Amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material and preparation method thereof

Abstract

The invention relates to the technical field of new materials, and discloses an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material which is prepared by using polyethylene grafted phosphorus-containing starch as a modifier, carrying out blending modification on high-density polyethylene and using a polyethylene molecular chain introduced by a phosphorus-containing starch side chain as a compatilizer. The polyethylene grafted phosphorus-containing starch and the high-density polyethylene have good interfacial compatibility, the influence on the mechanical tensile strength and other mechanical properties of the high-density polyethylene is avoided, meanwhile, the starch is used as an expansion carbon source, and the side chain grafted phosphaphenanthrene derivative is used as a phosphorus-containing flame retardant, so that the phosphorus-containing flame-retardant polyethylene is prepared. The high-density polyethylene prepared by the preparation method has the advantages that the high-density polyethylene is used as a raw material, phosphoric acid compounds and phosphorus-oxygen free radicals are generated by thermal decomposition during combustion, and the phosphoric acid compounds are high in water absorption, so that the starch can be dehydrated and carbonized, a continuous and stable carbon barrier layer is formed in the high-density polyethylene, and smoke escape can be inhibited, molten drops can be prevented, and oxygen and heat insulation effects can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, in particular to a flame-retardant polyethylene composite material modified with amino-terminated phosphorus-containing starch and a preparation method thereof. Background Art

[0002] High-density polyethylene has comprehensive properties such as non-toxicity, odorlessness, excellent electrical insulation, and excellent chemical stability. It can be made into industrial accessories, medical supplies, films, decorative panels and other products through extrusion, injection molding, blow molding and other processing methods. It plays an important role in industrial production and daily life. However, traditional polyethylene is easy to burn, has poor flame retardancy and fire resistance, and can continue to burn after being away from the fire source, which hinders the development and application of high-density polyethylene. Adding flame retardants is usually an effective way to improve flame retardancy and fire resistance.

[0003] Starch is abundant, cheap and easy to obtain, and can be used as an expanding carbon source. It has broad application prospects in the field of flame retardancy. Starch can also be used as a toughening agent to improve the mechanical properties of polymer materials such as polyamide and polypropylene. Patent CN106496975B "A polylactic acid / starch expanding flame retardant composite material and its preparation method" discloses phosphated maleic anhydride grafted modified starch, which can effectively promote the carbonization ability of polylactic acid and enhance high-temperature thermal stability and flame retardant properties. Therefore, phosphorus-containing flame retardants can be grafted on starch as flame retardants to improve the flame retardancy and fire resistance of high-density polyethylene. However, if the amount of additive flame retardant is too large, the compatibility with the polymer matrix is ​​poor, which will affect the mechanical strength and other properties of the material. 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 polyethylene flame retardant composite material modified with amino-terminated phosphorus-containing starch and a preparation method thereof, which endows the high-density polyethylene material with excellent flame retardancy and fire resistance.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a flame retardant polyethylene composite material modified by amino-terminated phosphorus-containing starch, the preparation method of which comprises the following steps: (1) Add starch and sodium hydroxide to an ethanol solvent, add chloroacetic acid at 35-50 °C, and react for 1-2 h to obtain carboxymethyl starch.

[0006] (2) Add carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add N-hydroxysuccinimide (NHS) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCL), activate at 15-40 °C for 10-30 min, then add diaminophosphaphenanthrene derivative, react for 24-48 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch.

[0007] (3) Add amino-terminated phosphorus-containing starch to xylene solvent, stir evenly, then add xylene solution containing maleic anhydride grafted polyethylene, dropwise add p-toluenesulfonic acid as a catalyst, heat up to react, perform vacuum distillation after the reaction, wash with toluene and dichloromethane and dry to obtain polyethylene grafted phosphorus-containing starch.

[0008] (4) High-density polyethylene, polyethylene grafted phosphorus-containing starch, and antioxidant 1010 are added to a high-speed mixer and mixed evenly, and then the materials are placed in a twin-screw extruder, melt-blended, and extruded into granules to obtain an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material.

[0009] Preferably, in the step (2), by weight, carboxymethyl starch is 100 parts, N-hydroxysuccinimide is 20-55 parts, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 70-180 parts, and diaminophosphaphenanthrene derivative is 120-300 parts.

[0010] Preferably, the reaction temperature in step (3) is 120-160°C and the reaction time is 20-40 h.

