A method for preparing a sheet-form structure cyanuric acid / melamine complex

Abstract

The application discloses a preparation method of a sheet structure cyanuric acid / melamine composite. The method comprises the following steps: adding an inhibitor, cyanuric acid and melamine in water, reacting at a temperature of 90-98 DEG C for 2-4 hours, and then filtering, washing and drying to obtain the sheet structure cyanuric acid / melamine composite, wherein the molar ratio of the cyanuric acid and the melamine is (0.95-1.05):1, and the mass ratio of the total amount of the cyanuric acid and the melamine, the inhibitor and water is 1:(0.005-0.007):(2-5), and the inhibitor is a sodium naphthalene sulfonate formaldehyde polycondensate, a polydiallyldimethylammonium chloride and a melamine polyphosphate with a mass ratio of 3:(1-2):(1-2). The method can prepare the sheet structure cyanuric acid / melamine composite, the particle size of which reaches the nanometer level, the dispersibility is good, and the flame retardancy is good.

Description

Technical Field

[0001] This invention relates to the field of flame retardant technology, specifically to a cyanuric acid / melamine composite. Background Technology

[0002] Melamine / cyanuric acid composite is a nitrogen-containing, halogen-free, environmentally friendly flame retardant. It is environmentally friendly, safe for users, and has good thermal stability. It has good synergistic effects with phosphorus-based flame retardants, halogen-based flame retardants, etc., and is widely used in engineering plastics, rubber, elastomers, adhesives and other fields.

[0003] The molecular structure of the cyanuric acid / melamine complex is a triazine ring molecular complex formed by hydrogen bonding between cyanuric acid and melamine. Both cyanuric acid and melamine molecules contain benzene-like rings of mesitylezimine. Due to the conjugation effect of the large π electron clouds in these benzene-like rings, the atomic groups bound to their molecules possess positive and negative charge properties. The carbonyl group in the cyanuric acid molecule is an electron-withdrawing group, while the amino group in the melamine molecule is an electron-donating group. When these two groups come into contact, they attract each other, causing the two molecules to bond together. Therefore, under certain conditions, cyanuric acid and melamine molecules readily react to form a more structurally stable cyanuric acid / melamine complex.

[0004] There are three methods for preparing cyanuric acid / melamine composites: the high-temperature melting method, the urea method, and the cyanuric acid method. The high-temperature melting method directly synthesizes cyanuric acid and melamine through a melt reaction at high temperatures, which is energy-intensive, has a long reaction cycle, and requires harsh reaction conditions. The urea method generates cyanuric acid from urea under specific reaction conditions, and the cyanuric acid then reacts with melamine; this method also involves high reaction temperatures and high energy consumption. The cyanuric acid method involves dissolving cyanuric acid and melamine in water to form a suspension, which is then prepared under specific temperature conditions. Currently, the most commonly used method is the cyanuric acid method, which is simple, has high yield, high purity, and is environmentally friendly. However, the resulting cyanuric acid / melamine composite has a large particle size range, leading to dispersion difficulties. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a cyanuric acid / melamine composite with good dispersibility and a sheet-like structure.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for preparing a sheet-like cyanuric acid / melamine composite, which involves adding an inhibitor, cyanuric acid, and melamine to water, reacting at a temperature range of 90-98°C for 2-4 hours, and then filtering, washing, and drying to obtain the composite. The molar ratio of cyanuric acid to melamine is (0.95-1.05):1, and the mass ratio of the total amount of cyanuric acid and melamine, the inhibitor, and water is 1:(0.005-0.007):(2-5). The inhibitor is sodium naphthalenesulfonate formaldehyde condensate, polydiallyl dimethyl ammonium chloride, and melamine polyphosphate in a mass ratio of 3:(1-2):(1-2).

[0007] Preferably, 0.1%-0.5% of nano-montmorillonite by mass of the total mass of cyanuric acid and melamine is added to the reaction system as seed crystals.

[0008] Preferably, the molar ratio of cyanuric acid to melamine is 1:1, and the mass ratio of the total amount of cyanuric acid and melamine, nano-montmorillonite, inhibitor, and water is 1:0.003:0.005:4. The inhibitor is sodium naphthalene sulfonate formaldehyde condensate, polydiallyl dimethyl ammonium chloride, and melamine polyphosphate in a mass ratio of 3:1:1.5.

[0009] Preferably, the molecular weight of the sodium naphthalene sulfonate formaldehyde condensate is 4000-5000 Da.

[0010] Preferably, the nano-montmorillonite is quaternary ammonium salt modified montmorillonite.

[0011] Preferably, the molecular weight of the melamine polyphosphate in the inhibitor is 8000-12000 Da.

[0012] Preferably, the reaction temperature is 96-98℃, the pH is adjusted to 4.5-5.0 with acetic acid during the reaction, and the temperature is lowered to 50℃ at 2℃ / min after the reaction, followed by filtration.

[0013] Preferably, in the reaction, mechanical stirring is performed at 10-20 rpm, and ultrasonic-assisted dispersion is performed at an ultrasonic frequency of 40 kHz and a power of 200 W.

