DOPO-VC-nano calcium carbonate flame retardant as well as preparation method and application thereof

Abstract

The invention provides a DOPO-VC-nano calcium carbonate flame retardant and a preparation method and application thereof.The preparation method comprises the following steps that glutaraldehyde and glycine are subjected to oil bath heating in a solvent, a product is taken and dried after the reaction is completed, and an intermediate product is obtained; performing oil bath heating on DOPO and the intermediate product in a solvent, and drying the product after the reaction is completed to obtain a DOPO-coated VC flame retardant; the molar ratio of glutaraldehyde to glycine is 1: (2-3); the molar ratio of the DOPO to the intermediate product is (2-3): 1. The three-source integrated flame retardant is synthesized from DOPO and elements containing hydroxyl, N and the like, and meanwhile, the flame retardant can participate in the co-curing process of epoxy resin, so that the EP composite material with efficient flame retardance is obtained; in addition, the flame retardant can also be applied to EP together with nano calcium carbonate, so that the flame retardant property of the EP composite material is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardants, and in particular to a DOPO@VC-nano calcium carbonate flame retardant and a preparation method and application thereof. Background Art

[0002] With the rapid development of polymer materials, they have found widespread application in areas such as automobiles and home furnishings. However, most polymer materials are flammable and, once burned, release a large amount of heat in a short period of time. For example, epoxy resin (EP) has an oxygen index of only around 22%, making flame retardancy crucial.

[0003] Currently, adding flame retardants is one of the most widely used methods to effectively produce flame-retardant EP composites. DOPO (6H-dibenz(C,E)(1,2)oxaphosphorin-6-oxide, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) is widely used in epoxy resins. However, single or unmodified DOPO has disadvantages such as low flame retardancy, requiring modification or compounding with nanomaterials. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to propose a DOPO@VC-nano calcium carbonate flame retardant and its preparation method and application. A chemical synthesis reaction is used to prepare DOPO@VC with integrated acid source, carbon source and gas source functions using glycine (GLY), glutaraldehyde, DOPO, etc. as raw materials. Nano calcium carbonate is combined with DOPO@VC to further enhance the flame retardant properties of the flame retardant and give epoxy resin more excellent flame retardant properties.

[0005] The technical solution of the present invention is achieved as follows: A method for preparing a DOPO@VC flame retardant comprises the following steps: (1) Glutaraldehyde and glycine are heated in an oil bath in a solvent. After the reaction is complete, the product is dried to obtain an intermediate product. (2) DOPO and the intermediate product are heated in an oil bath in a solvent. After the reaction is complete, the product is dried to obtain DOPO@VC flame retardant; The molar ratio of the glutaraldehyde to the glycine is 1:2-3; the molar ratio of the DOPO to the intermediate product is 2-3:1.

[0006] A further solution is that in step (1), 40 to 50 mL of solvent is added to every 3 to 5 g of reactant, and the solvent includes dichloromethane, chloroform or acetone; in step (2), 40 to 50 mL of solvent is added to every 1 to 3 g of reactant, and the solvent includes dichloromethane, chloroform or acetone.

[0007] A further solution is that in step (1), the temperature of the oil bath is 50-70°C and the time is 5-10 h; in step (2), the temperature of the oil bath is 70-90°C and the time is 5-10 h.

[0008] A further solution is that in step (1), the drying temperature is 55-65°C and the drying time is at least 12 h; in step (2), the drying temperature is 55-65°C and the drying time is at least 12 h.

[0009] A further solution is that in step (1), stirring is further performed for 5 to 10 hours during the oil bath; and in step (2), stirring is further performed for 5 to 10 hours during the oil bath.

[0010] In one aspect, the present invention provides a DOPO@VC flame retardant prepared by the above-mentioned preparation method.

[0011] On the other hand, the present invention also provides a DOPO@VC-nano calcium carbonate flame retardant, which is obtained by mixing the above-mentioned DOPO@VC flame retardant with nano calcium carbonate.

[0012] The present invention provides use of the above-mentioned DOPO@VC flame retardant and / or the above-mentioned DOPO@VC-nano calcium carbonate flame retardant in improving the flame retardant properties of epoxy resin.

[0013] A further solution is to add 3 to 7 parts of the DOPO@VC flame retardant or DOPO@VC-nano calcium carbonate flame retardant to every 100 parts of epoxy resin by weight to obtain a DOPO@VC-EP composite material or DOPO@VC-nano calcium carbonate-EP composite material with improved flame retardancy of the epoxy resin.

