PP-RCT special material and preparation method thereof

Abstract

The application relates to a polypropylene special material, in particular to a PP-RCT special material and a preparation method thereof. The fourth generation PP-RCT polypropylene pipe special material with a beta crystal structure has high impact resistance and high heat distortion temperature, but due to the difficulty in product development, the related core technology threshold is high, and the domestic market of the special material has been in a vacancy state. The PP-RCT special material and the polypropylene pipe prepared by the application have the core performances of the processing performance, tensile resistance, bending resistance, impact resistance, heat resistance, long-term water pressure resistance performance and long-term stable use which are obviously improved, are superior to the GB / T 18742-2017 national PP-RCT national standard, reach or are superior to the level of imported products (the northern Europe chemical trademark is Beta PPR RA7050). The vacancy of the domestic market is filled, has a wide market prospect, and economic and social benefits are remarkable.

Description

Technical Field

[0001] This invention relates to a special material for polypropylene, specifically to a special material for PP-RCT and its preparation method. Background Technology

[0002] In recent years, with the market's increasing demand for high-performance and functional polypropylene, the development of specialty polypropylene materials has received growing attention. Random copolymer polypropylene, due to its high impact strength, heat distortion temperature, and good toughness and ductility under high-speed tensile conditions, has found applications in industrial pipelines, battery casings, filter presses, automotive accessories, and films, and its application areas continue to expand. Among these, PP-RCT (Poly Propylene Random Crystallinity Temperature, high-temperature resistant β-crystalline polypropylene) pipe material is a high-end product in the PPR pipe material category, and many downstream pipe manufacturers are attempting to develop this specification for the high-end PPR market. The use of PP pipes began in the 1980s, and researchers successively developed the first-generation homopolymer polypropylene PPH, the second-generation block copolymer polypropylene PPB, and the third-generation random copolymer polypropylene PPR pipe material. Due to differences in molecular structure, the three raw materials exhibit significant performance variations: PPH has high strength but poor toughness; PPB shows improved toughness compared to PPH, but its strength and heat resistance are significantly reduced; PPR, on the other hand, boasts excellent strength, toughness, and heat resistance. The third-generation polypropylene pipe material, PPR, is α-crystalline polypropylene. This material offers advantages such as increased rigidity, higher heat distortion temperature, creep resistance, reduced turbidity, and improved surface gloss. However, α-crystalline PPR pipes suffer from brittleness at low temperatures, and their toughness and heat resistance require further improvement.

[0003] The fourth-generation PP-RCT polypropylene pipe material with a β-crystalline structure can simultaneously improve the impact resistance and heat distortion temperature of polypropylene. Following the release of the 2018 standard for polypropylene piping systems (GB / T 18742-2017), PP-RCT polypropylene pipe materials now have a formal standard. Due to the high technical difficulty and threshold in developing this material, certification work such as designated-point grading certification is required. Currently, the only PP-RCT material that has achieved industrialized production is Borealis's Beta PPRRA7050 pipe material. This material significantly improves the impact resistance and heat resistance of the material by adding a β-nucleating agent. The pipe has a design stress of 1.0 MPa and a service life of up to 50 years at 90℃, which is 20℃ higher than the service temperature of α-crystalline PPR (1.0 MPa, 50 years at 70℃), and the pipe grade can be lowered by one level. Due to the high difficulty in product development and the high barriers to entry in related core technologies, there has always been a large market demand for such special materials. In recent years, with the development of market demand and industry, there is an urgent need to improve the performance of polypropylene pipe special materials to fill market demand. Summary of the Invention

[0004] To address the above technical issues, this application presents a PP-RCT (PolyPropylene Random Crystallinity Temperature, high-temperature resistant β-crystalline polypropylene) special material whose processing performance, tensile strength, flexural strength, impact resistance, heat resistance, long-term water pressure resistance, and long-term stable use all meet or exceed the levels of imported products. The specific preparation method is as follows:

[0005] Preparation of polypropylene resin powder: Using the Spheripol-II process, the main catalyst, co-catalyst, and external electron donor are activated in a pre-contact tank. After activation, the mixture enters a prepolymerization reactor for propylene prepolymerization. After prepolymerization, the mixture enters two loop reactors connected in series. The molecular weight and molecular weight distribution are adjusted by hydrogen to obtain polypropylene particles. At the same time, ethylene is added to the first and second loop reactors for random copolymerization to obtain polypropylene resin particles. The polypropylene particles are then steamed to obtain polypropylene resin powder.