[0011] Preferably, in step (3), the amino-terminated phosphorus-containing starch is 100 parts, the maleic anhydride grafted polyethylene is 30-120 parts, and the p-toluenesulfonic acid is 1.5-6 parts, by weight.

[0012] Preferably, in step (4), the high-density polyethylene is 100 parts and the polyethylene-grafted phosphorus-containing starch is 2-10 parts by weight.

[0013] 3. Beneficial technical effects Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a flame-retardant polyethylene composite material modified with terminal amino-phosphorus starch. The catalyst system of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide is used to activate the carboxyl groups of carboxymethyl starch, and the carboxyl groups of the carboxymethyl starch are subjected to amidation reaction with the amino groups of diaminophosphoraphenanthrene derivatives for cross-linking. Part of the amino groups are not reacted, so that the aminophosphoraphenanthrene derivatives are introduced into the side chains of the starch to obtain the terminal amino-phosphorus starch. Then, p-toluenesulfonic acid is used as a catalyst to react the amino groups of the aminophosphoraphenanthrene derivatives with the anhydride groups of maleic anhydride grafted polyethylene, and polyethylene molecular chains are further introduced into the side chains of the starch to obtain the polyethylene grafted phosphorus starch.

[0014] Polyethylene grafted phosphorus starch is used as a modifier to perform blending modification on high-density polyethylene. The polyethylene molecular chain introduced into the side chain of phosphorus starch serves as a compatibilizer, so that the polyethylene grafted phosphorus starch and high-density polyethylene have good interface compatibility, and the phosphorus starch is evenly dispersed in the high-density polyethylene. Therefore, phase separation does not occur between the two, and the mechanical properties of high-density polyethylene such as mechanical tensile strength are avoided. At the same time, starch is used as an expansion carbon source, and the side-chain grafted phosphaphenanthrene derivative is used as a phosphorus-containing flame retardant. When burned, it is thermally decomposed to produce phosphoric acid compounds and phosphorus oxygen free radicals. The phosphoric acid compounds have strong water absorption and can dehydrate and carbonize the starch to form a continuous and stable carbon barrier layer in the high-density polyethylene, which can inhibit smoke escape and anti-melting droplet effect, as well as oxygen and heat insulation effects. The phosphorus oxygen free radical can capture hydrogen free radicals and hydroxyl free radicals generated in the combustion chain reaction, inhibit the combustion chain reaction, thereby significantly enhancing the flame retardancy and fire resistance of the high-density polyethylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the reaction for preparing amino-terminated phosphorus-containing starch. DETAILED DESCRIPTION

[0016] To achieve the above object, the present invention provides the following embodiments and examples: A flame retardant polyethylene composite material modified with amino-terminated phosphorus-containing starch, the preparation method of which comprises the following steps: (1) Add starch and sodium hydroxide to an ethanol solvent, add chloroacetic acid at 35-50 °C, and react for 1-2 h to obtain carboxymethyl starch.

[0017] (2) Add 100 parts by weight of carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add 20-55 parts of N-hydroxysuccinimide and 70-180 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, activate at 15-40°C for 10-30 min, then add 120-300 parts of diaminophosphaphenanthrene derivative, react for 24-48 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch.

[0018] (3) Add 100 parts by weight of amino-terminated phosphorus-containing starch to a xylene solvent, stir evenly, then add a xylene solution containing 30-120 parts of maleic anhydride grafted polyethylene, dropwise add 1.5-6 parts of p-toluenesulfonic acid as a catalyst, raise the temperature to 120-160°C and react for 20-40 hours, distill under reduced pressure after the reaction, wash with toluene and dichloromethane and dry to obtain polyethylene grafted phosphorus-containing starch.

[0019] (4) Add 100 parts of high-density polyethylene, 2-10 parts of polyethylene grafted phosphorus-containing starch, and antioxidant 1010 into a high-speed mixer and mix them evenly. Then, place the materials into a twin-screw extruder, melt-blend, and extrude into granules to obtain an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material. Example 1

[0020] (1) Add starch and sodium hydroxide to ethanol solvent, add chloroacetic acid at 35 °C, and react for 1 h to obtain carboxymethyl starch.

[0021] (2) Add 100 parts by weight of carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add 20 parts of N-hydroxysuccinimide and 70 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, activate at 15°C for 10 min, then add 120 parts of diaminophosphaphenanthrene derivative, react for 24 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch.

