Solid phosphate flame retardant and preparation method thereof

Abstract

The invention discloses a solid phosphate flame retardant and a preparation method thereof, and belongs to the technical field of flame-retardant material preparation. The preparation method comprises the following steps: adding a phosphating reagent and a catalyst into a reaction kettle, stirring, heating, adding epoxy olefin, reacting while maintaining the pressure, and cooling to room temperature after the reaction is finished to obtain an intermediate solution; adjusting the pH value of the intermediate solution to 7-8 by using a sodium hydroxide solution, adding a metal salt aqueous solution at normal temperature, and rapidly stirring to obtain a crude product; and filtering the crude product, washing and filtering the obtained solid twice, drying and grinding to obtain the product. The solid phosphate is prepared by adopting two-step reaction of epoxy olefin ring-opening addition and metal salt double decomposition, the reaction condition is mild, the process is simple, few byproducts are produced, the product yield is high, and halogen-free phosphate can be prepared according to customer requirements; the solid phosphate flame retardant prepared by the method disclosed by the invention is used for preparing a molding material, the preparation process can be simplified on the premise of not influencing the performance, and the advantages are more obvious.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant material preparation, and specifically to a solid phosphate flame retardant and a preparation method thereof. Background Art

[0002] With the rapid economic development today, polymer materials have been widely used. However, their flammability poses safety hazards. Therefore, the flame retardant modification of polymer materials is extremely important. Solid organic phosphate flame retardants have been a hot topic newly developed in recent years.

[0003] Currently, the most commercially successful solid phosphonate flame retardant is diethyl phosphinate. Patent CN1660858A discloses a preparation method of diethyl phosphinate. Under the conditions of an initiator and high pressure, ethylene and hypophosphite react in a solvent through a free radical addition reaction to obtain alkyl phosphinate.

[0004] Patent CN1280582A discloses a preparation method of dialkyl hypophosphite. This method first uses yellow phosphorus and alkyl halide to generate salts containing alkylphosphonic acid, phosphoric acid, and hypophosphorous acid, then reacts with ethylene using free radical initiation, and then reacts with a metal compound to obtain dialkyl hypophosphite.

[0005] In the preparation methods disclosed in the above patents, the free radicals are easily quenched and inactivated in water, and it is easy to generate by-products of monoalkyl phosphinate. The solvent recovery process is complex, and the reaction equipment must be made of high-pressure corrosion-resistant materials. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a solid phosphate flame retardant and a preparation method thereof, with a simple preparation process, mild reaction conditions, and adjustable process.

[0007] The present invention is achieved through the following technical solutions:

[0008] A solid phosphate flame retardant and a preparation method thereof, including the following steps:

[0009] a. Add a phosphating reagent and a catalyst to a reaction kettle, stir evenly, heat up, add epoxy olefin, and react for 6 - 8 h under pressure. After the reaction is completed, cool to room temperature to obtain an intermediate solution.

[0010] b. Adjust the pH of the intermediate solution to 7 - 8 with a sodium hydroxide solution, add an aqueous metal salt solution at room temperature, and stir rapidly for 20 - 40 min to obtain a crude product;

[0011] c. Filter the crude product, wash the obtained solid twice by water filtration, dry, and grind to obtain the product.

[0012] Preferably, in the step (1), the phosphating reagent is one or more of an aqueous solution of sodium dihydrogen phosphate, an aqueous solution of phosphoric acid, and an aqueous solution of phosphorous acid.

[0013] Preferably, the mass fraction of the phosphating reagent aqueous solution in the step (1) is 40% to 90%;

[0014] Preferably, the epoxy olefin in the step (1) is one or more of propylene oxide, epichlorohydrin, and epoxy butane.

[0015] Preferably, the molar ratio of the epoxy olefin to the phosphating reagent in the step (1) is (0.5 to 3):1.

