Flame-retardant epoxy curing agent and preparation method thereof

Abstract

The invention relates to the technical field of curing agents, and discloses a flame-retardant epoxy curing agent and a preparation method thereof.The flame-retardant epoxy curing agent is prepared from raw materials including 1-thiophospha-4-hydroxymethyl-2, 6, 7-trioxabicyclo [2.2. 2] octane (SPEPA), allyltriethoxysilane, p-amino benzyl chloride, methyl diaminodiethylamine and the like through Suzuki coupling reaction, addition reaction and quaternization reaction, and the flame-retardant epoxy curing agent is prepared. The flame-retardant epoxy curing agent is prepared. The flame retardant elements contained in the curing agent are used for improving the flame retardant property of the curing agent, the antibacterial structure contained in the curing agent is used for improving the antibacterial property of the curing agent, and the prepared flame-retardant epoxy curing agent has good antibacterial property and flame retardant property.

Description

Technical Field

[0001] The invention relates to the technical field of curing agents, in particular to a flame retardant epoxy curing agent and a preparation method thereof. Background Art

[0002] Flame retardant epoxy curing agents are a type of chemical additive specifically used in the curing process of epoxy resins and other types of resins. These curing agents can effectively improve the flame retardant properties of the cured material and reduce the burning rate and flame propagation ability of the material in a fire. The working principle of flame retardant curing agents is usually to delay the spread of flames and the combustion of materials by releasing gas, forming a protective layer or absorbing heat under high temperature conditions.

[0003] For example, the patent with application publication number CN202010752487.4 discloses a flame retardant epoxy curing agent and a preparation method thereof. The invention introduces nitrogen and phosphorus elements through molecular design to achieve a synergistic flame retardant effect. No toxic or harmful substances are released during combustion, which is more environmentally friendly and safe. The phosphorus-containing and nitrogen-containing groups are connected with acrylic ester bridges, and flexible chain segments are introduced into the molecular structure to improve the compatibility of the curing agent and the epoxy system, and improve the mechanical properties of the polymer product. The introduction of a rigid ring structure increases the cross-linking in the system, further improves the mechanical properties of the resin, and at the same time improves the thermal stability and chemical stability of the product, and enhances the flame retardant properties. However, the material cured by this invention is not suitable for humid or moist environments. In such environments, bacteria are easily bred, shortening the service life. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a flame retardant epoxy curing agent and a preparation method thereof. The prepared flame retardant epoxy curing agent has good antibacterial and flame retardant properties.

[0006] (II) Technical solution

[0007] A flame retardant epoxy curing agent and a preparation method thereof, characterized in that the preparation method is as follows:

[0008] (1) Add 1-sulfanylphospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2.2.2]octane (SPEPA) and allyltriethoxysilane to a toluene solvent, introduce nitrogen, raise the temperature to 90-110° C., react for 5-10 hours, evacuate the reaction, cool the temperature to 30-50° C., add anhydrous ethanol, stir and disperse for 0.5-1.5 hours, filter, and dry to obtain intermediate 1;

[0009] (2) Add intermediate 1, inhibitor and catalyst to toluene solvent, heat to 60-80°C, stir and dissolve for 1-3h, add p-aminobenzyl chloride, react for 8-12h, and after the reaction is complete, distill under reduced pressure, heat to 70-90°C, pour into deionized water at the same temperature, add 10% by mass dilute hydrochloric acid, stir and cool to 20-30°C, filter, wash with deionized water until neutral, and dry to obtain intermediate 2;

[0010] (3) Add methyldiaminodiethylamine and intermediate 2 into N,N-dimethylformamide (DMF) solvent, then add ethyl acetate catalyst, heat and stir to react, cool to room temperature, extract with ether, filter and dry to obtain a flame retardant epoxy curing agent.

[0011] Preferably, in step (1), the molar ratio of SPEPA to allyltriethoxysilane is 1:0.2-0.3.

[0012] Preferably, in step (2), the molar ratio of intermediate 1, inhibitor, catalyst and p-aminobenzyl chloride is 1:0.008-0.012:0.15-0.25:2-2.5.

[0013] Preferably, in step (3), the molar ratio of intermediate 2, methyldiaminodiethylamine and ethyl acetate is 1:0.8-1.2:0.04-0.06.

[0014] Preferably, in step (2), the inhibitor is hydroquinone and the catalyst is AlCl3.

