Preparation method and application of flame-retardant polypropylene material

Abstract

The invention relates to the technical field of high polymer material modification, in particular to a preparation method and application of a flame-retardant polypropylene material, and the method comprises the following steps: performing modification treatment on chitosan through phosphorylation reaction to obtain a phosphoric acid modified chitosan flame retardant; and mixing the phosphoric acid modified chitosan flame retardant with a specified solvent, and then adding a soluble metal salt solution to carry out pyrohydrolysis reaction. The phosphorus flame retardant chitosan is used for modification treatment to prepare a phosphoric acid chitosan precursor, the modified phosphoric acid chitosan is intercalated between layered double hydroxides to obtain the phosphorus and nitrogen synergistic composite flame retardant modifier, and the modifier is used for flame retardant modification of polypropylene in a blending addition manner, so that the flame retardant property of the polypropylene is improved, and the flame retardant property of the polypropylene is improved. Therefore, the flame retardant property of the material is effectively improved, the problem that a flame retardant of a common flame-retardant polypropylene material is easy to separate out can be solved, and the influence of precipitates on the appearance and the harm caused by human health in the application process are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material modification, in particular to a preparation method of a flame retardant polypropylene material and application thereof. Background Art

[0002] The range hood is a kitchen appliance that purifies the kitchen environment. It can quickly extract the oil smoke that is harmful to the human body during the cooking process and discharge it outdoors, reducing indoor pollution. It also has anti-toxic and explosion-proof safety protection functions. The impeller is the key component of the range hood to extract oil smoke. Its main function is to generate negative pressure through rotation to extract the oil smoke generated in the kitchen. The materials of the range hood impeller are generally divided into metal and plastic. The metal impeller is more durable, but the noise is louder than the plastic impeller and the price is higher. The plastic impeller has relatively low noise and lower cost. Common plastic impeller materials include ABS (acrylonitrile-butadiene-styrene copolymer) and PP (polypropylene). Due to the presence of open flames and high temperatures in the cooking environment, most of the plastic materials in the range hood need to meet non-flammable or flame retardant requirements. For the flame retardant modification of PP, a flame retardant modifier of a certain amount of halogen flame retardant or phosphorus flame retardant is usually added to the raw material, and then a flame retardant impeller is obtained through injection molding.

[0003] However, flame-retardant modified plastics prepared directly by blending usually have defects such as excessive flame retardant dosage and reduced mechanical properties of materials due to poor interface compatibility between flame retardants and plastic substrates. In addition, the organic flame retardant inside the material is easy to decompose and precipitate under high temperature and high humidity conditions, which not only reduces the flame retardant performance, but also causes white spots, white lines, white circles and other problems on the surface of the material, which not only affects the appearance of the impeller, but the precipitated small molecules of flame retardants can also cause harm to human health. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a preparation method of a flame retardant polypropylene material and application thereof.

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing a flame retardant polypropylene material, the method comprising:

[0006] The chitosan is modified by phosphorylation reaction to obtain a phosphoric acid-modified chitosan flame retardant;

[0007] The phosphoric acid-modified chitosan flame retardant is mixed with a specified solvent, and then a soluble metal salt solution is added to perform a thermal hydrolysis reaction to obtain a composite flame retardant modifier;

[0008] The polypropylene material, the composite flame retardant modifier, the antioxidant, the toughening agent and the compatibilizer are vacuum dried, mixed and extruded to obtain the flame retardant polypropylene material.

[0009] In combination with the first aspect, the step of modifying chitosan by phosphorylation to obtain a phosphoric acid-modified chitosan flame retardant comprises:

[0010] Chitosan was added to a methanesulfonic acid solution at a reaction temperature of 0 to 5°C, and then a phosphoric acid activator was added, and the mixture was mechanically stirred and reacted for 2 to 4 hours under a nitrogen atmosphere.

[0011] Add a certain amount of peroxide initiator and phosphorus flame retardant to the mixed solution, start stirring, and fully react at 30-50°C for 2-5h;

[0012] The product is precipitated with ether, then washed, filtered, and vacuum dried at 60-80° C. for 12-24 hours to obtain a phosphoric acid-modified chitosan flame retardant.