[0016] Preferably, the catalyst in the step (1) is one of boron trifluoride diethyl etherate, titanium tetrachloride, tetrabutyl titanate, and aluminum trichloride, and the addition amount of the catalyst is 0.1% to 1% (wt) of the phosphating reagent.

[0017] Preferably, the reaction temperature in the step (1) is 60 to 100 °C, the reaction time is 4 to 8 h, and the reaction pressure is maintained at 0 to 0.5 MPa.

[0018] Preferably, the metal salt in the step (2) is one or more of aluminum sulfate, magnesium sulfate, zinc sulfate, and ferric chloride.

[0019] Preferably, the molar ratio of the metal salt to the phosphating reagent in the step (2) is 1:(2 to 6).

[0020] Preferably, the mass fraction of the metal salt aqueous solution in the step (2) is 10% to 50%.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention prepares solid phosphate by two-step reactions of epoxy olefin ring-opening addition and metal salt metathesis. The reaction conditions are mild, the process is simple, the by-products are few, the product yield is high, and halogen-free phosphate can be prepared according to customer requirements; the solid phosphate flame retardant prepared by the method of the present invention is used to prepare molding materials, and its tensile, bending, and flame retardant properties are comparable to those of the prior art comparative examples, and it can simplify the preparation process without affecting the performance, and the advantages are more obvious. Specific Embodiments

[0023] The present invention will be further described below in conjunction with examples and comparative examples:

[0024] The raw materials used in the comparative examples and examples of the present invention are all general industrial-grade products.

[0025] I. Preparation of solid phosphate flame retardant:

[0026] Example 1

[0027] Add 240 kg of aqueous sodium dihydrogen phosphate solution (50% wt) and 0.6 kg of boron trifluoride etherate into the reaction kettle, stir, heat up to 80 °C, add 74 kg of epichlorohydrin under normal pressure, react for 8 h under normal pressure after the feeding is completed, and cool to room temperature after the reaction is completed to obtain an intermediate solution.

[0028] Adjust the pH of the intermediate solution to 7 - 8 with sodium hydroxide solution, add 152 kg of aqueous aluminum sulfate solution (30% / wt) at room temperature, and stir rapidly for 30 min to obtain a crude product.

[0029] Filter the crude product, wash and filter the obtained solid twice with water, dry, and grind to obtain 145.5 kg of product (yield: 91.64% of the theoretical value).

[0030] The structural formula of the product is:

[0031]

[0032] Example 2

[0033] Add 115.3 kg of phosphoric acid solution (85% wt) and 0.6 kg of titanium tetrachloride into the reaction kettle, stir evenly, heat up to 70 °C, add 128 kg of propylene oxide, maintain the reaction pressure at 0.2 MPa, react for 6 h after the feeding is completed, and cool to room temperature after the reaction is completed to obtain an intermediate solution.

[0034] Adjust the pH of the intermediate solution to 7 - 8 with sodium hydroxide solution, add 300 kg of aqueous magnesium sulfate solution (20% / wt) at room temperature, and stir rapidly for 30 min to obtain a crude product.

[0035] Filter the crude product, wash and filter the obtained solid twice with water, dry, and grind to obtain 207.2 kg of product (yield: 92.09% of the theoretical value).

[0036] The structural formula of the product is:

[0037]

[0038] Example 3

[0039] Add 164 kg of phosphorous acid solution (50% wt) and 0.5 kg of tetrabutyl titanate into the reaction kettle, stir, heat up to 90 °C, add 102 kg of epichlorohydrin under normal pressure, react for 7 h after the feeding is completed, and cool to room temperature after the reaction is completed to obtain an intermediate solution.

[0040] Adjust the pH of the intermediate solution to 7 - 8 with sodium hydroxide solution, add 205 kg of aqueous zinc sulfate solution (40% / wt) at room temperature, and stir rapidly for 30 min to obtain a crude product.

[0041] The crude product was filtered. The obtained solid was washed with water and filtered twice, dried, and ground to obtain 188.5 kg of product (yield: 91.5% of the theoretical value).

