Functional diatomite flame-retardant modified epoxy resin coating and preparation method thereof

Abstract

The invention relates to the technical field of epoxy resin, and discloses a functional diatomite flame-retardant modified epoxy resin coating, which is characterized in that diatomite reacts with toluene 2, 4-diisocyanate to obtain isocyanated diatomite, the isocyanated diatomite reacts with polysulfide rubber to obtain polysulfide rubber modified diatomite, the polysulfide rubber modified diatomite reacts with alkenylated phosphaphenanthrene to obtain polysulfide rubber modified diatomite, and the polysulfide rubber modified diatomite reacts with alkenylated phosphaphenanthrene to obtain the functional diatomite flame-retardant modified epoxy resin coating. The phosphaphenanthrene-based polysulfide rubber modified diatomite is mixed with epoxy resin to obtain the functional diatomite flame-retardant modified epoxy resin coating, and the diatomite and the polysulfide rubber can absorb and disperse stress, so that the toughness of the composite coating is enhanced; and phosphaphenanthrene flame-retardant molecules grafted on the surface of the nano diatomite can generate a large amount of oxyacid of phosphorus during combustion, so that carbon formation of a composite coating matrix can be promoted, a compact carbon layer is formed, and the flame retardance of the composite coating is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resins, in particular to a functional diatomaceous earth flame retardant modified epoxy resin coating and a preparation method thereof. Background Art

[0002] Epoxy resin is a high molecular polymer that is easy to process, has strong adhesion and high chemical stability. It has shown great application value in the fields of machinery, electronics, national defense science and technology, etc., and the coatings prepared with epoxy resin as the matrix also have good performance. Therefore, it has received widespread attention in recent years. However, with the deepening of research, researchers have found that epoxy resin is relatively brittle and has weak flame retardant properties, which to a certain extent limits its further application. Therefore, it needs to be modified. Filling with nanomaterials is one of the more popular and effective modification methods in recent years, that is, filling inorganic nanomaterials with excellent performance into epoxy resin, or blending organic polymers such as polysulfide rubber with enhanced toughening effects with epoxy resin, combining the advantages of inorganic nanomaterials and organic polymer materials, improving the toughness and other comprehensive properties of epoxy resin, thereby further expanding the application range of epoxy resin.

[0003] Diatomaceous earth is an inorganic nanomaterial with excellent performance. After mixing it with a polymer, the composite material formed has the excellent properties of nano-diatomaceous earth and polymer, and has greatly improved a series of properties of the polymer such as high temperature resistance, flame retardancy and mechanical properties. Chinese patents such as CN102965050A disclose a feasible method of filling diatomaceous earth into an epoxy resin matrix to form a high-performance composite material. However, most of these patents do not modify the surface of diatomaceous earth, ignoring the problem of poor dispersibility of diatomaceous earth. In addition, the functionality of diatomaceous earth is limited. When added alone to a polymer matrix, it often cannot achieve a multi-faceted modification effect. Therefore, it is necessary to modify the surface of diatomaceous earth and enhance the functionality of nano-diatomaceous earth so as to facilitate its further application in the field of additives for polymers. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a functional diatomite flame retardant modified epoxy resin coating and a preparation method thereof, which solves the problem of poor toughness and flame retardancy of epoxy resin.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a functional diatomite flame retardant modified epoxy resin coating, wherein the preparation method of the functional diatomite flame retardant modified epoxy resin coating comprises the following steps: (1) Add toluene solvent and diatomaceous earth into a reactor, disperse them uniformly by ultrasonication, continue to add toluene-2,4-diisocyanate, mix them uniformly, react at 80-100° C. for 4-8 hours, cool the product, centrifuge, wash and dry it to obtain isocyanate diatomaceous earth; (2) Add N,N-dimethylacetamide solvent and isocyanate diatomaceous earth into the reactor, disperse them uniformly by ultrasonication, continue to add polysulfide rubber and catalyst, mix them uniformly and transfer them to an oil bath pot, increase the temperature to react, filter after the reaction is completed, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add N,N-dimethylacetamide solvent and polysulfide rubber modified diatomaceous earth to the reactor, and after ultrasonic dispersion for 20-40 minutes, continue to add acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 2,4,6-tri(N,N-dimethylaniline)phenol, stir and mix well, then transfer to an oil bath, stir and react at 20-40°C for 12-36h, centrifuge, wash and dry after the reaction to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add epoxy resin, phosphaphenanthrene polysulfide rubber modified diatomaceous earth, 0.6-1.5% of defoaming agent polyether modified polysiloxane and 2-6% of filler talc into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

[0006] Preferably, in step (1), the mass ratio of toluene solvent, diatomaceous earth and toluene-2,4-diisocyanate is 150-400:10:6-15.

