Polypropylene composition as well as preparation method and application thereof

Abstract

The polypropylene composition comprises the following components in parts by weight: 50-70 parts of polypropylene; 12-33 parts of nano ceramic powder and glass fiber; 2-5 parts of a flame retardant; the flame retardant is selected from a combination of a hypophosphite flame retardant, a brominated flame retardant and diethylhexyl chloride, and the weight ratio of the hypophosphite flame retardant to the brominated flame retardant to the diethylhexyl chloride is (2.5-3.5): (3.5-4.5): (0.8-1.2); the weight ratio of the nano ceramic powder to the glass fiber is 1: (10-15). According to the invention, through the filling of the nano ceramic powder and the glass fiber in a specific proportion and content and the specific flame retardant, the size of liquid drops of the polypropylene composition in a flame-retardant test process can be obviously reduced, so that a cotton cushion is not ignited, the flame-retardant grade of V-0 is reached, and the polypropylene composition has the advantage of good dimensional stability.

Description

Technical Field

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

[0002] Polypropylene is the most widely used general-purpose plastic. In recent years, as the popularity of modified polypropylene materials in China has increased, the proportion of engineering polypropylene materials has increased. Currently, modified polypropylene materials are widely used in automobiles, home appliances, power tools, electronics and electrical fields, bringing huge cost advantages to the entire industry.

[0003] However, polypropylene has obvious disadvantages in some performance aspects, such as large shrinkage, dimensional instability, and flammability. In order to reduce the shrinkage of polypropylene, improve dimensional stability and increase strength, the industry usually adds fillers such as mineral powder and fiber. The addition of fillers will greatly improve the dimensional stability of polypropylene, but with the addition of mineral powder and fiber, some flame retardant properties of polypropylene are greatly attenuated, especially the flame retardant polypropylene V-2 system, which is the most widely used flame retardant polypropylene on the market. This flame retardant system mainly relies on dripping to take away heat to achieve a flame retardant effect. The addition of glass fiber or mineral powder will make it more difficult for polypropylene to drip, making the droplets too large when dripping, resulting in the dripping igniting the cotton pad during the flame retardant test. Therefore, it is difficult for such polypropylene compositions to reach the V-0 flame retardant level. Summary of the invention

[0004] The object of the present invention is to overcome the above technical defects and provide a filled flame-retardant polypropylene composition having V-0 flame retardancy and good dimensional stability.

[0005] The present invention is achieved through the following technical solutions: A polypropylene composition, comprising the following components in parts by weight: Polypropylene 50-70 parts; 12-33 parts of nano ceramic powder and glass fiber; Flame retardant 2-5 parts; The flame retardant is selected from the combination of hypophosphite flame retardant / bromine flame retardant / cobalt, and the weight ratio of hypophosphite flame retardant:bromine flame retardant:cobalt is (2.5-3.5):(3.5-4.5):(0.8-1.2); The weight ratio of nano ceramic powder to glass fiber is 1:(9.5-15).

[0006] Preferably, the weight ratio of nano ceramic powder to glass fiber is 1:(12-13).

[0007] The average diameter of the glass fiber is 9-14 μm; preferably, the average diameter of the glass fiber is 9-11 μm.

[0008] The average particle size of the nano ceramic powder is 10-100 nm, preferably 40-70 nm.

[0009] The nano ceramic powder is selected from at least one of nano silicon nitride, nano titanium nitride, nano titanium carbide, nano zirconium carbide, and nano silicon carbide; preferably nano silicon carbide.

[0010] The hypophosphite flame retardant is selected from at least one of inorganic hypophosphite flame retardants and organic hypophosphite flame retardants; the inorganic hypophosphite flame retardant is selected from at least one of aluminum hypophosphite, calcium hypophosphite, and magnesium hypophosphite; the organic hypophosphite flame retardant is selected from at least one of aluminum diethyl hypophosphite and magnesium diethyl hypophosphite; the brominated flame retardant is selected from at least one of decabromodiphenylethane, octabromoether, octabromo s-ether, and brominated epoxy.

[0011] The polypropylene is selected from at least one of homopolypropylene and copolymer polypropylene, and the melt mass flow rate of the polypropylene is selected from 2-300 g / 10 min, and the test conditions are 230 °C and 2.16 kg.

