Preparation method and application of novel flame retardant

Abstract

The invention discloses a preparation method and application of a novel flame retardant, and the preparation method comprises the following steps: S1, mixing an organophosphorus compound and ethanol, stirring, heating to 35-40 DEG C, adding sodium hydroxide in batches, and dispersing for 1-2 hours; s2, adding 2, 4-bis (chloromethyl) trimethylbenzene in batches, heating to 70-78 DEG C, and reacting for 6-8 hours; s3, evaporating the ethanol to dryness, adding dichloromethane and water, stirring for layering, washing an organic layer once, and decolorizing with activated carbon for 2 hours; and drying the dichloromethane by distillation, adding ethanol for recrystallization, and drying to obtain the product. The melting point of the phosphorus-containing flame retardant is high (more than 200 DEG C) and is far higher than that of a commercially available phosphate flame retardant (105 DEG C). Meanwhile, after the flame retardant is mixed with hydroxyl-free resin (such as vinyl benzyl ether polyphenyl ether resin and the like), a flame retardant with relatively low thermal expansion rate, relatively high heat resistance, relatively high glass transition temperature and relatively low dielectric constant can be prepared.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardants, and in particular to a preparation method and application of a novel flame retardant. Background Art

[0002] Nowadays, science and technology are developing rapidly, especially the application of polymer materials is very extensive. Polymer materials such as plastics, rubber, fiber, etc., most of these materials can burn. Especially for plastics, if they are to be used in transportation, construction, electrical equipment, aviation, space flight, etc., it is urgent to solve their combustion resistance problem. Flame retardants are indispensable as substances that can increase the flame retardancy of polymer materials. The use of flame retardants generally should meet the following conditions: do not reduce the physical properties of polymer materials, such as heat resistance, mechanical strength, and electrical properties; the decomposition temperature should not be too high, but it cannot be decomposed at the processing temperature, and it has good durability, good weather resistance, and low price.

[0003] The high-end application areas of flame retardants, such as circuit boards, have high requirements. Currently, there are few types of flame retardants on the market. Halogen-containing flame retardants are not environmentally friendly. The use of general phosphorus-containing flame retardants results in defects such as poor flame retardancy, poor heat resistance of the substrate, and a large thermal expansion coefficient of the substrate. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology that the prior art uses halogen-containing flame retardants that are not environmentally friendly and the flame retardant effect of phosphorus-containing flame retardants is not ideal, the purpose of the present invention is to provide a new flame retardant that can achieve higher glass transition temperature, lower dielectric properties, halogen-free flame retardancy, and lower thermal expansion coefficient of the substrate when combined with suitable resin materials.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a novel flame retardant comprises the following steps:

[0007] S1. Mix the organophosphorus compound and ethanol, stir and heat to 35-40°C, add sodium hydroxide in batches, and disperse for 1-2 hours;

[0008] S2, adding 2,4-bis(chloromethyl)trimethylbenzene in batches, raising the temperature to 70-78°C, and reacting for 6-8 hours;

[0009] S3, evaporate the ethanol, add dichloromethane and water, stir and separate the layers, wash the organic layer with water once, and decolorize with activated carbon for 2 hours; evaporate the dichloromethane again, add ethanol for recrystallization, and dry to obtain the product.

[0010] Preferably, the organic phosphorus compound is ditolylphosphine oxide or diphenylphosphine oxide.

[0011] Preferably, the molar ratio of the organic phosphorus compound, sodium hydroxide and 2,4-bis(chloromethyl)trimethylbenzene is (2-2.2):(2-2.2):1.

[0012] Preferably, the mass ratio of ethanol for reaction to 2,4-bis(chloromethyl)trimethylbenzene is 8:1.

[0013] Preferably, the mass ratio of dichloromethane to 2,4-bis(chloromethyl)trimethylbenzene is 9:1.

[0014] Preferably, the mass ratio of ethanol for recrystallization to 2,4-bis(chloromethyl)trimethylbenzene is (4-6):1.

[0015] The flame retardant synthesis steps are as follows:

[0016]

[0017] The compound structural formula is:

[0018]

[0019] The phosphorus-containing flame retardant prepared by the present invention is derivatized by dimethylbenzene phosphine oxide, and has no reactive functional groups and contains 2 phosphorus atoms per molecule, and has better dielectric properties than general phosphorus-containing resins; general phosphorus-containing resins have polar groups that cause excessively high dielectric properties, such as the phosphorus-containing phenolic resin, DOPO-bisphenol A phenolic resin, which is widely used in the art, and contains hydroxyl groups, which are polar functional groups and cause excessively high dielectric properties; and the phosphorus-containing flame retardant of the present invention has a high melting point (greater than 200° C.), which is much higher than the low-melting-point non-reactive phosphorus-containing flame retardants currently widely used in the industry, such as phosphazene compounds and phosphate compounds. The present invention is used in combination with suitable resins to prepare prepregs, resin films, laminates and circuit boards with lower thermal expansion coefficients, higher heat resistance, higher glass transition temperatures, and lower dielectric constants and dielectric losses.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The phosphorus-containing flame retardant of the present invention does not contain halogen in its structure, which complies with various environmental protection policies and directives in the world today;

[0022] 2. The phosphorus-containing flame retardant of the present invention does not contain polar functional groups such as hydroxyl groups, does not participate in the reaction, and has better dielectric properties;