[0013] In combination with the first aspect, the phosphoric acid modified chitosan flame retardant is prepared by including the following raw materials in parts by weight: 5-10 parts of phosphoric acid activator, 5-10 parts of peroxide initiator, 30-45 parts of phosphorus flame retardant, 5-15 parts of ether, and the concentration of methane sulfonic acid solution is 3-8%.

[0014] In combination with the first aspect, the step of mixing the phosphoric acid-modified chitosan flame retardant with a specified solvent and then adding a soluble metal salt solution to perform a thermal hydrolysis reaction to obtain a composite flame retardant modifier comprises:

[0015] Slowly adding a certain amount of soluble divalent and trivalent metal salt solutions into a mixed solution of sodium dodecyl sulfate (SDS) and phosphoric acid-modified chitosan flame retardant;

[0016] adding an alkaline solution to the mixed solution and stirring to promote a hydrothermal reaction;

[0017] The mixed solution after the reaction is filtered, washed and vacuum dried to obtain a composite flame retardant modifier.

[0018] In combination with the first aspect, the composite flame retardant modifier is prepared by including the following raw materials in parts by weight:

[0019] 20-70 parts of trivalent metal salt, 10-30 parts of sodium dodecylbenzene sulfonate, 20-40 parts of phosphoric acid modified chitosan flame retardant, and 50-200 parts of alkaline substance.

[0020] In combination with the first aspect, the temperature of the hydrothermal reaction is 60-110° C., the time is 10-24 h, and the pH is 7-10.

[0021] In combination with the first aspect, the steps of vacuum drying the polypropylene material, the composite flame retardant modifier, the antioxidant, the toughening agent and the compatibilizer, mixing and extruding to obtain the flame retardant polypropylene material include:

[0022] In a vacuum environment, polypropylene, antioxidant, toughening agent, compatibilizer, and composite flame retardant modifier are dried;

[0023] Mix them with antioxidants in a high-speed mixer for 2-10 minutes according to a preset ratio;

[0024] Add the mixed material from the main feed port, with a rotation speed of 60-150rpm, a feed section temperature of 195-205℃, and three sections of the screw center temperature of 205-215℃, 210-220℃, and 200-210℃;

[0025] The die head temperature is between 180-200°C, and the extruder is used to extrude and granulate to obtain a flame retardant polypropylene material.

[0026] In combination with the first aspect, the flame retardant polypropylene material is prepared from the following raw materials in parts by weight: 70-95 parts of polypropylene, 0.3-4 parts of antioxidant, 0.5-4 parts of toughening agent, 3-8 parts of compatibilizer, 10-20 parts of glass fiber, and 5-15 parts of composite flame retardant modifier.

[0027] In a second aspect, the present application provides an application of a flame retardant polypropylene material, the flame retardant polypropylene material is applied to an impeller of a range hood, and the flame retardant polypropylene material is used for flame retardancy.

[0028] In combination with the second aspect, flame-retardant polypropylene materials are also used in range hoods and stoves.

[0029] The embodiments of the present invention bring the following beneficial effects: the preparation method and application of the flame-retardant polypropylene material provided in the present application, the method comprising: modifying chitosan through a phosphorylation reaction to obtain a phosphoric acid-modified chitosan flame retardant; mixing the phosphoric acid-modified chitosan flame retardant with a specified solvent and adding a soluble metal salt solution for thermal hydrolysis to obtain a composite flame-retardant modifier; vacuum drying the polypropylene material, the composite flame-retardant modifier, an antioxidant, a toughening agent and a compatibilizer, mixing and extruding to obtain a flame-retardant polypropylene material.

[0030] The present application uses a phosphorus-based flame retardant chitosan for modification to prepare a phosphate chitosan precursor, and intercalates the modified phosphate chitosan between layers of a layered double metal hydroxide to obtain a phosphorus and nitrogen synergistic composite flame retardant modifier, which is used for flame retardant modification of polypropylene by a blending and addition method, thereby effectively improving the flame retardant properties of the material, solving the problem of easy precipitation of flame retardants in ordinary flame retardant polypropylene materials, and reducing the impact of the precipitates on the appearance during the application process and the harm to human health.

[0031] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 The invention relates to a method for preparing a flame retardant polypropylene material. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are 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.

[0036] In order to facilitate the understanding of this embodiment, the technical terms designed in this application are briefly introduced below.

