Composite flame retardant based on synergistic flame retardancy of nano-layered compounds and preparation method thereof

Abstract

The invention discloses a composite flame retardant based on the synergistic flame retardancy of a nano-layered compound and a preparation method thereof, and relates to the technical field of flame retardants. The composite flame retardant of the invention is prepared from a nano-layered compound, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate; the composite flame retardant prepared by the invention has good compatibility with a variety of resin matrices, and can achieve uniform dispersion of the flame retardant in the resin matrix without adding a compatibilizer, thereby giving full play to its flame retardant effect.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardants, and in particular to a composite flame retardant based on the synergistic flame retardancy of nano-layered compounds and a preparation method thereof. Background Art

[0002] Flame retardant is a functional additive that can make flammable polymers flame retardant. It is mainly designed for the flame retardancy of polymer materials. Flame retardants are divided into additive flame retardants and reactive flame retardants according to the method of use. Among them, additive flame retardants are added to polymers by physical mixing. They are easy to use and have strong applicability. They are the most widely used flame retardants. Reactive flame retardants participate in the polymerization reaction as a monomer, so that the polymer itself contains flame retardant components, has good stability, and has a long-lasting flame retardant effect.

[0003] Composite flame retardants are usually used in combination of two or more flame retardants to improve the flame retardant effect of the flame retardant. The compatibility of flame retardants with substrates is an important factor affecting their application effect. Some flame retardants have poor compatibility with substrates, which may lead to reduced material performance, such as poor processing fluidity and reduced physical and mechanical properties. Although the addition of compatibilizers can improve the compatibility of flame retardants with substrates, it is still difficult to achieve good dispersion of flame retardants in the substrate, which will also increase the preparation cost. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a composite flame retardant based on the synergistic flame retardancy of nano-layered compounds and a preparation method thereof. The composite flame retardant has excellent flame retardant properties and can reduce the amount of the flame retardant while ensuring the flame retardant effect.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0006] One of the purposes of the present invention is to provide a composite flame retardant based on nano-layered compounds for synergistic flame retardancy. The composite flame retardant is prepared from nano-layered compounds, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate.

[0007] The second purpose of the present invention is to provide a method for preparing a composite flame retardant based on the synergistic flame retardancy of nano-layered compounds, wherein 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tri(4-aminophenyl)thiophosphate are added to an organic solvent for addition reaction, and then the nano-layered compound is added for condensation reaction, filtered, washed with water, and dried to obtain a composite flame retardant.

[0008] The beneficial effects of the present invention are:

[0009] 1. The composite flame retardant prepared by the present invention has good compatibility with the resin matrix (including polyvinyl alcohol, polylactic acid, epoxy resin, etc.), and the flame retardant can be evenly dispersed in the resin matrix without adding a compatibilizer, thereby giving full play to its flame retardant effect.

[0010] 2. The composite flame retardant prepared by the present invention combines the excellent flame retardant properties of inorganic flame retardants, organophosphorus flame retardants and organosilicon flame retardants, can reduce the amount of flame retardants added, and will not cause a significant decrease in the physical and mechanical properties of the composite material while exerting its flame retardant effect. DETAILED DESCRIPTION

[0011] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0012] The invention provides a composite flame retardant based on the synergistic flame retardancy of nano-layered compounds. The composite flame retardant is prepared from nano-layered compounds, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate.

[0013] Furthermore, the nano-layered compound includes but is not limited to one or more of montmorillonite, expanded graphite, and black phosphorus. The geometric morphology of the nano flame retardant affects its flame retardant effect on polymers. Among the three types of nano flame retardants with spherical, tubular and layered structures, the nano flame retardant with a layered structure has a better flame retardant effect. Montmorillonite is a layered silicate mineral, and its layered structure gives it good fire resistance and can effectively prevent the material from burning in a fire. The unique pore structure of expanded graphite can produce a large amount of gas during thermal decomposition, thereby expanding into a porous material, showing excellent flame retardant properties. Black phosphorus is a layered material with a graphene-like structure, good thermal stability, and high flame retardant efficiency.

[0014] Furthermore, the weight percentage of the nano-layered compound in the composite flame retardant is 20 to 80%. Preferably, the weight percentage of the nano-layered compound in the composite flame retardant is 40 to 60%.