[0015] Preferably, in the step (3), the heating temperature is 50-70° C. and the reaction time is 5-7 h.

[0016] Another object of the present invention is to use the flame retardant epoxy curing agent of the present invention in epoxy resin curing, a method for using the flame retardant epoxy curing agent in epoxy resin curing process: adding epoxy resin E51 to allyl glycidyl ether (AGE), heating to 80-100°C, stirring and mixing, adding curing agent, then heating to 110-130°C, vigorously stirring for 10-30min, placing in an oven, heating to 70-90°C, degassing for 30-50min, pouring into a polytetrafluoroethylene mold, heating to 110-120°C, pre-curing for 1-3h, then heating to 140-160°C, curing for 5-7h, and obtaining a sample.

[0017] Preferably, the mass ratio of epoxy resin E51 to curing agent is 1:0.2-0.3.

[0018] (III) Beneficial technical effects

[0019] The invention uses SPEPA, allyl triethoxysilane, p-aminobenzyl chloride, methyldiaminodiethylamine and the like as raw materials, and obtains a flame retardant epoxy curing agent through Suzuki coupling reaction, addition reaction and quaternization reaction. The preparation method is simple and the structure is novel.

[0020] The flame-retardant epoxy curing agent prepared by the present invention contains a quaternary ammonium salt group, and the positively charged ammonium ion contained in the group can be combined with the bacterial cell membrane with a negative charge, adsorbed and penetrated the cell membrane, thereby interfering with the integrity of the cell membrane, causing the permeability of the membrane to increase, causing the leakage of proteins and nucleic acids in the cell, and finally causing the death of the bacterial cell. At the same time, the quaternary ammonium salt group can interfere with the activity of the enzyme and affect the ion balance in the cell, thereby interfering with the metabolic process of the bacteria and affecting its energy production and other physiological functions.

[0021] The flame retardant epoxy curing agent prepared by the present invention contains silicon, nitrogen, phosphorus and sulfur, wherein the thiophosphate group contains three excellent flame retardant elements of silicon, phosphorus and sulfur, and the -NH2 group and the quaternary ammonium salt group both contain the flame retardant element of nitrogen, and the three groups are embedded in the flame retardant epoxy curing agent through molecular reaction. The silicon element isolates the fire source by forming a protective silicon oxide layer to reduce heat conduction, and the silicon element will generate a high temperature resistant glassy substance at high temperature to isolate material transportation and energy transfer. Nitrogen element forms nitrogen dioxide and other nitrides under high temperature conditions, and these gases will dilute the content of combustion-supporting gases such as oxygen in the flame, thereby further reducing the intensity of the flame. Nitrogen element forms nitrogen dioxide and other nitrides under high temperature conditions, and these gases will dilute the content of combustion-supporting gases such as oxygen in the flame, thereby further reducing the intensity of the flame. The flame retardant epoxy curing agent prepared by the invention has good antibacterial and flame retardant properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the synthetic route of flame retardant curing agent. DETAILED DESCRIPTION

[0023] Example 1

[0024] (1) 10 mmol of 1-thiophospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2.2.2]octane (SPEPA) and 3 mmol of allyltriethoxysilane were added to 50 ml of toluene solvent, nitrogen was introduced, the temperature was raised to 90° C., and the reaction was carried out for 5 h. After the reaction was completed, the mixture was evacuated and the temperature was lowered to 30° C. Anhydrous ethanol was added and stirred for 0.5 h, the mixture was filtered and dried to obtain intermediate 1.

[0025] (2) Add 10 mmol of intermediate 1, 0.08 mmol of hydroquinone inhibitor and 0.15 mmol of AlCl3 catalyst to 50 ml of toluene solvent, heat to 60°C, stir and dissolve for 1 hour, add 20 mmol of p-aminobenzyl chloride, react for 8 hours, and after the reaction is completed, distill under reduced pressure and heat to 70°C. Pour it into deionized water at the same temperature, add 10% by mass dilute hydrochloric acid, stir and cool to 20°C, filter, wash with deionized water until neutral, and dry to obtain intermediate 2.

[0026] (3) Add 10 mmol of methyldiaminodiethylamine and 10 mmol of intermediate 2 to 50 ml of N,N-dimethylformamide (DMF) solvent, then add 0.6 mmol of ethyl acetate catalyst, heat to 70°C, stir to react for 5 h, cool to room temperature, extract with ether, filter and dry to obtain a flame retardant epoxy curing agent.