[0037] Layered double hydroxide (LDH) is a typical anionic layered compound, whose lamellar skeleton is composed of divalent and trivalent metal hydroxides. The lamellar layer is positively charged and has a large number of hydroxyl groups on the surface. The compensating anions and water molecules between the layers are combined with the main lamellar layer through hydrogen bonds, electrostatic forces and ionic bonds. The exchangeability of anions between LDH layers not only enables the modifier to be organically combined with LDH, but also provides advantageous conditions for its composite with the polymer matrix. In addition, when the polymer / LDH composite material is subjected to high temperature, LDH releases interlayer bound water and CO2, which plays a role in diluting oxygen and reducing the surface temperature of the polymer. In addition, the metal hydroxide of the LDH lamellar layer undergoes a special catalytic reaction with the polymer during the combustion and degradation process, forming a dense carbon layer on the surface of the composite material, thereby effectively isolating the external heat and oxygen from penetrating into the interior of the polymer, and slowing down the mass loss rate of the polymer during thermal degradation. Therefore, LDH can effectively improve the flame retardant properties of polypropylene materials as a modifier. In addition, LDH-based modifiers provide more dispersion space for flame retardants due to their high specific surface area and adjustable interlayer spacing, which helps to improve the uniformity of the dispersion of flame retardants in the substrate and avoid the aggregation and sedimentation of flame retardants, thereby improving the overall stability and performance of the modified materials and solving the problem of easy precipitation of flame retardants.

[0038] Chitosan is a natural, easily available, low-cost polysaccharide polymer that is biodegradable, biocompatible, environmentally friendly and non-toxic. Secondly, its molecular skeleton is carbon-rich and contains a certain number of side chain groups, hydroxyl and amino groups. During the thermal decomposition process, it can be carbonized in the polymer to hinder combustion, and at the same time, it will release non-toxic, non-corrosive and non-flammable gases such as CO2, NH3 and N2, thereby playing a flame retardant role. Finally, the amino and hydroxyl groups on the chitosan molecule make it highly reactive; it can be molecularly designed, and a variety of flame retardant elements can be introduced to change its physical and chemical properties, improve flame retardant efficiency, and expand its applicability.

[0039] Phosphorus-based flame retardants have the advantages of high efficiency and environmental protection. They can quickly generate phosphoric acid or polyphosphoric acid during the combustion process. These substances can not only promote the formation of a carbon layer and improve the flame retardant properties of the material, but also dilute the concentration of combustible gases, reduce the effective combustion heat, and quickly extinguish the flame. In addition, the gas released by phosphorus-based flame retardants when heated can expand to form a carbon layer, effectively isolating oxygen and heat, protecting the material from further combustion, while reducing the generation of toxic gases and improving environmental safety.

[0040] After introducing the technical terms involved in this application, the application scenarios and design concepts of the embodiments of this application are briefly introduced.

[0041] Traditional flame-retardant modified plastics usually have defects such as excessive use of flame retardants and reduced mechanical properties of materials due to poor interface compatibility. In addition, the organic flame retardants inside the material are easily decomposed and precipitated under high temperature and high humidity environments, causing the precipitated flame retardants to affect the appearance of the impeller and cause harm to human health.

[0042] Based on this, the embodiment of the present application provides a method for preparing a flame retardant polypropylene material and application thereof.

[0043] Example 1

[0044] The present application provides a method for preparing a flame retardant polypropylene material. Figure 1 As shown, the method includes:

[0045] S110, modifying chitosan through a phosphorylation reaction to obtain a phosphoric acid-modified chitosan flame retardant.

[0046] S120, mixing the phosphoric acid-modified chitosan flame retardant with a specified solvent, adding a soluble metal salt solution, and performing a thermal hydrolysis reaction to obtain a composite flame retardant modifier.

[0047] S130, vacuum drying the polypropylene material, the composite flame retardant modifier, the antioxidant, the toughening agent and the compatibilizer, mixing and extruding to obtain a flame retardant polypropylene material.

[0048] The present application uses a phosphorus-based flame retardant chitosan for modification, and intercalates the modified phosphate chitosan between the layers of a layered double metal hydroxide to obtain a composite phosphorus and nitrogen synergistic composite flame retardant modifier, which is used for flame retardant modification of polypropylene by a blending and addition method, thereby effectively improving the flame retardant properties of the material, and can solve the problem of easy precipitation of flame retardants in ordinary flame retardant polypropylene materials.

