A flame retardant toughening agent, epoxy resin composite material and preparation method thereof

Abstract

A flame retardant toughening agent, epoxy resin composite material and preparation method thereof, which relate to the technical field of epoxy resin, and solve the technical problem that the existing epoxy resin cannot take into account rigidity, toughness and flame retardancy. Under a nitrogen atmosphere, isophorone diisocyanate and dibutyltin dilaurate are dissolved in a solvent, and at 64°C, an organic compound PP dissolved in the solvent is dripped through a constant pressure dropping funnel, and refluxed to react; after vacuum evaporation of the solvent, a solution containing phosphorus and nitrogen with flexible chain segments capped with N=C=O is obtained. Vacuum drying is performed to obtain a flame retardant toughening agent. The epoxy resin composite material, the raw materials include 10-20 parts of a flame retardant toughening agent, 100 parts of an epoxy resin, and 25 parts of a curing agent. The provided composite material has excellent performance, a wide range of applications, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resins, and in particular to a flame retardant toughening agent, an epoxy resin composite material and a preparation method thereof. Background Art

[0002] Epoxy resin (EP) has been widely used in many industrial fields such as electronics, electrical, machinery manufacturing, chemical corrosion protection, aerospace, shipping, chemical building materials, water conservancy and electricity due to its excellent mechanical properties, bonding properties, corrosion resistance, electrical insulation and heat resistance. However, on the one hand, the brittleness caused by the high cross-linking density of epoxy resin itself limits its development in many fields; on the other hand, the flammability of the EP network system can cause serious fires, causing serious harm to people's lives and property safety.

[0003] Researchers in this field generally believe that it is difficult to achieve both rigidity and ductility at the same time. In this regard, the rigid-flexible structure can very well adjust the contradictory problem that the rigidity and toughness of the EP matrix cannot be improved at the same time. The synergistic flame retardant effect of the phosphorus-containing group and the nitrogen-containing group is significant, which can simultaneously improve the gas phase flame retardancy and condensed phase flame retardancy of the composite material, and achieve a 1+1>2 effect on the overall flame retardant effect of the material. However, the introduction of phosphorus-containing groups will have a negative impact on the mechanical properties of the composite material.

[0004] Therefore, how to combine rigid-flexible structures with phosphorus- and nitrogen-containing groups for use as flame retardant toughening agents for epoxy resins, while improving the comprehensive mechanical properties and flame retardant properties of composite materials, has become a hot topic for researchers in this field. Summary of the invention

[0005] In order to solve the technical problem that the existing epoxy resin cannot have both rigidity, toughness and flame retardancy, the present invention provides a flame retardant toughening agent, an epoxy resin composite material and a preparation method thereof.

[0006] The technical solution of the present invention is as follows:

[0007] A flame retardant toughening agent, the structural formula is as follows:

[0008] .

[0009] The present invention also provides a method for preparing the flame retardant toughening agent, comprising the following steps:

[0010] Under nitrogen atmosphere, isophorone diisocyanate (IPDI) and dibutyltin dilaurate (DA) are dissolved in a solvent, and the organic compound PP dissolved in the solvent is added dropwise through a constant pressure dropping funnel at 64°C, and refluxed to react;

[0011] After the solvent is evaporated in vacuum, a solution containing phosphorus and nitrogen with flexible chain segments terminated by N=C=O is obtained. After vacuum drying, a flame retardant toughening agent is obtained;

[0012] Wherein, the structural formula of the organic compound PP is as follows:

[0013] .

[0014] Preferably, the reflux reaction time is 2h~4h.

[0015] Preferably, the organic compound PP is prepared by the following steps:

[0016] Under a nitrogen atmosphere, polyethylene glycol (PEG-200) and triethylamine (TEA) are dissolved in a solvent, and then dripped into a flask of phenylphosphoryl dichloride (PPDC) dissolved in the solvent through a constant pressure dropping funnel at 0°C~5°C. After complete injection, the mixture is heated to room temperature for reaction; after the reaction is completed, the solvent is filtered and evaporated in vacuum to obtain a crude product, which is then dried in vacuum to obtain the organic compound PP.