[0007] Preferably, in step (2), the mass ratio of N,N-dimethylacetamide solvent, isocyanate diatomaceous earth, polysulfide rubber and catalyst is 450-1200:10:12-25:0.2-0.6.

[0008] Preferably, the catalyst in step (2) is triethylamine.

[0009] Preferably, the reaction temperature in step (2) is 80-100° C., and the stirring reaction is performed for 6-18 hours.

[0010] Preferably, in step (3), N,N-dimethylacetamide solvent, polysulfide rubber modified diatomaceous earth, acryloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 The mass ratio of O4P) to catalyst is 300-850:10:0.8-2:0.1-0.25.

[0011] Preferably, in step (4), the mass ratio of the epoxy resin to the phosphaphenanthrene polysulfide rubber modified diatomaceous earth is 100:2-6.

[0012] 3. Beneficial technical effects Compared with the prior art, the present invention has the following beneficial technical effects: The functional diatomite flame retardant modified epoxy resin coating has a large number of hydroxyl groups on the surface of the diatomite. After reacting with toluene 2,4-diisocyanate, the surface will contain a large number of isocyanate groups. Under the action of a catalyst triethylamine, the isocyanate groups can react with the terminal mercapto groups in the polysulfide rubber to obtain the polysulfide rubber modified diatomite. Under the catalytic action of the catalyst 2,4,6-tris(N,N-dimethylaniline)phenol, by controlling the amount of acryloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, part of the terminal mercapto groups in the polysulfide rubber modified diatomite structure undergo Michael addition reaction with the alkenyl groups in the structure to obtain the phosphaphenanthrene-based polysulfide rubber modified diatomite. Thus, the phosphaphenanthrene flame retardant small molecules and polysulfide rubber macromolecules are covalently grafted on the surface of the diatomite through a chemical bond connection mode, thereby effectively enhancing the functionality of the nano diatomite and providing greater convenience for its further application.

[0013] The functional diatomite flame retardant modified epoxy resin coating is prepared by mixing epoxy resin, diatomite modified by phosphaphenanthrene polysulfide rubber and various additives to obtain the functional diatomite flame retardant modified epoxy resin coating. Since part of the terminal thiol groups in the polysulfide rubber that are not involved in the reaction can participate in the curing reaction of the epoxy resin, the diatomite modified by phosphaphenanthrene polysulfide rubber and the epoxy resin matrix have good compatibility, which is conducive to the uniform dispersion of nano diatomite in the matrix. When the composite coating is impacted by external force, the cracks generated by the stress will be hindered by the nano diatomite during the extension process, and then turn to the two ends of the nano diatomite for diffusion, resulting in The energy required for crack extension is greatly increased, and the nano-diatomite itself has a high strength and can absorb stress, thereby improving the impact strength and other properties of the composite coating to a certain extent. At the same time, the polysulfide rubber grafted on the surface of the nano-diatomite as a flexible long chain can effectively improve the flexibility of the epoxy resin matrix, thereby enhancing its ability to absorb plastic deformation work, thereby further enhancing the toughness of the composite coating. The phosphaphenanthrene flame retardant molecules grafted on the surface of the nano-diatomite will generate a large amount of phosphorus oxygen-containing acids when burned, which can promote the carbonization of the composite coating matrix and form a dense carbon layer, thereby effectively improving the flame retardant properties of the composite coating. DETAILED DESCRIPTION