[0049] In combination with the first aspect, step S110 includes:

[0050] S111, adding chitosan to a methanesulfonic acid solution at a reaction condition of 0 to 5°C, then adding a phosphoric acid activator, and reacting with mechanical stirring for 2 to 4 hours under a nitrogen environment.

[0051] The phosphoric acid activator is one or more of H3PO4 (phosphoric acid), Et3PO4 (triethyl phosphate), P2O5 (phosphorus pentoxide) and butanol. The reaction temperature is 0°C, 2°C, 5°C, etc., and the mechanical stirring reaction time can be 2 hours, 2.5 hours, 3.2 hours, 4 hours, etc.

[0052] S112, adding a certain amount of peroxide initiator and phosphorus flame retardant to the mixed solution, starting stirring, and fully reacting at 30-50° C. for 2-5 hours.

[0053] Among them, the designated solvent in step S110 is the peroxide initiator and phosphorus flame retardant in step S112, the peroxide initiator includes dibenzoyl peroxide (BPO) or tert-butyl perbenzoate; the phosphorus flame retardant includes 2-carboxyethyl phenylphosphinic acid (CEPPA), methyl phenyl hypophosphorous acid (HMPPA), 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and other substances. In step S112, the reaction temperature can be 30°C, 40°C, 45°C, 50°C, etc., and the reaction time can be 2h, 2.5h, 3.5h, 4h, 4.5h, 5h, etc.

[0054] S113, precipitating the product with ether, then washing, filtering, and vacuum drying at 60-80° C. for 12-24 hours to obtain a phosphoric acid-modified chitosan flame retardant.

[0055] It can be understood that the reaction temperature in step S113 can be 60° C., 75° C., 80° C., etc., and the drying time can be 12 h, 18 h, 20 h, 24 h, etc.

[0056] In combination with the first aspect, the phosphoric acid modified chitosan flame retardant is prepared by including the following raw materials in parts by weight: 100 parts of chitosan, 5-10 parts of phosphoric acid activator, 5-10 parts of peroxide initiator, 30-45 parts of phosphorus flame retardant, 5-15 parts of ether, and the concentration of methane sulfonic acid solution is 3-8 parts.

[0057] In combination with the first aspect, step S120 includes:

[0058] S121, slowly adding a certain amount of soluble divalent and trivalent metal salt solutions into a mixed solution of sodium dodecyl sulfate (SDS) and phosphoric acid-modified chitosan flame retardant;

[0059] S122, adding an alkaline solution to the mixed solution and stirring to promote a hydrothermal reaction;

[0060] S123, filtering, washing, and vacuum drying the mixed solution after the reaction to obtain a composite flame retardant modifier.

[0061] Among them, the cation in the soluble divalent and trivalent metal salt solution is Cu 2+ 、Zn 2t 、Ni 2+ Mg 2+ , Fe 3+ 、Al 3+ The anion in the soluble divalent metal salt and soluble trivalent metal salt solution is NO 3- , It can be understood that the soluble divalent metal salt solution is composed of any of the above-mentioned divalent cations and divalent anions; similarly, the soluble trivalent metal salt solution is composed of any of the above-mentioned trivalent cations and trivalent anions.

[0062] In combination with the first aspect, the composite flame retardant modifier is prepared by including the following raw materials in parts by weight: 20-70 parts of trivalent metal salt, 10-30 parts of sodium dodecylbenzene sulfonate, 20-40 parts of phosphoric acid modified chitosan flame retardant, and 50-200 parts of alkaline substance.

[0063] It can be understood that the trivalent metal salt can be 20 parts, 45 parts, 60 parts, 70 parts, etc., the sodium dodecylbenzene sulfonate can be 10 parts, 20 parts, 25 parts, 30 parts, etc., the phosphoric acid modified chitosan flame retardant can be 20 parts, 30 parts, 35 parts, 40 parts, etc., the alkaline substance can be 50 parts, 60 parts, 75 parts, 105 parts, 120 parts, 150 parts, 180 parts, 200 parts, etc.