[0017] Preferably, the solvent is tetrahydrofuran.

[0018] Preferably, the reaction time at room temperature is 5 h to 8 h.

[0019] The present invention also provides an epoxy resin composite material, the raw materials of which include the following components in parts by weight:

[0020] 10-20 parts of the flame retardant toughening agent, 100 parts of epoxy resin, and 25 parts of curing agent.

[0021] Preferably, the epoxy resin is bisphenol A epoxy resin, and the curing agent is 4,4'-diaminodiphenylmethane.

[0022] A method for preparing an epoxy resin composite material comprises the following steps:

[0023] The flame retardant toughening agent is dissolved in a solvent and mixed with an epoxy resin, and then vacuumed after being stirred evenly. When there are no bubbles in the mixture in the vacuum, a curing agent is added and mixed evenly. The mixed sample is quickly poured into a preheated mold for curing to obtain an epoxy resin composite material.

[0024] Preferably, the preheating temperature of the mold is 120°C;

[0025] The specific curing process is: after curing at 120° C. for 2 hours, adjusting the temperature to 150° C., and then curing for another 2.5 hours.

[0026] Compared with the prior art, the specific beneficial effects of the present invention are:

[0027] The N=C=O group in the flame-retardant toughening agent PPI provided by the present invention can react with the curing agent and participate in the construction of the epoxy network system to achieve good compatibility and promote curing. The phosphorus-containing group and the nitrogen-containing group in the PPI have a synergistic flame retardant effect when the composite material is burned, which can simultaneously improve the gas phase flame retardant ability and condensed phase flame retardant ability of the composite material. The rigid-flexible structure in the PPI participates in the construction of the epoxy network system, so the rigidity and toughness of the composite material are improved, and a composite material with excellent performance is obtained. It can meet the newer and higher requirements for materials in the fields of electronics and electrical engineering.

[0028] The composite material provided by the invention has excellent performance, wide application fields and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The infrared spectra of the reactants and the flame retardant toughening agent prepared in Example 1;

[0030] Figure 2 The NMR of phenylphosphoryl dichloride, organic compound PP and flame retardant toughening agent in Example 1 is 31 P spectrum;

[0031] Figure 3 The stress-strain curves of the bending tests of the epoxy composite materials in Examples 1 to 5 and the comparative example are shown;

[0032] Figure 4 1 is a stress-strain curve diagram of the tensile test of the epoxy composite material in Examples 1 to 5 and the comparative example;

[0033] Figure 5 It is a bar graph of the limiting oxygen index of the epoxy composite material in Examples 1 to 5 and the comparative example. DETAILED DESCRIPTION

[0034] In order to make the technical solution 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 specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as a limitation to the present invention.

[0035] The raw materials and equipment used in the present invention are all known products, which are obtained by purchasing commercially available products.

[0036] Example 1.

[0037] (1) In a three-necked round-bottom flask, polyethylene glycol (PEG-200) (22 g, 0.11 mol) and triethylamine (10.1 g, 0.1 mol) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, phenylphosphoryl dichloride (PPDC) (9.75 g, 0.05 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 0-5 °C through a constant pressure dropping funnel. After complete injection, the reaction mixture was slowly heated to room temperature and reacted for another 5 h. The crude product was obtained after suction filtration and vacuum evaporation of the solvent. The desired organic compound PP was obtained by vacuum drying at 60 °C for 12 h.

