A kind of polypropylene composite material with weather resistance and flame retardancy and preparation method thereof

Abstract

The invention discloses a polypropylene composite material with weather resistance and flame retardancy and a preparation method thereof, and belongs to the field of thermoplastic high molecular polymer materials. The invention comprises the following steps: a benzyl-containing hindered phenol antioxidant, bromine and a free radical initiator react to obtain a brominated hindered phenol antioxidant; the brominated hindered phenol antioxidant reacts with an amino-terminated organosiloxane to obtain a hindered phenol-organosiloxane; hindered phenol-organosiloxane, a carbon-carbon double bond-terminated organosiloxane and an organic weak acid react to obtain a carbon-carbon double bond-terminated hindered phenol-organosiloxane; hindered phenol-organosiloxane and propylene are polymerized under the action of a composite catalyst to obtain a polypropylene composite material. The invention directly introduces a functional group with flame retardancy and antioxidant properties into the main chain of polypropylene by covalent crosslinking during the preparation process of polypropylene, and then polymerizes to obtain a polypropylene composite material with weather resistance and flame retardancy.

Description

Technical Field

[0001] The invention belongs to the field of thermoplastic high molecular polymer materials, and in particular relates to a polypropylene composite material with weather resistance and flame retardancy and a preparation method thereof. Background Art

[0002] In modern life, polymer materials are everywhere. Plastics, rubbers, fibers, coatings, adhesives, etc. are widely used in the fields of construction, electronics, automobiles, decoration and food packaging. The development of polymer materials has become one of the important foundations of modern economic construction and scientific and technological development. Polypropylene (PP) is a thermoplastic polymer polymerized from propylene monomers. It is widely used in fields such as furniture and daily necessities, pipeline materials, automotive materials, food packaging and building materials because of its excellent processing properties (excellent mechanical properties and good toughness), excellent chemical stability (acid and alkali corrosion resistance), good shock absorption performance, excellent wear resistance and low price. The wide application of polypropylene materials has provided great convenience for our production and life. However, since the oxygen index of polypropylene is only about 18%, it belongs to the category of flammable materials. It has defects such as flammability and easy oxidation. In the event of a fire, polypropylene is very flammable. A large amount of heat will be released during the combustion process, and there will be serious molten droplets. The molten droplets with flames are very likely to cause secondary fires, which will cause us significant loss of life and property. Therefore, improving the weather resistance and flame retardancy of polypropylene materials is of great significance to improving the application safety and durability of polypropylene materials. In the prior art, the weather resistance and flame retardancy of polypropylene materials are mostly improved by putting antioxidants, flame retardants and polypropylene materials into plastic processing equipment, and preparing weather-resistant and flame-retardant polypropylene materials through processing processes such as blending, granulation and molding.

[0003] Patent CN115477811A discloses a polypropylene composition for highly weather-resistant and flame-retardant injection molding materials and a polypropylene injection molding material. The invention uses polypropylene, fluorine-containing silane, flame retardant, anti-copper harm agent, processing aid and antioxidant as raw materials. Through the interaction of polypropylene, fluorine-containing silane, flame retardant and antioxidant, the flame retardancy and weather resistance of the polypropylene injection molding material are improved.

[0004] Patent CN102627805A discloses an environmentally friendly highly flame-retardant and highly weather-resistant polypropylene. The invention uses copolymer polypropylene and / or homopolymer polypropylene as raw materials, and mixes and processes them by adding flame retardants, anti-ultraviolet absorbers, light stabilizers, antioxidants, anti-copper damage agents and processing aids. The interaction between halogen-free environmentally friendly flame retardants and anti-ultraviolet absorbers and light stabilizers improves the weather resistance and flame retardancy of polypropylene materials.

[0005] Patent CN108976591A discloses a method for preparing highly weather-resistant and flame-retardant polypropylene masterbatch. The invention mixes a homemade weathering agent with polypropylene, color powder, phosphorus-based flame retardant, fumed silica, and antioxidant to form granules. The weathering agent is modified and loaded, and the interaction between fumed silica, phosphorus-based flame retardant, and antioxidant is combined to improve the weather resistance and flame retardancy of the polypropylene masterbatch.