[0064] In combination with the first aspect, the temperature of the hydrothermal reaction in step S122 is 60-110°C, the time is 10-24h, and the pH is 7-10. The specific reaction temperature can be 60°C, 75°C, 80°C, 100°C, 110°C, etc., the reaction time is 10h, 15h, 18h, 20h, 24h, etc., and the pH is 7, 8.5, 9, 10, etc.

[0065] In combination with the first aspect, step S130 includes:

[0066] S131, drying the polypropylene, antioxidant, toughening agent, compatibilizer and the composite flame retardant modifier under a vacuum environment.

[0067] S132, mixing them with an antioxidant in a high-speed mixer for 2-10 minutes according to a preset ratio.

[0068] The mixing time may be 2 minutes, 5 minutes, 8 minutes, 10 minutes, etc.

[0069] S133, add the mixed material from the main material port, at a rotation speed of 60-150rpm, a temperature of the feeding section of 195-205°C, and three temperatures of the center of the screw of 205-215°C, 210-220°C, and 200-210°C.

[0070] The rotation speed can be 60rpm, 80rpm, 120rpm, 150rpm, etc., and the temperature at the unloading end can be 195℃, 200℃, 205℃, etc.

[0071] S134, the die head temperature is between 180-200°C, and the extruder is used for extrusion granulation to obtain a flame retardant polypropylene material.

[0072] The touch head temperature may be 180°C, 185°C, 190°C, 195°C, 200°C, etc.

[0073] In combination with the first aspect, the flame retardant polypropylene material is prepared from the following raw materials in parts by weight: 70-95 parts of polypropylene, 0.3-4 parts of antioxidant, 0.5-4 parts of toughening agent, 3-8 parts of compatibilizer, 10-20 parts of glass fiber, and 5-15 parts of composite flame retardant modifier.

[0074] In this embodiment, the vacuum temperature in step S131 is 40-100° C., and the drying treatment time is 1-10 hours.

[0075] The antioxidant includes pentaerythritol tetrakis[methyl-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid n-octadecanol, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)trione, triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and the like.

[0076] The toughening agent includes one of ethylene-propylene copolymer, ethylene-hexene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, styrene-butadiene-styrene copolymer, and hydrogenated styrene-butadiene-styrene copolymer.

[0077] The compatibilizer includes one or more of EVA (ethylene-vinyl acetate copolymer), EPDM (ethylene-propylene-diene monomer copolymer), and SEBS (styrene-ethylene-butadiene-styrene copolymer).

[0078] As an practicable method, under the reaction condition of 0° C., 100 parts by mass of chitosan are added to 500 parts by mass of a 5% methanesulfonic acid solution, and then 5 parts by mass of phosphorus pentoxide are added, and the reaction is carried out under a nitrogen environment with mechanical stirring for 2 hours.

[0079] Subsequently, 8 parts by weight of dibenzoyl peroxide (BPO) and 30 parts by weight of 2-carboxyethylphenylphosphinic acid (CEPPA) are added to the mixed solution, stirring is started, and the mixture is fully reacted at 30-50° C. for 2-5 hours (such as 2 hours, 3 hours, 4.5 hours, 5 hours, etc.). After the reaction is completed, 50 parts by weight of 20% ether is added to precipitate the product, which is then washed, filtered, and vacuum dried at 60° C. for 12 to 24 hours (such as 12 hours, 18 hours, 24 hours, etc.) to finally obtain a phosphoric acid-modified chitosan flame retardant.

[0080] Based on 100 parts by mass of divalent metal salt, add CuSO4 (100 parts by mass), Al2(SO4)3 (20 parts by mass), sodium dodecylbenzene sulfonate (10 parts by mass), modified chitosan flame retardant (30 parts by mass), and urea (50 parts by mass) into 5000 parts by mass of distilled water. The hydrothermal reaction was carried out under continuous stirring at 60°C and pH=7 for 10 hours. After the reaction, the product was filtered and washed with a large amount of distilled water. Finally, the composite flame retardant modifier (SDS-PCF-LDH) was obtained after vacuum drying for 12 hours.