[0038] (2) In a three-necked round-bottom flask, isophorone diisocyanate (IPDI) (9.78 g, 0.044 mol) and dibutyltin dilaurate (0.101 g, 5% of the total mass of the reactants) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, PP (10.44 g, 0.02 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask through a constant pressure dropping funnel at 64 °C. The mixture was refluxed at 64 °C for 2.5 h. After the solvent was evaporated in vacuum, a solution containing phosphorus and nitrogen with flexible chain segments terminated by N=C=O was obtained. The desired flame retardant toughening agent PPI was obtained by vacuum drying at 60 °C for 6 h.

[0039] The infrared spectra of each reactant and the flame retardant toughening agent PPI are shown in Figure 1 ; NMR 31 P spectrum see Figure 2 The appearance of N=C=O and NH can prove the successful synthesis of flame retardant toughening agent PPI.

[0040] (3) Dissolve 5 parts of PPI in a solvent and mix with 100 parts of epoxy resin, stir well and evacuate. When there are no bubbles in the mixture in a vacuum, add 25 parts of molten diaminodiphenylmethane (DDM) as a curing agent at 80°C and mix well. Pour the mixed sample into a mold quickly, preheat the mold at 120°C for 20 minutes, cure at 120°C for 2 hours, adjust the temperature to 150°C, and post-cure for 2.5 hours to obtain an epoxy resin composite material.

[0041] Example 2.

[0042] (1) In a three-necked round-bottom flask, polyethylene glycol (22 g, 0.11 mol) and triethylamine (10.1 g, 0.1 mol) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, phenylphosphoryl dichloride (9.75 g, 0.05 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 0°C to 5°C through a constant pressure dropping funnel. After complete injection, the reaction mixture was slowly heated to room temperature and reacted for another 5 h. The crude product was obtained after suction filtration and vacuum evaporation of the solvent. The desired organic compound PP was obtained by vacuum drying at 60°C for 12 h.

[0043] (2) In a three-necked round-bottom flask, isophorone diisocyanate (9.78 g, 0.044 mol) and dibutyltin dilaurate (0.101 g, 5% of the total mass of the reactants) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, PP (10.44 g, 0.02 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 64 °C through a constant pressure dropping funnel. The mixture was refluxed at 64 °C for 2.5 h. After the solvent was evaporated in vacuum, a solution containing phosphorus and nitrogen with flexible chain segments terminated by N=C=O was obtained. The desired flame retardant toughening agent PPI was obtained by vacuum drying at 60 °C for 6 h.

[0044] (3) Dissolve 10 parts of PPI in a solvent and mix with 100 parts of epoxy resin, stir well and evacuate. When there are no bubbles in the mixture in a vacuum, add 25 parts of molten diaminodiphenylmethane (DDM) as a curing agent at 80°C and mix well. Pour the mixed sample into a mold quickly, preheat the mold at 120°C for 20 minutes, cure at 120°C for 2 hours, adjust the temperature to 150°C, and post-cure for 2.5 hours to obtain an epoxy resin composite material.

[0045] Example 3.

[0046] (1) In a three-necked round-bottom flask, polyethylene glycol (22 g, 0.11 mol) and triethylamine (10.1 g, 0.1 mol) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, phenylphosphoryl dichloride (9.75 g, 0.05 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 0°C to 5°C through a constant pressure dropping funnel. After complete injection, the reaction mixture was slowly heated to room temperature and reacted for another 5 h. The crude product was obtained after suction filtration and vacuum evaporation of the solvent. The desired organic compound PP was obtained by vacuum drying at 60°C for 12 h.

[0047] (2) In a three-necked round-bottom flask, isophorone diisocyanate (9.78 g, 0.044 mol) and dibutyltin dilaurate (0.101 g, 5% of the total mass of the reactants) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, PP (10.44 g, 0.02 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 64 °C through a constant pressure dropping funnel. The mixture was refluxed at 64 °C for 2.5 h. After the solvent was evaporated in vacuum, a solution containing phosphorus and nitrogen with flexible chain segments terminated by N=C=O was obtained. The desired flame retardant toughening agent PPI was obtained by vacuum drying at 60 °C for 6 h.