[0015] The present invention also provides a method for preparing a composite flame retardant based on the synergistic flame retardancy of nano-layered compounds, comprising adding 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate to an organic solvent for an addition reaction, then adding the nano-layered compound for a condensation reaction, filtering, washing with water, and drying to obtain the composite flame retardant.

[0016] In the present invention, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tri(4-aminophenyl)thiophosphate react with epoxy groups and amino groups to obtain an addition product, and the addition product reacts with hydroxyl groups on the surface of nano-layered compounds under anhydrous conditions to obtain a composite flame retardant.

[0017] Furthermore, the organic solvent, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, tri(4-aminophenyl)thiophosphate and nano-layered compound are dried before the reaction. The free water contained in the reaction raw materials is removed by drying to ensure that the reaction is carried out under anhydrous conditions. In the presence of water, 3-(2,3-epoxypropoxy)propyltrimethoxysilane will hydrolyze, and the methoxy group will be hydrolyzed into a hydroxyl group.

[0018] Furthermore, the organic solvent is N,N-dimethylformamide (DMF). DMF has good solubility for 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate, and can also be removed by water washing during post-treatment. Of course, the optional organic solvent is not limited to DMF. The existing organic solvents in the art that have good solubility for 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate, do not react with 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate, and are easily removed during post-treatment can be used.

[0019] Furthermore, the molar ratio of the 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to tri(4-aminophenyl)phosphorothioate is (3-3.3):1. A slightly excessive amount of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane can completely react with tri(4-aminophenyl)phosphorothioate, and a small amount of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane that has not reacted with tri(4-aminophenyl)phosphorothioate can improve the compatibility of the nano-layered compound and the addition product and promote the condensation reaction.

[0020] Furthermore, the reaction temperature of the addition reaction is 20 to 80°C, and the reaction time is 1 to 10 hours. The addition reaction can be carried out at room temperature or under heating conditions. The lower the reaction temperature, the slower the reaction speed and the longer the reaction time.

[0021] Furthermore, the reaction temperature of the condensation reaction is 20 to 80°C, and the reaction time is 1 to 10 hours. The condensation reaction can be carried out at room temperature or under heating conditions. The lower the reaction temperature, the slower the reaction speed and the longer the reaction time.

[0022] The reaction raw materials and reaction solvents in the following examples and comparative examples were dried before the reaction. The reaction solvent and solution-type raw materials were dried using molecular sieves, and the solid-type raw materials were dried in an oven.

[0023] Example 1

[0024] 70.9 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 38.7 g of tri(4-aminophenyl)thiophosphate were added to 1 L of DMF for addition reaction at 80° C. for 5 h, followed by 150 g of montmorillonite for condensation reaction at 80° C. for 5 h. After the reaction, the reaction solution was centrifuged and filtered, the filter residue was washed with water, and vacuum dried to obtain a composite flame retardant.

[0025] Example 2

[0026] 74.2 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 38.7 g of tris(4-aminophenyl)thiophosphate were added to 1 L of DMF for addition reaction at 60° C. for 5 h, followed by 100 g of expanded graphite for condensation reaction at 60° C. for 8 h. After the reaction, the reaction solution was centrifuged and filtered, the filter residue was washed with water, and vacuum dried to obtain a composite flame retardant.

[0027] Example 3

[0028] 78.0 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 38.7 g of tris(4-aminophenyl)thiophosphate were added to 1 L of DMF for addition reaction at 20° C. for 4 h, and then 120 g of black phosphorus was added for condensation reaction at 20° C. for 10 h. After the reaction, the reaction solution was centrifuged and filtered, the filter residue was washed with water, and vacuum dried to obtain a composite flame retardant.

[0029] Example 4

[0030] 75.4 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 38.7 g of tris(4-aminophenyl)thiophosphate were added to 1 L of DMF for addition reaction, and the reaction was carried out at 50° C. for 5 h, followed by adding 120 g of expanded graphite for condensation reaction, and the reaction was carried out at 50° C. for 8 h. After the reaction was completed, the reaction solution was centrifuged and filtered, the filter residue was washed with water, and vacuum dried to obtain a composite flame retardant.

[0031] Example 5

[0032] 78.0 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 38.7 g of tris(4-aminophenyl)thiophosphate were added to 1 L of DMF for addition reaction at 80 ° C for 3 h, and then 150 g of black phosphorus was added for condensation reaction at 50 ° C for 10 h. After the reaction, the reaction solution was centrifuged and filtered, the filter residue was washed with water, and vacuum dried to obtain a composite flame retardant.