[0081] Subsequently, polypropylene, composite flame retardant modifier, glass fiber, antioxidant (tetrakis[methyl-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester), toughening agent (ethylene-propylene copolymer), and compatibilizer (EVA (ethylene-vinyl acetate copolymer)) were vacuum dried at 40°C for 1 hour, and polypropylene, antioxidant, toughening agent, compatibilizer, glass fiber, and composite flame retardant modifier were mixed in a high-speed mixer at a mass feed ratio of 70%, 2%, 2%, 4%, 12%, and 10%, respectively, for 2 minutes, and the mixed material was added from the main feed port, and extruded into granules through an extruder. The speed of the screw extruder was 100 rpm, the temperature of the feeding section was 200°C, the temperatures of the three sections in the center of the screw were 210°C, 215°C, and 205°C, and the die temperature was 190°C, and finally a flame retardant polypropylene material was obtained.

[0082] Example 2

[0083] As an practicable method, 100 parts by mass of chitosan is added to 500 parts by mass of a 5% methanesulfonic acid solution at a reaction temperature of 3° C., and then 5 parts by mass of phosphorus pentoxide are added, and the mixture is mechanically stirred and reacted for 3.5 hours under a nitrogen environment.

[0084] Subsequently, 8 parts by mass of dibenzoyl peroxide (BPO) and 30 parts by mass of 2-carboxyethylphenylphosphinic acid (CEPPA) were added to the mixed solution, stirring was started, and the mixture was fully reacted at 30-50°C for 2-5 hours. After the reaction, 50 parts by mass of 20% ether was added to precipitate the product, which was then washed, filtered, and vacuum dried at 70°C for 22 hours to finally obtain a phosphoric acid-modified chitosan flame retardant.

[0085] Based on 100 parts by mass of divalent metal salt, ZnCO3 (100 parts by mass), Al2(SO4)3 (20 parts by mass), sodium dodecylbenzene sulfonate (10 parts by mass), modified chitosan flame retardant (30 parts by mass), and urea (50 parts by mass) were added to 5000 parts by mass of distilled water. The hydrothermal reaction was carried out under continuous stirring at 60°C and pH=7 for 10 hours. After the reaction, the product was filtered and washed with a large amount of distilled water. Finally, the composite flame retardant modifier (SDS-PCF-LDH) was obtained after vacuum drying for 12 hours.

[0086] Subsequently, polypropylene, composite flame retardant modifier, glass fiber, antioxidant (tetrakis[methyl-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester), toughening agent (ethylene-propylene copolymer), and compatibilizer (EVA (ethylene-vinyl acetate copolymer)) were vacuum dried at 80°C for 5 hours, and polypropylene, antioxidant, toughening agent, compatibilizer, glass fiber, and composite flame retardant modifier were mixed in a high-speed mixer at a mass feed ratio of 70%, 2%, 2%, 4%, 12%, and 10%, respectively, for 8 minutes, and the mixed material was added from the main feed port, and extruded and granulated by an extruder. The speed of the screw extruder was 100 rpm, the temperature of the feeding section was 200°C, the temperatures of the three sections in the center of the screw were 210°C, 215°C, and 205°C, and the die temperature was 190°C, and finally a flame-retardant polypropylene material was obtained.

[0087] Example 3

[0088] As an practicable method, under the reaction condition of 5° C., 100 parts by mass of chitosan are added to 500 parts by mass of a 5% methanesulfonic acid solution, and then 5 parts by mass of phosphorus pentoxide are added, and the reaction is carried out under a nitrogen environment with mechanical stirring for 4 hours.

[0089] Subsequently, 8 parts by mass of dibenzoyl peroxide (BPO) and 30 parts by mass of 2-carboxyethylphenylphosphinic acid (CEPPA) were added to the mixed solution, stirring was started, and the mixture was fully reacted at 50°C for 5 hours. After the reaction, 50 parts by mass of 20% ether was added to precipitate the product, which was then washed, filtered, and vacuum dried at 80°C for 24 hours to finally obtain a phosphoric acid-modified chitosan flame retardant.

[0090] Similarly, taking 100 parts by mass of divalent metal salt as the benchmark, add CuSO4 (100 parts by mass), Al2(SO4)3 (20 parts by mass), sodium dodecylbenzene sulfonate (10 parts by mass), modified chitosan flame retardant (30 parts by mass), and urea (50 parts by mass) into 5000 parts by mass of distilled water. The hydrothermal reaction was carried out under continuous stirring at 60°C and pH=7 for 10 hours. After the reaction, the product was filtered to obtain the product, and washed with a large amount of distilled water. Finally, the composite flame retardant modifier (SDS-PCF-LDH) was obtained after vacuum drying for 12 hours.