[0023] 3. The phosphorus-containing flame retardant of the present invention has a high melting point (greater than 200°C), which is much higher than the commercially available phosphate flame retardant, and a decomposition temperature of more than 350°C, which is convenient for industrial formulation processing. At the same time, after mixing it with a resin that does not contain hydroxyl groups (such as vinyl benzyl ether polyphenylene ether resin, etc.), it can be mixed into a flame retardant with a lower thermal expansion coefficient, higher heat resistance, higher glass transition temperature, and lower dielectric constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is the H-NMR spectrum of the final product obtained in Example 1 of the present invention;

[0026] Figure 2 is the DSC spectrum of the final product obtained in Example 1 of the present invention;

[0027] Figure 3 is the TGA spectrum of the final product obtained in Example 1 of the present invention;

[0028] Figure 4 is the H-NMR spectrum of the final product obtained in Example 2 of the present invention;

[0029] Figure 5 is the DSC spectrum of the final product obtained in Example 2 of the present invention;

[0030] Figure 6 It is the TGA spectrum of the final product obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] Mix 66.8g of xylylphosphine oxide and 255g of ethanol, stir and heat to 35°C, add 12.1g of sodium hydroxide in batches, and disperse for 1 hour. Add 30g of 2,4-bis(chloromethyl)trimethylbenzene in batches, heat to 70°C, and react for 6 hours. Evaporate the ethanol, add 300g of dichloromethane and 200g of water, stir and separate, wash the organic layer once with 150g of water, and decolorize with 3g of activated carbon for 2 hours. Evaporate the dichloromethane, add 150g of ethanol for recrystallization, and dry to obtain the product;

[0034] The obtained compounds were confirmed and characterized through various tests, and the spectra are shown in the attachment.

[0035] Figure 1 The H-NMR spectrum of the final product can confirm that the structure is correct; Figure 2 The DSC spectrum of the final product shows that the melting point of the product is 239.42°C; Figure 3 The TGA spectrum of the final product shows that the decomposition temperature is 389.33°C, which is much higher than the low melting point non-reactive phosphorus-containing flame retardants currently widely used in the industry, such as phosphazene compounds and phosphate compounds.

[0036] The flame retardant synthesis steps are as follows:

[0037]

[0038] Example 2

[0039] The difference between this embodiment and embodiment 1 is that diphenylphosphine oxide is used instead of ditolylphosphine oxide, and the obtained compound is confirmed and characterized by various tests. Figure 4 The H-NMR spectrum of the final product can confirm that the structure is correct; Figure 5 The DSC spectrum of the final product shows that the melting point of the product is 216.37°C; Figure 6 This is the TGA spectrum of the final product, and it can be seen that the decomposition temperature is 387.52°C.

[0040] The flame retardant synthesis steps are as follows:

[0041]

[0042] Table 1 below is a formula composition ratio table containing flame retardants (unit: weight parts), and the formula is obtained by fully mixing the components to obtain the corresponding formula composition:

[0043] Table 1

[0044]

[0045] Table 2 below shows the corresponding formula test data:

[0046] Table 2

[0047]

[0048]

[0049] From the test table data, it can be seen that the compounds 1 and 2 of the present invention and their corresponding formulas 1 and 2 have lower swelling rate, higher heat resistance, higher glass transition temperature, and lower dielectric constant compared to other formulas. The formula of the present invention has good flame retardancy due to the presence of a specific phosphorus-containing flame retardant, and can effectively achieve the flame retardant effect of UL94V-0. From the comparison of the test data of formulas 1 / 2 / 5, it can be seen that the addition of styrene polymer to the formula of the present invention further reduces the dielectric loss and obtains better dielectric properties).

[0050] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a novel flame retardant, characterized in that: The following steps are involved: S1. Mix the organophosphorus compound and ethanol, stir and heat to 35-40°C, add sodium hydroxide in batches, and disperse for 1-2 hours; S2, adding 2,4-bis(chloromethyl)trimethylbenzene in batches, raising the temperature to 70-78°C, and reacting for 6-8 hours; S3, evaporate the ethanol, add dichloromethane and water, stir and separate the layers, wash the organic layer with water once, and decolorize with activated carbon for 2 hours; evaporate the dichloromethane again, add ethanol for recrystallization, and dry to obtain the product.

2. The method for preparing a novel flame retardant according to claim 1, characterized in that: The organic phosphorus compound is ditolylphosphine oxide or diphenylphosphine oxide.

3. The method for preparing a novel flame retardant according to claim 1, characterized in that: The molar ratio of the organic phosphorus compound, sodium hydroxide and 2,4-bis(chloromethyl)trimethylbenzene is (2-2.2):(2-2.2):

1.

4. The method for preparing a novel flame retardant according to claim 1, characterized in that: The mass ratio of ethanol to 2,4-bis(chloromethyl)trimethylbenzene for the reaction is 8:

1.

5. The method for preparing a novel flame retardant according to claim 1, characterized in that: The mass ratio of dichloromethane to 2,4-bis(chloromethyl)trimethylbenzene in S3 is 9:

1.

6. The method for preparing a novel flame retardant according to claim 1, characterized in that: The mass ratio of ethanol to 2,4-bis(chloromethyl)trimethylbenzene used for recrystallization is (4-6):

1.

7. An application of a novel flame retardant prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The novel flame retardant is applied to resins without hydroxyl groups, such as vinyl benzyl ether polyphenylene ether resin. The novel flame retardant is mixed with the resin without hydroxyl groups to form a flame retardant with lower thermal expansion coefficient, higher heat resistance, higher glass transition temperature and lower dielectric constant.

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