[0027] (4) Add 100 g of epoxy resin E51 to 10 g of allyl glycidyl ether (AGE), heat to 80°C, stir to mix, add 20 g of curing agent, heat to 110°C, stir vigorously for 30 min, place in an oven, heat to 90°C, degas for 50 min, pour into a polytetrafluoroethylene mold, heat to 110°C, pre-cure for 3 h, heat to 160°C, cure for 7 h, and obtain a sample.

[0028] Example 2

[0029] (1) 10 mmol of SPEPA and 2 mmol of allyltriethoxysilane were added to 50 ml of toluene solvent, nitrogen was introduced, the temperature was raised to 110°C, and the reaction was carried out for 10 hours. After the reaction was completed, vacuum was evacuated, the temperature was lowered to 50°C, anhydrous ethanol was added, and stirred for 1.5 hours, filtered, and dried to obtain intermediate 1.

[0030] (2) Add 10 mmol of intermediate 1, 0.12 mmol of hydroquinone inhibitor and 2.5 mmol of AlCl3 catalyst to 50 ml of toluene solvent, heat to 80°C, stir and dissolve for 3 h, add 25 mmol of p-aminobenzyl chloride, react for 12 h, and after the reaction is complete, distill under reduced pressure and heat to 90°C. Pour it into deionized water at the same temperature, add 10% by mass dilute hydrochloric acid, stir and cool to 30°C, filter, wash with deionized water until neutral, and dry to obtain intermediate 2.

[0031] (3) 11 mmol of methyldiaminodiethylamine and 10 mmol of intermediate 2 were added to DMF solvent, and then 0.4 mmol of ethyl acetate catalyst was added. The temperature was raised to 60° C. and stirred for reaction for 7 h. The mixture was cooled to room temperature, extracted with ether, filtered and dried to obtain a flame retardant epoxy curing agent.

[0032] (4) Add 100 g of epoxy resin E51 to 10 g of AGE, heat to 80°C, stir to mix, add 20 g of curing agent, heat to 110°C, stir vigorously for 30 min, place in an oven, heat to 90°C, degas for 50 min, pour into a polytetrafluoroethylene mold, heat to 110°C, pre-cure for 3 h, heat to 160°C, cure for 7 h, and obtain a sample.

[0033] Example 3

[0034] (1) 10 mmol of SPEPA and 2.5 mmol of allyltriethoxysilane were added to 50 ml of toluene solvent, nitrogen was introduced, the temperature was raised to 95°C, and the reaction was carried out for 7 hours. After the reaction was completed, the mixture was evacuated, the temperature was lowered to 40°C, anhydrous ethanol was added, and the mixture was stirred and dispersed for 0.8 hours. The mixture was filtered and dried to obtain intermediate 1.

[0035] (2) Add 10 mmol of intermediate 1, 0.09 mmol of hydroquinone inhibitor and 2 mmol of AlCl3 catalyst to 50 ml of toluene solvent, heat to 65°C, stir and dissolve for 1.5 hours, add 22 mmol of p-aminobenzyl chloride, react for 9 hours, and after the reaction is completed, distill under reduced pressure and heat to 75°C. Pour it into deionized water at the same temperature, add 10% by mass dilute hydrochloric acid, stir and cool to 25°C, filter, wash with deionized water until neutral, and dry to obtain intermediate 2.

[0036] (3) 9 mmol of methyldiaminodiethylamine and 10 mmol of intermediate 2 were added to DMF solvent, and then 0.5 mmol of ethyl acetate catalyst was added. The temperature was raised to 50° C. and stirred for reaction for 6 h. The mixture was cooled to room temperature, extracted with ether, filtered and dried to obtain a flame retardant epoxy curing agent.

[0037] (4) Add 100 g of epoxy resin E51 to 10 g of AGE, heat to 80°C, stir to mix, add 20 g of curing agent, heat to 110°C, stir vigorously for 30 min, place in an oven, heat to 90°C, degas for 50 min, pour into a polytetrafluoroethylene mold, heat to 110°C, pre-cure for 3 h, heat to 160°C, cure for 7 h, and obtain a sample.

[0038] Example 4

[0039] The difference between this embodiment and embodiment 1 is that the amount of the flame retardant curing agent used in embodiment 1 is 24 g.