[0014] To achieve the above object, the present invention provides the following specific implementation methods and examples: A functional diatomite flame retardant modified epoxy resin coating, the preparation method of which comprises the following steps: (1) Adding toluene solvent and diatomaceous earth into a reactor, dispersing them uniformly by ultrasonication, and then adding toluene-2,4-diisocyanate, wherein the mass ratio of toluene solvent, diatomaceous earth and toluene-2,4-diisocyanate is 150-400:10:6-15, mixing them uniformly, reacting them at 80-100° C. for 4-8 hours, cooling the product, centrifuging, washing and drying, and obtaining isocyanate diatomaceous earth; (2) Add N,N-dimethylacetamide solvent and isocyanate diatomaceous earth to the reactor, disperse them uniformly by ultrasonication, continue to add polysulfide rubber and triethylamine, wherein the mass ratio of N,N-dimethylacetamide solvent, isocyanate diatomaceous earth, polysulfide rubber and triethylamine is 450-1200:10:12-25:0.2-0.6, mix them uniformly and transfer them to an oil bath pot, increase the temperature to 80-100°C, stir and react for 6-18h, and after the reaction is completed, filter, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add N,N-dimethylacetamide solvent and polysulfide rubber modified diatomaceous earth to the reactor, and after ultrasonic dispersion for 20-40 minutes, continue to add acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 2,4,6-tris(N,N-dimethylaniline)phenol, wherein N,N-dimethylacetamide solvent, polysulfide rubber modified diatomaceous earth, acryloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 The mass ratio of O4P) to the catalyst is 300-850:10:0.8-2:0.1-0.25, and the mixture is stirred and evenly mixed, and then transferred to an oil bath pot, stirred and reacted at 20-40° C. for 12-36 hours, and after the reaction is completed, centrifuged, washed and dried to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add epoxy resin, phosphaphenanthrene polysulfide rubber modified diatomaceous earth, 0.6-1.5% of defoaming agent polyether modified polysiloxane and 2-6% of filler talcum powder in a mass ratio of 100:2-6 into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

[0015] Example 1

[0016] (1) Add 90 mL of toluene solvent and 5 g of diatomaceous earth into a reactor, disperse them evenly by ultrasonication, then add 3 g of toluene-2,4-diisocyanate, mix evenly, and react at 80° C. for 4 h. After cooling, the product is centrifuged, washed, and dried to obtain isocyanate diatomaceous earth; (2) Add 240 mL of N,N-dimethylacetamide solvent and 5 g of isocyanate diatomaceous earth into the reactor, disperse them evenly with ultrasound, continue to add 6 g of polysulfide rubber and 0.1 g of triethylamine, mix evenly and transfer to an oil bath, raise the temperature to 80 ° C, stir and react for 6 h, filter after the reaction, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add 160 mL of N,N-dimethylacetamide solvent and 5 g of polysulfide rubber modified diatomaceous earth to the reactor, and after ultrasonic dispersion for 20 min, continue to add 0.4 g of acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 0.05g of 2,4,6-tri(N,N-dimethylaniline)phenol, stir and mix evenly, then transfer to an oil bath, stir and react at 20°C for 12h, centrifuge, wash and dry after the reaction, to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add 50 g of epoxy resin, 1 g of phosphaphenanthryl polysulfide rubber modified diatomaceous earth, 0.3 g of defoaming agent polyether modified polysiloxane and 1 g of filler talcum powder into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

[0017] Example 2

[0018] (1) Add 120 mL of toluene solvent and 5 g of diatomaceous earth into a reactor, disperse them evenly by ultrasonication, then add 4 g of toluene-2,4-diisocyanate, mix evenly, and react at 85° C. for 5 h. After cooling, the product is centrifuged, washed, and dried to obtain isocyanate diatomaceous earth; (2) Add 350 mL of N,N-dimethylacetamide solvent and 5 g of isocyanate diatomaceous earth into the reactor, disperse them evenly with ultrasound, continue to add 7.5 g of polysulfide rubber and 0.15 g of triethylamine, mix evenly and transfer to an oil bath, raise the temperature to 85 ° C, stir and react for 8 h, filter after the reaction, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add 240 mL of N,N-dimethylacetamide solvent and 5 g of polysulfide rubber modified diatomaceous earth to the reactor, and after ultrasonic dispersion for 25 min, continue to add 0.6 g of acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 0.07g of 2,4,6-tri(N,N-dimethylaniline)phenol, stir and mix well, then transfer to an oil bath, stir and react at 25°C for 16h, centrifuge, wash and dry after the reaction, to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add 50 g of epoxy resin, 1.5 g of phosphaphenanthryl polysulfide rubber modified diatomaceous earth, 0.4 g of defoaming agent polyether modified polysiloxane and 1.5 g of filler talcum powder into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