[0012] By weight, it further includes 0-2 parts of an auxiliary agent, and the auxiliary agent is selected from at least one of antioxidants and lubricants. It should be noted that the weight percentage content of the polypropylene resin in the polypropylene composition of the present invention is not less than 30 wt%.

[0013] The antioxidant can be: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; 2,5-di-tert-butyl-4-hydroxybenzyl dimethylamine; diethyl 3,5-di-tert-butyl-4-hydroxybenzyl phosphate; stearyl 3,5-di-tert-butyl-4-hydroxybenzyl phosphate; 3,5-di-tert-butyl-4-hydroxyphenyl-3,5-distearyl-thiotriazolylamine; 2,6-di-tert-butyl-4-hydroxymethylphenol; 2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylglycidyl allyl ether)-1,3,5-triazine; N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamide); N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine; octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; pentaerythrityl tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; triethylene glycol bis[3-(3,5-dimethyl-4-hydroxyphenyl)propionate]; dipropylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; 2,2'-thiobisethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], etc.

[0014] The lubricant can be at least one of stearate lubricants, fatty acid lubricants, and stearate ester lubricants; the stearate lubricants are selected from at least one of calcium stearate, magnesium stearate, and zinc stearate; the fatty acid lubricants are selected from at least one of fatty acids, fatty acid derivatives, and fatty acid esters; the stearate ester lubricants are selected from at least one of pentaerythritol stearate.

[0015] The preparation method of the polypropylene composition of the present invention includes the following steps: mixing each component evenly according to the ratio, extruding and pelletizing through a twin-screw extruder, and the temperature range of the screw is 190-220°C to obtain the polypropylene composition.

[0016] The application of the polypropylene composition of the present invention is used for preparing flame-retardant polypropylene parts for vehicle interiors and flame-retardant polypropylene parts for aircraft interiors.

[0017] The present invention has the following beneficial effects: By using nano-ceramic powder and glass fiber filled in specific proportions and contents, and a specific flame retardant, the present invention can significantly reduce the size of the droplets during the flame retardancy test of the polypropylene composition, so that it will not ignite the cotton pad, achieving a V-0 flame retardant rating, and having the advantage of good dimensional stability. Embodiment

[0018] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made. These all belong to the protection scope of the present invention.

[0019] The raw materials used in the present invention are sourced as follows: Homopolypropylene: grade PPH-Y26, Zhenhai Refining & Chemical.

[0020] Random copolymer polypropylene: grade PP EP548R, CNOOC and Shell Petrochemical Company Limited.

[0021] The following nano-ceramic powders are purchased from Chengdu Organic Chemicals Co., Ltd., Chinese Academy of Sciences, and experimental samples with different particle sizes are obtained through screening.

[0022] Nano-silicon nitride A: average particle size is 10.2 nm; Nano-silicon nitride B: average particle size is 41.5 nm; Nano-silicon nitride C: average particle size is 68.7 nm; Nano-silicon nitride D: average particle size is 96.4 nm; Nano-titanium nitride: average particle size is 40.9 nm; Nano-titanium carbide: average particle size is 50.0 nm; Nano-zirconium carbide: average particle size is 43.3 nm; Nano-silicon carbide: average particle size is 44.5 nm; Glass fiber A: average diameter 10 μm, grade T438HP, Taishan Fiberglass; Glass fiber B: average diameter 13 μm, grade T438G, Taishan Fiberglass; Glass fiber C: average diameter 17 μm, grade T635B, Taishan Fiberglass; Decabromodiphenylethane: SAYTEX 8010, Albemarle; Aluminum hypophosphite: m-116, Shanghai Lidao; Dicumyl peroxide: DM-23, Wuxi Zhufeng Fine Chemicals; Antimony trioxide, Jeff Group: Preparation method of the polypropylene compositions in the examples and comparative examples: According to the ratio, the components are mixed evenly and extruded and pelletized by a twin-screw extruder. The temperature range of the screw is 190 - 220 °C to obtain the flame-retardant polypropylene composition.

[0023] Test methods for each item: (1) Vertical flammability: The vertical burning performance is tested according to ASTM UL94.