[0040] Example 5

[0041] The difference between this embodiment and embodiment 1 is that the amount of the flame retardant curing agent used in embodiment 1 is 28 g.

[0042] Example 6

[0043] The difference between this embodiment and embodiment 1 is that the amount of the flame retardant curing agent used in embodiment 1 is 30 g.

[0044] Comparative Example 1

[0045] (1) Add 10 mmol of allyltriethoxysilane, 0.08 mmol of hydroquinone inhibitor, and 0.15 mmol of AlCl3 catalyst to 50 ml of toluene solvent, heat to 60°C, stir and dissolve for 1 hour, add 20 mmol of p-aminobenzyl chloride, react for 8 hours, and after the reaction is completed, distill under reduced pressure, heat to 70°C, pour it into deionized water at the same temperature, add 10% by mass dilute hydrochloric acid, stir and cool to 20°C, filter, wash with deionized water until neutral, and dry to obtain intermediate a.

[0046] (2) 10 mmol of methyldiaminodiethylamine and 10 mmol of intermediate 2 were added to DMF solvent, and then 0.6 mmol of ethyl acetate catalyst was added, the temperature was raised to 70° C., stirred for reaction for 5 h, cooled to room temperature, extracted with ether, filtered and dried to obtain a flame retardant epoxy curing agent a, wherein the synthesis route of the flame retardant epoxy curing agent a is as follows:

[0047]

[0048] (3) Add 100 g of epoxy resin E51 to 10 g of AGE, heat to 80 °C, stir and mix, add 20 g of flame retardant epoxy curing agent a, heat to 110 °C, stir vigorously for 30 min, place in an oven, heat to 90 °C, degas for 50 min, pour into a polytetrafluoroethylene mold, heat to 110 °C, pre-cure for 3 h, then heat to 160 °C, cure for 7 h, and obtain a sample.

[0049] Flame retardancy testing

[0050] The limiting oxygen index (LOI) was measured by using an HC-2CZ oxygen index meter (Nanjing, China) to evaluate the combustion behavior index of the sample to be tested (130×6.5×3.2 mm). The flame retardant performance of the present invention is characterized by the oxygen index.

[0051] Table 1: Oxygen index test results of various embodiments and comparative examples

[0052] Oxygen index / % Example 1 30 Example 2 31 Example 3 31 Example 4 35 Example 5 37 Example 6 38 Comparative Example 1 27

[0053] The larger the oxygen index, the better the flame retardant performance. It can be seen from Table 1 that the oxygen indexes of Examples 1-3 are similar, and changing the amount of reactants used to generate the curing agent will not change the flame retardant properties of the curing agent. The oxygen index of Examples 4-6 is significantly increased relative to Example 1. This is because the amount of flame retardant curing agent in Examples 4-6 is increased, so its flame retardant performance is increased. Comparative Example 1 has a lower oxygen index than Example 1, so its flame retardant performance is poor, because Examples 1-6 contain more Si, P, S, and N elements. The Si element can form a protective layer at high temperature, reduce the contact between oxygen and combustible materials, thereby effectively inhibiting the flame spread mode and improving the flame retardant performance of the material. The P, S, and N elements can generate oxides containing P, S, and N at high temperatures. These gases do not support combustion in the flame, thereby further reducing the intensity of the flame. Therefore, the curing agent prepared by the present invention has good flame retardant properties.

[0054] Antibacterial performance testing:

[0055] Step 1: Place E. coli on an agar plate at 37°C and culture for 14-16 hours. Take a single colony and place it in liquid culture medium at 200 rpm for 12 hours. Dilute the culture medium to an absorbance of 0.1 and store.

[0056] Step 2: Take the same mass of Examples 1-6, the pure epoxy resin E51 cured sample and the sample of Comparative Example 1, wash them three times with deionized water, soak them in 75% alcohol for 10 minutes, and rinse them with PBS buffer.