[0022] (3) Add 100 parts by weight of amino-terminated phosphorus-containing starch to a xylene solvent, stir evenly, then add a xylene solution containing 30 parts of maleic anhydride grafted polyethylene, dropwise add 1.5 parts of p-toluenesulfonic acid as a catalyst, heat to 120 °C and react for 20 h. After the reaction, distill under reduced pressure, wash with toluene and dichloromethane and dry to obtain polyethylene grafted phosphorus-containing starch.

[0023] (4) 100 parts of high-density polyethylene, 2 parts of polyethylene grafted phosphorus-containing starch, and 0.5 parts of antioxidant 1010 were added into a high-speed mixer and mixed evenly. Then the materials were placed into a twin-screw extruder, melt-blended, and extruded into granules to obtain an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material. Example 2

[0024] (1) Add starch and sodium hydroxide to ethanol solvent, add chloroacetic acid at 40 °C, and react for 1.5 h to obtain carboxymethyl starch.

[0025] (2) Add 100 parts by weight of carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add 30 parts of N-hydroxysuccinimide and 100 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, activate at 20°C for 10 min, then add 180 parts of diaminophosphaphenanthrene derivative, react for 48 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch.

[0026] (3) Add 100 parts by weight of amino-terminated phosphorus-containing starch to a xylene solvent, stir evenly, then add a xylene solution containing 60 parts of maleic anhydride grafted polyethylene, dropwise add 3 parts of p-toluenesulfonic acid as a catalyst, heat to 120 °C and react for 30 h. After the reaction, distill under reduced pressure, wash with toluene and dichloromethane and dry to obtain polyethylene grafted phosphorus-containing starch.

[0027] (4) 100 parts of high-density polyethylene, 5 parts of polyethylene grafted phosphorus-containing starch, and 0.5 parts of antioxidant 1010 were added into a high-speed mixer and mixed evenly. Then the materials were placed into a twin-screw extruder, melt-blended, and extruded into granules to obtain an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material. Example 3

[0028] (1) Add starch and sodium hydroxide to ethanol solvent, add chloroacetic acid at 40 °C, and react for 1.5 h to obtain carboxymethyl starch.

[0029] (2) Add 100 parts by weight of carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add 42 parts of N-hydroxysuccinimide and 140 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, activate at 30°C for 20 min, then add 240 parts of diaminophosphaphenanthrene derivative, react for 36 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch.

[0030] (3) Add 100 parts by weight of amino-terminated phosphorus-containing starch to a xylene solvent, stir evenly, then add 90 parts of a xylene solution containing maleic anhydride grafted polyethylene, dropwise add 4.5 parts of a catalyst, p-toluenesulfonic acid, raise the temperature to 140 °C and react for 30 h. After the reaction, perform vacuum distillation, wash with toluene and dichloromethane, and dry to obtain the polyethylene grafted phosphorus-containing starch.

[0031] (4) 100 parts of high-density polyethylene, 7 parts of polyethylene grafted phosphorus-containing starch, and 0.3 parts of antioxidant 1010 were added into a high-speed mixer and mixed evenly. Then the materials were placed into a twin-screw extruder, melt-blended, and extruded into granules to obtain an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material. Example 4

[0032] (1) Add starch and sodium hydroxide to ethanol solvent, add chloroacetic acid at 50 °C, and react for 2 h to obtain carboxymethyl starch.

[0033] (2) Add 100 parts by weight of carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add 55 parts of N-hydroxysuccinimide and 180 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, activate at 40°C for 130 min, then add 300 parts of diaminophosphaphenanthrene derivative, react for 48 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch.

[0034] (3) Add 100 parts by weight of amino-terminated phosphorus-containing starch to a xylene solvent, stir evenly, then add a xylene solution containing 120 parts of maleic anhydride grafted polyethylene, dropwise add 6 parts of p-toluenesulfonic acid as a catalyst, heat to 160 °C and react for 40 h. After the reaction, perform vacuum distillation, wash with toluene and dichloromethane and dry to obtain polyethylene grafted phosphorus-containing starch.

[0035] (4) 100 parts of high-density polyethylene, 10 parts of polyethylene grafted phosphorus-containing starch, and 0.5 parts of antioxidant 1010 were added into a high-speed mixer and mixed evenly. Then the materials were placed into a twin-screw extruder, melt-blended, and extruded into granules to obtain an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material.