[0006] Patent CN116120660A discloses a highly weather-resistant flame-retardant reinforced polypropylene composite material and a preparation method thereof. The invention uses a polypropylene modified flame-retardant masterbatch prepared by mixing polypropylene, microencapsulated flame retardant, flame retardant synergist, weathering agent and processing aid with a long glass fiber reinforced polypropylene masterbatch prepared by mixing polypropylene, glass fiber, compatibilizer and processing aid, and extrudes the halogen flame retardant. The halogenated flame retardant is modified by microencapsulation. Even if the flame retardant system after microencapsulation decomposes to produce acidic substances during use, it will be coated in the local environment and will not come into contact with the hindered amine light stabilizer, so that the light stabilizer continues to play a good anti-ultraviolet and weathering effect, effectively protecting the polypropylene matrix, thereby achieving the weather resistance and flame retardancy of the polypropylene material.

[0007] The above methods for improving the weather resistance and flame retardancy of polypropylene are all achieved by mixing polypropylene with corresponding flame retardants and antioxidants. This modification method is prone to produce adverse reactions with polypropylene at high temperatures during mixed extrusion due to the amount of flame retardants and antioxidants used, resulting in the breakage of the molecular chains of polypropylene and the reduction of the mechanical properties and thermal stability of polypropylene materials.

[0008] Therefore, by modifying the monomers used to synthesize polypropylene, a polypropylene composite material with weather resistance and flame retardancy is obtained by polymerization, which can not only achieve the weather resistance and flame retardancy of polypropylene, but also avoid the defect of adverse reaction with polypropylene due to the additional addition of flame retardants and antioxidants. Summary of the invention

[0009] In view of the deficiencies of the prior art, the present invention directly introduces flame retardant and antioxidant functional groups into the main chain of polypropylene by covalent crosslinking during the preparation of polypropylene, and then obtains a polypropylene composite material with weather resistance and flame retardant properties by polymerization. Specifically, the technical solution of the present invention includes the following contents:

[0010] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, the preparation method comprising the following steps:

[0011] The benzyl hindered phenol antioxidant is dried and introduced into a reaction kettle filled with a chlorine-containing solvent, and then bromine and a free radical initiator are introduced into the reaction kettle for mixing and stirring, the reaction kettle is closed and the air inside the reaction kettle is replaced with an inert gas, and then heated to 60° C. to 80° C. for reaction for 5 h to 10 h to obtain a brominated hindered phenol antioxidant;

[0012] The brominated hindered phenol antioxidant, amino-terminated organosiloxane and anhydrous tetrahydrofuran are mixed in a mass ratio of 1:1-2:3-4, heated to 40°C-50°C, and refluxed for 3h-5h to obtain hindered phenol-organosiloxane;

[0013] The hindered phenol-organosiloxane, the carbon-carbon double bond-terminated organosiloxane and the organic weak acid are mixed in a mass ratio of 1:2-3:0.1-0.2, and then hydrolyzed at 50°C-60°C for 30min-50min and condensed at 90°C-110°C for 20min-30min to obtain the carbon-carbon double bond-terminated hindered phenol-organosiloxane;

[0014] Add the composite catalyst to the hindered phenol-organosiloxane, and then add 0.1 to 0.5 m 3 Propylene is introduced at a ventilation rate of / h and heated to 50°C to 70°C for reaction for 10h to 15h to obtain the polypropylene composite material.

[0015] Furthermore, the benzyl-containing hindered phenol antioxidant includes 2,6-di-tert-butyl-p-ethylphenol or 2,2'-methylenebis(6-tert-butyl-4-methylphenol).

[0016] Furthermore, the chlorine-containing solvent includes chlorobenzene or chloroform.

[0017] Furthermore, the free radical initiator includes benzoyl peroxide, diisopropylbenzene peroxide or methyl ethyl ketone peroxide. The purpose of the free radical initiator is to generate free radicals under a heating environment to initiate the homolytic cleavage of bromine, and then to undergo a free radical substitution reaction with the hydrogen on the benzyl carbon of the benzyl hindered phenol antioxidant.

[0018] Furthermore, the mass ratio of the benzyl-containing hindered phenol antioxidant: the chlorine-containing solvent: bromine: the free radical initiator is 1:2-3:1:0.1-0.3.

