Method for preparing fluorine-silicon-containing polyphosphate ester and flame retardant epoxy resin

Abstract

Disclosed are a fluorine-silicon-containing polyphosphate ester and method for preparation thereof, having a chemical structural formula of: ##STR00001##
wherein R.sub.1 is ##STR00002##
R.sub.2 is ##STR00003##
n=10˜100. The fluorine-silicon-containing polyphosphate ester of the present invention uses silicon phosphorus and fluorine for improving flame retardancy. Phosphorus catalyzes the system to form a phosphorus-rich carbon layer, performing a protective-layer function and thereby preventing further breakdown of the epoxy resin. The silicon-containing epoxy resin forms a silica-containing carbon layer during the process of combustion, strengthening the carbon-layer structure and further improving the protective function of the carbon-layer. The introduction of elemental fluorine improves the thermal stability of the epoxy resin, thereby improving the flame retardancy performance of the system.

Claims

1. A method for preparing a fluorine-silicon-containing polyphosphate ester, a chemical formula of the fluorine-silicon-containing polyphosphate ester is: ##STR00010## wherein: R.sub.1 is ##STR00011## R.sub.2 is ##STR00012## and n=10-100, comprising: (1) successively adding a silicon-containing compound, trimethylamine, and a first organic solvent into a reaction vessel in an ice bath, then dripping 2-chloro-1, 3, 2-dioxaphospholane-2-oxide, and reacting for 4-12 hours at room temperature; filtering to remove triethylamine hydrochloride to obtain a filtrate after the reaction, repeatedly washing the filtrate with water to obtain an organic phase, drying the organic phase with anhydrous magnesium sulfate, and filtering; finally rotary evaporating to remove a solvent of the organic phase to obtain a silicon-containing cyclic phosphate ester monomer; the silicon-containing compound is trimethylsilanol, triphenylsilanol, or aminopropyl polyhedral oligomeric silsesquioxane; a mass ratio of the 2-chloro-1, 3, 2-dioxaphospholane-2-oxide and the first organic solvent is 1:5-50; a molar ratio of the silicon-containing compound, the trimethylamine, and the 2-chloro-1, 3, 2-dioxaphospholane-2-oxide is 1:1-2:1-2; and (2) adding a fluorine-containing compound, tin 2-ethylhexanoate, and a second organic solvent into the silicon-containing cyclic phosphate ester monomer obtained in step (1), to obtain a mixture, then heating up to 35-80° C. and reacting for 6-12 hours; finally rotary evaporating and drying to remove a solvent of the mixture to obtain the fluorine-silicon-containing polyphosphate ester; the fluorine-containing compound is 3,5-bis (trifluoromethyl) benzyl alcohol or tetrafluoropropanol; a mass ratio of the silicon-containing cyclic phosphate ester monomer and the second organic solvent is 1:5-50, a molar ratio of the silicon-containing cyclic phosphate ester monomer, the fluorine-containing compound, and the tin 2-ethylhexanoate is 1:0.01-0.05:0.002-0.01.

2. The method according to claim 1, wherein the first organic solvent is dichloromethane, toluene or ethyl acetate.

3. The method according to claim 1, wherein the second organic solvent is dichloromethane, trichloromethane or tetrahydrofuran.

4. A flame retardant epoxy resin comprising the fluorine-silicon-containing polyphosphate ester prepared by the method according to claim 1.

5. The flame retardant epoxy resin according to claim 4 prepared by a method, the method comprising: heating an epoxy resin prepolymer to 70-110° C., adding the fluorine-silicon-containing polyphosphate ester to the epoxy resin prepolymer to obtain a second mixture in which 2-90 wt % of the second mixture is the fluorine-silicon-containing polyphosphate ester, and stirring until the second mixture is uniformly transparent; then adding a curing agent 4,4′-diaminodiphenylmethane (DDM) according to a stoichiometric ratio until the curing agent DDM is completely dissolved, pouring the second mixture into an aluminum mold, and then setting a curing procedure to cure the second mixture to obtain the flame retardant epoxy resin.

