Flame-retardant polypropylene composition, process for its preparation and use

Abstract

The application discloses a kind of flame-retardant polypropylene compositions and its preparation method and application.The flame-retardant polypropylene compositions include the following components calculated by weight parts: polypropylene resin 70 parts;3~8 parts of compatilizer;15~25 parts of aluminum hypophosphite flame retardant;2~5 parts of antioxidant aid;0.5~2 parts of metal passivator;Wherein, the molecular weight of the antioxidant aid is not less than 900, and contains benzene ring structure.The application can effectively improve the heat water performance and copper aging performance of the composition by using polypropylene resin as the base resin, adding antioxidant aid with benzene ring of specific molecular weight and aluminum hypophosphite flame retardant.

Description

Technical Field

[0001] This invention belongs to the field of halogen-free flame retardant technology, specifically relating to a flame retardant polypropylene composition, its preparation method, and its application. Background Technology

[0002] The German standard PP-9Y automotive wiring harness is used in low-voltage wiring harnesses within vehicles for communication signals and low-voltage power transmission. It meets all performance requirements of ISO 6722. The challenges lie in the polypropylene automotive wiring harness's ability to withstand 45° angled burning, 3000 hours of copper aging at 125°C without cracking during winding, and 35 days of immersion in a 10g / L NaCl solution at 85°C with a 48V DC voltage applied, without breakdown at 1kV. Compared to halogenated flame retardant systems, halogen-free flame retardants require the addition of large amounts of phosphorus-nitrogen flame retardants, making flame retardancy, copper aging, and salt water resistance more challenging. Furthermore, ISO 6722 has been superseded by ISO 19642, which has higher flame retardant requirements, reducing the afterflame time from <70s to <30s, posing a greater challenge to the flame retardant system and negatively impacting hot water resistance.

[0003] In existing technologies, to meet the 3000-hour copper aging requirement, a large amount of antioxidants is typically added. However, a large amount of antioxidants poses a risk of precipitation during long-term immersion in salt water. This precipitation can create defects in the resin system, easily forming electrical trees under an electric field, leading to decreased insulation performance, breakdown points, and reduced hot water resistance. Therefore, there is a need in this field to develop a polypropylene composition with good copper aging performance, excellent hot water resistance, and good flame retardant properties. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing flame-retardant polypropylene compositions in that they cannot simultaneously possess both hot water resistance and copper aging resistance, and to provide a flame-retardant polypropylene composition.

[0005] Another object of the present invention is to provide a method for preparing the flame-retardant polypropylene composition.

[0006] Another object of the present invention is to provide the application of the flame-retardant polypropylene composition.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A flame-retardant polypropylene composition comprising the following components in parts by weight:

[0009] 70 parts of polypropylene resin;

[0010] 3-8 parts compatibilizer;

[0011] 15-25 parts of aluminum hypophosphite flame retardant;

[0012] Antioxidant 2-5 parts;

[0013] Metal passivating agent 0.5~2 parts;

[0014] The antioxidant has a molecular weight of not less than 900 and contains a benzene ring structure.

[0015] In this invention, polypropylene resin is used as the matrix resin, and a benzene ring-containing antioxidant with a specific molecular weight is added to it. In conjunction with an aluminum hypophosphite flame retardant, the hot water resistance and copper aging resistance of the polypropylene composition can be effectively improved. Specifically, adjusting the molecular weight of the antioxidant can reduce its precipitation. Moreover, the benzene ring conjugated structure contains electrophilic groups compared to the polymer matrix, which has the ability to capture electrons. It can absorb the energy of high-energy electrons during excitation or ionization, reduce the number of high-energy electrons, suppress the impact of high-energy electrons on the polymer molecular chain, and improve the hot water resistance and copper aging resistance of the polypropylene composition.

[0016] It should be noted that, in the flame-retardant polypropylene composition of the present invention, the polypropylene resin content is preferably not less than 60 wt%.

[0017] It should be noted that the molecular weight of the antioxidant adjuvant described in this invention is not less than 900, such as, but not limited to, not less than 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2050, or 2100, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0018] Furthermore, the molecular weight of the antioxidant is 950~2050.

[0019] It should be noted that the antioxidant adjuvant described in this invention is 2 to 5 parts, for example, but not limited to 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4 parts, 4.2 parts, 4.5 parts, 4.8 parts, or 5 parts, as well as the specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, the specific values ​​included in the range will not be exhaustively listed in this invention.

[0020] Furthermore, the number of benzene ring structures in the antioxidant is a positive integer from 1 to 10.

[0021] Furthermore, the number of benzene ring structures in the antioxidant is a positive integer from 2 to 7.