[0019] Furthermore, the inert gas includes helium or argon. The purpose of introducing the inert gas is to exhaust oxygen in the air and prevent oxygen from decomposing bromine.

[0020] Furthermore, the amino-terminated organosiloxane includes 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane or γ-aminopropylmethyldiethoxysilane, the carbon-carbon double bond-terminated organosiloxane includes dimethoxymethylvinylsilane, vinyltrimethoxysilane or vinyltriethoxysilane, the nitrogen atom of the amino-terminated organosiloxane acts as a nucleophilic reagent to attack the carbon atom connected to the bromine atom in the brominated hindered phenol antioxidant, thereby replacing the chlorine atom, and the carbon-carbon double bond-terminated organosiloxane is used to provide a carbon-carbon double bond for polymerization reaction with propylene.

[0021] Furthermore, the organic weak acid includes acetic acid or propionic acid.

[0022] Furthermore, the composite catalyst is composed of a metallocene catalyst and triethylaluminum mixed in a mass ratio of 1:7-9. The metallocene catalyst reacts with triethylaluminum to remove a ligand of the metallocene to activate the metal. After activation, an activated coordination complex is formed with the carbon-carbon double bond, thereby initiating a polymerization reaction.

[0023] Furthermore, the metallocene catalyst includes titanocene dichloride or zirconocene dichloride.

[0024] Furthermore, the mass ratio of the hindered phenol-organosiloxane:composite catalyst is 1:0.008-0.01.

[0025] A polypropylene composite material is prepared by a method for preparing a polypropylene composite material with weather resistance and flame retardancy.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention first modifies a benzyl-containing hindered phenol antioxidant, thereby introducing a functional group bromine group to obtain a brominated hindered phenol antioxidant, and then using the property that the carbon atom connected to the bromine group is easily attacked by a nucleophilic reagent to introduce siloxane into the brominated hindered phenol antioxidant through a nucleophilic reaction using an amino-terminated organosiloxane to replace the bromine atom to obtain a hindered phenol-organosiloxane, and then using the organosiloxane hydrolysis to generate Si-OH bonds, and introducing a carbon-carbon double bond-terminated organosiloxane into the hindered phenol-organosiloxane through condensation between the Si-OH bonds to obtain a carbon-carbon double bond-terminated hindered phenol-organosiloxane, and then under the action of a composite catalyst, the carbon-carbon double bond-terminated hindered phenol-organosiloxane is mixed with propylene to react to obtain a polypropylene composite material with weather resistance and flame retardancy. The invention utilizes the high bond energy of the silicon-oxygen bond and has thermal stability at high temperature, so that the prepared polypropylene composite material has a thermally stable structure. Then the silicon-oxygen bond at high temperature can form a silicon-oxygen compound layer (such as a silicon dioxide layer). The protective layer can isolate oxygen and heat and prevent oxidation reactions during combustion. The polypropylene composite material containing the silicon-oxygen bond will not produce toxic and harmful gases such as chlorides, and has certain environmental protection. The phenolic hydroxyl group on the hindered phenol antioxidant has the function of releasing active hydrogen atoms and combining with other free radicals to achieve antioxidant function. The synergistic coordination achieved on the main chain structure of polypropylene is achieved by integrating the silicon-oxygen bond and the phenolic hydroxyl group. In the initial monomer polymerization stage of the synthetic polypropylene material, the polypropylene is modified, thereby improving the weather resistance and flame retardant properties of the polypropylene composite material.

[0028] (2) Through the preparation method of the present invention, since the halogen atoms are replaced, the polypropylene composite material finally obtained does not contain halogen atoms, and does not generate harmful gases such as hydrogen chloride at high temperatures. In addition, the polypropylene composite material exhibits good impact strength and tensile strength in mechanical properties. While achieving weather resistance and flame retardancy, the mechanical properties are also optimized. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0031] Embodiment 1:

[0032] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0033] 2 kg of chlorobenzene was poured into the reactor, and then 1 kg of 2,6-di-tert-butyl-p-ethylphenol was dried in a 60°C vacuum drying oven and then introduced into the reactor to stir and dissolve, and then 1 kg of bromine and 100 g of benzoyl peroxide were introduced into the reactor to mix and stir evenly with 2,6-di-tert-butyl-p-ethylphenol, the reactor was closed, and the air in the reactor was purged with helium until the oxygen content inside the reactor was detected to be less than 0.5% by the oxygen content monitor, and the purging was stopped. At this time, the reactor was heated to 60°C and the reaction was timed at this temperature for 5 hours. After the reaction was completed, chlorobenzene was removed by vacuum distillation to obtain brominated 2,6-di-tert-butyl-p-ethylphenol.

