple, rapid, and easy to scale up. Using water as a dispersant, it has low VOC emissions, offering environmental advantages. It is safe and harmless to the human body and can be used as a coating material for flammable substrates such as polyurethane foam, wood, and fabrics, showing broad application prospects in construction, interior decoration, and electronic appliances.

Description

Technical Field

[0001] This invention relates to a core-shell structured hydrophobic and flame-retardant dual-functional polymer coating material and its preparation method, belonging to the technical field of flame-retardant and hydrophobic functional polymer materials. Background Technology

[0002] With society's increasing demands for material safety and environmental protection, the development of efficient and environmentally friendly flame retardant technologies has become a key research focus in the field of polymer materials.

[0003] Among numerous flame retardant systems, phosphorus-containing small molecule compounds (such as phosphate esters and phosphonates) can be used as flame retardant additives in coating materials such as polyacrylates and polyurethanes due to their good flame retardant effects in both the gas and condensed phases and their low smoke toxicity. However, small molecule flame retardants generally suffer from poor thermal stability and easy migration and volatilization, which limits their long-term effectiveness.

[0004] In contrast, polymeric flame retardants exhibit superior overall performance in terms of synergistic flame retardancy and service stability. For example, ammonium polyphosphate (APP), when heated, promotes the formation of a more stable and denser expanded char layer. This char layer effectively insulates against heat and oxygen, thus providing a more durable and efficient barrier protection in the condensed phase. Therefore, its flame retardant efficiency is significantly higher than many small-molecule phosphates. However, as an inorganic salt polymer, APP lacks the viscosity and cohesiveness necessary for coating film formation and must still be blended with other polymer resin substrates before it can be used as a coating material. Furthermore, phosphorus-containing flame retardants typically have strong hydrophilicity, making them prone to leaching in humid environments. This leads to a rapid decline in flame retardant performance, severely impacting the service life and reliability of the coating material.

[0005] To address this issue, "core-shell structure" materials, with flame retardants as the "core" and hydrophobic substances as the "shell," can effectively shield against moisture erosion through the hydrophobic shell, protecting the flame-retardant core components and thus significantly improving the wash resistance and environmental stability of the flame-retardant coating. However, most core-shell structures in existing research are constructed through physical coating methods such as physical adsorption, electrostatic interactions, or simple in-situ precipitation. These coatings based on weak interactions often suffer from weak bonding, structural instability, and are prone to cracking or peeling under mechanical stress or long-term use. Once the shell is damaged, the hydrophilic flame-retardant core remains exposed to the environment, resulting in limited improvement in durability.

[0006] Therefore, how to construct a core-flame-retardant and shell-hydrophobic polymer structure through stable chemical bonding is the key technology for obtaining durable and stable flame-retardant and hydrophobic polymer coatings, and it is also a research focus in this field. Summary of the Invention

[0007] To address the above deficiencies, the first technical problem solved by this invention is to provide a core-shell structure polymer coating material with both hydrophobic and flame-retardant functions.

[0008] The present invention relates to a core-shell structure hydrophobic and flame-retardant bifunctional polymer coating material, which has a core-shell structure. The monomers of the core polymer include phosphorus-containing flame-retardant monomers, and the monomers of the shell polymer include fluorine-containing monomers. The core and shell are connected by covalent bonds.

[0009] In one embodiment of the present invention, the structural formula of the phosphorus-containing flame-retardant monomer is as follows:

[0010]

[0011] Wherein, R1 is selected from hydrogen or alkyl; R2 is selected from hydrogen or alkyl.

[0012] In one embodiment of the present invention, the structural formula of the fluorinated monomer is:

[0013]

[0014] Where n is any integer from 1 to 15, and m is any integer from 3 to 16.

[0015] In some specific embodiments of the present invention, the phosphorus-containing flame-retardant monomer is at least one selected from vinylphosphonic acid, dimethyl vinylphosphonate, diethyl vinylphosphonate, diisopropyl vinylphosphonate, and dibutyl vinylphosphonate; the fluorine-containing monomer is 3,3,4,4,5,5,6,6,6-nonafluorohexyl methacrylate, 4,4,5,5,6,6,7,7,8,8,9,9,9-tridecylfluorononyl methacrylate, and 3,3,4,4,5,5,6,6... At least one of the following: 7,7,8,8,8-octadexofluoromethacrylate, 3,3,4,4,5,5,6,6,7,7,8,9,9,9-pentadecafluorononylmethacrylate, 4,4,5,5,6,6,7,7,8,9,9,10,10,10-pentadecafluorodecylmethacrylate, and 3,3,4,4,5,5,6,6,7,7,8,9,9,10,10,10-heptadecylfluorodecylmethacrylate.