6. The flame retardant epoxy resin according to claim 5, wherein the epoxy resin prepolymer is E51 bisphenol A epoxy resin.

7. The flame retardant epoxy resin according to claim 5, wherein a mass ratio of the epoxy resin prepolymer and the curing agent 4,4′-diaminodiphenylmethane is 8:2.02.

8. The flame retardant epoxy resin according to claim 5, wherein the curing procedure comprises: curing at 120° C. for 4 hours, curing at 140° C. for 2 hours, and curing at 180° C. for 2 hours.

Description

DRAWINGS

(1) FIG. 1 shows the structure of fluorine-silicon-containing polyphosphate ester in embodiment 1.

(2) FIG. 2 shows the .sup.1H NMR (a), .sup.19F NMR (b) and .sup.31P NMR (c) spectra of fluorine-silicon-containing polyphosphate ester in embodiment 1.

(3) FIG. 3 shows the water surface angle images of flame retardant epoxy resin prepared in embodiment 1 and pure epoxy resin, the above picture is pure epoxy resin, and the below picture is flame retardant epoxy resin prepared in embodiment 1.

DETAILED DESCRIPTION

(4) The following is a further description of the technical schemes of the present invention through specific embodiments in conjunction with the accompanying drawings.

(5) In the embodiments described below, the epoxy resin prepolymer is E51 bisphenol A epoxy resin.

Embodiment 1

(6) (1) 8.00 g (9.14 mmol) of aminopropyl polyhedral oligomeric silsesquioxane (NH.sub.2—POSS), 1.12 g (11.06 mmol) of triethylamine and 25 mL of dichloromethane were sequentially added to a single-mouth flask under ice bath, and then 1.96 g (13.75 mmol) of 2-chloro-1,3,2-dioxaphospholane-2-oxide was slowly added with a syringe. After reaction at room temperature for 8 h, triethylamine hydrochloride was removed by filtration, then the filtrate was extracted and washed repeatedly with water for several times. The organic phase was dried with anhydrous magnesium sulfate and treated with vacuum filtered. Finally silicon-containing cyclic phosphate ester monomer was obtained by rotary evaporation to obtain.

(7) (2) 6.08 g (6.20 mmol) of the silicon-containing cyclic phosphate ester monomer obtained in the step (1) was added into a single-mouth bottle, and 13.60 mg (0.10 mmol) of tetrafluoropropanol and 20.00 mg (0.04 mmol) of tin 2-ethylhexanoate and 10 mL of tetrahydrofuran were added and heated to 80° C. After reacting for 6 h, the solvent was rotary evaporated and dried to obtain a fluorine-silicon-containing polyphosphate ester (as shown in FIG. 1).

(8) (3) 20 g of epoxy resin prepolymer was heated to 90° C., 2.78 g of fluorine-silicon-containing polyphosphate ester obtained in step (2) was added and stirred until the mixture was uniformly transparent. Then 5.05 g of DDM was added until it was completely dissolved, the mixture was poured into the aluminium mold and cured at 120° C. for 4 h, at 140° C. for 2 h and at 180° C. for 2 h to obtain the flame retardant epoxy resin.

(9) According to GB/T 2406-2009, the oxygen index of the flame retardant epoxy resin was 32.4%.

(10) According to GB/T 30693-2014, the water contact angle of the flame retardant epoxy resin was 87.7 degrees (as shown in FIG. 2).

Embodiment 2

(11) (1) The synthesis of silicon-containing cyclic phosphate ester monomer was the same as that of embodiment 1.

(12) (2) The synthesis of fluorine-silicon-containing polyphosphate ester was the same as that of embodiment 1.

