Polypropylene composition, pipe material and process for its preparation and use

Abstract

This invention relates to the field of polypropylene compositions for pipes, specifically to polypropylene compositions, pipe materials, their preparation methods, and applications. The polypropylene composition contains a ternary random copolymer, an antioxidant, and a light stabilizer; and optionally, it also contains a color masterbatch and / or an acid scavenger; the antioxidant content is 0.1-1.5 parts by weight relative to 100 parts by weight of the ternary random copolymer, and the light stabilizer content is 0.03-0.8 parts by weight; the ternary random copolymer is a copolymer formed from propylene monomer, ethylene monomer, and 1-hexene monomer. This polypropylene composition and the pipes prepared therefrom possess good physical properties and excellent long-term hydrostatic performance, showing promising application prospects in the field of pressure-bearing pipes.

Description

Technical Field

[0001] This invention relates to the field of polypropylene compositions for pipes, and more specifically to polypropylene compositions, pipe materials, their preparation methods and applications. Background Technology

[0002] Polymer materials are widely used in piping systems, such as fluid transport, which involves conveying liquids or gases, such as water (drinking water, sewage, wastewater, or wastewater). Because the fluid can be pressurized during transport, and the transported fluid has a variable temperature, typically ranging from 0-30°C or exceeding 70°C, and the ambient temperature can drop to -20°C or lower during pipe installation (e.g., in industrial applications where both fluid and ambient temperatures can reach -20°C or even lower), the performance requirements for pipes are high. Meanwhile, polyolefin materials offer good overall performance, withstand high and low temperatures, and have good weather resistance, making them a preferred raw material for pipes, with polyethylene, polypropylene, and polybutene being the most common.

[0003] Although polypropylene (PP) pipes have good hydrostatic properties, high rigidity and heat resistance, the raw material itself has a series of problems such as poor low-temperature toughness, insufficient rigidity-toughness balance and low long-term creep resistance, which have long plagued the industry's development. The development of relevant solutions is a technical problem that the industry urgently needs to solve.

[0004] CN1249110A discloses a pressure pipe for hot water pipes prepared using a polypropylene composition obtained by adding a β-crystal nucleating agent to random copolymer polypropylene. The β-crystal nucleating agent is a mixture of 5,12-dihydroquinone (2,3-b)acridin-7,14-dione and quinone (2,3-b)acridin-6,7,13,14(5H,12H)-tetraone, N,N'-dicyclohexyl-2,6-naphthyldimethylamide, any one or more of a dicarboxylic acid having at least 7 carbon atoms and a salt of a Group II metal element. The pressure pipe did not leak or rupture under hydrostatic testing conditions of 95°C, 3.5 MPa ring stress, and 1500 h, but its creep resistance under higher temperature and longer duration conditions cannot be guaranteed.

[0005] CN104558859A discloses a polypropylene composition, its preparation method, and pipes made therefrom. This invention overcomes the shortcomings of existing polypropylene compositions in pipes, such as low pressure resistance and high low-temperature brittleness. Polypropylene pipes made from this composition not only have high pressure resistance and low low-temperature brittleness, but also good heat resistance, exhibiting significantly better overall performance than ordinary polypropylene pipes. However, the composition involved in this patent uses a β-nucleating agent modification technique, which requires stringent molding process conditions for the β-crystal form, and the invention does not explicitly address the long-term creep resistance of the pipes.

[0006] CN103665587A discloses a polypropylene composition, polypropylene granules, and a method for preparing the same. The polypropylene composition contains a random copolymer of propylene, an antioxidant, and a β-crystalline nucleating agent. The purpose of this invention is to overcome the shortcomings of existing technologies where pressure pipes prepared using polypropylene compositions exhibit poor long-term hydrostatic thermal stability. A polypropylene composition is provided, and pipes made from this composition can pass long-term thermal stability tests under hydrostatic conditions. However, the matrix resin of this composition is a random copolymer of propylene and ethylene, and β-crystalline polypropylene requires stringent molding process conditions. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of low pressure resistance, high low-temperature brittleness, and low long-term pressure resistance of polypropylene pipes in the prior art.