[0016] In one embodiment of the present invention, the molar ratio of phosphorus-containing flame retardant monomer to fluorine-containing monomer is 1:(1.0~2.2).

[0017] The present invention also provides a method for preparing the core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material described in this invention.

[0018] The present invention discloses a method for preparing a core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material, comprising the following steps:

[0019] Phosphorus-containing flame-retardant monomers, surfactants, functional additives, and water are placed in a reactor at -10 ℃ to 150 ℃, and an initiator is added simultaneously. The mixture is stirred for 2 to 4 hours under a protective atmosphere to form a uniform and stable core emulsion. Then, fluorine-containing monomers, surfactants, and water are added, and the mixture is stirred and reacted for 2 to 4 hours to obtain a core-shell structured hydrophobic flame-retardant bifunctional polymer coating material.

[0020] In one embodiment of the present invention, the surfactant is at least one of allyloxyhydroxypropyl sulfonate, allylnonylphenol polyoxyethylene ether ammonium sulfate, and 2-acrylamido-2-methylpropanesulfonate; the functional additive is at least one of propylene glycol methyl ether, diethylene glycol monomethyl ether, and propylene glycol methyl ether acetate; and the initiator is at least one of potassium persulfate, ammonium persulfate, and 4,4'-azobis(4-cyanopentanoic acid).

[0021] In one embodiment of the present invention, the stirring speed is 300-400 rpm.

[0022] The protective atmosphere described in this invention is an atmosphere that does not participate in the reaction, including but not limited to a nitrogen atmosphere or an inert atmosphere.

[0023] As a preferred technical solution, the reaction temperature is 40–100℃.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) This invention relates to a core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material, containing elements such as P and F and possessing a core-shell structure, with flame-retardant and hydrophobic functional groups linked by stable chemical bonds. The core structure provides the flame-retardant effect; the shell structure, with its low surface energy, imparts hydrophobicity to the material, improving its service life; simultaneously, the multiple P / F elements in the structure exert a synergistic flame-retardant effect, resulting in excellent flame-retardant performance and hydrophobic properties.

[0026] 2) The core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material of this invention has the advantages of readily available raw materials, simple and rapid processing, and ease of large-scale production. Using water as a dispersant results in low VOC emissions, offering environmental advantages; compared to solvent-based systems, it is safe and harmless to the human body.

[0027] 3) The core-shell structure hydrophobic and flame-retardant dual-functional polymer coating material of the present invention can be used as a coating material for flammable substrates such as polyurethane foam, wood, and fabrics, and has broad application prospects in the fields of construction, interior decoration, and electronics. Attached Figure Description

[0028] Figure 1 These are FTIR images of the products obtained in Examples 1 and 2 of the present invention.

[0029] Figure 2The images shown are physical pictures of the products obtained in Embodiment 1 and Comparative Example 1 of the present invention, wherein the left side is Embodiment 1 of the present invention and the right side is Comparative Example 1 of the present invention.

[0030] Figure 3 This is a transmission electron microscope image of the product obtained in Example 1 of the present invention.

[0031] Figure 4 This is a diagram showing the limiting oxygen index of the flame-retardant foam material determined in Example 3 of the present invention.

[0032] Figure 5 This is a water contact angle diagram of the flame-retardant foam material obtained in Example 3 of the present invention. Detailed Implementation

[0033] The present invention relates to a core-shell structure hydrophobic and flame-retardant bifunctional polymer coating material, which has a core-shell structure. The monomers of the core polymer include phosphorus-containing flame-retardant monomers, and the monomers of the shell polymer include fluorine-containing monomers. The core and shell are connected by covalent bonds.

[0034] This invention proposes a novel flame-retardant and hydrophobic polymer emulsion resin with a "core-shell structure." Through aqueous microemulsion polymerization, a polymer emulsion resin with a phosphorus-containing monomer as the flame-retardant core and a fluoropolymer as the hydrophobic shell is directly constructed. In this design, the core polymer provides highly efficient phosphorus-based flame-retardant properties; the shell polymer, with its low surface energy, imparts excellent hydrophobicity to the material; more importantly, the polymer chains connected by covalent bonds between the core and shell achieve a strong bond, resulting in stable and durable flame-retardant and hydrophobic dual-functionality. Simultaneously, the multiple phosphorus and fluoropolymers in the structure exert a synergistic flame-retardant effect. This core-shell structure hydrophobic and flame-retardant dual-functional polymer coating material can be directly used as a coating material in fields such as thermal insulation foam, wood, and textiles, and can be used for extended periods in humid or corrosive environments, demonstrating significant technological advancement and application potential.