[0014] A further solution is a method for preparing the DOPO@VC-EP composite material, comprising: adding an epoxy resin at 85-95°C, then adding the DOPO@VC and mixing, adding a curing agent, mixing again, pouring into a preheated mold, heating to 110-130°C and holding for 1-3 hours, then heating to 140-160°C and curing for 1-3 hours, and finally heating to 170-190°C and holding for 0.5-1.5 hours to obtain the DOPO@VC-EP composite material; The preparation method of the DOPO@VC-nano-calcium carbonate-EP composite material comprises: adding epoxy resin at 85-95°C, then adding the DOPO@VC and nano-calcium carbonate, mixing evenly, adding a curing agent, mixing evenly again, pouring into a preheated mold, heating to 110-130°C, holding for 1-3 hours, then heating to 140-160°C for curing for 1-3 hours, and finally heating to 170-190°C, holding for 0.5-1.5 hours to obtain the DOPO@VC-nano-calcium carbonate-EP composite material.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention utilizes DOPO and elements containing hydroxyl groups and nitrogen to synthesize a three-source integrated flame retardant. The flame retardant can also participate in the co-curing process of epoxy resin to obtain an EP composite material with high-efficiency flame retardant properties. In addition, the flame retardant can also be used together with nano-calcium carbonate in EP to further enhance the flame retardant properties of the EP composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 IR spectra of glutaraldehyde, GLY and intermediates; Figure 2 IR spectra of the intermediate product, DOPO, and DOPO@VC; Figure 3 The synthetic route of DOPO@VC; Figure 4 This is a graph showing the heat release rate of EP and its modified EP changing with time. DETAILED DESCRIPTION

[0017] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0018] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0019] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0020] Cone calorimetry is performed according to ISO 5660-1; limiting oxygen index is performed according to ISO 4589-2; and horizontal and vertical burning values are performed according to ISO 9773–1998.

[0021] Example 1 The specific process of DOPO@VC synthesis is as follows: (1) Use a graduated cylinder to measure 1.9 mL of glutaraldehyde, 3 g of glycine (the molar ratio of the two is 1:2), and 40 mL of dichloromethane as a solvent (double the amount if the raw material is doubled). Place them in a three-necked flask, heat in an oil bath at 60°C and stir for 6 h. Wash the product, filter it, and dry it in an oven at 60°C for more than 12 h to obtain the intermediate product.

[0022] (2) Weigh 1.0189 g of DOPO and 0.5 g of the intermediate product from step (1) (the molar ratio of the two is 2:1) and 40 mL of dichloromethane as solvent, place them in a three-necked flask, heat and stir in an oil bath at 80°C for 6 h, wash the product, filter it, and dry it in an oven at 60°C for more than 12 h to obtain DOPO@VC.

[0023] like Figure 1 As shown in the figure, after glutaraldehyde and GLY react under certain conditions, the aldehyde group of glutaraldehyde (1717cm -1 ) and the amino group of GLY (1519cm -1 ) did not appear in the intermediate product, and at 1666cm -1 The characteristic peak of Schiff base was found at , and the aldehyde group on the carboxyl group of GLY was almost the same as the aldehyde group on the intermediate product. The results show that the reaction between glutaraldehyde and GLY forms a Schiff base.

[0024] like Figure 2 As shown, the Schiff base of the intermediate product (1666 cm -1 ) and DOPO pH (2431 cm -1 ) did not appear in the final product DOPO@VC, but NH (1523 cm -1 )、P=O(1233cm -1 ) and PO (907cm -1 ), indicating that DOPO and the intermediate Schiff base underwent a synthesis reaction.

[0025] After glutaraldehyde and GLY react under certain conditions, the aldehyde group of glutaraldehyde (1717cm -1 ) and the amino group of GLY (1519cm -1 ) did not appear in the intermediate product, and at 1666cm -1 The characteristic peak of Schiff base was found at , and the aldehyde group on the carboxyl group of GLY was almost the same as the aldehyde group on the intermediate product. The results show that the reaction between glutaraldehyde and GLY forms a Schiff base.

[0026] The reaction process is as follows Figure 3 shown.

[0027] Example 2 The difference between this embodiment and embodiment 1 is that the molar ratio of glutaraldehyde to glycine is 1:3, and the remaining steps are the same as those in embodiment 1.

[0028] Example 3 The difference between this embodiment and embodiment 1 is that the molar ratio of DOPO to the intermediate product is 3:1, and the remaining steps are the same as those in embodiment 1.

[0029] Example 4 The difference between this embodiment and embodiment 1 is that, in steps (1) and (2), the reaction is carried out by heating the oil bath at 80° C. with stirring for 5 to 10 h, and the remaining steps are the same as those in embodiment 1.

[0030] Example 5 Preparation of DOPO@VC-nano calcium carbonate-EP composite material, the specific process is as follows: (1) DOPO@VC prepared in Example 1 and nano-calcium carbonate were doped into EP in a certain ratio: 100 parts of epoxy resin, 21.4 parts of curing agent, and 5 parts of doping raw material.

[0031] (2) First, add epoxy resin into a three-necked flask and heat it to 90 °C to make the epoxy resin in a fluid state. Then add DOPO@VC and nano-calcium carbonate, mix and stir evenly, add curing agent 4,4'-diaminodiphenylmethane, stir thoroughly again, and pour it into the preheated polytetrafluoroethylene sheet. After completion, put it into a vacuum drying oven, heat it to 120 °C for 2 h, then continue to heat it to 150 °C for curing 2 h, and finally heat it to 180 °C for 1 h. Take out the cured composite epoxy resin sample while it is hot to obtain DOPO@VC-nano-calcium carbonate-EP composite material.