[0006] Preparation of PP-RCT Special Material: Polypropylene resin powder is mixed with processing aids including β-crystal nucleating agent, primary antioxidant, secondary antioxidant, and acid scavenger. The mixture is then melted, kneaded, extruded, granulated, and dried in an extruder to obtain the PP-RCT special material. This PP-RCT special material is further processed into polypropylene pipes.

[0007] The mass ratio of propylene to ethylene is 93-98:2-7;

[0008] The main catalyst is a Ziegler-Natta type catalyst; the Ziegler-Natta type catalyst is selected from at least one of CS, HR, DQ, DJD, ZNM series, ZNM1 catalyst or ZN118 catalyst produced by Basell.

[0009] The co-catalyst is selected from at least one of triethylaluminum, trimethylaluminum, and methylaluminoxane;

[0010] The external electron donor is selected from at least one of alkoxysilane compounds, phthalates, di-n-butyl phthalate, diphenyldimethoxysilane, and succinate; the alkoxysilane compound is selected from at least one of cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, and diisopropyldimethoxysilane.

[0011] The amount of the main catalyst is 10-100 ppm relative to the total mass of propylene and ethylene; the amount of the co-catalyst is 120-280 ppm; and the amount of the external electron donor is 30-120 ppm.

[0012] The catalyst is supported on a catalyst support, which is selected from one of Al2O3, Al(OH)3, MgO, TiO2, MgCl2, Mg(OH)Cl, Mg(OR)2, Fe(OH)3, Ni(OH)2, NiCl2, CoCl2, and SiO2, wherein the number of carbon atoms in the alkoxy group -OR is a positive integer from 1 to 10.

[0013] The concentration of hydrogen is 10-300 ppm. Hydrogen is used as a chain initiator in the prepolymerization reaction. Adjusting its concentration can adjust the molecular weight and molecular weight distribution of polypropylene obtained by polymerization.

[0014] The concentration of ethylene is 30,000-85,000 ppm. The introduction of ethylene can reduce the chain length of polypropylene molecules and improve the toughness of the material.

[0015] The prepolymerization process includes a first loop reactor and a second loop reactor, wherein the hydrogen concentration in the first loop reactor is 100-300 ppm and the hydrogen concentration in the second loop reactor is 10-150 ppm; the ethylene concentration in the first loop reactor is 30000-55000 ppm and the ethylene concentration in the second loop reactor is 65000-85000 ppm.

[0016] The processing aids include β-crystal nucleating agents, primary antioxidants, secondary antioxidants, and acid scavengers;

[0017] The mass ratio of the polypropylene particles: β-crystal nucleating agent: primary antioxidant: secondary antioxidant: acid scavenger is 100:(0.05-0.25):(0.2-0.6):(0.2-0.5):(0.05-0.15).

[0018] The β nucleating agent is selected from at least one of the following: fused ring compound nucleating agents with quasi-planar structures, salts of Group IIA metal elements and their dicarboxylic acid complexes, aromatic diamide nucleating agents, or rare earth nucleating agents.

[0019] Preferably, the β-nucleating agent is selected from at least one of aromatic diamide nucleating agents, salts of Group IIA metal elements and their dicarboxylic acid complexes, or rare earth nucleating agents;

[0020] The nucleating agent of the quasi-planar fused ring compound is selected from γ-crystalline quinacridone, quinacridone red E3B, and triphenyldithiazide TPDT(C). 18 H 10 N2S2), anthracene ANTR (C 14 H 10 ), PHNTR (C 14 H 10 ), diphenylamine sulfide MBIM (C 12 At least one of H8NS) or mercaptobenzimidazole PT (C2H6N2S).

[0021] The group IIA metal salts and their dicarboxylic acid complex nucleating agents are selected from at least one of the following: a mixture of calcium stearate and pimelic acid, and calcium imide. Specifically, the nucleating agent produced by Guangzhou Chenghe Technology Co., Ltd., with the trade name NAB-82, can be selected.

[0022] The aromatic diamide nucleating agent is selected from at least one of cyclohexylamine 2,6-phthalic acid (DVTH), cyclohexylamine 2,6-phthalic acid (NC), and diphenylhexadiamide. Specifically, it can be a nucleating agent produced by Shanxi Chemical Research Institute with the trade names TMB4 and TMBS, or produced by Beijing Jihaichuan Technology Development Co., Ltd. with the trade names JHC671 and JHC673.