[0091] Subsequently, polypropylene, composite flame retardant modifier, glass fiber, antioxidant (tetrakis[methyl-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester), toughening agent (ethylene-propylene copolymer), and compatibilizer (EVA (ethylene-vinyl acetate copolymer)) were vacuum dried at 100°C for 10 hours, and polypropylene, antioxidant, toughening agent, compatibilizer, glass fiber, and composite flame retardant modifier were mixed in a high-speed mixer at a mass feed ratio of 70%, 2%, 2%, 4%, 12%, and 10%, respectively, for 2-10 minutes, and the mixed material was added from the main feed port, and extruded and granulated by an extruder, the speed of the screw extruder was 100rpm, the temperature of the feeding section was 200°C, the temperatures of the three sections in the center of the screw were 210°C, 215°C, and 205°C, and the die head temperature was 190°C, and finally a flame retardant polypropylene material was obtained.

[0092] Example 4

[0093] As an practicable method, the contents of chitosan, 2-carboxyethyl phenylphosphinic acid (CEPPA) and composite flame retardant modifier (SDS-PCF-LDH) in the flame retardant polypropylene material composition are adjusted to obtain Comparative Examples 1 to 9, and the prepared materials are tested for limiting oxygen index, vertical combustion performance, residual carbon value and tensile strength. The obtained comparison table is shown in Table 1-1.

[0094] Table 1-1 is a schematic table comparing the performance of the flame-retardant polypropylene material provided in the example and the flame-retardant polypropylene material prepared in Comparative Examples 1 to 9.

[0095]

[0096]

[0097] The following conclusions can be drawn from the test results shown in Table 1-1:

[0098] (1) The flame retardant properties of the material prepared without using the composite flame retardant modifier (SDS-PCF-LDH) are greatly reduced (see Comparative Example 3 for details).

[0099] (2) The composite flame retardant modifier (SDS-PCF-LDH) only adds chitosan, and does not add 2-carboxyethylphenylphosphinic acid (CEPPA). The material prepared has improved charring properties during combustion, but poor flame retardancy (see Comparative Example 2 for details); The composite flame retardant modifier (SDS-PCF-LDH) only adds 2-carboxyethylphenylphosphinic acid (CEPPA), and does not add chitosan. The charring properties during combustion are poor, but the flame retardancy is improved (see Comparative Example 1 for details).

[0100] (3) Increasing the chitosan content in the composite flame retardant modifier (SDS-PCF-LDH) will increase the carbonization rate of the material, and increasing the content of 2-carboxyethylphenylphosphinic acid (CEPPA) will increase the limiting oxygen index of the material (refer to comparative examples 9, 7, 6, 5, 4, and 3).

[0101] (4) Using an excessive amount of composite flame retardant modifier (SDS-PCF-LDH) reduces the mechanical properties of the material (refer to Comparative Example 8).

[0102] Among them, the limiting oxygen index (LOI) is the minimum oxygen concentration that maintains balanced combustion in a nitrogen and oxygen mixture under the test conditions specified in GB / 8624-2012.

[0103] The residual carbon value was measured using an American TA (MDSCQ100) thermogravimetric analyzer in an air atmosphere with a heating rate of 10°C / min and a heating range of 30-700°C.

[0104] In a second aspect, the present application provides an application of a flame retardant polypropylene material, the flame retardant polypropylene material is applied to an impeller of a range hood, and the flame retardant polypropylene material is used for flame retardancy.

[0105] In this embodiment, the injection molding process is used to prepare a flame-retardant polypropylene material suitable for the range hood impeller, which effectively improves the flame retardant effect of the polypropylene material and solves the problem that the flame retardant is easy to precipitate and the material has poor flame retardant performance.

[0106] In combination with the second aspect, flame-retardant polypropylene materials are also used in range hoods and stoves.

[0107] The flame-retardant polypropylene material provided in the present application has good flame retardancy and can also be used in plastic material scenarios with flame retardancy requirements such as range hoods and stoves.