[0048] (3) Dissolve 15 parts of PPI in a solvent and mix with 100 parts of epoxy resin, stir well and evacuate. When there are no bubbles in the mixture in a vacuum, add 25 parts of molten diaminodiphenylmethane (DDM) as a curing agent at 80°C and mix well. Pour the mixed sample into a mold quickly, preheat the mold at 120°C for 20 minutes, cure at 120°C for 2 hours, adjust the temperature to 150°C, and post-cure for 2.5 hours to obtain an epoxy resin composite material.

[0049] Example 4.

[0050] (1) In a three-necked round-bottom flask, polyethylene glycol (22 g, 0.11 mol) and triethylamine (10.1 g, 0.1 mol) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, phenylphosphoryl dichloride (9.75 g, 0.05 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 0°C to 5°C through a constant pressure dropping funnel. After complete injection, the reaction mixture was slowly heated to room temperature and reacted for another 5 h. The crude product was obtained after suction filtration and vacuum evaporation of the solvent. The desired organic compound PP was obtained by vacuum drying at 60°C for 12 h.

[0051] (2) In a three-necked round-bottom flask, isophorone diisocyanate (9.78 g, 0.044 mol) and dibutyltin dilaurate (0.101 g, 5% of the total mass of the reactants) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, PP (10.44 g, 0.02 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 64 °C through a constant pressure dropping funnel. The mixture was refluxed at 64 °C for 2.5 h. After the solvent was evaporated in vacuum, a solution containing phosphorus and nitrogen with flexible chain segments terminated by N=C=O was obtained. The desired flame retardant toughening agent PPI was obtained by vacuum drying at 60 °C for 6 h.

[0052] (3) Dissolve 20 parts of PPI in a solvent and mix with 100 parts of epoxy resin, stir well and evacuate. When there are no bubbles in the mixture in a vacuum, add 25 parts of molten diaminodiphenylmethane (DDM) as a curing agent at 80°C and mix well. Pour the mixed sample into a mold quickly, preheat the mold at 120°C for 20 minutes, cure at 120°C for 2 hours, adjust the temperature to 150°C, and post-cure for 2.5 hours to obtain an epoxy resin composite material.

[0053] Example 5.

[0054] (1) In a three-necked round-bottom flask, polyethylene glycol (22 g, 0.11 mol) and triethylamine (10.1 g, 0.1 mol) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, phenylphosphoryl dichloride (9.75 g, 0.05 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 0°C to 5°C through a constant pressure dropping funnel. After complete injection, the reaction mixture was slowly heated to room temperature and reacted for another 5 h. The crude product was obtained after suction filtration and vacuum evaporation of the solvent. The desired organic compound PP was obtained by vacuum drying at 60°C for 12 h.

[0055] (2) In a three-necked round-bottom flask, isophorone diisocyanate (9.78 g, 0.044 mol) and dibutyltin dilaurate (0.101 g, 5% of the total mass of the reactants) were dissolved in 100 ml of tetrahydrofuran under a nitrogen atmosphere. Subsequently, PP (10.44 g, 0.02 mol) dissolved in 50 ml of tetrahydrofuran was dripped into the flask at 64 °C through a constant pressure dropping funnel. The mixture was refluxed at 64 °C for 2.5 h. After the solvent was evaporated in vacuum, a solution containing phosphorus and nitrogen with flexible chain segments terminated by N=C=O was obtained. The desired flame retardant toughening agent PPI was obtained by vacuum drying at 60 °C for 6 h.

[0056] (3) Dissolve 25 parts of PPI in a solvent and mix with 100 parts of epoxy resin, stir well and evacuate. When there are no bubbles in the mixture in a vacuum, add 25 parts of molten diaminodiphenylmethane (DDM) as a curing agent at 80°C and mix well. Pour the mixed sample into a mold quickly, preheat the mold at 120°C for 20 minutes, cure at 120°C for 2 hours, adjust the temperature to 150°C, and post-cure for 2.5 hours to obtain an epoxy resin composite material.