[0023] The rare earth nucleating agents are mainly multi-component complexes containing rare earth elements and calcium, wherein the complexes have a carbon chain length of C4-C6. 26 For different or the same structure of organic ligands, you can choose nucleating agents produced by Beijing Jihaichuan Technology Development Co., Ltd. with the trade name JHC672 or Guangzhou Weilinna New Material Technology Co., Ltd. with the trade name WBG.

[0024] The primary antioxidant is a hindered phenolic antioxidant, and the secondary antioxidant is selected from either thioester antioxidants or phosphite antioxidants.

[0025] The hindered phenolic antioxidant is selected from at least one of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2'-methylenebis(4-methyl-6-tert-butyl)phenol, or octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;

[0026] The thioester antioxidant is selected from at least one of dilaurate thiodipropionate, octadecyl thiodipropionate, or 2-mercaptophenylimidazolium.

[0027] The phosphite antioxidant is selected from at least one of the following: triphenyl phosphite, pentaerythritol diphosphite, triphenyl phosphite, trinonylphenyl phosphite, tris(2,4-di-tert-butylphenyl phosphite), bis-(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, or tetrakis(2,4-di-tert-butylphenol) 4,4'-biphenyl diphosphite.

[0028] The acid absorbent is selected from at least one of calcium carbonate, talc, mica, calcium stearate, kaolin, silica, hydrotalcite, or aluminum hydroxide, and has a particle size of <10 micrometers.

[0029] The processing aid also includes a fluorinated polymer PPA, which is added at a mass ratio of 0.01-0.1% of the total mass of the polypropylene particles and the processing aid.

[0030] The prepared PP-RCT pipe material has a weight-average molecular weight to number-average molecular weight ratio of 3-7:1. The wider this ratio, the better the processing performance; if it is too wide, the material strength will decrease.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) Technical Effects: The polypropylene pipes prepared from the PP-RCT special material of this invention exhibit significantly improved core properties such as processing performance, tensile strength, bending strength, impact resistance, heat resistance, long-term water pressure resistance, and long-term stable use. These properties surpass the national standard GB / T 18742-2017 for PP-RCT and reach or exceed the level of imported products (Beta PPR RA7050 from Borealis). This fills a market gap and plays a leading and exemplary role in the overall development of polypropylene technology.

[0033] The main technical specifications of the product applied for meet the following standards:

[0034] Table 1 Performance indicators of polypropylene pipes prepared from the PP-RCT special material of this application

[0035]

[0036]

[0037] The processing of the special material PA14D-3 was successful in the processing and application test conducted by the pipe company. The physical properties, oxidation induction period, thermodynamic properties and β crystal form retention rate of the prepared pipes were all good and higher than the national standard. The hydrostatic data of hot and cold water and the oxidation induction period data after 1000h of hot water at 95℃ were both higher than the PP-RCT national standard.

[0038] (2) Economic Benefits: Currently, the market price of Borealis Beta PPR RA7050 special material is 13,000 yuan / ton, which is 1,500-2,000 yuan / ton higher than the market price of conventional PPR pipe special materials. This invention, through the development of PA14D-3 (PP-RCT) special material, greatly increases the added value of the product. The development of this project can fill the gap in PP-RCT polypropylene pipe special materials, has broad market prospects, and significant economic and social benefits. Detailed Implementation

[0039] Example 1

[0040] Preparation method:

[0041] Preparation of polypropylene resin powder: The main catalyst, co-catalyst and external electron donor are activated in a pre-contact tank. After activation, the mixture is fed into a prepolymerization reactor for propylene prepolymerization. After prepolymerization, the mixture is fed into two loop reactors connected in series. The molecular weight is adjusted by hydrogen to obtain polypropylene particles. At the same time, ethylene is added to the first loop reactor and the second loop reactor for random copolymerization to obtain polypropylene resin particles. The polypropylene particles are then steamed to obtain polypropylene resin powder.

[0042] Preparation of PP-RCT Special Material: Polypropylene resin powder is mixed with processing aids including β-crystal nucleating agent, primary antioxidant, secondary antioxidant, and acid scavenger. The mixture is then melted, kneaded, extruded, pelletized, and dried in an extruder to obtain the PP-RCT special material. This PP-RCT special material is further processed into polypropylene pipes.

[0043] The raw material usage for preparing polypropylene resin powder is as follows:

[0044] By mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0045] The main catalyst is ZNM1 catalyst manufactured by Basell, and the dosage is 10-100 ppm relative to the total mass of propylene and ethylene.

[0046] The co-catalyst is triethylaluminum, and the dosage is 120-280 ppm relative to the total mass of propylene and ethylene.