[0036] Comparative Example 1 (1) Add starch and sodium hydroxide to ethanol solvent, add chloroacetic acid at 50 °C, and react for 1 h to obtain carboxymethyl starch.

[0037] (2) 100 parts of high-density polyethylene, 5 parts of carboxymethyl starch, and 0.5 parts of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The materials were then placed in a twin-screw extruder for melt blending and extrusion granulation to obtain a starch-modified polyethylene composite material.

[0038] Comparative Example 2 (1) Add starch and sodium hydroxide to ethanol solvent, add chloroacetic acid at 40 °C, and react for 2 h to obtain carboxymethyl starch.

[0039] (2) Add 100 parts by weight of carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add 25 parts of N-hydroxysuccinimide and 70 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, activate at 15°C for 20 min, then add 150 parts of diaminophosphaphenanthrene derivative, react for 48 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch.

[0040] (3) 100 parts of high-density polyethylene, 2 parts of amino-terminated phosphorus starch, and 0.8 parts of antioxidant 1010 were added into a high-speed mixer and mixed evenly. Then the materials were placed into a twin-screw extruder, melt-blended, and extruded into granules to obtain a starch-modified polyethylene composite material.

[0041] The amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material was pressed into a strip specimen with a specification of 8 cm×0.5 cm×0.5 cm. The tensile strength of the specimen was tested using a tensile testing machine based on GB / T 1040.1-2018 as the standard.

[0042]

[0043] The amino-terminated phosphorus-containing starch modified polyethylene flame retardant composite material was made into a sheet film sample of 1 cm×1 cm×0.2 cm, and the limiting oxygen index was tested by HC-2 oxygen index tester according to GB / T 2406.1-2008 standard.

[0044]

Claims

1. A method for preparing a flame-retardant polyethylene composite material modified with amino-terminated phosphorus-containing starch, characterized in that: The preparation method comprises the following steps: (1) Add starch and sodium hydroxide to an ethanol solvent, add chloroacetic acid at 35-50 °C, and react for 1-2 h to obtain carboxymethyl starch; (2) Add carboxymethyl starch to dimethyl sulfoxide solvent, heat and stir to dissolve, then add N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, activate at 15-40 °C for 10-30 min, then add diaminophosphaphenanthrene derivative, react for 24-48 h, add distilled water after the reaction for precipitation, filter, wash with deionized water and dichloromethane and dry to obtain amino-terminated phosphorus starch; (3) Adding amino-terminated phosphorus-containing starch to a xylene solvent, stirring evenly, then adding a xylene solution containing maleic anhydride grafted polyethylene, dropping a catalyst of p-toluenesulfonic acid, heating to react, performing vacuum distillation after the reaction, washing with toluene and dichloromethane, and drying to obtain polyethylene grafted phosphorus-containing starch; (4) High-density polyethylene, polyethylene grafted phosphorus-containing starch, and antioxidant 1010 are added to a high-speed mixer and mixed evenly, and then the materials are placed in a twin-screw extruder, melt-blended, and extruded into granules to obtain an amino-terminated phosphorus-containing starch modified polyethylene flame-retardant composite material.

2. The method for preparing a flame-retardant polyethylene composite material modified with amino-terminated phosphorus-containing starch according to claim 1, characterized in that: In the step (2), by weight, the carboxymethyl starch is 100 parts, the N-hydroxysuccinimide is 20-55 parts, the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 70-180 parts, and the diaminophosphaphenanthrene derivative is 120-300 parts.

3. The method for preparing a flame-retardant polyethylene composite material modified with amino-terminated phosphorus-containing starch according to claim 1, characterized in that: The reaction temperature in step (3) is 120-160°C and the reaction time is 20-40 h.

4. The method for preparing a flame-retardant polyethylene composite material modified with amino-terminated phosphorus-containing starch according to claim 1, characterized in that: In the step (3), the amino-terminated phosphorus-containing starch is 100 parts, the maleic anhydride grafted polyethylene is 30-120 parts, and the p-toluenesulfonic acid is 1.5-6 parts, by weight.

5. The method for preparing a flame-retardant polyethylene composite material modified with amino-terminated phosphorus-containing starch according to claim 1, characterized in that: In the step (4), the high-density polyethylene is 100 parts and the polyethylene grafted phosphorus-containing starch is 2-10 parts by weight.

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