[0034] Weigh 1 kg of brominated 2,6-di-tert-butyl-p-ethylphenol, 1 kg of 3-aminopropyltrimethoxysilane and 3 kg of anhydrous tetrahydrofuran, mix and stir evenly, heat to 40° C. and reflux for 3 hours, then distill off the anhydrous tetrahydrofuran to obtain 2,6-di-tert-butyl-p-ethylphenol-organosiloxane.

[0035] Place the flask in a constant temperature water bath at 50°C, then take 1kg of 2,6-di-tert-butyl-p-ethylphenol-organosiloxane, 2kg of dimethoxymethylvinylsilane and 100g of acetic acid, mix them, then add 1kg of deionized water and stir to react for 30 minutes. After the reaction is completed, continue to heat to 90°C and react for 20 minutes to obtain 2,6-di-tert-butyl-p-ethylphenol-organosiloxane terminated with a carbon-carbon double bond. Take part of the carbon-carbon double bond terminated 2,6-di-tert-butyl-p-ethylphenol-organosiloxane and mix with dichloromethane, then add red-brown bromine water, and observe that the red-brown color fades, indicating that the carbon-carbon double bond termination is successfully constructed.

[0036] 1 kg of carbon-carbon double bond-terminated 2,6-di-tert-butyl-p-ethylphenol-organosiloxane was placed in a reactor and a composite catalyst consisting of 1 g of dichlorobis(pentyl)titaniacin and 7 g of triethylaluminum was added. 3 Propylene was introduced into the reactor at a ventilation rate of / h to polymerize with 2,6-di-tert-butyl-p-ethylphenol-organosiloxane terminated with a carbon-carbon double bond in an environment of 50°C for 10 hours. After the reaction, the solution in the reactor was poured into a cold methanol solution to precipitate, and then filtered and dried to obtain a polypropylene composite material.

[0037] Embodiment 2:

[0038] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0039] 2 kg of chlorobenzene was poured into the reactor, and then 1 kg of 2,6-di-tert-butyl-p-ethylphenol was dried in a 60°C vacuum drying oven and then introduced into the reactor to stir and dissolve, and then 1 kg of bromine and 200 g of benzoyl peroxide were introduced into the reactor to mix and stir evenly with 2,6-di-tert-butyl-p-ethylphenol, the reactor was closed, and the air in the reactor was purged with helium until the oxygen content inside the reactor was detected to be less than 0.5% by the oxygen content monitor, and the purging was stopped. At this time, the reactor was heated to 65°C and the reaction was timed at this temperature for 6 hours. After the reaction was completed, chlorobenzene was removed by vacuum distillation to obtain brominated 2,6-di-tert-butyl-p-ethylphenol.

[0040] Weigh 1 kg of brominated 2,6-di-tert-butyl-p-ethylphenol, 1.5 kg of 3-aminopropyltrimethoxysilane and 3 kg of anhydrous tetrahydrofuran, mix and stir evenly, heat to 40° C. and reflux for 4 hours, then distill off the anhydrous tetrahydrofuran to obtain 2,6-di-tert-butyl-p-ethylphenol-organosiloxane.

[0041] Place the flask in a constant temperature water bath at 50°C, then take 1kg of 2,6-di-tert-butyl-p-ethylphenol-organosiloxane, 2kg of vinyl trimethoxysilane and 150g of acetic acid, mix them, then add 1kg of deionized water, mix and stir for 35 minutes, and continue to heat to 95°C for 20 minutes after the reaction to obtain 2,6-di-tert-butyl-p-ethylphenol-organosiloxane terminated with a carbon-carbon double bond. Take part of the carbon-carbon double bond terminated 2,6-di-tert-butyl-p-ethylphenol-organosiloxane, mix and stir with dichloromethane, and then add red-brown bromine water to it, and observe that the red-brown color fades, indicating that the carbon-carbon double bond termination is successfully constructed.