[0047] The catalyst support is magnesium chloride;

[0048] The electron donor is dicyclopentyldimethoxysilane, and the amount used is 30-120 ppm relative to the total mass of propylene and ethylene.

[0049] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 100-300 ppm / 10-150 ppm.

[0050] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 30,000-50,000 ppm / 65,000-85,000 ppm.

[0051] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0052] Polypropylene resin powder (melt flow rate MI = 0.2-0.4 g / 10 min), 100 parts;

[0053] The β-crystal nucleating agent was Jihaichuan JHC673, 0.20 parts;

[0054] The main antioxidants are pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.38 parts; and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 0.12 parts.

[0055] The auxiliary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite, 0.30 parts;

[0056] The acid absorbent is calcium stearate, 0.10 parts.

[0057] Example 2

[0058] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0059] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0060] The main catalyst is ZNM1 catalyst manufactured by Basell, and the amount used is 10-90 ppm relative to the total mass of propylene and ethylene.

[0061] The co-catalyst is triethylaluminum, and the dosage is 120-250 ppm relative to the total mass of propylene and ethylene.

[0062] The catalyst support is magnesium chloride;

[0063] The electron donor is cyclohexylmethyldimethoxysilane, and the amount used is 30-110 ppm relative to the total mass of propylene and ethylene.

[0064] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 100-200 ppm / 50-140 ppm.

[0065] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 30,000-35,000 ppm / 70,000-85,000 ppm.

[0066] Example 3

[0067] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0068] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0069] The main catalyst is Basell's ZNM1 catalyst, and the dosage is 30-80 ppm relative to the total mass of propylene and ethylene.

[0070] The co-catalyst is trimethylaluminum, and the amount used is 120-230 ppm relative to the total mass of propylene and ethylene;

[0071] The catalyst support is magnesium chloride;

[0072] The electron donor is dicyclopentyldimethoxysilane, and the amount used is 30-100 ppm relative to the total mass of propylene and ethylene.

[0073] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 120-270 ppm / 30-100 ppm.

[0074] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 30,000-50,000 ppm / 70,000-85,000 ppm.

[0075] Example 4

[0076] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0077] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0078] The main catalyst is ZNM1 catalyst manufactured by Basell, and the dosage is 20-70 ppm relative to the total mass of propylene and ethylene.

[0079] The co-catalyst is triethylaluminum, and the dosage is 130-230 ppm relative to the total mass of propylene and ethylene.

[0080] The catalyst support is alumina;

[0081] The electron donor is cyclohexylmethyldimethoxysilane, and the amount used is 30-105 ppm relative to the total mass of propylene and ethylene.

[0082] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 150-250 ppm / 20-80 ppm.

[0083] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 35,000-38,000 ppm / 70,000-78,000 ppm.

[0084] Example 5

[0085] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0086] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0087] The main catalyst is a DQ series catalyst, and the dosage is 30-90 ppm relative to the total mass of propylene and ethylene.

[0088] The co-catalyst is methylaluminoxane, and the amount used is 120-210 ppm relative to the total mass of propylene and ethylene.

[0089] The catalyst support is silicon dioxide;

[0090] The electron donor is cyclohexylmethyldimethoxysilane, and the amount used is 40-100 ppm relative to the total mass of propylene and ethylene.

[0091] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 200-300 ppm / 60-100 ppm.

[0092] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 35,000-40,000 ppm / 70,000-85,000 ppm.

[0093] Example 6

[0094] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0095] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0096] The main catalyst is a CS series catalyst, and the dosage is 20-60 ppm relative to the total mass of propylene and ethylene.

[0097] The co-catalyst is triethylaluminum, and the dosage is 140-220 ppm relative to the total mass of propylene and ethylene.

[0098] The catalyst support is magnesium chloride;

[0099] The electron donor is cyclohexylmethyldimethoxysilane, and the amount used is 40-110 ppm relative to the total mass of propylene and ethylene.

[0100] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 150-300 ppm / 50-100 ppm.

[0101] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 30,000-40,000 ppm / 65,000-78,000 ppm.

[0102] Example 7

[0103] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0104] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0105] The main catalyst is Basell's ZN118 catalyst, and the dosage is 10-50 ppm relative to the total mass of propylene and ethylene.

[0106] The co-catalyst is triethylaluminum, and the dosage is 140-220 ppm relative to the total mass of propylene and ethylene.

[0107] The catalyst support is magnesium chloride;

[0108] The electron donor is cyclohexylmethyldimethoxysilane, and the amount used is 35-105 ppm relative to the total mass of propylene and ethylene.