[0032] The reaction raw material ratio is as follows: Table 1 EP composite material raw material ratio

[0033] Application Example 1 After experimental testing, the flame retardant performance results are shown in Figure 4 (cone calorimetry heat release value), and Table 2 shows the cone calorimetry heat release value, limiting oxygen index value (LOI) and horizontal vertical burning value (UL-94).

[0034] Table 2 Core data related to flame retardancy of EP and its modified EP

[0035] As shown in Table 2 above, the peak heat release of DOPO@VC@EP material is 767 kW / m 2The limiting oxygen index value is 24.5, and the horizontal and vertical combustion value is V-1 level; the heat release peak of DOPO@VC-nano calcium carbonate-EP composite material (DOPO@VC / nano calcium carbonate@EP) is 501 kW / m 2 The limiting oxygen index value is 28.5, the horizontal and vertical combustion values are V-0 level, and the performance of each index is better than EP, DOPO@VC@EP material, and nano calcium carbonate@EP material.

[0036] The flame retardant properties of the DOPO@VC materials and the DOPO@VC@EP materials synthesized in Examples 2 to 4 are the same as those in Example 1.

[0037] Comparative Example 1 The difference between this comparative example and Example 2 is that the nano-calcium carbonate is replaced by talc powder, and a DOPO@VC-talc powder-EP composite material is obtained according to the same preparation method as Example 2.

[0038] The peak heat release of DOPO@VC-talc-EP composite material was 731 kW / m 2 , the limiting oxygen index value is 24.8.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a DOPO@VC flame retardant, characterized in that: The steps include: (1) Glutaraldehyde and glycine are heated in an oil bath in a solvent. After the reaction is complete, the product is dried to obtain an intermediate product. (2) DOPO and the intermediate product are heated in an oil bath in a solvent. After the reaction is complete, the product is dried to obtain DOPO@VC flame retardant; The molar ratio of the glutaraldehyde to the glycine is 1:2-3; the molar ratio of the DOPO to the intermediate product is 2-3:

1.

2. A method for preparing a DOPO@VC flame retardant according to claim 1, characterized in that: In step (1), 40 to 50 mL of solvent is added to every 3 to 5 g of reactant, and the solvent includes dichloromethane, chloroform or acetone; in step (2), 40 to 50 mL of solvent is added to every 1 to 3 g of reactant, and the solvent includes dichloromethane, chloroform or acetone.

3. A method for preparing a DOPO@VC flame retardant according to claim 1, characterized in that: In step (1), the temperature of the oil bath is 50-70°C and the time is 5-10 h; in step (2), the temperature of the oil bath is 70-90°C and the time is 5-10 h.

4. A method for preparing a DOPO@VC flame retardant according to claim 1, characterized in that: In step (1), the drying temperature is 55-65°C, and the drying time is at least 12 h; in step (2), the drying temperature is 55-65°C, and the drying time is at least 12 h.

5. A method for preparing a DOPO@VC flame retardant according to claim 1, characterized in that: In step (1), stirring is performed for 5 to 10 hours during the oil bath; and in step (2), stirring is performed for 5 to 10 hours during the oil bath.

6. A DOPO@VC flame retardant prepared by the preparation method according to any one of claims 1 to 5.

7. A DOPO@VC-nano calcium carbonate flame retardant, characterized in that: The method comprises mixing the DOPO@VC flame retardant according to claim 6 with nano calcium carbonate.

8. Use of the DOPO@VC flame retardant according to claim 6 and / or the DOPO@VC-nano calcium carbonate flame retardant according to claim 7 in improving the flame retardant properties of epoxy resin.

9. The use according to claim 8, characterized in that By weight, 3 to 7 parts of the DOPO@VC flame retardant or DOPO@VC-nano calcium carbonate flame retardant are added to every 100 parts of epoxy resin to obtain a DOPO@VC-EP composite material or a DOPO@VC-nano calcium carbonate-EP composite material with improved flame retardancy of the epoxy resin.

10. The use according to claim 9, characterized in that The preparation method of the DOPO@VC-EP composite material comprises: adding epoxy resin at 85-95°C, then adding the DOPO@VC and mixing, adding a curing agent, mixing again, pouring into a preheated mold, heating to 110-130°C and holding for 1-3 hours, then heating to 140-160°C and curing for 1-3 hours, and finally heating to 170-190°C and holding for 0.5-1.5 hours to obtain the DOPO@VC-EP composite material; The preparation method of the DOPO@VC-nano-calcium carbonate-EP composite material comprises: adding epoxy resin at 85-95°C, then adding the DOPO@VC and nano-calcium carbonate, mixing evenly, adding a curing agent, mixing evenly again, pouring into a preheated mold, heating to 110-130°C, holding for 1-3 hours, then heating to 140-160°C for curing for 1-3 hours, and finally heating to 170-190°C, holding for 0.5-1.5 hours to obtain the DOPO@VC-nano-calcium carbonate-EP composite material.

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