[0019] Example 3

[0020] (1) Add 180 mL of toluene solvent and 5 g of diatomaceous earth into a reactor, disperse them evenly by ultrasonication, continue to add 5 g of toluene-2,4-diisocyanate, mix evenly, and react at 90° C. for 6 h. After cooling, the product is centrifuged, washed and dried to obtain isocyanate diatomaceous earth; (2) Add 450 mL of N,N-dimethylacetamide solvent and 5 g of isocyanate diatomaceous earth into the reactor, disperse them evenly with ultrasound, continue to add 9 g of polysulfide rubber and 0.2 g of triethylamine, mix evenly and transfer to an oil bath, raise the temperature to 90 ° C, stir and react for 12 h, filter after the reaction, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add 320 mL of N,N-dimethylacetamide solvent and 5 g of polysulfide rubber modified diatomaceous earth to the reactor, and after ultrasonic dispersion for 30 min, continue to add 0.7 g of acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 0.09g of 2,4,6-tri(N,N-dimethylaniline)phenol, stir and mix well, then transfer to an oil bath, stir and react at 30°C for 24h, centrifuge, wash and dry after the reaction, to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add 50 g of epoxy resin, 2 g of phosphaphenanthryl polysulfide rubber modified diatomaceous earth, 0.5 g of defoaming agent polyether modified polysiloxane and 2 g of filler talcum powder into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

[0021] Example 4

[0022] (1) Add 200 mL of toluene solvent and 5 g of diatomaceous earth into a reactor, disperse them uniformly by ultrasonication, continue to add 6 g of toluene-2,4-diisocyanate, mix them uniformly, and react at 95°C for 7 h. After cooling, the product is centrifuged, washed and dried to obtain isocyanate diatomaceous earth; (2) Add 550 mL of N,N-dimethylacetamide solvent and 5 g of isocyanate diatomaceous earth into the reactor, disperse them evenly with ultrasound, continue to add 11 g of polysulfide rubber and 0.25 g of triethylamine, mix evenly and transfer to an oil bath, raise the temperature to 95 ° C, stir and react for 16 h, filter after the reaction, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add 400 mL of N,N-dimethylacetamide solvent and 5 g of polysulfide rubber modified diatomaceous earth to the reactor, and after ultrasonic dispersion for 35 min, continue to add 0.85 g of acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 0.11g of 2,4,6-tri(N,N-dimethylaniline)phenol, stir and mix well, then transfer to an oil bath, stir and react at 35°C for 30h, centrifuge, wash and dry after the reaction, to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add 50 g of epoxy resin, 2.5 g of phosphaphenanthryl polysulfide rubber modified diatomaceous earth, 0.6 g of defoaming agent polyether modified polysiloxane and 2.5 g of filler talcum powder into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

[0023] Example 5

[0024] (1) Add 230 mL of toluene solvent and 5 g of diatomaceous earth into a reactor, disperse them uniformly by ultrasonication, continue to add 7.5 g of toluene-2,4-diisocyanate, mix them uniformly, react at 100 °C for 8 h, cool the product, centrifuge, wash and dry it to obtain isocyanate diatomaceous earth; (2) Add 640 mL of N,N-dimethylacetamide solvent and 5 g of isocyanate diatomaceous earth into the reactor, disperse them evenly by ultrasonication, continue to add 12.5 g of polysulfide rubber and 0.3 g of triethylamine, mix evenly and transfer to an oil bath, raise the temperature to 100 ° C, stir and react for 18 h, filter after the reaction is completed, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add 450 mL of N,N-dimethylacetamide solvent and 5 g of polysulfide rubber modified diatomaceous earth to the reactor, and after ultrasonic dispersion for 40 min, continue to add 1 g of acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 0.125g of 2,4,6-tri(N,N-dimethylaniline)phenol, stir and mix well, then transfer to an oil bath, stir and react at 40°C for 36h, centrifuge, wash and dry after the reaction, to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add 50 g of epoxy resin, 3 g of phosphaphenanthryl polysulfide rubber modified diatomaceous earth, 0.75 g of defoaming agent polyether modified polysiloxane and 3 g of filler talcum powder into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