[0057] Step 3: Place the samples of Examples 1-6, Comparative Example 1 and the pure epoxy resin E51 cured sample in bacterial culture solution for 24 hours, rinse with PBS buffer 3 times, and stain the bacteria with a stain for 10 minutes. Analyze the bacteria with a fluorescence microscope. 4 / cm 2 ) / (live bacteria+dead bacteria)(10 4 / cm 2 )}×100%

[0058] Table 2: Antibacterial test results of each embodiment and comparative example

[0059] <![CDATA[Live bacteria 10 4 / cm 2 > <![CDATA[Dead bacteria 10 4 / cm 2 > Sterilization rate / % Example 1 3.6 30.5 89.4 Example 2 3.4 30.8 90.1 Example 3 3.2 30.7 90.6 Example 4 2.6 31.2 93.3 Example 5 0.6 32.5 98.1 Example 6 0.1 32.9 99.7 Epoxy resin E51 35.6 3.2 8.2

[0060] The larger the sterilization rate, the better the antibacterial performance. It can be seen from Table 2 that the sterilization rates of Examples 1-3 are similar, and the sterilization rates of Examples 4-6 are significantly increased relative to Example 1. This is because the amount of flame retardant curing agent used in Examples 4-6 is increased, so its sterilization performance is increased. The sterilization rate of epoxy resin E51 is lower than that of Example 1, so its antibacterial performance is poor, because Examples 1-6 and Comparative Example 1 contain more quaternary ammonium salt groups, and the positively charged ammonium ions contained in the groups can combine with the negatively charged bacterial cell membrane, adsorb and penetrate the cell membrane, thereby interfering with its integrity, resulting in increased membrane permeability, causing leakage of proteins and nucleic acids in the cells, and ultimately leading to bacterial cell death. Therefore, the curing agent prepared by the present invention has good antibacterial performance.

[0061] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A flame retardant epoxy curing agent and a preparation method thereof, characterized in that: The preparation method is as follows: (1) Add 1-sulfanylphospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2.2.2]octane (SPEPA) and allyltriethoxysilane to a toluene solvent, introduce nitrogen, raise the temperature to 90-110° C., react for 5-10 hours, evacuate the reaction, cool the temperature to 30-50° C., add anhydrous ethanol, stir and disperse for 0.5-1.5 hours, filter, and dry to obtain intermediate 1; (2) Add intermediate 1, inhibitor and catalyst to toluene solvent, heat to 60-80°C, stir and dissolve for 1-3h, add p-aminobenzyl chloride, react for 8-12h, and after the reaction is complete, distill under reduced pressure, heat to 70-90°C, pour into deionized water at the same temperature, add 10% by mass dilute hydrochloric acid, stir and cool to 20-30°C, filter, wash with deionized water until neutral, and dry to obtain intermediate 2; (3) Add methyldiaminodiethylamine and intermediate 2 into N,N-dimethylformamide (DMF) solvent, then add ethyl acetate catalyst, heat and stir to react, cool to room temperature, extract with ether, filter and dry to obtain a flame retardant epoxy curing agent.

2. The method for preparing a flame retardant epoxy curing agent according to claim 1, characterized in that: In the step (1), the molar ratio of SPEPA to allyltriethoxysilane is 1:0.2-0.

3.

3. The method for preparing a flame retardant epoxy curing agent according to claim 1, characterized in that: In the step (2), the molar ratio of the intermediate 1, the polymerization inhibitor, the catalyst, and p-aminobenzyl chloride is 1:0.008-0.012:0.15-0.25:2-2.

5.

4. The method for preparing a flame retardant epoxy curing agent according to claim 1, characterized in that: In the step (3), the molar ratio of intermediate 2, methyldiaminodiethylamine and ethyl acetate is 1:0.8-1.2:0.04-0.

06.

5. The method for preparing a flame retardant epoxy curing agent according to claim 1, characterized in that: In the step (2), the inhibitor is hydroquinone and the catalyst is AlCl3.

6. The method for preparing a flame retardant epoxy curing agent according to claim 1, characterized in that: In the step (3), the heating temperature is 50-70°C and the reaction time is 5-7h.

7. A method for epoxy resin curing process using a flame retardant epoxy curing agent according to any one of claims 1 to 6, characterized in that: Add epoxy resin E51 to allyl glycidyl ether (AGE), heat to 80-100°C, stir to mix, add curing agent, heat to 110-130°C, stir vigorously for 10-30min, place in an oven, heat to 70-90°C, degas for 30-50min, pour into a polytetrafluoroethylene mold, heat to 110-120°C, pre-cure for 1-3h, then heat to 140-160°C, cure for 5-7h, and obtain a sample.

8. A method for epoxy resin curing process using a flame retardant epoxy curing agent according to claim 7, characterized in that: The mass ratio of epoxy resin E51 and curing agent is 1:0.2-0.3.

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