[0109] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 150-250 ppm / 60-130 ppm.

[0110] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 30,000-40,000 ppm / 70,000-78,000 ppm.

[0111] Example 8

[0112] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0113] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0114] The main catalyst is an HR series catalyst, and the dosage is 10-40 ppm relative to the total mass of propylene and ethylene.

[0115] The co-catalyst is trimethylaluminum, and the dosage is 120-190 ppm relative to the total mass of propylene and ethylene.

[0116] The catalyst support is silicon dioxide;

[0117] The electron donor is dicyclopentyldimethoxysilane, and the amount used is 30-100 ppm relative to the total mass of propylene and ethylene.

[0118] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 120-270 ppm / 20-80 ppm.

[0119] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 35,000-50,000 ppm / 65,000-80,000 ppm.

[0120] Example 9

[0121] The preparation method and the raw material ratio for preparing PP-RCT special material are the same as in Example 1.

[0122] Specifically, by mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0123] The main catalyst is Basell's ZN118 catalyst, and the dosage is 30-80 ppm relative to the total mass of propylene and ethylene.

[0124] The co-catalyst is methylaluminoxane, and the amount used is 130-220 ppm relative to the total mass of propylene and ethylene;

[0125] The catalyst support is aluminum hydroxide;

[0126] The electron donor is dicyclopentyldimethoxysilane, and the amount used is 40-120 ppm relative to the total mass of propylene and ethylene.

[0127] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 120-260 ppm / 30-120 ppm.

[0128] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 30,000-40,000 ppm / 65,000-80,000 ppm.

[0129] Example 10

[0130] The preparation method is the same as in Example 1.

[0131] The raw material usage for preparing polypropylene resin powder is as follows:

[0132] By mass percentage, the propylene content in production is dynamically controlled at 93.0-98.0%, and the ethylene content is dynamically controlled at 2.0-7.0%.

[0133] The main catalyst is Basell's ZN118 catalyst, and the dosage is 10-80 ppm relative to the total mass of propylene and ethylene.

[0134] The co-catalyst is triethylaluminum, and the dosage is 120-240 ppm relative to the total mass of propylene and ethylene.

[0135] The catalyst support is magnesium chloride;

[0136] The electron donor is cyclohexylmethyldimethoxysilane, and the amount used is 30-120 ppm relative to the total mass of propylene and ethylene.

[0137] The concentration of monocyclic hydrogen / dicyclic hydrogen, relative to the total mass of propylene and ethylene, is 150-250 ppm / 30-90 ppm.

[0138] The concentration of monocyclic ethylene / dicyclic ethylene, relative to the total mass of propylene and ethylene, is 30,000-35,000 ppm / 65,000-80,000 ppm.

[0139] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0140] Polypropylene resin powder (MI = 0.2-0.5 g / 10 min), 100 parts;

[0141] The β-crystal nucleating agent is mercaptobenzimidazole (PT), 0.15 parts;

[0142] The main antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], 0.45 parts;

[0143] The auxiliary antioxidants are tris(2,4-di-tert-butylphenyl) phosphite, 0.25 parts; and dilaurate thiodipropionate, 0.20 parts.

[0144] The acid absorbent is calcium stearate, 0.10 parts.

[0145] Example 11

[0146] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0147] The raw material quantities for preparing PP-RCT special material are as follows (by weight):

[0148] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0149] The β-crystal nucleating agent is produced by Guangzhou Chenghe Technology Co., Ltd., and its trade name is NAB-82. 0.20 parts;

[0150] The main antioxidant is 1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 0.40 parts;

[0151] The auxiliary antioxidants are trinonylphenyl phosphite, 0.20 parts; and octadecyl thiodipropionate, 0.20 parts.

[0152] The acid absorbent is calcium carbonate, 0.10 parts;

[0153] PPA, a fluorinated polymer, 0.10 parts.

[0154] Example 12

[0155] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0156] The raw material quantities for preparing PP-RCT special material are as follows (by weight):

[0157] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0158] The β-crystal nucleating agent was produced by Shanxi Chemical Research Institute and its trade name is TMBS. 0.25 parts;

[0159] The main antioxidant is 2,2'-methylenebis(4-methyl-6-tert-butyl)phenol, 0.45 parts;

[0160] The auxiliary antioxidants are tris(2,4-di-tert-butylphenyl) phosphite, 0.25 parts; and dilaurate thiodipropionate, 0.22 parts.

