Preparation method of cyanuric acid / melamine compound with sheet structure

Abstract

The invention discloses a preparation method of a cyanuric acid / melamine compound with a sheet structure, which comprises the following steps: adding an inhibitor, cyanuric acid and melamine in a molar ratio of (0.95-1.05): 1 into water, reacting for 2-4 hours in a temperature range of 90-98 DEG C, filtering, washing and drying to obtain the cyanuric acid / melamine compound with the sheet structure, the mass ratio of the total amount of cyanuric acid and melamine to the inhibitor to water is 1: (0.005-0.007): (2-5), and the inhibitor is prepared from sodium naphthalene sulfonate formaldehyde polycondensate, poly (diallyldimethylammonium chloride) and melamine polyphosphate according to the mass ratio of 3: (1-2): (1-2). The cyanuric acid / melamine compound with the sheet structure can be prepared, the particle size reaches the nanoscale, and the cyanuric acid / melamine compound is good in dispersity and flame retardance.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardants, and specifically to a cyanuric acid / melamine complex. Background Art

[0002] The cyanuric acid / melamine complex is a nitrogen-containing halogen-free environmentally friendly flame retardant, which 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 the fields of engineering plastics, rubbers, elastomers, adhesives, etc.

[0003] The molecular structure of the cyanuric acid / melamine complex is a triazine ring molecular complex formed by cyanuric acid and melamine through hydrogen bonds. Both the molecular structures of cyanuric acid and melamine contain benzene-ring-like 1,3,5-triazine rings. Due to the conjugation of the large π electron clouds in the benzene-ring-like rings, the atomic groups bound to their molecules have positive and negative charge properties. The carbonyl group in the cyanuric acid molecule is an electron-withdrawing group, and 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 combine together. Therefore, under certain conditions, the cyanuric acid molecule and the melamine molecule easily react to form a more stable cyanuric acid / melamine complex.

[0004] There are three preparation methods for the cyanuric acid / melamine complex: the high-temperature melting method, the urea method, and the cyanuric acid method. Among them, the high-temperature melting method directly synthesizes cyanuric acid and melamine through a melting reaction under high-temperature conditions, with high energy consumption, a long reaction cycle, and harsh reaction conditions. The urea method generates cyanuric acid under certain reaction conditions, and then cyanuric acid reacts with melamine, with a high reaction temperature and high energy consumption. The cyanuric acid method dissolves cyanuric acid and melamine in water to form a suspension, which can be prepared under certain temperature conditions. Currently, the most commonly used method is the cyanuric acid method, which has a simple process, high yield, high purity, and is environmentally friendly. However, the particle size range of the generated cyanuric acid / melamine complex is relatively large, and there is a problem of difficult dispersion. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method for a cyanuric acid / melamine complex with a good dispersibility and a flaky structure.

[0006] To solve the above technical problems, the preparation method of the sheet-like cyanuric acid / melamine composite of the present invention comprises adding an inhibitor, cyanuric acid and melamine to water, reacting within the temperature range of 90-98 °C for 2-4 h, and then filtering, 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 to water is 1:(0.005-0.007):(2-5). The inhibitor is a sodium naphthalene sulfonate formaldehyde condensate, poly(diallyldimethylammonium chloride), and melamine polyphosphate with a mass ratio of 3:(1-2):(1-2).

[0007] Preferably, 0.1%-0.5% of the total mass of cyanuric acid and melamine is added to the reaction system as crystal seeds in the form of nano-montmorillonite.

[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, the inhibitor to water is 1:0.003:0.005:4. The inhibitor is a sodium naphthalene sulfonate formaldehyde condensate, poly(diallyldimethylammonium chloride), and melamine polyphosphate with 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 °C. During the reaction process, the pH is adjusted to 4.5-5.0 with acetic acid. After the reaction, the temperature is decreased to 50 °C at a rate of 2 °C / min, and then filtered.

[0013] Preferably, during the reaction, mechanical stirring is carried out at 10-20 rpm, and ultrasonic-assisted dispersion is used. The ultrasonic frequency is 40 kHz and the power is 200 W.

