A preparation method of a MOFs-based composite material for polyester flame retardation, product and application thereof

Abstract

The present application relates to a kind of preparation method of MOFs-based composite for polyester flame retardant and its product and application, belong to the preparation technical field of flame-retardant composite.The preparation method of the present application adopts white product (DP) (the phosphorus compound radical (PO· and HPO·) generated when DP burns can react with active radical (H· and HO·), terminate radical chain reaction when burning), ZIF-67 (non-combustible gas is generated in the pyrolysis process of ZIF-67, can dilute combustible gas and oxygen concentration, inhibit the size growth of carbonaceous microzone in combustion process, promote the formation and stability of dense carbon layer, help to inhibit the smoke release when MOFs-based composite burns, and CoO contained in residual carbon can catalyze oxidation CO into CO2, reduce the release of CO) and polyethylene terephthalate melt mixing reaction, ZIF-67 and DP exist synergistic effect, make the flame-retardant property of MOFs-based composite enhance, finally improve the efficiency of polyester flame retardant.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of flame-retardant composite materials, and relates to a preparation method of MOFs-based composite material for flame-retardant polyester, a product thereof and application of the product. BACKGROUND

[0002] Polyethylene terephthalate (PET), commonly known as polyester, is the synthetic fiber with the largest output and excellent performance in the world, and is widely used in clothing, home, building and other fields. However, polyester is extremely flammable, and the limiting oxygen index is only 19% to 22%, which is easy to melt and shrink under the action of fire to form a large amount of melt drops, causing secondary combustion and even secondary disasters, and there is a serious safety hazard. Therefore, it is of important practical significance to study the flame retardation of polyester to improve its safety.

[0003] Metal-organic frameworks (MOFs) as a class of promising advanced porous materials have attracted extensive attention in the fields of gas storage, gas separation, chemical sensors, catalysis, etc. Scientists have designed and synthesized MOFs with various particle forms and excellent performance. It has been proved that the method of blending MOF particles into polymer matrix is an effective method for preparing MOF-polymer composites. The advantages of MOFs are as follows: (1) better compatibility with polymer matrix, strong interaction with polymer chains, and no need for any organic modification; (2) the organic ligand in the structure of MOFs not only helps to improve the compatibility, but also provides flame-retardant elements or groups, including nitrogen-containing groups and aromatic structures, and the transition metal oxides produced by pyrolysis of the organic ligand have a positive catalytic effect on promoting the formation of carbon and inhibiting the release of smoke; (3) the high specific surface area of MOFs is conducive to the formation of strong interfacial interaction between nano-filler and polymer matrix. Therefore, MOFs are potential flame retardants for improving the fire safety of polymer materials, and have become an attractive alternative to traditional nanoparticles in the field of flame retardation.

[0004] The environmentally friendly new phosphorus-containing flame retardant derivative (DOPO-PEEA) has attracted extensive attention from researchers and the industry due to its high-efficiency and multi-functional flame-retardant characteristics, i.e. low smoke and low toxicity, excellent flame-retardant effect. Therefore, a compound flame retardant (ZDP) can be formed by selecting a methyl imidazole cobalt salt skeleton structure material (ZIF-67, Z) and a phosphorus-based flame retardant (DOPO-PEEA, DP), and a flame-retardant ZDP-PET composite can be prepared by using a melt blending method to improve the flame-retardant effect of polyester. SUMMARY

[0005] Therefore, one of the purposes of the present application is to provide a preparation method of MOFs-based composite material for flame-retardant polyester; the second purpose of the present application is to provide a MOFs-based composite material for flame-retardant polyester; and the third purpose of the present application is to provide an application of the MOFs-based composite material for flame-retardant polyester in preparing flame-retardant polyester material.

[0006] To achieve the above purposes, the present application provides the following technical solutions.