[0022] Specifically, the number of benzene ring structures in the antioxidant can be determined by testing methods such as 1H NMR, 1C NMR, and infrared spectroscopy.

[0023] Specifically, the molecular weight of the antioxidant can be obtained by calculating the relative molecular mass of the raw material or by GPC testing.

[0024] Furthermore, the melt flow rate of the polypropylene resin at 230°C and a load of 2.16 kg is 0.5~12 g / 10 min.

[0025] Specifically, the test standard for the melt flow rate of the polypropylene resin is ISO 1133-1-2011.

[0026] Specifically, the polypropylene resin may be homopolymer polypropylene resin and / or copolymer polypropylene resin.

[0027] Furthermore, the aluminum hypophosphite flame retardant is aluminum hypophosphite and / or coated aluminum hypophosphite.

[0028] Furthermore, the aluminum hypophosphite is coated aluminum hypophosphite.

[0029] Furthermore, the coated aluminum hypophosphite includes silicone-coated aluminum hypophosphite and / or melamine resin-coated aluminum hypophosphite.

[0030] It should be noted that the organosilicon-coated aluminum hypophosphite described in this invention can be self-made or commercially available, and its source is not limited.

[0031] In some preferred embodiments, the organosilicon-coated aluminum hypophosphite is prepared by the following method:

[0032] The aluminum hypophosphite and silane coupling agent are stirred at 75-85℃ for 2-6 hours to obtain the product.

[0033] Specifically, the silane coupling agent accounts for 0.5 to 5 wt% of the aluminum hypophosphite.

[0034] Specifically, the silane coupling agent includes one or more of vinyltriethoxysilane, vinyltrimethoxysilane, or aminosilane.

[0035] The melamine resin-coated aluminum hypophosphite described in this invention can be self-made or commercially available, and its source is not limited.

[0036] In some preferred embodiments, the melamine resin-coated aluminum hypophosphite is obtained by in-situ polymerization of aluminum hypophosphite dispersion and melamine resin prepolymer.

[0037] Specifically, aluminum hypophosphite is dispersed in a solvent to form an aluminum hypophosphite dispersion, then melamine resin prepolymer is added, and the mixture is reacted at 50-90°C and pH 8-11 for 2-6 hours. The mixture is then washed, filtered, and dried to obtain the final product.

[0038] Specifically, the melamine resin prepolymer is obtained by stirring melamine and formaldehyde at 70°C for 30 minutes.

[0039] Specifically, the mass ratio of aluminum hypophosphite, melamine, and formaldehyde is 1:(0.1~0.3):(0.2~0.6).

[0040] Specifically, the D50 of the aluminum hypophosphite flame retardant is ≤20μm.

[0041] Specifically, the D50 of the aluminum hypophosphite flame retardant is 3~20μm.

[0042] Specifically, the D50 of the aluminum hypophosphite flame retardant was tested using a Malvern laser particle size analyzer.

[0043] Furthermore, the metal passivating agent includes hydrazide-based metal passivating agents and / or amide-based metal passivating agents.

[0044] Furthermore, the metal passivating agent is an acylhydrazine-based metal passivating agent.

[0045] Specifically, the hydrazide-based metal passivating agent is N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine.

[0046] The amide-based metal passivating agent is 2,2-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate.

[0047] Specifically, the metal passivating agent may be Irganox® MD 1024 and / or SONOX 1027.

[0048] Furthermore, the compatibilizer is maleic anhydride-grafted polypropylene.

[0049] Specifically, the maleic anhydride content in the compatibilizer is 0.5~1.5wt%.

[0050] Specifically, the compatibilizer has a melt flow rate of 0.5~15g / 10min at 230℃ and 2.16kg load.

[0051] Specifically, the test standard for the melt flow rate is ISO 1133-2011.

[0052] Furthermore, without affecting the hot water resistance and copper aging resistance of the flame-retardant polypropylene composition of the present invention, the flame-retardant polypropylene composition of the present invention further includes 1 to 5 parts of lubricant.

[0053] Specifically, the lubricant can be a silicone lubricant.

[0054] This invention also protects a method for preparing the above-mentioned flame-retardant polypropylene composition, comprising the following steps:

[0055] The components are mixed evenly to obtain a premix, and the premix is ​​then subjected to intensive mixing and extrusion granulation to obtain a flame-retardant polypropylene composition.

[0056] Furthermore, the mixing speed is 1000-2000 rpm.

[0057] Furthermore, the extrusion temperature is 130–155°C.