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

[0015] Preferably, after the reaction is completed, the reaction solution is filtered through a plate and frame filter press, and the filter cake is washed 3 times with hot water at 50 °C.

[0016] Mechanism of action: The present invention uses a naphthalene sulfonate formaldehyde condensate, poly(diallyldimethylammonium chloride), and melamine polyphosphate in specific proportions as inhibitors. The naphthalene sulfonate formaldehyde condensate guides the self-assembly of cyanuric acid and melamine molecules in an ordered arrangement in the planar direction through π-π conjugation, laying the foundation for the formation of a flaky structure. Poly(diallyldimethylammonium chloride) carries a positive charge and uses electrostatic repulsion to effectively prevent the aggregation of cyanuric acid / melamine complexes 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 complexes, blocking the longitudinal growth of the cyanuric acid / melamine complexes and promoting their expansion in the two-dimensional plane, which helps to form a regular flaky structure. Nano-montmorillonite is added as a seed in the reaction system. Nano-montmorillonite has a layered structure, providing an additional template for the growth of cyanuric acid / melamine complexes. The cyanuric acid / melamine complexes can grow between the layers and on the surface of nano-montmorillonite, guiding the molecules to expand in the two-dimensional plane, thereby increasing the length and width of the product and forming a more regular flaky structure, while also improving the dispersibility of the product. Montmorillonite is modified with quaternary ammonium salts, and cetyltrimethylammonium bromide is inserted into the interlayers of montmorillonite to expand the interlayer spacing, providing lateral growth space for the cyanuric acid / melamine complexes. The negative charges on the surface of montmorillonite form hydrogen bonds with the amino groups (-NH2) of the cyanuric acid / melamine complexes, guiding their arrangement along the layered structure and inhibiting the growth in the vertical direction.

[0017] The beneficial effects of the present invention are as follows: The present invention can produce a cyanuric acid / melamine complex with a flaky structure, with a particle size reaching the nanometer level and good dispersibility. It can be widely used in fields such as coatings, soft rubbers, elastomers, and plastics. Nylon parts made from it can easily pass the UL94 V-0 level and GWIT 800°C. Description of the drawings

[0018] Figure 1 is a scanning electron microscope (SEM) image of the cyanuric acid / melamine complex with a flaky structure in Example 1;

[0019] Figure 2 is a scanning electron microscope (SEM) image of the cyanuric acid / melamine complex with a flaky structure in Example 7; Detailed implementation manners

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

[0021] For those conditions not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

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

[0023] Cyanuric acid: Also known as: Cyanuric acid, CAS No.: 108-80-5;

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

[0025] Naphthalenesulfonate formaldehyde condensate: CAS No.: 9008-63-3;

[0026] Poly(diallyldimethylammonium chloride): CAS No.: 26062-79-3;

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

[0028] Deionized water is used for water.

[0029] The quaternary ammonium salt modified montmorillonite is obtained by the following method: Montmorillonite is added to deionized water, with a particle size of 100 - 150 nm, and the CAS number of montmorillonite is 1318-93-0. After sufficient stirring, a dispersion with a concentration of 55 g / L is obtained. Cetyltrimethylammonium bromide (CAS No.: 57-09-0) is added to the dispersion, and the temperature is raised to 85 °C. After sufficient stirring and reflux condensation reaction for 2 h, it is filtered, washed with water, and dried to obtain. The mass ratio of montmorillonite to cetyltrimethylammonium bromide is 1:0.3.

[0030] Example 1:

[0031] It includes the following steps:

[0032] (1) Premixing of raw materials: The raw materials include water, inhibitor, nano-montmorillonite, cyanuric acid and melamine. All raw materials are premixed at 60 °C, stirred at 300 - 350 rpm for 5 minutes, and heated to 96 °C at a rate of 2 °C / min. 1 mole of each of cyanuric acid and melamine is taken. The mass ratio of the total amount of cyanuric acid and melamine, nano-montmorillonite, inhibitor to water is 1:0.003:0.005:4. The inhibitor is a naphthalenesulfonate formaldehyde condensate, poly(diallyldimethylammonium chloride), and melamine polyphosphate with a mass ratio of 3:1:1.5.