[0007] 1. A preparation method of MOFs-based composite material for flame-retardant polyester, comprising the following steps:

[0008] (1) adding a dichloromethane solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) into a mixed dichloromethane solution of pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) and triethylamine, stirring to mix them uniformly, adding ethanol to dissolve after removing the solvent under stirring, and then washing and drying the filtered product to obtain a white product (DP);

[0009] (2) mixing a methanol solution of cobalt nitrate hexahydrate and a methanol solution of 2-methylimidazole, stirring magnetically at room temperature to mix them uniformly, repeatedly washing after centrifugation, and drying in a vacuum oven at 80-100℃ for 10-12h to obtain ZIF-67;

[0010] (3) melt-mixing the white product in step (1), ZIF-67 in step (2) and polyethylene terephthalate (PET) to mix them uniformly and compound to obtain a product, which is the MOFs-based composite material for flame-retardant polyester (ZDP-PET).

[0011] Preferably, in step (1), the molar volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to dichloromethane in the dichloromethane solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is 45-48:100, mmol:mL;

[0012] The molar volume ratio of pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2, 6, 7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA), triethylamine and dichloromethane in the mixed solution is 45-48:55-57:100, mmol:mmol:mL.

[0013] Preferably, in step (1), the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2, 6, 7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) is 0.9-1.2:1.

[0014] Preferably, in step (1), the drying is carried out at 80-90℃ for 8-10h under vacuum.

[0015] Preferably, in step (2), the molar volume ratio of cobalt nitrate hexahydrate and methanol in the methanol solution of cobalt nitrate hexahydrate is 4-4.2:100, mmol:mL.

[0016] The molar volume ratio of 2-methylimidazole and methanol in the methanol solution of 2-methylimidazole is 16-18:100, mmol:mL.

[0017] Preferably, in step (2), the molar ratio of cobalt nitrate hexahydrate and 2-methylimidazole is 1:4-4.5.

[0018] Preferably, in step (3), the mass ratio of the white product in step (1), ZIF-67 in step (2) and polyethylene terephthalate (PET) is 4-8:2-6:90.

[0019] Preferably, in step (3), the raw materials need to be dried before melting, and the specific drying conditions are: drying in a vacuum oven at 90-100℃ for 12-14h.

[0020] 2. The MOFs-based composite material prepared by the above preparation method.

[0021] 3. The application of the above MOFs-based composite material in preparing polyester flame-retardant materials.

[0022] The beneficial effects of the present application are:

[0023] 1. The application discloses a preparation method of a MOFs-based composite material for polyester flame retardation, which adopts white product (DP) (DP can generate phosphorus compound free radicals (PO· and HPO·) when burning, which can react with active free radicals (H· and HO·) to terminate the radical chain reaction during burning), ZIF-67 (ZIF-67 can generate non-combustible gas during pyrolysis, which can dilute the concentration of combustible gas and oxygen, inhibit the size growth of carbonaceous microzones during combustion, promote the formation and stability of dense carbon layer, help to inhibit the smoke release during the combustion of the MOFs-based composite material (ZDP-PET), and CoO contained in the residual carbon can catalyze the oxidation of CO to CO2, reducing the release of CO), and polyethylene terephthalate (PET) melt mixing reaction. ZIF-67 and DP have a synergistic effect, so that the flame retardant performance of the MOFs-based composite material (ZDP-PET) is enhanced, and the polyester flame retardation efficiency is finally improved.

[0024] 2. The application discloses a MOFs-based composite material for polyester flame retardation, which is obtained by adding 2wt% of ZIF-67 and 8% of DP to polyethylene terephthalate (PET), so that the limiting oxygen index value reaches 30.2%, and the UL-94 V-0 level is obtained. Compared with the pure PET system, the peak heat release rate is further reduced by 42.1%, and the total heat release amount at 800s is reduced by 16.5%.

[0025] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following specification, in certain respects, are deemed obvious from consideration of the following specification, or are learned from practice of the present application. The objects and other advantages of the present application can be realized and attained by the below description. DETAILED DESCRIPTION

[0026] The embodiments of the present application are illustrated by specific examples below, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure. The present application can also be implemented or applied by different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0027] Example 1

[0028] (1) A dichloromethane solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) (46.2 mmol (10.0 g) of DOPO was dissolved in 100 mL of dichloromethane) was added to a mixed solution (46.2 mmol (8.34 g) of pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) and 55.6 mmol (5.60 g) of triethylamine were dissolved in 100 mL of dichloromethane) (where the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) was 1:1), and stirred for 12 h to mix uniformly, and after completely removing the solvent, 100 mL of ethanol was added to dissolve while stirring, filtered, washed with ethanol, and dried at 80°C under vacuum to obtain a white product (DP).