(13) (3) 20 g of epoxy resin prepolymer was heated to 90° C., and 6.26 g of fluorine-silicon-containing polyphosphate ester obtained in step (2) was added, the mixture was stirred until it was uniformly transparent. Then 5.05 g of DDM was added to the mixture until it was completely dissolved. The flame retardant epoxy resin was obtained by pouring the mixture into the aluminium mold and cured at 120° C. for 4 hours, 140° C. for 2 hours, and 180° C. for 2 hours.

(14) According to GB/T 2406-2009, the oxygen index of the flame retardant epoxy resin is 33.1%.

(15) According to GB/T 30693-2014, the water contact angle of the flame retardant epoxy resin is 90.5 degrees.

Embodiment 3

(16) (1) The preparation of silicon-containing cyclic phosphate ester monomer is the same as that of embodiment 1.

(17) (2) 6.08 g (6.20 mmol) of silicon-containing cyclic phosphate ester monomer obtained in step (1), 24.41 mg (0.10 mmol) of 3,5-bis (trifluoromethyl) benzyl alcohol, 20.00 mg (0.04 mmol) of tin 2-ethylhexanoate and 10 mL of tetrahydrofuran were added into a single-mouth bottle, the reaction temperature was raised to 80° C. and reacted for 6 h. After the reaction, the solvent was rotary evaporated and dried to obtain fluorine-silicon-containing polyphosphate ester.

(18) (3) 20 g of epoxy resin prepolymer was heated to 90° C., 2.78 g of fluorine-silicon-containing polyphosphate ester obtained in step (2) was added and stirred until the mixture was uniformly transparent. Then 5.05 g of DDM was added until it was completely dissolved, then the mixture was poured into the aluminium mold and cured at 120° C. for 4 h, 140° C. for 2 h and 180° C. for 2 h to obtain the flame retardant epoxy resin.

(19) According to GB/T 2406-2009, the oxygen index of the flame retardant epoxy resin is 30.9%.

(20) According to GB/T 30693-2014, the water contact angle of the flame retardant epoxy resin is 87.9 degrees.

Embodiment 4

(21) (1) The preparation of silicon-containing cyclic phosphate ester monomer is the same as that of embodiment 3.

(22) (2) The preparation of fluorine-silicon-containing polyphosphate ester is the same as that of embodiment 3.

(23) (3) 20 g of epoxy resin prepolymer was heated to 90° C., 2.78 g of fluorine-silicon-containing polyphosphate ester obtained in step (2) was added and stirred until the mixture was uniformly transparent. Then 5.05 g of DDM was added until it was completely dissolved, the mixture was poured into the aluminium mold and cured at 120° C. for 4 h, 140° C. for 2 h and 180° C. for 2 h to obtain flame retardant epoxy resin.

(24) According to GB/T 2406-2009, the oxygen index of the flame retardant epoxy resin is 32.7%.

(25) According to GB/T 30693-2014, the water contact angle of the flame retardant epoxy resin is 91.6 degrees.

Embodiment 5

(26) (1) 1.03 g (9.14 mmol) of trimethylsilanol, 1.12 g (11.06 mmol) of triethylamine and 20 mL of dichloromethane were added to a single mouth bottle under ice bath, then 1.96 g (13.75 mmol) of 2-chloro-1,3,2-dioxaphospholane-2-oxide was slowly dripped with a syringe and react for 8 hours. Then triethylamine hydrochloride was removed by filtration, the filtrate was extracted and washed three times with water, the organic phase was dried with anhydrous magnesium sulfate. After vacuum filtered, the solvent was removed by rotary evaporation to obtain silicon-containing cyclic phosphate ester monomer.

(27) (2) 6.08 g (6.20 mmol) of silicon-containing cyclic phosphate ester monomer obtained in step (1) 24.41 mg (0.10 mmol) of 3,5-bis(trifluoromethyl) benzyl alcohol, 20.00 mg (0.04 mmol) of tin 2-ethylhexanoate and 10 mL of tetrahydrofuran were added into a single-mouth bottle, the reaction temperature was raised to 80° C. and reacted for 6 h. After the reaction, the solvent was rotary evaporated and dried to obtain fluorine-silicon-containing polyphosphate ester.