[0024] (2) Droplet size test: The combustion test plan is ignited normally according to the ASTM UL94 method, but the place where the cotton wool is placed is replaced with a round glass dish with clean water inside. After the sample is ignited, the droplets drip from the sample into the water. The droplets are collected after entering the water, and the average diameter of the droplets is tested using a two-dimensional impact tester.

[0025] (3) Dimensional stability: Shrinkage test: According to GB-T 15585-1995 Determination of shrinkage of thermoplastic injection molding, the dimensional stability is judged by the shrinkage.

[0026] Table 1: Weight parts of each component of polypropylene composition of Examples 1-7 and test results Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Homopolypropylene 60 70 50 60 60 60 Random copolymer polypropylene 60 Nano silicon nitride A 1.8 1.8 1.1 3 1.8 1.8 1.54 Glass fiber A 18.2 18.2 10.9 30 18.46 Glass fiber B 18.2 Glass fiber C 18.2 Aluminum hypophosphite 1.125 1.125 1.875 0.75 1.125 1.125 1.125 Decabromodiphenylethane 1.5 1.5 2.5 1 1.5 1.5 1.5 Dicumyl 0.375 0.375 0.625 0.25 0.375 0.375 0.375 Flame retardancy, 2mm V0 V0 V0 V0 V0 V0 V0 Droplet diameter, mm 3.2 3.5 3.8 3.9 3.8 4.8 2.8 Shrinkage rate, % 0.66 0.63 0.66 0.62 0.62 0.64 0.61 It can be seen from Examples 1 / 5 / 6 that glass fibers of different diameters were used. It was found that the glass fiber C had the largest droplets in the combustion test due to its large diameter, and the risk of dripping and ignition was also greater.

[0027] It can be seen from Examples 1 / 7 / 8 / 9 that by using different ratios of ceramic powder to glass fiber and adopting the most preferred mixing ratio, the material obtained has the smallest droplets in the combustion test and the risk of secondary disasters caused by dripping and ignition is minimized.

[0028] Table 2: Weight parts of each component of the polypropylene composition of Examples 8-11 and test results Example 8 Example 9 Example 10 Example 11 Homopolypropylene 60 60 60 60 Nano silicon nitride A 1.43 1.25 1.8 1.8 Glass fiber A 18.57 18.75 18.2 18.2 Aluminum hypophosphite 1.125 1.125 0.960 1.281 Decabromodiphenylethane 1.5 1.5 1.732 1.281 Dicumyl 0.375 0.375 0.308 0.438 Flame retardancy, 2mm V0 V0 V0 V0 Droplet diameter, mm 2.6 3.9 3.4 3.3 Shrinkage rate, % 0.60 0.63 0.66 0.59 Table 3: Weight parts of each component of the polypropylene composition of Examples 12-18 and test results Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Homopolypropylene 60 60 60 60 60 60 60 Nano silicon nitride B 1.8 Nano silicon nitride C 1.8 Nano silicon nitride D 1.8 Nano titanium nitride 1.8 Nano titanium carbide 1.8 Nano zirconium carbide 1.8 Nano silicon carbide 1.8 Glass fiber A 18.2 18.2 18.2 18.2 18.2 18.2 18.2 Aluminum hypophosphite 1.125 1.125 1.125 1.125 1.125 1.125 1.125 Decabromodiphenylethane 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Dicumyl 0.375 0.375 0.375 0.375 0.375 0.375 0.375 Flame retardancy, 2mm V0 V0 V0 V0 V0 V0 V0 Droplet diameter, mm 2.8 2.6 3.1 3.8 3.7 3.2 3.3 Shrinkage rate, % 0.64 0.62 0.63 0.65 0.64 0.62 0.66 It can be seen from Examples 1 / 12 / 13 / 14 that silicon nitride of different particle sizes also has a certain influence on the combustion test results, and selecting ceramic powder with a suitable particle size has a better anti-dripping effect.

[0029] It can be seen from Examples 12-18 that by comparing different types of ceramic powders, it is found that other types of ceramic powders can also achieve a flame retardant level of V0 for the system, but the droplet size is larger.

[0030] It can be seen from the above examples that the flame retardancy of the polypropylene composition of the present application reaches V-0, and the particle size of the dripping matter is less than 5 mm, and the shrinkage rate is less than 0.7%.