[0058] The present invention also protects the use of the above-mentioned flame-retardant polypropylene composition in the preparation of cable materials.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] This invention provides a flame-retardant polypropylene composition. By using polypropylene resin as the matrix resin and adding an antioxidant containing benzene rings of a specific molecular weight, the hot water resistance and copper aging resistance of the polypropylene composition can be effectively improved in conjunction with aluminum hypophosphite flame retardants. Detailed Implementation

[0061] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0062] 1. Raw materials used in each embodiment and comparative example:

[0063] Polypropylene resin:

[0064] Polypropylene resin 1: Moplen EP240H, a copolymer polypropylene, with a melt flow rate of 2 g / 10 min at 230°C and a load of 2.16 kg, purchased from Basel, Germany;

[0065] Polypropylene resin 2: PP FC709M, copolymer polypropylene, with a melt flow rate of 10 g / 10min at 230℃ and 2.16kg load, purchased from China National Petroleum Corporation.

[0066] Aluminum hypophosphite flame retardants:

[0067] Coated aluminum hypophosphite 1: Organosilicon coated aluminum hypophosphite, self-made, with a D50 of 7μm, is obtained by stirring aluminum hypophosphite and vinyltriethoxysilane (accounting for 2wt% of aluminum hypophosphite) at 80℃ for 4h, filtering, vacuum drying the filtrate solids, and then pulverizing and sieving them.

[0068] 2. Coated aluminum hypophosphite: Melamine resin coated aluminum hypophosphite, self-made, with a D50 of 8 μm, was obtained by dispersing aluminum hypophosphite in an ethanol-water solution (ethanol to water volume ratio of 1:6) and sonicating for 30 min; then, melamine resin prepolymer (obtained by stirring melamine and formaldehyde at 70℃ for 30 min) was added, and the mixture was reacted at 70℃ and pH 9 for 4 hours. The mixture was then washed, filtered, dried, pulverized, and sieved. The mass ratio of aluminum hypophosphite, melamine, and formaldehyde was 1:0.2:0.4.

[0069] Aluminum hypophosphite: purchased from Maclean, 10 μm;

[0070] Melamine polyphosphate: purchased from Maclean, 10 μm;

[0071] Antioxidant adjuvants:

[0072] Antioxidant 1: Tetra(2,4-di-tert-butylphenol)-4,4′-biphenyl diphosphite, SONGNOX PQ, CAS No.: 119345-01-6, molecular weight 1035, number of benzene rings 6, purchased from Matsubara Sangyo Co., Ltd.

[0073] Antioxidant 2: Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), IRGANOX 1010, CAS No.: 6683-19-8, molecular weight 1178, number of benzene rings 4, purchased from BASF.

[0074] Antioxidant 3: Polymer of 2-propanone and N-phenylaniline, CHINOX 1325, CAS No.: 34137-09-02, molecular weight 1042, number of benzene rings 3, produced by Double Bond Chemical Co., Ltd.

[0075] Antioxidant 4: Poly2,2,4-trimethyl-1,2-dihydroquinoline, Flectol TMQ, Poly2,2,4-trimethyl-1,2-dihydroquinoline, CAS No.: 26780-96-1, molecular weight 2150, number of benzene rings 10, purchased from Vanderbilt, Inc., USA.

[0076] Antioxidant 5: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, Irganox 1330, CAS No.: 1709-70-2, molecular weight 775, number of benzene rings 3, purchased from BASF;

[0077] Antioxidant 6: N,N'''-1,2-ethylenedimethylbis[N-[3-[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazin-2-yl]amino]propyl]-N,N''-dibutyl-N,N''-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-1,3,5-triazin-2,4,6-triamine, CHISORB 519, CAS No.: 106990-43-6, molecular weight 2286, number of benzene rings 0, purchased from Shuangjian Chemical Co., Ltd.;

[0078] Metal passivating agent:

[0079] Metal passivator 1: Irganox® MD 1024, bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine, purchased from BASF;

[0080] Metal passivating agent 2: SONOX 1027, 2,2-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate, purchased from Sanfeng Chemical Co., Ltd.

[0081] Compatibilizer: Maleic anhydride-grafted polypropylene, QB510E, purchased from Mitsui Chemicals, Japan;

[0082] It should be noted that the same raw materials were used in the parallel experiments of the examples and comparative examples.

[0083] 2. The polypropylene compositions in each embodiment and comparative example were prepared according to the formulations in Tables 1-2 and the following preparation methods:

[0084] The components are added to a high-speed mixer in proportion and mixed evenly at a speed of 1000~2000 rpm. The mixture is then fed into a twin-screw extruder and extruded and granulated at 150~180℃ to obtain a polypropylene composition.