(28) (3) 20 g of epoxy resin prepolymer was heated to 90° C., and 2.78 g of fluorine-silicon-containing polyphosphate ester obtained in step (2) was added, the mixture was stirred until it was uniformly transparent, 5.05 g of DDM was added to the mixture until it was completely dissolved. The flame retardant epoxy resin was obtained by pouring the mixture into the aluminium mold, and cured at 120° C. for 4 hours, 140° C. for 2 hours, 180° C. for 2 hours.

(29) According to GB/T 2406-2009, the oxygen index of the flame retardant epoxy resin is 32.5%.

(30) According to GB/T 30693-2014, the water contact angle of the flame retardant epoxy resin is 89.7 degrees.

(31) It is known to those skilled in the field that the technical scheme of the present invention can still achieve the same or similar technical effect as the above-mentioned embodiments when it changes in the following range, and it still belongs to the scope of protection of the present invention:

(32) A fluorine-silicon-containing polyphosphate ester has a chemical formula structure of:

(33) ##STR00007##

(34) wherein R.sub.1 is

(35) ##STR00008##
R.sub.2 is

(36) ##STR00009##
n=10˜100.

(37) The preparation method of the fluorine-silicon-containing polyphosphate ester described above comprises the following steps:

(38) (1) Silicon-containing compound, triethylamine and a first organic solvent were successively added to the reaction vessel under the ice bath, then 2-chloro-1,3,2-dioxaphospholane-2-oxide is slowly dripped, and reacted for 4˜12 hours at room temperature. Then triethylamine hydrochloride is filtered out, the filtrate is repeatedly washed with water for several times. The organic phase is dried with anhydrous magnesium sulfate and treated with filter. Finally the solvent is removed by rotary evaporation to obtain silicon-containing cyclic phosphate ester monomer. The silicon-containing compound mentioned above is trimethylsilanol, triphenylsilanol or aminopropyl polyhedral oligomeric silsesquioxane (NH.sub.2—POSS). The mass ratio of 2-chloro-1,3,2-dioxaphospholane-2-oxide to the first organic solvent is 1:5˜50. The molar ratio of the silicon-containing compound, triethylamine and 2-chloro-1,3,2-dioxaphospholane-2-oxide is 1:1˜2:1˜2.

(39) (2) Fluorine-containing compound, tin 2-ethylhexanoate and a second organic solvent are added to the silicon-containing cyclic phosphate ester monomer obtained in step (1), then heated up to 35˜80° C. and reacted for 6˜12 h. Finally the solvent is rotary evaporated and dried to obtain the fluorine-silicon-containing polyphosphate. The fluorine-containing compound mentioned above is 3,5-bis(trifluoromethyl) benzyl alcohol or tetrafluoropropanol. The mass ratio of silicon-containing cyclic phosphate ester monomer to the second organic solvent is 1:5˜5. The molar ratio of silicon-containing cyclic phosphate ester monomer, fluorine-containing compound and tin 2-ethylhexanoate is 1:0.01˜0.05:0.002˜0.01.

(40) The first organic solvent is dichloromethane, toluene or ethyl acetate. The second organic solvent is dichloromethane, trichloromethane or tetrahydrofuran.

(41) The application of the fluorine-silicon-containing polyphosphate ester in the preparation of flame retardant epoxy resin, specifically: the epoxy resin prepolymer is heated to 70˜110° C., where 2-90 wt % fluorine-silicon-containing polyphosphate ester is added, and stirred until the mixture is uniformly transparent, then a curing agent (DDM) is added according to stoichiometric ratio until it is completely dissolved. The mixture is poured into an aluminum mold, then a curing procedure was set to cure the mixture, a flame retardant epoxy resin was obtained.

(42) As mentioned above, these are only preferred embodiments of the present invention, so the scope of embodiment of the present invention cannot be limited accordingly. That is, the equivalent changes and modifications made according to the patent scope and description content of the present invention should still be within the scope of the present invention.