[0031] Table 4: Weight parts of each component of the comparative polypropylene composition and test results Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Homopolypropylene 60 60 60 60 60 60 60 Nano silicon nitride A 0 1 3.33 4 1.8 1.8 1.8 Glass fiber A 20 19 16.67 16 18.2 18.2 18.2 Aluminum hypophosphite 1.125 1.125 1.125 1.125 0.75 1.5 Decabromodiphenylethane 1.5 1.5 1.5 1.5 1.875 1.125 2.5 Dicumyl 0.375 0.375 0.375 0.375 0.375 0.375 Antimony trioxide 0.5 Flame retardancy, 2mm V2 V2 V2 V2 HB V2 V2 Droplet diameter, mm 8.8 6.2 5.1 5.5 6.2 5.8 8.7 Shrinkage rate, % 0.75 0.71 0.76 0.78 0.93 0.74 0.71 It can be seen from Comparative Examples 1-4 that if the ratio of nano-ceramic powder to glass fiber is not within the scope of the present invention, the dripping particles will ignite the cotton pad, so only the flame retardancy of V2 can be achieved.

[0032] As can be seen from Comparative Examples 5 / 6, if the compounding ratio of the hypophosphite flame retardant / brominated flame retardant / dicumyl is not within the scope of the present invention, the flame retardancy is poor.

[0033] As can be seen from Comparative Example 7, the dripping particles of the traditional bromine-antimony flame retardant system are relatively large, and it is difficult to achieve V-0 flame retardancy in the polypropylene system.

Claims

1. A polypropylene composition, characterized in that, by weight, it comprises the following components: 50 - 70 parts of polypropylene; 12 - 33 parts of nano-ceramic powder and glass fiber; 2 - 5 parts of flame retardant; the flame retardant is selected from the combination of hypophosphite flame retardant / brominated flame retardant / diphenylmethane, and the weight ratio of hypophosphite flame retardant: brominated flame retardant: diphenylmethane is (2.5 - 3.5):(3.5 - 4.5):(0.8 - 1.2); the weight ratio of nano-ceramic powder to glass fiber is 1:(9.5 - 15).

2. The polypropylene composition according to claim 1, characterized in that, the weight ratio of nano-ceramic powder to glass fiber is 1:(12 - 13).

3. The polypropylene composition according to claim 1, characterized in that, the average diameter of the glass fiber is 9 - 14 μm; preferably, the average diameter of the glass fiber is 9 - 11 μm.

4. The polypropylene composition according to claim 1, characterized in that, the average particle size of the nano-ceramic powder is 10 - 100 nm, preferably 40 - 70 nm.

5. The polypropylene composition according to claim 1, characterized in that, the nano-ceramic powder is selected from at least one of nano-silicon nitride, nano-titanium nitride, nano-titanium carbide, nano-zirconium carbide, nano-silicon carbide, preferably nano-silicon carbide.

6. The polypropylene composition according to claim 1, characterized in that, the hypophosphite flame retardant is selected from at least one of inorganic hypophosphite flame retardants and organic hypophosphite flame retardants; the inorganic hypophosphite flame retardants are selected from at least one of aluminum hypophosphite, calcium hypophosphite, and magnesium hypophosphite; the organic hypophosphite flame retardants are selected from at least one of aluminum diethyl hypophosphite and magnesium diethyl hypophosphite; the brominated flame retardants are selected from at least one of decabromodiphenylethane, octabromoether, octabromo s-ether, and brominated epoxy.

7. The polypropylene composition according to claim 1, characterized in that, the polypropylene is selected from at least one of homopolypropylene and copolymerized polypropylene.

8. The polypropylene composition according to claim 1, characterized in that, by weight, it further comprises 0 - 2 parts of additives, and the additives are selected from at least one of antioxidants and lubricants.

9. The preparation method of the polypropylene composition according to any one of claims 1 - 8, characterized in that, it comprises the following steps: according to the ratio, mix each component evenly, and extrude and pelletize through a twin-screw extruder, and the temperature range of the screw is 190 - 220 °C to obtain the polypropylene composition.

10. The application of the polypropylene composition according to any one of claims 1 - 8, characterized in that, it is used for preparing flame-retardant polypropylene parts for vehicle interiors and flame-retardant polypropylene parts for aircraft interiors.