[0029] (2) A methanol solution of cobalt nitrate hexahydrate (1.164 g, 4 mmol) was dissolved in methanol (100 mL), and a methanol solution of 2-methylimidazole (1.3 g, 18 mmol) was dissolved in methanol (100 mL) (the molar ratio of cobalt nitrate hexahydrate and 2-methylimidazole was 1:4.5), and mixed, and stirred magnetically at room temperature for 24 h to mix uniformly, centrifuged, repeatedly washed with methanol, and dried in a vacuum oven at 90°C for 11 h to obtain ZIF-67.

[0030] (3) 0.8 g of the white product in step (1), 0.2 g of ZIF-67 in step (2), and 9 g of polyethylene terephthalate (PET) were melt-mixed to mix and reconstitute to obtain a product, which was a MOFs-based composite material for polyester flame retardation (ZDP-PET).

[0031] Example 2

[0032] (1) A dichloromethane solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) (45 mmol (9.74 g) of DOPO was dissolved in 100 mL of dichloromethane) was added to a mixed solution (45 mmol (8.12 g) of pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) and 55 mmol (5.34 g) of triethylamine were dissolved in 100 mL of dichloromethane) (where the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) was 0.9:1), and stirred for 12 h to homogenize the mixture, and after completely removing the solvent, 100 mL of ethanol was added under stirring to dissolve, filtered, washed with ethanol, and dried at 80°C under vacuum to obtain a white product (DP).

[0033] (2) A methanol solution of cobalt nitrate hexahydrate (1.222 g, 4.2 mmol) was dissolved in methanol (100 mL), and a methanol solution of 2-methylimidazole (1.3 g, 16 mmol) was dissolved in methanol (100 mL) (where the molar ratio of cobalt nitrate hexahydrate and 2-methylimidazole was 1:4), and mixed, and stirred at room temperature for 24 h to homogenize the mixture, and after centrifugation, repeatedly washed with methanol, and dried in a vacuum oven at 80°C for 12 h to obtain ZIF-67.

[0034] (3) 0.4 g of the white product in step (1), 0.6 g of ZIF-67 in step (2), and 9 g of polyethylene terephthalate (PET) were melt-mixed to homogenize the mixture to obtain a product, which was a MOFs-based composite material for polyester flame retardation (ZDP-PET).

[0035] Example 3

[0036] (1) A dichloromethane solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) (48 mmol (10.39 g) of DOPO was dissolved in 100 mL of dichloromethane) was added to a mixed solution (48 mmol (8.66 g) of pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) and 57 mmol (5.74 g) of triethylamine were dissolved in 100 mL of dichloromethane) (where the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and pentaerythritol phosphate (1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane, PEPA) was 1.2:1), and stirred for 12 h to mix uniformly, and after completely removing the solvent, 100 mL of ethanol was added to dissolve under stirring, filtered, washed with ethanol, and dried at 80°C under vacuum to obtain a white product (DP).

[0037] (2) A methanol solution of cobalt nitrate hexahydrate (1.164 g, 4 mmol) was dissolved in methanol (100 mL), and a methanol solution of 2-methylimidazole (1.3 g, 18 mmol) was dissolved in methanol (100 mL) (the molar ratio of cobalt nitrate hexahydrate to 2-methylimidazole was 1:4), and mixed, and stirred magnetically at room temperature for 24 h to mix uniformly, centrifuged, repeatedly washed with methanol, and dried in a vacuum oven at 100°C for 10 h to obtain ZIF-67.

[0038] (3) 0.4 g of the white product in step (1), 0.6 g of ZIF-67 in step (2), and 9 g of polyethylene terephthalate (PET) were melt-mixed to obtain a product, which was a MOFs-based composite material for polyester flame retardation (ZDP-PET).