[0035] In one embodiment of the present invention, the structural formula of the phosphorus-containing flame-retardant monomer is as follows:

[0036]

[0037] Wherein, R1 is selected from hydrogen or alkyl; R2 is selected from hydrogen or alkyl.

[0038] In some specific embodiments of the present invention, the phosphorus-containing flame retardant monomer is at least one of vinylphosphonic acid, dimethyl vinylphosphonate, diethyl vinylphosphonate, diisopropyl vinylphosphonate, and dibutyl vinylphosphonate.

[0039] In one embodiment of the present invention, the structural formula of the fluorinated monomer is:

[0040]

[0041] Where n is any integer from 1 to 15, and m is any integer from 3 to 16.

[0042] The introduction of fluorinated monomers can yield long-chain fluorinated compounds with different structures and different hydrophobic properties.

[0043] In some specific embodiments of the present invention, the fluorinated monomer is at least one of 3,3,4,4,5,5,6,6,6-nonafluorohexyl methacrylate, 4,4,5,5,6,6,7,7,8,8,9,9,9-tridecylfluorononyl methacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecylfluorooctyl methacrylate, 3,3,4,4,5,5,6,6,7,7,8,9,9,9-pentadecafluorononyl methacrylate, 4,4,5,5,6,6,7,7,8,9,9,10,10,10-pentadecafluorodecyl methacrylate, and 3,3,4,4,5,5,6,6,7,7,8,9,9,10,10,10-heptafluorodecyl methacrylate.

[0044] In one embodiment of the present invention, the molar ratio of phosphorus-containing flame retardant monomer to fluorine-containing monomer is 1:(1.0~2.2).

[0045] The present invention discloses a method for preparing a core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material, comprising the following steps:

[0046] Phosphorus-containing flame-retardant monomers, surfactants, functional additives, and water are placed in a reactor at -10 ℃ to 150 ℃, and an initiator is added simultaneously. The mixture is stirred for 2 to 4 hours under a protective atmosphere to form a uniform and stable core emulsion. Then, fluorine-containing monomers, surfactants, and water are added, and the mixture is stirred and reacted for 2 to 4 hours to obtain a core-shell structured hydrophobic flame-retardant bifunctional polymer coating material.

[0047] The method of this invention involves free radical copolymerization of a phosphorus-containing flame-retardant monomer in the core layer and a fluorine-containing monomer in the shell layer, while simultaneously adding an initiator, surfactant, functional additives, and water. The resulting compound has the following structure:

[0048]

[0049] Wherein, R1 is selected from hydrogen or alkyl; R2 is selected from hydrogen or alkyl; and R3 is selected from fluorinated olefins of C4 to C17.

[0050] The surfactant can be a commonly used surfactant in the art. In one embodiment of the present invention, the surfactant is at least one of sodium allyloxyhydroxypropyl sulfonate, allylnonylphenol polyoxyethylene ether ammonium sulfate, and sodium 2-acrylamido-2-methylpropanesulfonate.

[0051] In one embodiment of the present invention, the functional additive is at least one of propylene glycol methyl ether, diethylene glycol monomethyl ether, and propylene glycol methyl ether acetate.

[0052] The initiator is a water-soluble thermal decomposition initiator, and commonly used initiators in the art are all suitable for this invention. In one embodiment of this invention, the initiator is at least one selected from potassium persulfate, ammonium persulfate, and 4,4'-azobis(4-cyanopentanoic acid).

[0053] In one embodiment of the present invention, the stirring speed is 300-400 rpm.

[0054] The protective atmosphere described in this invention is an atmosphere that does not participate in the reaction, including but not limited to a nitrogen atmosphere or an inert atmosphere.

[0055] As a preferred technical solution, the reaction temperature is 40–100℃.

[0056] In some specific embodiments, after adding fluorinated monomers, surfactants, and water, the mixture is stirred until the emulsion emits a bluish tint.

[0057] To minimize the introduction of impurity ions, the water used in this invention is preferably deionized water.

[0058] The core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material of this invention can be applied to a substrate using conventional coating methods and then dried. In one specific embodiment of this invention, the coating method is brush application, and the weight gain of the material is controlled by the amount applied each time and the number of brush strokes.