[0042] 1 kg of carbon-carbon double bond-terminated 2,6-di-tert-butyl-p-ethylphenol-organosiloxane was placed in a reactor and a composite catalyst consisting of 1 g of dichlorobis(pentyl)titaniacin and 7 g of triethylaluminum was added. 3 Propylene was introduced into the reactor at a ventilation rate of / h to polymerize with 2,6-di-tert-butyl-p-ethylphenol-organosiloxane terminated with a carbon-carbon double bond in an environment of 55°C for 12 hours. After the reaction, the solution in the reactor was poured into a cold methanol solution to precipitate, and then filtered and dried to obtain a polypropylene composite material.

[0043] Embodiment 3:

[0044] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0045] 2.5 kg of chlorobenzene was poured into the reactor, and then 1 kg of 2,6-di-tert-butyl-p-ethylphenol was dried in a 60°C vacuum drying oven and then introduced into the reactor to stir and dissolve, and then 1 kg of bromine and 200 g of diisopropylbenzene peroxide were introduced into the reactor to mix and stir evenly with 2,6-di-tert-butyl-p-ethylphenol, the reactor was closed, and the air in the reactor was purged with helium until the oxygen content inside the reactor was detected to be less than 0.5% by the oxygen content monitor, and the purging was stopped. At this time, the reactor was heated to 70°C and the reaction was timed at this temperature for 8 hours. After the reaction was completed, chlorobenzene was removed by vacuum distillation to obtain brominated 2,6-di-tert-butyl-p-ethylphenol.

[0046] Weigh 1 kg of brominated 2,6-di-tert-butyl-p-ethylphenol, 1.5 kg of 3-aminopropyltriethoxysilane and 3.5 kg of anhydrous tetrahydrofuran, mix and stir evenly, heat to 45° C. and reflux for 4 hours, then distill off the anhydrous tetrahydrofuran to obtain 2,6-di-tert-butyl-p-ethylphenol-organosiloxane.

[0047] Place the flask in a constant temperature water bath at 55°C, then take 1kg of 2,6-di-tert-butyl-p-ethylphenol-organosiloxane, 2.5kg of vinyl trimethoxysilane and 150g of propionic acid, mix them, then add 1kg of deionized water, mix and stir for 40min, and continue to heat to 100°C after the reaction for 25min to obtain 2,6-di-tert-butyl-p-ethylphenol-organosiloxane terminated with a carbon-carbon double bond. Take part of the 2,6-di-tert-butyl-p-ethylphenol-organosiloxane terminated with a carbon-carbon double bond, mix and stir with dichloromethane, then add red-brown bromine water, and observe that the red-brown color fades, indicating that the carbon-carbon double bond termination is successfully constructed.

[0048] 1 kg of carbon-carbon double bond-terminated 2,6-di-tert-butyl-p-ethylphenol-organosiloxane was placed in a reactor and a composite catalyst consisting of 1 g of dichlorobis(pentyl)titaniacin and 8 g of triethylaluminum was added. 3 Propylene was introduced into the reactor at a ventilation rate of / h to polymerize with 2,6-di-tert-butyl-p-ethylphenol-organosiloxane terminated with a carbon-carbon double bond in an environment of 60°C for 14 hours. After the reaction, the solution in the reactor was poured into a cold methanol solution to precipitate, and then filtered and dried to obtain a polypropylene composite material.

[0049] Embodiment 4:

[0050] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0051] Pour 2.5 kg of chloroform into the reactor, then dry 1 kg of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) in a 60°C vacuum oven and introduce it into the reactor to stir and dissolve, then introduce 1 kg of bromine and 200 g of methyl ethyl ketone peroxide into the reactor and mix and stir evenly with 2,2'-methylenebis(6-tert-butyl-4-methylphenol), close the reactor, purge the air in the reactor with argon until the oxygen content inside the reactor is detected to be lower than 0.5% by the oxygen content monitor, stop purge, heat the reactor to 75°C and time the reaction at this temperature for 9 hours. After the reaction is completed, remove chlorobenzene by vacuum distillation to obtain brominated 2,2'-methylenebis(6-tert-butyl-4-methylphenol).