[0014] Preferably, all raw materials are premixed at 60°C, stirred at 300-350 rpm for 5 minutes, and heated to the reaction temperature at 2°C / min.

[0015] Preferably, after the reaction is completed, the reaction solution is filtered by a plate and frame filter press, and the filter cake is washed three times with 50°C hot water.

[0016] Mechanism of Action: This invention employs a specific ratio of sodium naphthalenesulfonate formaldehyde condensate, polydiallyldimethylammonium chloride, and melamine polyphosphate as inhibitors. Sodium naphthalenesulfonate formaldehyde condensate, through π-π conjugation, guides cyanuric acid and melamine molecules to form an ordered arrangement of self-assembly devices in the planar direction, laying the foundation for the formation of sheet-like structures. Polydiallyldimethylammonium chloride carries a positive charge and, through electrostatic repulsion, effectively prevents the aggregation of the cyanuric acid / melamine complex during the reaction, improving the dispersibility of the product. The phosphate groups in the melamine polyphosphate molecules can form weak hydrogen bonds with the cyanuric acid / melamine complex. This effect blocks the longitudinal growth of the cyanuric acid / melamine complex, promoting its two-dimensional expansion and contributing to the formation of regular sheet-like structures. Nano-montmorillonite is added to the reaction system as seed crystals. Nano-montmorillonite, with its layered structure, provides an additional template for the growth of the cyanuric acid / melamine complex. The cyanuric acid / melamine composite can grow both between the layers and on the surface of nano-montmorillonite, guiding molecules to expand in a two-dimensional plane, thereby increasing the length and width of the product and forming a more regular sheet-like structure, while also improving the product's dispersibility. Quaternary ammonium salt modification of montmorillonite, with hexadecyltrimethylammonium bromide inserted into the interlayer of montmorillonite, expands the interlayer spacing, providing lateral growth space for the cyanuric acid / melamine composite. The negative charge on the montmorillonite surface forms hydrogen bonds with the amino groups (-NH2) of the cyanuric acid / melamine composite, guiding its alignment along the layered structure and inhibiting vertical growth.

[0017] The beneficial effects of this invention are: this invention can produce a sheet-like cyanuric acid / melamine composite with a particle size reaching the nanoscale and good dispersibility. It can be widely used in coatings, soft rubber, elastomers, plastics and other fields. Nylon parts made from it can easily pass UL94 V-0 level and GWIT 800℃. Attached Figure Description

[0018] Figure 1 This is a scanning electron microscope (SEM) image of the sheet-like cyanuric acid / melamine composite of Example 1;

[0019] Figure 2 This is a scanning electron microscope (SEM) image of the cyanuric acid / melamine composite with the morphological structure of Example 7; Detailed Implementation

[0020] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0021] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0022] The raw materials involved in the embodiments of the present invention are as follows:

[0023] Cyanuric acid: also known as cyanuric acid, CAS number: 108-80-5;

[0024] Melamine: CAS No.: 108-78-1;

[0025] Sodium naphthalene sulfonate formaldehyde condensate: CAS No.: 9008-63-3;

[0026] Polydiallyldimethylammonium chloride: CAS No.: 26062-79-3;

[0027] Melamine polyphosphate: CAS No.: 15541-60-3;

[0028] The water used is deionized water.

[0029] Quaternary ammonium salt modified montmorillonite was obtained as follows: Montmorillonite (particle size: 100-150 nm, CAS number: 1318-93-0) was added to deionized water. After thorough stirring, a dispersion with a concentration of 55 g / L was obtained. Hexadecyltrimethylammonium bromide (CAS number: 57-09-0) was added to the dispersion, the temperature was raised to 85°C, and the mixture was stirred thoroughly and refluxed for 2 hours. The mixture was then filtered, washed with water, and dried to obtain the final product. The mass ratio of montmorillonite to hexadecyltrimethylammonium bromide was 1:0.3.

[0030] Example 1:

[0031] Includes the following steps:

[0032] (1) Raw material premixing: The raw materials include water, inhibitor, nano-montmorillonite, cyanuric acid and melamine. All raw materials are premixed at 60℃ and stirred at 300-350 rpm for 5 minutes, and then heated to 96℃ at 2℃ / min. 1 mole each of cyanuric acid and melamine is used. The mass ratio of the total amount of cyanuric acid and melamine, nano-montmorillonite, inhibitor and water is 1:0.003:0.005:4. The inhibitor is sodium naphthalenesulfonate formaldehyde condensate, polydiallyl dimethyl ammonium chloride and melamine polyphosphate in a mass ratio of 3:1:1.5.

[0033] The molecular weight of sodium naphthalene sulfonate formaldehyde condensate is 4000-5000 Da.

[0034] Melamine polyphosphate has a molecular weight of 8000-12000 Da.