[0042] The structural formula of the product is:

[0043]

[0044] Example 4

[0045] 173 kg of aqueous phosphoric acid solution (85% wt) and 0.9 kg of aluminum trichloride were added to the reaction kettle, stirred, heated to 80 °C, 240 kg of epoxy butane was added, the reaction pressure was maintained at 0.1 MPa, and after the feeding was completed, the reaction was carried out for 8 h. After the reaction was completed, it was cooled to room temperature to obtain an intermediate solution.

[0046] The pH of the intermediate solution was adjusted to 7 - 8 with sodium hydroxide solution, and 271 kg of aqueous ferric chloride solution (30% / wt) was added at room temperature, and it was rapidly stirred for 30 min to obtain a crude product.

[0047] The crude product was filtered. The obtained solid was washed with water and filtered twice, dried, and ground to obtain 356.7 kg of product (yield: 91.58% of the theoretical value).

[0048] The structural formula of the product is:

[0049]

[0050] Example 5

[0051] 288 kg of aqueous sodium dihydrogen phosphate solution (50% wt) and 0.56 kg of boron trifluoride etherate were added to the reaction kettle, stirred, heated to 85 °C, 46 kg of epichlorohydrin and 29 kg of propylene oxide were added, the reaction pressure was maintained at 0.1 MPa, and after the feeding was completed, the reaction was carried out for 8 h. After the reaction was completed, it was cooled to room temperature to obtain an intermediate solution.

[0052] The pH of the intermediate solution was adjusted to 7 - 8 with sodium hydroxide solution, and 150 kg of aqueous magnesium sulfate solution (20% / wt) and 103 kg of aqueous zinc sulfate solution (40% / wt) were added at room temperature, and it was rapidly stirred for 30 min to obtain a crude product.

[0053] The crude product was filtered. The obtained solid was washed with water and filtered twice, dried, and ground to obtain 177.3 kg of product (yield: 91.17% of the theoretical value).

[0054] The structural formula of the product is:

[0055]

[0056] Comparative Example 1 (prepared with reference to CN1660858A)

[0057] Dissolve 1500 g of sodium hypophosphite monohydrate and 14 g of concentrated sulfuric acid in 7.5 kg of water, and add it to a 16 L pressure reactor made of glazed steel with a jacket. Heat it up to 100 °C, and add ethylene to the reactor through a pressure reducing valve of 6 bar until saturation is reached. Dissolve 22 g of sodium percarbonate in 300 g of water, and uniformly meter it in within 6 h under the conditions of an ethylene pressure of 20 bar and 110 °C while continuously stirring. Continue the reaction for 1 h, reduce the pressure and cool it to below about 90 °C, and add 3 kg of aqueous aluminum sulfate tetradecahydrate solution (46% / wt) within 1 h. Filter the obtained solid, wash it with 2 L of hot water, and dry it under vacuum at 130 °C to obtain the product. Yield: 1692 g (91.96% of the theoretical value).

[0058] The structural formula of the product is:

[0059]

[0060] Comparative Example 2 (prepared with reference to CN1660858A)

[0061] Dissolve 1.5 kg of sodium hypophosphite monohydrate in 7.5 kg of water, and add it to a 16 L pressure reactor made of glazed steel with a jacket. Heat it up to 100 °C, and add ethylene to the reactor through a pressure reducing valve of 6 bar until saturation is reached. Dissolve 33 g of sodium persulfate in 300 g of water, and uniformly meter it in within 6 h under the conditions of an ethylene pressure of 6 bar and 100 - 110 °C while continuously stirring. Continue the reaction for 1 h, reduce the pressure and cool it to below about 90 °C, add 700 g of concentrated sulfuric acid within 30 min, then add 362 g of aluminum hydroxide and heat the mixture in a closed reactor at 150 °C for 8 h. After the reaction is completed, cool it to room temperature, filter the obtained solid, wash it with 2 L of hot water, and dry it under vacuum at 130 °C to obtain the product. Yield: 1670 g (91.71% of the theoretical value).