[0052] Weigh 1 kg of brominated 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 1.5 kg of γ-aminopropylmethyldiethoxysilane and 4 kg of anhydrous tetrahydrofuran, mix and stir evenly, heat to 50°C and reflux for 4 hours, then distill off the anhydrous tetrahydrofuran to obtain 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane.

[0053] Place the flask in a constant temperature water bath at 55°C, then take 1kg of 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane, 2.5kg of vinyl triethoxysilane and 200g of propionic acid, mix, then add 1kg of deionized water, mix and stir for 45min, and continue to heat to 105°C for 25min to obtain carbon-carbon double bond terminated 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane. Take part of the carbon-carbon double bond terminated 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane and mix and stir with dichloromethane, then add red-brown bromine water, and observe that the red-brown color fades, indicating that the carbon-carbon double bond termination is successfully constructed.

[0054] 1 kg of carbon-carbon double bond-terminated 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane was placed in a reaction kettle and a composite catalyst consisting of 1 g of zirconium and 8 g of triethylaluminum was added. 3 Propylene was introduced into the reactor at a ventilation rate of 1000 g / h and polymerized with 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane terminated with a carbon-carbon double bond at 65°C for 14 hours. After the reaction, the solution in the reactor was poured into a cold methanol solution to precipitate, and then filtered and dried to obtain a polypropylene composite material.

[0055] Embodiment 5:

[0056] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0057] Pour 3kg of chloroform into the reactor, then dry 1kg of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) in a 60℃ vacuum oven and introduce it into the reactor to stir and dissolve, then introduce 1kg of bromine and 300g of methyl ethyl ketone peroxide into the reactor and mix and stir evenly with 2,2'-methylenebis(6-tert-butyl-4-methylphenol), close the reactor, purge the air in the reactor with argon until the oxygen content in the reactor is detected by the oxygen content monitor to be less than 0.5%, stop purge, heat the reactor to 80℃ and time the reaction at this temperature for 10h. After the reaction is completed, remove chlorobenzene by vacuum distillation to obtain brominated 2,2'-methylenebis(6-tert-butyl-4-methylphenol).

[0058] Weigh 1 kg of brominated 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2 kg of γ-aminopropylmethyldiethoxysilane and 4 kg of anhydrous tetrahydrofuran, mix and stir evenly, heat to 50°C and reflux for 5 hours, then distill off the anhydrous tetrahydrofuran to obtain 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane.

[0059] Place the flask in a constant temperature water bath at 60°C, then take 1kg of 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane, 3kg of vinyl triethoxysilane and 200g of propionic acid, mix, then add 1kg of deionized water, mix and stir for 50min, and after the reaction, continue to heat to 110°C and react for 30min to obtain carbon-carbon double bond terminated 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane. Take part of the carbon-carbon double bond terminated 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane and mix and stir with dichloromethane, then add red-brown bromine water, and observe that the red-brown color fades, indicating that the carbon-carbon double bond termination is successfully constructed.

[0060] 1 kg of carbon-carbon double bond-terminated 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane was placed in a reaction kettle and a composite catalyst consisting of 1 g of zirconium and 9 g of triethylaluminum was added at 0.5 m 3 Propylene was introduced into the reactor at a ventilation rate of 1000 g / h and polymerized with 2,2'-methylenebis(6-tert-butyl-4-methylphenol)-organosiloxane terminated with a carbon-carbon double bond at 70°C for 15 hours. After the reaction, the solution in the reactor was poured into a cold methanol solution to precipitate, which was then filtered and dried to obtain a polypropylene composite material.

[0061] Comparative Example 1:

[0062] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0063] The benzyl-containing hindered phenol antioxidant 2,2'-methylenebis(6-tert-butyl-4-methylphenol) in Example 5 was replaced with 2,6-di-tert-butyl-p-methylphenol, and the other conditions were kept the same as in Example 5.

[0064] Comparative Example 2:

[0065] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0066] The benzyl hindered phenol antioxidant 2,2'-methylenebis(6-tert-butyl-4-methylphenol) in Example 5 was substituted for the benzyl hindered phenol antioxidant 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate n-octadecyl alcohol ester, and the other conditions were kept the same as in Example 5.