[0161] The acid absorbent is calcium stearate, 0.10 parts.

[0162] Example 13

[0163] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0164] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0165] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0166] The β-crystal nucleating agent is produced by Beijing Jihaichuan Technology Development Co., Ltd., and its trade name is JHC671. 0.20 parts;

[0167] The main antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], 0.40 parts;

[0168] The auxiliary antioxidants are trinonylphenyl phosphite, 0.25 parts; and dilaurate thiodipropionate, 0.20 parts.

[0169] The acid absorbent is calcium stearate, 0.05 parts;

[0170] PPA, a fluorinated polymer, 0.10 parts.

[0171] Example 14

[0172] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0173] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0174] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0175] The β-crystal nucleating agent is produced by Beijing Jihaichuan Technology Development Co., Ltd., and its trade name is JHC673. 0.15 parts;

[0176] The main antioxidants are pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.38 parts; and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 0.12 parts.

[0177] The auxiliary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite, 0.30 parts;

[0178] The acid absorbent is hydrotalcite, 0.10 parts.

[0179] Example 15

[0180] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0181] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0182] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0183] The β-crystal nucleating agent was produced by Guangzhou Weilinna New Material Technology Co., Ltd., and its trade name is WBG. The nucleating agent was 0.25 parts.

[0184] The main antioxidants are pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.25 parts; and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 0.20 parts.

[0185] The auxiliary antioxidants are tris(2,4-di-tert-butylphenyl) phosphite, 0.20 parts; and pentaerythritol diphosphite (bis-(2,4-di-tert-butylphenyl)phosphite), 0.10 parts.

[0186] The acid absorbent is calcium stearate, 0.10 parts.

[0187] Example 16

[0188] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0189] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0190] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0191] The β-crystal nucleating agent was produced by Guangzhou Weilinna New Material Technology Co., Ltd., and its trade name is WBG. The nucleating agent was 0.08 parts.

[0192] The main antioxidants are pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.30 parts; and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 0.25 parts;

[0193] The auxiliary antioxidants are tris(2,4-di-tert-butylphenyl) phosphite, 0.25 parts; and pentaerythritol diphosphite (bis-(2,4-di-tert-butylphenyl)-1,000 parts.

[0194] The acid absorbent is hydrotalcite, 0.10 parts.

[0195] Example 17

[0196] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0197] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0198] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0199] The β-crystal nucleating agent was produced by Beijing Jihaichuan Technology Development Co., Ltd., and its trade name was JHC672. 0.18 parts were used.

[0200] The main antioxidant is 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 0.27 parts;

[0201] The auxiliary antioxidants are tris(2,4-di-tert-butylphenyl) phosphite, 0.18 parts; bis-(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, 0.12 parts; and octadecyl thiodipropionate, 0.10 parts.

[0202] The acid absorbent is hydrotalcite, 0.10 parts.

[0203] Example 18

[0204] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0205] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0206] Polypropylene resin powder (MI = 0.2-0.4 g / 10 min), 100 parts;

[0207] The β-crystal nucleating agent was produced by Beijing Jihaichuan Technology Development Co., Ltd., and its trade name was JHC671. 0.13 parts were used.

[0208] The main antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], 0.30 parts;

[0209] The auxiliary antioxidants are tris(2,4-di-tert-butylphenyl) phosphite, 0.18 parts; and pentaerythritol diphosphite (bis-(2,4-di-tert-butylphenyl)phosphite), 0.12 parts.

[0210] The acid absorbent is hydrotalcite, 0.10 parts;

[0211] PPA, a fluorinated polymer, 0.10 parts.

[0212] Example 19

[0213] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0214] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0215] Polypropylene resin powder (MI = 0.2-0.5 g / 10 min), 100 parts;

[0216] The β-crystal nucleating agent was produced by Guangzhou Weilinna New Material Technology Co., Ltd., and its trade name is WBG. The nucleating agent was 0.25 parts.

[0217] The main antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], 0.30 parts;

[0218] The auxiliary antioxidant is dilaurate thiodipropionate, 0.20 parts;

[0219] The acid absorbent is kaolin, 0.15 parts;

[0220] PPA, a fluorinated polymer, 0.02 parts.

[0221] Example 20

[0222] The preparation method is the same as in Example 1, and the amount of raw materials used to prepare the polypropylene resin powder is the same as in Example 10.