[0108] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0109] Finally, it should be noted that the above embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing a flame retardant polypropylene material, characterized in that: The method comprises: The chitosan is modified by phosphorylation reaction to obtain a phosphoric acid-modified chitosan flame retardant; The phosphoric acid-modified chitosan flame retardant is mixed with a specified solvent, and then a soluble metal salt solution is added to perform a thermal hydrolysis reaction to obtain a composite flame retardant modifier; The polypropylene material, the composite flame retardant modifier, the antioxidant, the toughening agent and the compatibilizer are vacuum dried, mixed and extruded to obtain the flame retardant polypropylene material.

2. The method according to claim 1, characterized in that: The step of modifying chitosan by phosphorylation to obtain a phosphoric acid-modified chitosan flame retardant comprises: Chitosan was added to a methanesulfonic acid solution at a reaction temperature of 0 to 5°C, and then a phosphoric acid activator was added, and the mixture was mechanically stirred and reacted for 2 to 4 hours under a nitrogen atmosphere. Add a certain amount of peroxide initiator and phosphorus flame retardant to the mixed solution, start stirring, and fully react at 30-50°C for 2-5h; The product is precipitated with ether, then washed, filtered, and vacuum dried at 60 to 80° C. for 12 to 24 hours to obtain the phosphoric acid-modified chitosan flame retardant.

3. The method according to claim 1, characterized in that The phosphoric acid modified chitosan flame retardant is prepared from the following raw materials in parts by weight: 5-10 parts of phosphoric acid activator, 5-10 parts of peroxide initiator, 30-45 parts of phosphorus flame retardant, 5-15 parts of ether, and the concentration of methane sulfonic acid solution is 3-8%.

4. The method according to claim 1, characterized in that The step of mixing the phosphoric acid-modified chitosan flame retardant with a specified solvent and then adding a soluble metal salt solution to perform a thermal hydrolysis reaction to obtain a composite flame retardant modifier comprises: Slowly adding a certain amount of soluble divalent or trivalent metal salt solution into a mixed solution of sodium dodecyl sulfate (SDS) and the phosphoric acid-modified chitosan flame retardant; adding an alkaline solution to the mixed solution and stirring to promote a hydrothermal reaction; The mixed solution after the reaction is filtered, washed and vacuum dried to obtain a composite flame retardant modifier.

5. The method according to claim 1, characterized in that The composite flame retardant modifier is prepared by including the following raw materials in parts by weight: 20-70 parts of trivalent metal salt, 10-30 parts of sodium dodecylbenzene sulfonate, 20-40 parts of the phosphoric acid modified chitosan flame retardant, and 50-200 parts of alkaline substances.

6. The method according to claim 4, characterized in that The temperature of the hydrothermal reaction is 60-110° C., the time is 10-24 hours, and the pH is 7-10.

7. The method according to claim 1, characterized in that The step of vacuum drying the polypropylene material, the composite flame retardant modifier, the antioxidant, the toughening agent and the compatibilizer, mixing and extruding to obtain the flame retardant polypropylene material comprises: Drying polypropylene, antioxidant, toughening agent, compatibilizer and the composite flame retardant modifier under vacuum environment; Mix them with antioxidants in a high-speed mixer for 2-10 minutes according to a preset ratio; Add the mixed material from the main feed port, at a speed of 60-150rpm, a temperature of the feeding section of 195-205℃, and three sections of the screw center at temperatures of 205-215℃, 210-220℃, and 200-210℃; The die head temperature is between 180-200° C., and the flame-retardant polypropylene material is obtained by extrusion granulation through an extruder.

8. The method according to claim 7, characterized in that The flame retardant polypropylene material comprises the following raw materials in parts by weight: 70-95 parts of polypropylene, 0.3-4 parts of antioxidant, 0.5-4 parts of toughening agent, 3-8 parts of compatibilizer, 10-20 parts of glass fiber and 5-15 parts of composite flame retardant modifier.

9. An application of a flame retardant polypropylene material, characterized in that: The flame-retardant polypropylene material prepared by the method according to any one of claims 1 to 8 is applied to the impeller of a range hood, and the flame-retardant polypropylene material is used for flame retardancy.

10. The use of the flame retardant polypropylene material according to claim 9, characterized in that: The flame-retardant polypropylene material is also used in range hoods and stoves.

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