[0059] Commonly used substrates in this field are also applicable to this invention, including but not limited to rigid polyurethane foam (RPUF), wood, fabrics, etc.

[0060] The coating amount can also be the conventional amount used in this field. Generally, the weight gain of the coating is controlled within 15 ± 1 wt.

[0061] To explain the technical content, objectives, and effects of the present invention in detail, the following description, in conjunction with specific embodiments, further illustrates the content of the present invention, but does not limit the present invention to the scope of the embodiments described.

[0062] Example 1

[0063] 5 g of diethyl vinylphosphonate, 5 g of diisopropyl vinylphosphonate, 20 g of deionized water, 2 g of propylene glycol methyl ether acetate, 1 g of sodium allyl hydroxypropyl sulfonate, and 0.5 g of potassium persulfate were placed in a reactor at 60 °C and stirred at 300 rpm for 4 h under an inert atmosphere (N2) to form a homogeneous and stable core emulsion. 10 g of nonafluorohexyl 3,3,4,4,5,5,6,6,6-methacrylate, 20 g of deionized water, and 1 g of sodium allyl hydroxypropyl sulfonate were placed in the reactor and stirred until the emulsion emitted a bluish glow. After reacting for 4 h, the compound was obtained, which is the core-shell structured flame retardant emulsion C1.

[0064] The infrared characterization results of this flame retardant are shown below. Figure 1 As can be seen, by using the method of this invention, the C=C bond is opened during polymerization, and the flame retardant of this invention can be successfully synthesized.

[0065] See the actual product image of this flame retardant. Figure 2 To the left.

[0066] The transmission electron microscope image of the flame retardant is shown below. Figure 3 This proves that the emulsion has a core-shell structure.

[0067] Example 2

[0068] 5 g of dibutyl vinylphosphonate, 5 g of vinylphosphonic acid, 20 g of deionized water, 2 g of propylene glycol methyl ether acetate, 1 g of sodium 2-acrylamido-2-methylpropanesulfonate, and 0.5 g of potassium persulfate were placed in a reactor at 90 °C and stirred at 400 rpm for 2 h under an inert atmosphere (N2) to form a homogeneous and stable core emulsion. 10 g of octyl 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecylfluoromethacrylate, 20 g of deionized water, and 1 g of sodium 2-acrylamido-2-methylpropanesulfonate were placed in the reactor and stirred until the emulsion turned bluish. After reacting for 2 h, the core-shell structured flame retardant emulsion C2 was obtained.

[0069] The infrared characterization results of this flame retardant are shown below. Figure 1 .

[0070] Comparative Example 1

[0071] Diethyl vinylphosphonate, diisopropyl vinylphosphonate, and nonafluorohexyl 3,3,4,4,5,5,6,6,6-methacrylate were mixed in a mass ratio of 1:1:2 and physically blended uniformly using a vortex mixer to obtain a blend.

[0072] See the actual product image of this flame retardant. Figure 2 The right side of .

[0073] Comparative Example 2

[0074] Diethyl vinylphosphonate, 2-methacryloyloxyethyl phosphate, and 10 g of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecylfluoromethacrylate octyl ester were mixed in a mass ratio of 1:1:2 and physically blended evenly using a vortex mixer to obtain a blend.

[0075] Example 3

[0076] RPUF material was selected as the coating substrate. The core-shell structured flame retardant emulsion prepared in Example 1 was brushed onto the surface of the RPUF material. The sample was then placed in an oven and cured at 70 °C for 8 h to obtain the flame-retardant foam material. The limiting oxygen index and water contact angle of this material were measured, as detailed in [link to documentation]. Figure 4 and Figure 5 The results showed a limiting oxygen index (LOI) of 27% and a water contact angle of 130°. This demonstrates that the material exhibits excellent flame retardant and hydrophobic properties.

[0077] Following the method of this embodiment, the core-shell polymer flame retardant prepared in Example 1 was replaced with the blend of Comparative Example 1, and the other preparation processes were the same as above, resulting in a flame-retardant foam material. The limiting oxygen index (LOI) and water contact angle of the material were measured, and the results were: LOI of 22% and water contact angle of 120°.

[0078] As can be seen, compared with the embodiments of the present invention, the hydrophobic and flame retardant properties of the monomer blends are significantly reduced.

[0079] In this invention, the limiting oxygen index (LOI) test was performed using a JF 3 oxygen indexer according to ASTM D2863 19, with a sample size of 150×10×10 mm. 3 The water contact angle (WCA) was analyzed at room temperature using a JC2000D2H instrument with a water droplet volume of 5 μL. Each sample was tested at least five times.