[0035] (2) Reaction: The reaction was carried out at a temperature of 96-98℃ for 3 hours. During the reaction, the pH was adjusted to 4.5-5.0 with acetic acid. During the reaction, the mixture was mechanically stirred at 10-20 rpm and ultrasonically dispersed with an ultrasonic frequency of 40 kHz and a power of 200 W.

[0036] (3) After the reaction, the temperature was lowered to 50℃ at 2℃ / min. The reaction solution was filtered by a plate and frame filter press. The filter cake was washed three times with hot water at 50℃ and then dried to obtain the final product.

[0037] The above mechanical stirring allows more than 99% of the material to rotate.

[0038] Example 2: The difference between this example and Example 1 is that the raw materials do not contain nano-montmorillonite.

[0039] Example 3: The difference between this example and Example 1 is that mechanical stirring at 300-350 rpm is used in the reaction step, without ultrasonic assistance.

[0040] Example 4: The difference between this example and Example 1 is that the inhibitor used is only sodium naphthalene sulfonate formaldehyde condensate.

[0041] Example 5: The difference between this example and Example 1 is that the inhibitor used is only polydiallyldimethylammonium chloride.

[0042] Example 6: The difference between this example and Example 1 is that the inhibitor used is only melamine polyphosphate.

[0043] Example 7: The difference between this example and Example 1 is that no inhibitor or seed crystal is used.

[0044] Example 8: The total amount of cyanuric acid and melamine, nano-montmorillonite, inhibitor and water were in a mass ratio of 1:0.002:0.006:4. The inhibitor was sodium naphthalenesulfonate formaldehyde condensate, polydiallyl dimethyl ammonium chloride and melamine polyphosphate in a mass ratio of 3:1.2:1.5.

[0045] like Figure 1 and Figure 2 As shown, the morphology and dispersibility of the cyanuric acid / melamine composites prepared in Examples 1-8 were tested, and they were added to nylon at a mass ratio of 8% to prepare flame retardant materials. The flame retardant properties of the flame retardant materials were tested according to GB / T5169.11-2006 and the flammability performance standard of plastic materials UL94. The test results are shown in Table 1.

[0046] Glow wire ignition temperature (GWIT): The specimen was a 60mm×60mm×1.0mm injection-molded flame-retardant square plate, and the test was conducted according to the method in standard GB / T 5169.11-2006;

[0047] The longest afterflame time and fire rating of a single specimen were tested for flame-retardant material specimens according to standard UL94.

[0048] Table 1

[0049]

[0050] Note: The percentage in the UL94 (vertical burning) fire rating refers to the proportion of specimens in the total number of specimens in which the dripping material did not ignite the absorbent cotton.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a sheet-like cyanuric acid / melamine composite, characterized in that: The reaction is carried out by adding an inhibitor, cyanuric acid, and melamine to water, reacting at 90-98℃ for 2-4 hours, followed by filtration, washing, and drying. The molar ratio of cyanuric acid to melamine is (0.95-1.05):1, and the mass ratio of the total amount of cyanuric acid and melamine, the inhibitor, and water is 1:(0.005-0.007):(2-5). The inhibitor is sodium naphthalenesulfonate formaldehyde condensate, polydiallyl dimethyl ammonium chloride, and melamine polyphosphate in a mass ratio of 3:(1-2):(1-2). 0.1%-0.5% of nano-montmorillonite by mass of the total mass of cyanuric acid and melamine is added to the reaction system as seed crystals. During the reaction, mechanical stirring is performed at 10-20 rpm, and ultrasonic-assisted dispersion is used at a frequency of 40 kHz and a power of 200 W.

2. The preparation method according to claim 1, characterized in that: The molar ratio of cyanuric acid to melamine is 1:1, and the mass ratio of the total amount of cyanuric acid and melamine, nano-montmorillonite, inhibitor and water is 1:0.003:0.005:

4. The inhibitor is sodium naphthalene sulfonate formaldehyde condensate, polydiallyl dimethyl ammonium chloride and melamine polyphosphate in a mass ratio of 3:1:1.

5.

3. The preparation method according to claim 2, characterized in that: The molecular weight of the sodium naphthalene sulfonate formaldehyde condensate is 4000-5000 Da.

4. The preparation method according to claim 2, characterized in that: The nano-montmorillonite is quaternary ammonium salt modified montmorillonite.

5. The preparation method according to claim 4, characterized in that: The molecular weight of the melamine polyphosphate in the inhibitor is 8000-12000 Da.

6. The preparation method according to any one of claims 1-5, characterized in that: The reaction temperature is 96-98℃. During the reaction, the pH is adjusted to 4.5-5.0 with acetic acid. After the reaction, the temperature is lowered to 50℃ at a rate of 2℃ / min, and then filtered.

7. The preparation method according to claim 6, characterized in that: Premix all raw materials at 60℃, stir at 300-350 rpm for 5 minutes, and increase the temperature to the reaction temperature at 2℃ / min.

8. The preparation method according to claim 7, characterized in that: After the reaction was completed, the reaction solution was filtered by a plate and frame filter press, and the filter cake was washed three times with 50°C hot water.

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