[0057] Comparison ratio.

[0058] 25 parts of molten diaminodiphenylmethane (DDM) were mixed with 100 parts of epoxy resin, stirred evenly and then vacuumed. When there were no bubbles in the mixture in the vacuum, the mixed sample was quickly poured into the mold, the mold was preheated at 120°C for 20 minutes, and after curing at 120°C for 2 hours, the temperature was adjusted to 150°C and post-cured for 2.5 hours to obtain the epoxy resin composite material.

[0059] Effect example.

[0060] The toughness, elongation at break and limiting oxygen index of the epoxy composite materials modified by organic compounds containing phosphorus and nitrogen with flexible segments and different contents obtained in the above five embodiments and comparative examples were tested, and the bending test results are shown in FIG. Figure 3 , the test results of elongation at break are shown in Figure 4 , the test results of the limiting oxygen index are shown in Figure 5 From the test results, it can be seen that by adding 10 to 20 parts of the epoxy composite material prepared by the present invention to 100 parts of epoxy resin, the toughness, elongation at break and limiting oxygen index are significantly improved compared with the ordinary imidazole-cured E51 epoxy resin on the market, and the curing rate at 120°C is improved.

[0061] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A flame retardant toughening agent, characterized in that: The structural formula is as follows: 。 2. A method for preparing a flame retardant toughening agent as claimed in claim 1, characterized in that: The steps include: Under a nitrogen atmosphere, isophorone diisocyanate and dibutyltin dilaurate are dissolved in a solvent, and an organic compound PP dissolved in the solvent is added dropwise through a constant pressure dropping funnel at 64°C, and refluxed for reaction; After the solvent is evaporated in vacuum, vacuum drying is performed to obtain a flame retardant toughening agent; Wherein, the structural formula of the organic compound PP is as follows: 。 3. The method for preparing a flame retardant toughening agent according to claim 2, characterized in that: The reflux reaction time is 2h~4h.

4. The method for preparing a flame retardant toughening agent according to claim 2, characterized in that: The organic compound PP is prepared by the following steps: Under a nitrogen atmosphere, polyethylene glycol and triethylamine are dissolved in a solvent, and then dripped into a flask of phenylphosphoryl dichloride dissolved in the solvent through a constant pressure dropping funnel at 0°C to 5°C. After complete injection, the mixture is heated to room temperature for reaction; after the reaction is completed, suction filtration and vacuum evaporation of the solvent are performed to obtain a crude product, which is then vacuum dried to obtain an organic compound PP.

5. The method for preparing a flame retardant toughening agent according to claim 2 or 4, characterized in that: The solvent is tetrahydrofuran.

6. The method for preparing a flame retardant toughening agent according to claim 4, characterized in that: The reaction time at room temperature is 5h~8h.

7. An epoxy resin composite material, characterized in that: The raw materials include the following components in parts by weight: 10-20 parts of the flame retardant toughening agent according to claim 1, 100 parts of epoxy resin, and 25 parts of curing agent.

8. The epoxy resin composite material according to claim 7, characterized in that: The epoxy resin is bisphenol A epoxy resin, and the curing agent is 4,4'-diaminodiphenylmethane.

9. A method for preparing the epoxy resin composite material according to claim 7 or 8, characterized in that: The steps include: The flame retardant toughening agent is dissolved in a solvent and mixed with an epoxy resin, and then vacuumed after being stirred evenly. When there are no bubbles in the mixture in the vacuum, a curing agent is added and mixed evenly. The mixed sample is quickly poured into a preheated mold for curing to obtain an epoxy resin composite material.

10. The method for preparing the epoxy resin composite material according to claim 9, characterized in that: The preheating temperature of the mold is 120° C.; the curing process is specifically as follows: after curing at 120° C. for 2 hours, adjusting the temperature to 150° C., and then curing for another 2.5 hours.

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