[0033] Comparative Example 1

[0034] 78.0 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 38.7 g of tris(4-aminophenyl)thiophosphate and 150 g of black phosphorus were uniformly mixed to obtain a composite flame retardant.

[0035] The composite flame retardant obtained in the above-mentioned embodiments 1 to 5 and comparative example 1 is respectively applied to the preparation of polyvinyl alcohol film, and the specific preparation method is as follows: 100 parts of polyvinyl alcohol (polymerization degree of 1700, alcoholysis degree of 88%), 15 parts of composite flame retardant, 15 parts of calcium carbonate, 10 parts of zinc borate and 5 parts of polyethylene wax are added to a high-speed mixer, and mixed for 5 minutes at a speed of 1000r / min and a temperature of 60°C to obtain a premix; then the premix is ​​melted, extruded and granulated by a twin-screw extruder at a speed of 350r / min and a temperature of 140 to 180°C to obtain a polyvinyl alcohol composite material; finally, the polyvinyl alcohol composite material is added to a film blowing machine, and melted, extruded, blown, pulled and wound at a speed of 300r / min, a temperature of 140 to 180°C and an aspect ratio of 20 to obtain a polyvinyl alcohol film. The prepared polyvinyl alcohol film is subjected to performance tests, and the test results are shown in Table 1.

[0036] The longitudinal tensile strength and elongation at break of the film were tested according to standard GB / T 1040.3-2006; the oxygen index of the film was tested according to standard GB / T 2406.2-2009.

[0037] Table 1 Performance test results of polyvinyl alcohol film

[0038] Oxygen index (%) Tensile strength(MPa) Elongation at break (%) Example 1 29.6 35.8 98.3 Example 2 30.4 37.5 104.2 Example 3 31.2 33.7 95.7 Example 4 30.9 38.6 112.6 Example 5 31.5 32.4 90.8 Comparative Example 1 25.8 30.2 84.5 Comparative Example 2 24.7 28.1 79.3

[0039] In Table 1, Comparative Example 2 uses tris(4-aminophenyl)thiophosphate as a flame retardant.

[0040] As can be seen from Table 1, compared with the physical mixture of nano-layered compounds, 3-(2,3-epoxypropyloxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate used in Comparative Example 1, the composite flame retardants prepared by reacting nano-layered compounds, 3-(2,3-epoxypropyloxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate in Examples 1 to 5 can make the composite material have excellent flame retardant properties under the condition of the same addition amount, and the tensile properties of the composite material are better.

[0041] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A composite flame retardant based on the synergistic flame retardancy of nano-layered compounds, characterized in that: The composite flame retardant is prepared from nano-layered compounds, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tris(4-aminophenyl)thiophosphate.

2. The composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 1, characterized in that: The nano-layered compound is one or more of montmorillonite, expanded graphite and black phosphorus.

3. The composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 1, characterized in that: The weight percentage of the nano-layered compound in the composite flame retardant is 20-80%.

4. The composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 3, characterized in that: The weight percentage of the nano-layered compound in the composite flame retardant is 40-60%.

5. A method for preparing a composite flame retardant based on the synergistic flame retardancy of nano-layered compounds, characterized in that: 3-(2,3-epoxypropoxy)propyltrimethoxysilane and tri(4-aminophenyl)thiophosphate are added to an organic solvent for addition reaction, and then a nano-layered compound is added for condensation reaction, filtered, washed with water, and dried to obtain a composite flame retardant.

6. The method for preparing a composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 5, characterized in that: The organic solvent, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, tris(4-aminophenyl)thiophosphate and nano-layered compound are dried before the reaction.

7. The method for preparing a composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 5 or 6, characterized in that: The organic solvent is N,N-dimethylformamide.

8. The method for preparing a composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 5 or 6, characterized in that: The molar ratio of the 3-(2,3-epoxypropoxy)propyltrimethoxysilane to tris(4-aminophenyl)thiophosphate is (3-3.3):

1.

9. The method for preparing a composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 5 or 6, characterized in that: The reaction temperature of the addition reaction is 20-80° C., and the reaction time is 1-10 hours.

10. The method for preparing a composite flame retardant based on synergistic flame retardancy of nano-layered compounds according to claim 5 or 6, characterized in that: The reaction temperature of the condensation reaction is 20-80° C., and the reaction time is 1-10 hours.