[0033] The molecular weight of the naphthalenesulfonate formaldehyde condensate is 4000 - 5000 Da.

[0034] The molecular weight of the melamine polyphosphate is 8000 - 12000 Da.

[0035] (2) Reaction: React within the temperature range of 96 - 98 °C for 3 h. During the reaction, adjust the pH to 4.5 - 5.0 with acetic acid. During the reaction, stir mechanically at 10 - 20 rpm and assist with ultrasonic dispersion, with an ultrasonic frequency of 40 kHz and a power of 200 W.

[0036] (3) After the reaction, the temperature is decreased to 50 °C at a rate of 2 °C / min. The reaction solution is filtered through a plate and frame filter press. The filter cake is washed three times with hot water at 50 °C and then dried to obtain the product.

[0037] The above mechanical stirring is to enable more than 99% of the materials to follow the rotation.

[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 adopted in the reaction step without ultrasonic assistance.

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

[0041] Example 5: The difference between this example and Example 1 is that only poly(diallyldimethylammonium chloride) is used as the inhibitor.

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

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

[0044] Example 8: The mass ratio of the total amount of cyanuric acid and melamine, nano-montmorillonite, inhibitor to water is 1:0.002:0.006:4. The inhibitor is a sodium naphthalene sulfonate formaldehyde condensate, poly(diallyldimethylammonium chloride), and melamine polyphosphate with a mass ratio of 3:1.2:1.5.

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

[0046] Glow-wire ignition temperature (GWIT): The test piece is an injection-molded flame-retardant material square plate of 60 mm × 60 mm × 1.0 mm, and is tested according to the method in Standard GB / T 5169.11 - 2006;

[0047] The afterflame time of the longest single specimen and the fire rating are detected for the flame-retardant material test pieces according to Standard UL94.

[0048] Table 1

[0049]

[0050] Note: The percentage in the fire rating UL94 (vertical burning) refers to the proportion of specimens in which the dropped matter does not ignite the absorbent cotton among all specimens.

[0051] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a sheet-like structure cyanuric acid / melamine complex, characterized in that: It is prepared by adding an inhibitor, cyanuric acid and melamine into water, reacting at a temperature in the range of 90 - 98 °C for 2 - 4 h, and then filtering, 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 to water is 1:(0.005 - 0.007): (2 - 5). The inhibitor is a sodium naphthalene sulfonate formaldehyde condensate, poly(diallyldimethylammonium chloride), and melamine polyphosphate with a mass ratio of 3:(1 - 2):(1 - 2).

2. The preparation method according to claim 1, characterized in that: 0.1% - 0.5% of the total mass of cyanuric acid and melamine is added as a seed crystal into the reaction system.

3. The preparation method according to claim 2, 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, the inhibitor to water is 1:0.003:0.005:

4. The inhibitor is a sodium naphthalene sulfonate formaldehyde condensate, poly(diallyldimethylammonium chloride), and melamine polyphosphate with a mass ratio of 3:1:1.

5.

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

5. The preparation method according to claim 3, characterized in that: The nano - montmorillonite is a quaternary ammonium salt - modified montmorillonite.

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

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

8. The preparation method according to claim 7, characterized in that: During the reaction, mechanical stirring is carried out at 10 - 20 rpm, and ultrasonic - assisted dispersion is performed. The ultrasonic frequency is 40 kHz and the power is 200 W.

9. The preparation method according to claim 8, characterized in that: All raw materials are premixed at 60 °C, stirred at 300 - 350 rpm for 5 minutes, and then heated to the reaction temperature at a rate of 2 °C / min.

10. The preparation method according to claim 9, wherein: After the reaction is completed, the reaction solution is filtered through a plate - and - frame filter press, and the filter cake is washed 3 times with hot water at 50 °C.

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