[0080] Example 4

[0081] Wood was selected as the coating substrate. The core-shell polymer flame retardant emulsion prepared in Example 2 was applied to the surface of the wood by brushing. The sample was then placed in an oven and cured at 70°C for 8 hours to obtain flame-retardant wood material. The limiting oxygen index (LOI) of this material was 32%, and the water contact angle was 130°.

[0082] Following the method of this embodiment, the core-shell polymer flame retardant prepared in Example 2 was replaced with the blend of Comparative Example 2, and the other preparation processes were the same as above, resulting in a flame-retardant wood material. This material has a LOI of 23% and a water contact angle of 117°.

[0083] As can be seen, compared with the embodiments of the present invention, the hydrophobic and flame retardant properties of the monomer blends are significantly reduced.

[0084] Example 5

[0085] Fabric was selected as the coating substrate. The core-shell polymer flame retardant emulsion prepared in Example 1 was brushed onto the surface of the fabric. The sample was then placed in an oven and cured at 70°C for 8 hours to obtain the flame-retardant fabric. The limiting oxygen index (LOI) of this material was 28%, and the water contact angle was 120°.

Claims

1. A core-shell structured hydrophobic and flame-retardant dual-functional polymer coating material, characterized in that: It has a core-shell structure, with the core polymer having monomers including phosphorus-containing flame-retardant monomers and the shell polymer having monomers including fluorine-containing monomers, and the core and shell being connected by covalent bonds.

2. The core-shell structured hydrophobic and flame-retardant dual-functional polymer coating material according to claim 1, characterized in that: The structural formula of phosphorus-containing flame retardant monomers is: Wherein, R1 is selected from hydrogen or alkyl; R2 is selected from hydrogen or alkyl; The structural formula of the fluorinated monomer is: Where n is any integer from 1 to 15, and m is any integer from 3 to 16.

3. The core-shell structured hydrophobic and flame-retardant dual-functional polymer coating material according to claim 1, characterized in that: The phosphorus-containing flame retardant monomer is at least one of vinylphosphonic acid, dimethyl vinylphosphonate, diethyl vinylphosphonate, diisopropyl vinylphosphonate, and dibutyl vinylphosphonate. The fluorinated monomer is at least one of the following: 3,3,4,4,5,5,6,6,6-nonafluorohexyl methacrylate, 4,4,5,5,6,6,7,7,8,8,9,9,9-tridecylfluorononyl methacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8-octyltridecylfluoromethacrylate, 3,3,4,4,5,5,6,6,7,7,8,9,9,9-pentadecafluorononyl methacrylate, 4,4,5,5,6,6,7,7,8,9,9,10,10,10-pentadecafluorodecyl methacrylate, and 3,3,4,4,5,5,6,6,7,7,8,9,9,10,10,10-heptafluorodecyl methacrylate.

4. The core-shell structured hydrophobic and flame-retardant dual-functional polymer coating material according to claim 1, characterized in that: The molar ratio of phosphorus-containing flame retardant monomer to fluorine-containing monomer is 1: (1.0~2.2).

5. The method for preparing the core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Phosphorus-containing flame-retardant monomers, surfactants, functional additives, and water are placed in a reactor at -10 ℃ to 150 ℃, and an initiator is added simultaneously. The mixture is stirred for 2 to 4 hours under a protective atmosphere to form a uniform and stable core emulsion. Then, fluorine-containing monomers, surfactants, and water are added, and the mixture is stirred and reacted for 2 to 4 hours to obtain a core-shell structured hydrophobic flame-retardant bifunctional polymer coating material.

6. The method for preparing the core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material according to claim 5, characterized in that: The surfactant is at least one of allyloxyhydroxypropyl sulfonate, allylnonylphenol polyoxyethylene ether ammonium sulfate, and 2-acrylamido-2-methylpropanesulfonate. The functional additive is at least one of propylene glycol methyl ether, diethylene glycol monomethyl ether, and propylene glycol methyl ether acetate; The initiator is at least one of potassium persulfate, ammonium persulfate, and 4,4'-azobis(4-cyanopentanoic acid).

7. The method for preparing the core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material according to claim 5, characterized in that: The stirring speed is 300-400 rpm.

8. The method for preparing the core-shell structured hydrophobic and flame-retardant bifunctional polymer coating material according to claim 5, characterized in that: The reaction temperature is 40–100℃.

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