[0067] Comparative Example 3:

[0068] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0069] 1 kg of vinyl triethoxysilane was placed in a reactor containing 3 kg of anhydrous tetrahydrofuran and a composite catalyst consisting of 1 g of zirconium and 9 g of triethylaluminum was added. 3 Propylene was introduced into the reactor at a ventilation rate of / h to polymerize with vinyltriethoxysilane at 70°C for 15h. After the reaction, the solution in the reactor was poured into a cold methanol solution to precipitate, which was then filtered and dried to obtain a polypropylene composite material.

[0070] Comparative Example 4:

[0071] A method for preparing a polypropylene composite material with weather resistance and flame retardancy, specifically comprising the following preparation process:

[0072] 1 kg of dimethoxymethylvinylsilane, 1 kg of vinyltrimethoxysilane and 1 kg of vinyltriethoxysilane were placed in a reactor containing 6 kg of anhydrous tetrahydrofuran, and a composite catalyst composed of 3 g of zirconium and 25 g of triethylaluminum was added. 3 Propylene was introduced into the reactor at a ventilation rate of / h to polymerize with vinyltriethoxysilane at 70°C for 15h. After the reaction, the solution in the reactor was poured into a cold methanol solution to precipitate, which was then filtered and dried to obtain a polypropylene composite material.

[0073] Although the introduction of carbon-carbon double bond terminated organosiloxane alone can improve the flame retardant properties of polypropylene materials, the improvement effect is not obvious. Further increasing the amount of carbon-carbon double bond terminated organosiloxane and the amount of composite catalyst does not improve much, and the weather resistance and mechanical properties of the polypropylene composite material are also poor.

[0074] The oxygen index OI of the polypropylene composite materials obtained in Examples 1 to 5 and Comparative Examples 1 to 4 was determined according to the standard of "GB / T2406.2-2009 Determination of Combustion Behavior by Oxygen Index Method for Plastics"; the impact strength and tensile strength of the polypropylene composite materials obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were determined according to "GB / T1843-2008 Determination of Izod Impact Strength of Plastics" and "GB / T1040.1-2018 Determination of Tensile Properties of Plastics", and the results are shown in Table 1:

[0075] Table 1 Test results of impact strength and tensile strength

[0076] Sources Oxygen index OI (%) <![CDATA[Impact strength (J / m 2 )]]> Tensile strength(MPa) Example 1 23.3 6317.6 36 Example 2 29.8. 6651.3 43 Example 3 33.5 7208.2 51 Example 4 35.4 7441.4 56 Example 5 36.2 7501.8 58 Comparative Example 1 16.2 3421.5 23 Comparative Example 2 20.1 3564.3 27 Comparative Example 3 22.8 3528.1 28 Comparative Example 4 24.5 3784.5 31

[0077] The polypropylene composite materials obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were irradiated with a UV-313 ultraviolet lamp for 100 hours, and then the impact strength and tensile strength were measured in accordance with "GB / T1843-2008 Determination of Izod Impact Strength of Plastics" and "GB / T1040.1-2018 Determination of Tensile Properties of Plastics", respectively. The results are shown in Table 2:

[0078] Table 2 Test results of impact strength and tensile strength after irradiation with UV-313 ultraviolet lamp

[0079]

[0080]

[0081] From the above experimental results, we can see that:

[0082] (1) It can be seen from Examples 1 to 5 that the polypropylene composite material prepared by the preparation method of the present invention not only has good weather resistance and flame retardancy, but also has good mechanical properties of impact strength and tensile strength, and still has good impact strength retention rate and tensile strength retention rate after UV aging treatment.

[0083] (2) From Comparative Example 1, it can be concluded that since the antioxidant 2,6-di-tert-butyl-p-methylphenol has no benzyl group, bromine atoms cannot be introduced, and the subsequent nucleophilic substitution reaction cannot occur, so the hindered phenol antioxidant cannot be introduced into polypropylene through polymerization reaction, and finally the weather resistance and flame retardant effect of the synthesized polypropylene composite material are poor; from Comparative Example 2, it can be concluded that since the side containing the benzyl group has a long carbon chain of octadecane, the steric hindrance of the molecules participating in the reaction is increased, the reaction activity is reduced, resulting in the synthesized polypropylene composite material carrying less antioxidant active components and flame retardant structure, and the weather resistance and flame retardant effect are poor. By comparing Example 5 with Comparative Examples 1 and 2, it can be concluded that the benzyl-containing hindered phenol antioxidant used in the present invention has specific selectivity in chemical structure.