[0025] Comparative Example 1 (1) Add 100 mL of toluene solvent and 5 g of diatomaceous earth into a reactor, disperse them uniformly by ultrasonication, continue to add 3.2 g of toluene-2,4-diisocyanate, mix them uniformly, react at 85°C for 4 h, cool the product, centrifuge, wash and dry it to obtain isocyanate diatomaceous earth; (2) Add 260 mL of N,N-dimethylacetamide solvent and 5 g of isocyanate diatomaceous earth into the reactor, disperse them evenly with ultrasound, continue to add 6.2 g of polysulfide rubber and 0.14 g of triethylamine, mix evenly and transfer to an oil bath, raise the temperature to 85 ° C, stir and react for 8 h, filter after the reaction, wash and dry to obtain polysulfide rubber modified diatomaceous earth; (3) Add 50 g of epoxy resin, 1.2 g of polysulfide rubber modified diatomaceous earth, 0.35 g of defoaming agent polyether modified polysiloxane and 1 g of filler talcum powder into a high-speed mixer, mix well at high speed, defoam under vacuum and package to obtain a diatomaceous earth modified epoxy resin coating.

[0026] The composite coatings in the examples and comparative examples were placed in a mold for curing and prepared into rectangular parallelepiped specimens with a specification of 10 cm×10 cm×5 mm. The impact strength thereof was tested using an AOTSI-1000PL impact tester.

[0027]

[0028] The composite coatings in the embodiments and comparative examples were placed in a mold for curing and prepared into rectangular parallelepiped strips with a specification of 10 cm×10 cm×5 mm. They were wrapped with aluminum foil, ceramic fiber wool was placed at the bottom, a steel grid was placed on the surface and covered, and the heat radiation was set to 35 kW / m 2 The heat release rate of the composite coating was tested using a XU8560 cone calorimeter.

[0029]

Claims

1. A functional diatomite flame retardant modified epoxy resin coating, characterized in that: The following steps are involved: (1) Add diatomaceous earth to toluene solvent, disperse it evenly by ultrasonication, continue to add toluene-2,4-diisocyanate, mix evenly, react at 80-100°C for 4-8h, cool the product, centrifuge, wash and dry to obtain isocyanate diatomaceous earth; (2) adding isocyanate diatomaceous earth to N,N-dimethylacetamide solvent, dispersing it evenly by ultrasonication, adding polysulfide rubber and catalyst, mixing evenly and transferring to an oil bath, raising the temperature to react, filtering after the reaction, washing and drying to obtain polysulfide rubber modified diatomaceous earth; (3) Add polysulfide rubber modified diatomaceous earth to N,N-dimethylacetamide solvent, and after ultrasonic dispersion for 20-40 minutes, continue to add acryloyloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 O4P) and 2,4,6-tri(N,N-dimethylaniline)phenol, stir and mix well, then transfer to an oil bath, stir and react at 20-40°C for 12-36h, centrifuge, wash and dry after the reaction to obtain phosphaphenanthrene polysulfide rubber modified diatomite; (4) Add epoxy resin, phosphaphenanthrene polysulfide rubber modified diatomaceous earth, 0.6-1.5% of defoaming agent polyether modified polysiloxane and 2-6% of filler talc into a high-speed mixer, mix them evenly at high speed, defoam them in vacuum and package them to obtain a functional diatomaceous earth flame retardant modified epoxy resin coating.

2. The functional diatomite flame retardant modified epoxy resin coating according to claim 1, characterized in that: In the step (1), the mass ratio of toluene solvent, diatomaceous earth and toluene-2,4-diisocyanate is 150-400:10:6-15.

3. The functional diatomite flame retardant modified epoxy resin coating according to claim 1, characterized in that: In the step (2), the mass ratio of N,N-dimethylacetamide solvent, isocyanate diatomaceous earth, polysulfide rubber and catalyst is 450-1200:10:12-25:0.2-0.

6.

4. The functional diatomite flame retardant modified epoxy resin coating according to claim 1, characterized in that: The catalyst in step (2) is triethylamine.

5. The functional diatomite flame retardant modified epoxy resin coating according to claim 1, characterized in that: The reaction temperature in step (2) is 80-100° C., and the reaction is stirred for 6-18 hours.

6. The functional diatomite flame retardant modified epoxy resin coating according to claim 1, characterized in that: In the step (3), N,N-dimethylacetamide solvent, polysulfide rubber modified diatomaceous earth, acryloxy 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (C 16 H 13 The mass ratio of O4P) to catalyst is 300-850:10:0.8-2:0.1-0.

25.

7. The functional diatomite flame retardant modified epoxy resin coating according to claim 1, characterized in that: In the step (4), the mass ratio of the epoxy resin to the phosphaphenanthrene polysulfide rubber modified diatomaceous earth is 100:2-6.

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