[0085] 3. Performance Testing:

[0086] (1) Flame retardant performance test: The polypropylene compositions prepared in each example and comparative example were extruded into wire using an extrusion machine with a copper conductor of 0.5 mm. 2 The wire has a wall thickness of 0.2mm and an outer diameter of 1.5mm. The resulting wire is tested according to standard ISO 19642-2019. When burning at a 45° angle, the afterflame time is required to be <30s.

[0087] (2) Copper aging test: The wires were tested according to the standard ISO 19642-2019 until the winding cracks occurred after copper aging. The copper aging cracking time range can be divided into <3000h, ≥3000h, and >3500h. The longer the time, the better the aging resistance.

[0088] (3) Hot water resistance: The prepared wires are immersed in a sodium chloride solution at 85℃ and 10g / L for 35 days according to standard ISO 19642-2019. During the immersion process, a DC voltage of 48V is applied, and then the withstand voltage of 1KV is tested. It is required that the wires do not break down.

[0089] Examples 1-10 and Comparative Examples 1-5

[0090] Table 1. Amount (parts by weight) and properties of each component in the flame-retardant polypropylene compositions of Examples 1-10

[0091]

[0092] Table 2. Amounts (parts by weight) and properties of each component in the polypropylene compositions of each comparative example.

[0093]

[0094] As can be seen from Table 1, the flame-retardant polypropylene composition prepared by the present invention has good hot water resistance and copper aging performance. Specifically, it is not punctured after being soaked in hot salt water, the afterflame time at a 45° angle is not higher than 30s, and the copper aging time is not less than 3000h.

[0095] As can be seen from Comparative Example 1, if the molecular weight of the antioxidant additive used is too low, it is easy to precipitate. The precipitation of the antioxidant additive will form channels in the resin matrix. During the soaking process in salt water, the salt water can easily enter along the precipitation channels, causing breakdown and making the hot water resistance test fail.

[0096] As can be seen from Comparative Example 2, if the antioxidant additive used does not contain benzene rings, it cannot effectively reduce the kinetic energy of high-energy electrons, resulting in the failure of hot water resistance after soaking in salt water.

[0097] As can be seen from Comparative Examples 3 and 4, even when using the antioxidant additive of the present invention, the polypropylene composition obtained cannot meet the requirements if the dosage is too low or too high.

[0098] As can be seen from Comparative Example 5, even when using the antioxidant additive of the present invention, the hot water resistance and copper aging resistance of the polypropylene composition prepared by using other non-aluminum hypophosphite flame retardants cannot meet the requirements.

[0099] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A flame-retardant polypropylene composition, characterized in that, Includes the following components, calculated in parts by weight: 70 parts of polypropylene resin; 3-8 parts compatibilizer; 15-25 parts of aluminum hypophosphite flame retardant; Antioxidant 2-5 parts; Metal passivating agent 0.5~2 parts; The antioxidant has a molecular weight of not less than 900 and contains a benzene ring structure.

2. The flame-retardant polypropylene composition according to claim 1, characterized in that, The molecular weight of the antioxidant is 950~2050.

3. The flame-retardant polypropylene composition according to claim 1, characterized in that, The number of benzene rings in the antioxidant additive is a positive integer from 1 to 10.

4. The flame-retardant polypropylene composition according to claim 1, characterized in that, The aluminum hypophosphite flame retardant is aluminum hypophosphite and / or coated aluminum hypophosphite.

5. The flame-retardant polypropylene composition according to claim 1, characterized in that, The aluminum hypophosphite flame retardant is coated aluminum hypophosphite.

6. The flame-retardant polypropylene composition according to claim 5, characterized in that, The coated aluminum hypophosphite includes silicone-coated aluminum hypophosphite and / or melamine resin-coated aluminum hypophosphite.

7. The flame-retardant polypropylene composition according to claim 1, characterized in that, The particle size D50 of the aluminum hypophosphite flame retardant is ≤20μm.

8. The flame-retardant polypropylene composition according to claim 1, characterized in that, The metal passivating agent includes hydrazide-based metal passivating agents and / or amide-based metal passivating agents.

9. The flame-retardant polypropylene composition according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene.

10. The flame-retardant polypropylene composition according to claim 1, characterized in that, The melt flow rate of the polypropylene resin at 230°C and 2.16 kg load is 0.5~12 g / 10 min.

11. A method for preparing the flame-retardant polypropylene composition according to any one of claims 1 to 10, characterized in that, Includes the following steps: The components are mixed evenly to obtain a premix, and the premix is ​​then subjected to intensive mixing and extrusion granulation to obtain a polypropylene composition.

12. The use of the flame-retardant polypropylene composition according to any one of claims 1 to 10 in the preparation of cable materials.

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