[0223] The raw material consumption for preparing PP-RCT special material is as follows (by weight):

[0224] Polypropylene resin powder (MI = 0.2-0.5 g / 10 min), 100 parts;

[0225] The β-crystal nucleating agent is produced by Beijing Jihaichuan Technology Development Co., Ltd., and its trade name is JHC671. 0.25 parts;

[0226] The main antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], 0.60 parts;

[0227] The auxiliary antioxidant is dilaurate thiodipropionate, 0.20 parts;

[0228] The acid absorbent is calcium stearate, 0.15 parts;

[0229] PPA, a fluorinated polymer, 0.02 parts.

[0230] Experimental Example 1

[0231] The polypropylene pipes prepared in Examples 1-9 above were subjected to the following tests:

[0232] A) Melt Flow Rate: Melt flow rate (MFR) was determined according to GB / T 3682.1 standard and expressed in g / 10min. MFR is an indicator of polymer flowability and processability. The higher the melt flow rate, the lower the polymer viscosity. Here, MFR was measured at a temperature of 230℃ and a load of 2.16 kg.

[0233] B) Processing sensitivity was tested using a capillary extrusion experiment: A dual-orifice capillary rheometer (Rosand RH-7, Malvern) operating at constant speed in 190°C was used. A capillary die with a diameter of 1 mm and a length of 16 mm, and an orifice die with a diameter of 1 mm were used. The die entry angle was 180°, and the shrinkage ratio between the storage tank and the die was approximately 15.

[0234] C) Tensile yield strength was determined according to the method in GB / T 1040.2-2018;

[0235] D) The flexural modulus was determined according to the method in GB / T 9341-2008;

[0236] E) The impact strength of simply supported beams was determined according to the method in GB / T 1043.2-2018.

[0237] The test results are shown in Table 2:

[0238] Table 2 Performance test results of Examples 1-9

[0239]

[0240]

[0241] Experimental Example 2

[0242] The polypropylene pipes prepared in Examples 10-20 above were subjected to the following tests:

[0243] A) Melt Flow Rate: Melt flow rate (MFR) was determined according to GB / T 3682.1 standard and expressed in g / 10min. MFR is an indicator of the polymer's flowability and therefore processability. A higher melt flow rate generally indicates a lower polymer viscosity. Here, MFR was measured at 230°C and a load of 2.16 kg.

[0244] B) The flexural modulus was determined according to the method in GB / T 9341-2008;

[0245] C) Impact strength was determined according to the method in GB / T 1043.2-2018;

[0246] D) Tensile yield strength was determined according to the method in GB / T 1040.2-2018;

[0247] E) Oxidation induction period: The aging characteristics of the material were further tested through the oxidation induction period. The equipment used was a differential scanning calorimeter manufactured by Mettler Toledo Instruments. 5-10 mg of sample was placed in an aluminum dish. During the test, the sample in a nitrogen atmosphere was first heated to 210 °C at a rate of 20 °C / min. Then the gas was switched to oxygen at a flow rate of 50 mL / min. The time when the DSC curve of the test sample showed a strong endothermic peak was taken as the oxidation induction period of the material.

[0248] F) Hydrostatic test: According to GB / T6111-2018 standard, using type A end caps, a 95℃, 3.8MPa ring stress, and 1000h hydrostatic test is conducted. The pipe is considered to have passed if it does not leak or crack.

[0249] The test results are shown in Table 3:

[0250] Table 3 Performance test results of Examples 10-20

[0251]

[0252]

Claims

1. A method for preparing a PP-RCT-specific material, characterized in that, Includes the following steps: Propylene undergoes prepolymerization under the action of a main catalyst, a co-catalyst, and an external electron donor; the prepolymerized product undergoes random copolymerization with ethylene under the action of hydrogen to generate polypropylene particles; the polypropylene particles are blended, melted, compounded, extruded, and granulated with processing aids to obtain the PP-RCT special material. The main catalyst is a Ziegler-Natta type catalyst; The processing aids include β-crystal nucleating agents, primary antioxidants, secondary antioxidants, and acid scavengers.

2. The preparation method according to claim 1, characterized in that, The mass ratio of propylene to ethylene is 93-98:2-7.

3. The preparation method according to claim 1, characterized in that, The Ziegler-Natta type catalyst is selected from at least one of the CS, HR, DQ, DJD, and ZNM series.

4. The preparation method according to claim 1, characterized in that, The amount of the main catalyst is 10-100 ppm, the amount of the co-catalyst is 120-280 ppm, and the amount of the external electron donor is 30-120 ppm, relative to the total mass of propylene and ethylene.