[0084] (3) It can be seen from Comparative Examples 3 and 4 that although the introduction of carbon-carbon double bond-terminated organosiloxane alone can improve the flame retardant properties of the polypropylene material, the improvement effect is not obvious. Further increasing the amount of carbon-carbon double bond-terminated organosiloxane and the amount of composite catalyst does not improve much, and the weather resistance and mechanical properties of the polypropylene composite material are also poor.

[0085] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit 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.

Claims

1. A method for preparing a polypropylene composite material having weather resistance and flame retardancy, characterized in that: The preparation method comprises the following steps: The benzyl hindered phenol antioxidant is dried and introduced into a reactor filled with a chlorine-containing solvent, and then bromine and a free radical initiator are introduced into the reactor for mixing and stirring, the reactor is closed and the air inside the reactor is replaced with an inert gas, and then heated to 60° C. to 80° C. for reaction for 5 h to 10 h to obtain a brominated hindered phenol antioxidant; The brominated hindered phenol antioxidant, amino-terminated organosiloxane and anhydrous tetrahydrofuran are mixed in a mass ratio of 1:1-2:3-4, heated to 40°C-50°C, and refluxed for 3h-5h to obtain hindered phenol-organosiloxane; The hindered phenol-organosiloxane, the carbon-carbon double bond-terminated organosiloxane and the organic weak acid are mixed in a mass ratio of 1:2-3:0.1-0.2, and then hydrolyzed at 50°C-60°C for 30min-50min and condensed at 90°C-110°C for 20min-30min to obtain the carbon-carbon double bond-terminated hindered phenol-organosiloxane; Adding a composite catalyst to the hindered phenol-organosiloxane, then introducing propylene at a ventilation rate of 0.1-0.5 m³ / h and heating to 50° C.-70° C. for a reaction of 10-15 hours to obtain the polypropylene composite material; The composite catalyst is composed of a mixture of a metallocene catalyst and triethylaluminum in a mass ratio of 1:7-9.

2. The method for preparing a weather-resistant and flame-retardant polypropylene composite material according to claim 1, characterized in that: The benzyl-containing hindered phenol antioxidant includes 2,6-di-tert-butyl-p-ethylphenol or 2,2'-methylenebis(6-tert-butyl-4-methylphenol).

3. The method for preparing a weather-resistant and flame-retardant polypropylene composite material according to claim 1, characterized in that: The chlorinated solvent includes chlorobenzene or chloroform.

4. The method for preparing a weather-resistant and flame-retardant polypropylene composite material according to claim 1, characterized in that: The free radical initiator includes benzoyl peroxide, dicumyl peroxide or methyl ethyl ketone peroxide.

5. The method for preparing a weather-resistant and flame-retardant polypropylene composite material according to claim 1, characterized in that: The mass ratio of the benzyl-containing hindered phenol antioxidant: the chlorine-containing solvent: bromine: the free radical initiator is 1:2-3:1:0.1-0.

3.

6. The method for preparing a weather-resistant and flame-retardant polypropylene composite material according to claim 1, characterized in that: The amino-terminated organosiloxane includes 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane or γ-aminopropylmethyldiethoxysilane, and the carbon-carbon double bond-terminated organosiloxane includes dimethoxymethylvinylsilane, vinyltrimethoxysilane or vinyltriethoxysilane.

7. The method for preparing a weather-resistant and flame-retardant polypropylene composite material according to claim 1, characterized in that: The organic weak acid includes acetic acid or propionic acid.

8. The method for preparing a weather-resistant and flame-retardant polypropylene composite material according to claim 1, characterized in that: The mass ratio of the hindered phenol-organosiloxane:composite catalyst is 1:0.008-0.

01.

9. A polypropylene composite material prepared by the method for preparing a polypropylene composite material having weather resistance and flame retardancy according to any one of claims 1 to 8.

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