[0062] The structural formula of the product is:

[0063]

[0064] II. Application and testing:

[0065] (1) Preparation of samples

[0066] Mix the products of the comparative examples and examples with PBT, glass fiber, and additives at a weight ratio of 10:60:25:5 at 230 - 260 °C, and extrude them from a twin-screw extruder to prepare a flame-retardant thermoplastic polymer molding material, and prepare samples to test their combustion performance and mechanical properties.

[0067] (2) Performance testing

[0068] The tensile strength was tested according to the standard of GB / T 1040.1-2018, the flexural strength and deflection were tested according to the standard of GB / T 9341—2008, the limiting oxygen index (LOI) was tested according to the standard of GB / T 2406.1—2008, and the vertical burning test (UL-94) was tested according to the standard of GB / T 2048-2021. The test results are shown in the following table:

[0069]

[0070] As can be seen from the above table, the solid phosphate flame retardant prepared by the present invention is used to prepare molding materials, and its tensile, flexural and flame retardant properties are comparable to those of the comparative example. It is suitable for making polymer molding materials. However, the reaction conditions and preparation process of the present invention are simple and have obvious advantages.

[0071] In summary, the above are only the preferred embodiments of the present invention, and are not used to limit the scope of implementation of the present invention. Any equivalent changes and modifications made according to the shape, structure, features and spirit described in the scope of the claims of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A solid phosphate flame retardant and its preparation method, characterized in that: It includes the following steps: a. Add a phosphating reagent and a catalyst into a reaction kettle, stir evenly, heat up, add an epoxy olefin, react under a maintained pressure, and cool to room temperature after the reaction to obtain an intermediate solution; b. Adjust the pH of the intermediate solution to 7 - 8 with a sodium hydroxide solution, add an aqueous metal salt solution at room temperature, and stir rapidly for 20 - 40 min to obtain a crude product; c. Filter the crude product, wash and filter the obtained solid twice with water, dry, and grind to obtain the product.

2. The solid phosphate flame retardant and its preparation method according to claim 1, characterized in that: In the step (1), the phosphating reagent is one or more of an aqueous solution of sodium dihydrogen phosphate, an aqueous solution of phosphoric acid, and an aqueous solution of phosphorous acid.

3. The solid phosphate flame retardant according to claim 1 and its preparation method, characterized in that: In the step (1), the mass fraction of the aqueous phosphating reagent solution is 40% - 90%.

4. The solid phosphate flame retardant according to claim 1 and its preparation method are characterized in that: In the step (1), the epoxy olefin is one or more of propylene oxide, epichlorohydrin, and epoxy butane.

5. The solid phosphate flame retardant according to claim 1 and its preparation method, characterized in that: In the step (1), the molar ratio of the epoxy olefin to the phosphating reagent is (0.5 - 3):

1.

6. The solid phosphate flame retardant according to claim 1 and its preparation method are characterized in that: In the step (1), the catalyst is one of boron trifluoride etherate, titanium tetrachloride, tetrabutyl titanate, and aluminum trichloride, and the addition amount of the catalyst is 0.1% - 1% (wt) of the phosphating reagent.

7. A solid phosphate flame retardant and its preparation method according to claim 1, characterized in that: In the step (1), the reaction temperature is 60 - 100 °C, the reaction time is 4 - 8 h, and the reaction pressure is maintained at 0 - 0.5 MPa.

8. A solid phosphate flame retardant and its preparation method according to claim 1, characterized in that: In the step (2), the metal salt is one or more of aluminum sulfate, magnesium sulfate, zinc sulfate, and ferric chloride.

9. The solid phosphate flame retardant according to claim 1 and its preparation method are characterized in that: In the step (2), the molar ratio of the metal salt to the phosphating reagent is 1:(2 - 6).

10. The solid phosphate flame retardant and its preparation method according to claim 1, characterized in that: In the step (2), the mass fraction of the aqueous metal salt solution is 10% - 50%.

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