5. The preparation method according to claim 1, characterized in that, The co-catalyst is selected from at least one of triethylaluminum, trimethylaluminum, and methylaluminoxane.

6. The preparation method according to claim 1, characterized in that, The external electron donor is selected from at least one of alkoxysilane compounds, phthalates, di-n-butyl phthalate, diphenyl dimethoxysilane, and succinate; the alkoxysilane compound is selected from at least one of cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, and diisopropyldimethoxysilane.

7. The preparation method according to claim 1, characterized in that, The concentration of hydrogen gas is 10-300 ppm relative to the total mass of propylene and ethylene.

8. The preparation method according to claim 1, characterized in that, The main catalyst and the co-catalyst are supported on a catalyst support, which is selected from one of Al2O3, Al(OH)3, MgO, TiO2, MgCl2, Mg(OH)Cl, Mg(OR)2, Fe(OH)3, Ni(OH)2, NiCl2, CoCl2, and SiO2, wherein -OR is an alkoxy group, and the alkoxy group contains a positive integer number of carbon atoms from 1 to 10.

9. The preparation method according to claim 1, characterized in that, The mass ratio of the polypropylene particles, β-crystal nucleating agent, primary antioxidant, secondary antioxidant, and acid scavenger is 100:(0.05-0.25):(0.2-0.6):(0.2-0.5):(0.05-0.15).

10. The preparation method according to claim 1, characterized in that, based on the total mass of propylene and ethylene, The concentration of ethylene is 30,000-85,000 ppm.

11. The preparation method according to claim 1, characterized in that, The β-nucleating agent is selected from at least one of the following: fused ring compound nucleating agents with quasi-planar structures, salts of Group IIA metals and their dicarboxylic acid complexes, aromatic diamide nucleating agents, or rare earth nucleating agents.

12. The preparation method according to claim 1, characterized in that, The β-nucleating agent is selected from at least one of aromatic diamide nucleating agents, salts of Group IIA metal elements and their dicarboxylic acid complex nucleating agents, or rare earth nucleating agents.

13. The preparation method according to claim 12, characterized in that, The nucleating agent of the quasi-planar fused ring compound is selected from at least one of γ-crystalline quinacridone, triphenyldithiazide, anthracene, phenanthrene, diphenylamine sulfide, or mercaptobenzimidazole.

14. The preparation method according to claim 12, characterized in that, The salts of the Group IIA metal elements and their dicarboxylic acid complex nucleating agents are selected from at least one of a mixture of calcium stearate and pimelic acid or an imine salt of calcium.

15. The preparation method according to claim 12, characterized in that, The aromatic diamide nucleating agent is selected from at least one of cyclohexylamine 2,6-phthalic acid, cyclohexylamine 2,6-phthalic acid, and diphenylhexadiamide.

16. The preparation method according to claim 1, characterized in that, The primary antioxidant is a hindered phenolic antioxidant, and the secondary antioxidant is selected from either thioester antioxidants or phosphite antioxidants.

17. The preparation method according to claim 16, characterized in that, The hindered phenolic antioxidant is selected from at least one of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2'-methylenebis(4-methyl-6-tert-butyl)phenol, or octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

18. The preparation method according to claim 16, characterized in that, The thioester antioxidant is selected from at least one of dilaurate thiodipropionate, octadecyl thiodipropionate, or 2-mercaptophenylimidazole.

19. The preparation method according to claim 16, characterized in that, The phosphite antioxidant is selected from at least one of triphenyl phosphite, pentaerythritol diphosphite, triphenyl phosphite, trinonylphenyl phosphite, tris(2,4-di-tert-butylphenyl phosphite), bis-(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, or tetrakis(2,4-di-tert-butylphenol)4,4'-biphenyl diphosphite.

20. The preparation method according to claim 1, characterized in that, The acid absorbent is selected from at least one of calcium carbonate, talc, mica, calcium stearate, kaolin, silica, hydrotalcite, or aluminum hydroxide, and has a particle size of <10 micrometers.

21. The preparation method according to claim 1, characterized in that, The processing aid also includes fluorinated polymer PPA, which is added at a mass ratio of 0.01-0.1% of the total mass of polypropylene particles and processing aid.

22. A special material for PP-RCT, characterized in that, It is prepared by the preparation method according to any one of claims 1-21.

23. The PP-RCT special material according to claim 22, characterized in that, The weight-average molecular weight of the special material is 3-7:1 compared to the number-average molecular weight.

24. A PP-RCT pipe, characterized in that, It is prepared from the PP-RCT special material as described in claim 22 or 23.

Images