[0039] The MOFs-based composite materials prepared in the above-mentioned embodiments 1, 2 and 3 are subjected to performance testing, and the results are as follows: the MOFs-based composite material prepared by the present application for polyester flame retardation, by adding 2wt% of ZIF-67 and 8% of DP into polyethylene terephthalate (PET), the limiting oxygen index value reaches 30.2%, and UL-94 V-0 level is obtained, compared with the pure PET system, the peak heat release rate is further reduced by 42.1%, and the total heat release amount at 800s is reduced by 16.5%. By adding 4wt% of ZIF-67 and 6% of DP, the limiting oxygen index value reaches 29.4%, and UL-94 V-0 level is obtained, compared with the pure PET system, the peak heat release rate is further reduced by 40.5%, and the total heat release amount at 800s is reduced by 16.2%. By adding 6wt% of ZIF-67 and 4% of DP, the limiting oxygen index value reaches 28.7%, and UL-94 V-0 level is obtained, compared with the pure PET system, the peak heat release rate is further reduced by 39.2%, and the total heat release amount at 800s is reduced by 15.3%. Thus it is illustrated that the MOFs-based composite material prepared by the preparation method of the present application has good flame retardancy, and has good application prospect in the preparation of polyester flame retardant materials.

[0040] In summary, the present application discloses a preparation method of a MOFs-based composite material for polyester flame retardation, which adopts white product (DP) (the phosphorus compound free radicals (PO· and HPO·) generated during combustion of DP can react with active free radicals (H· and HO·) to terminate the free radical chain reaction during combustion), ZIF-67 (non-combustible gas is generated during pyrolysis of ZIF-67, which can dilute the concentration of combustible gas and oxygen, inhibit the size growth of carbonaceous microzones during combustion, promote the formation and stability of dense carbon layer, and help to inhibit the smoke release during combustion of the MOFs-based composite material (ZDP-PET), and CoO contained in the residual carbon can catalyze the oxidation of CO to CO2 to reduce the release of CO), and polyethylene terephthalate (PET) melt mixing reaction, and ZIF-67 and DP have synergistic effect, so that the flame retardant performance of the MOFs-based composite material (ZDP-PET) is enhanced, and the polyester flame retardation efficiency is ultimately improved.

[0041] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the technical solutions, which should be covered in the scope of claims of the present application.

Claims

1. A method for preparing a flame-retardant MOFs-based composite material for polyester, characterized in that: The preparation method comprises the following steps: (1) adding a dichloromethane solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to a dichloromethane mixed solution of pentaerythritol phosphate and triethylamine, stirring to mix uniformly, removing the solvent, adding ethanol to dissolve under stirring, filtering, washing, and drying to obtain a white product; (2) A methanol solution of cobalt nitrate hexahydrate and a methanol solution of 2-methylimidazole were mixed, magnetically stirred at room temperature to uniformly mix, centrifuged, and repeatedly washed, and dried in a vacuum oven at 80-100° C. for 10-12 h to obtain ZIF-67; (3) melt-mixing the white product in step (1), the ZIF-67 in step (2), and polyethylene terephthalate, and uniformly mixing and compounding to obtain a product that is a MOFs-based composite material for polyester flame retardancy; The mass ratio of the white product in step (1), the ZIF-67 in step (2), and the polyethylene terephthalate is 4-8:2-6:90; In step (1), the molar volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to dichloromethane in the dichloromethane solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 45 to 48:100, mmol:mL; The molar volume ratio of pentaerythritol phosphate, triethylamine and dichloromethane in the mixed solution is 45-48:55-57:100, mmol:mmol:mL; In step (1), the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to pentaerythritol phosphate is 0.9 to 1.2:

1.

2. The preparation method according to claim 1, characterized in that In step (1), the drying is performed by vacuum drying at 80-90° C. for 8-12 hours.

3. The preparation method according to claim 1, characterized in that In step (2), the molar volume ratio of cobalt nitrate hexahydrate to methanol in the methanol solution of cobalt nitrate hexahydrate is 4-4.2:100, mmol:mL; The molar volume ratio of 2-methylimidazole to methanol in the 2-methylimidazole methanol solution is 16-18:100, mmol:mL.

4. The preparation method according to claim 1, characterized in that In step (2), the molar ratio of the cobalt nitrate hexahydrate to 2-methylimidazole is 1:4 to 4.

5.

5. The preparation method according to claim 1, characterized in that In step (3), the raw materials need to be dried before melting. The specific drying conditions are: drying in a vacuum oven at 90-100° C. for 12-14 hours.

6. The MOFs-based composite material prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the MOFs-based composite material according to claim 6 in the preparation of polyester flame retardant materials.