[0008] To achieve the above objectives, a first aspect of the present invention provides a polypropylene composition comprising a ternary random copolymer, an antioxidant, and a light stabilizer; and optionally further comprising a color masterbatch and / or an acid scavenger; wherein, relative to 100 parts by weight of the ternary random copolymer, the antioxidant content is 0.1-1.5 parts by weight, the light stabilizer content is 0.03-0.8 parts by weight, the color masterbatch content is 0-4 parts by weight, and the acid scavenger content is 0-0.1 parts by weight; and the ternary random copolymer is a copolymer formed from propylene monomer, ethylene monomer, and 1-hexene monomer.

[0009] A second aspect of the present invention provides a method for preparing pipe material using the polypropylene composition described in the first aspect, the method comprising: mixing the components of the polypropylene composition; then heating and melting the mixture on a twin-screw extruder and extruding and granulating it to obtain the pipe material.

[0010] A third aspect of the present invention provides a tubular material prepared by the method described in the second aspect.

[0011] The fourth aspect of the present invention provides the application of the pipe material described in the third aspect in the field of pressure pipes.

[0012] Pipes made from the pipe material provided by this invention have excellent rigidity-toughness balance and outstanding long-term creep resistance. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] It should be noted that, in all aspects of the present invention, the same components or terms in each aspect are described only once in one aspect and not repeatedly, and those skilled in the art should not understand this as a limitation of the present invention.

[0015] As previously described, a first aspect of the present invention provides a polypropylene composition comprising a ternary random copolymer, an antioxidant, and a light stabilizer; and optionally further comprising a color masterbatch and / or an acid scavenger; wherein, relative to 100 parts by weight of the ternary random copolymer, the antioxidant content is 0.1-1.5 parts by weight, the light stabilizer content is 0.03-0.8 parts by weight, the color masterbatch content is 0-4 parts by weight, and the acid scavenger content is 0-0.1 parts by weight; the ternary random copolymer is a copolymer formed from propylene monomer, ethylene monomer, and 1-hexene monomer.

[0016] To further improve the rigidity-toughness balance and long-term creep resistance of the pipes prepared from the polypropylene composition provided by the present invention, preferably, the melt flow rate of the ternary random copolymer is 0.1-0.9 g / 10 min. More preferably, the melt flow rate of the ternary random copolymer is 0.20-0.40 g / 10 min.

[0017] Preferably, in the ternary random copolymer, the content of structural units provided by the ethylene monomer is 3.0-7.0 mol%, and the content of structural units provided by the 1-hexene monomer is 1.0-5.0 mol%.

[0018] More preferably, the content of the structural units provided by the ethylene monomer in the ternary random copolymer is 5.5-7.0 mol%, and the content of the structural units provided by the 1-hexene monomer is 1.5-2.5 mol%.

[0019] According to a preferred embodiment, the weight-average molecular weight (Mw) of the ternary random copolymer is 600,000 to 750,000.

[0020] Preferably, the molecular weight distribution Da of the ternary random copolymer is 4-7.5. The molecular weight distribution is calculated as follows:

[0021]

[0022] Preferably, the antioxidant is selected from at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants.

[0023] More preferably, the hindered phenolic antioxidant is selected from at least one of phenolic compounds containing hindered phenolic functional groups; even more preferably, the hindered phenolic antioxidant is selected from at least one of the phenolic compounds containing hindered phenolic functional groups.

[0024] In some embodiments of the present invention, the hindered phenolic antioxidant is selected from hindered phenolic antioxidants with a melting point of 100-260°C. Preferably, the hindered phenolic antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, and 1,3,5-(3,5-di-tert-butyl-4-hydroxybenzyl)-triazine-2,4,6-(1H,3H,5H)-trione.

[0025] In some embodiments of the present invention, the phosphite antioxidant is selected from phosphite antioxidants with a melting point greater than 160°C. Preferably, the phosphite antioxidant is tris(2,4-di-tert-butylphenyl) phosphite and / or bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

[0026] In some embodiments of the present invention, the thioester antioxidant is bis(octadecyl) thiodipropionate and / or dilauryl thiodipropionate.

[0027] Preferably, the antioxidant is a combination of a primary antioxidant and a co-antioxidant in a weight ratio of 1:0.4-0.6; and the primary antioxidant is selected from at least two hindered phenolic antioxidants with a melting point of 100-260°C, and the co-antioxidant is a phosphite antioxidant or a thioester antioxidant. The inventors have found that, in this preferred embodiment, the long-term creep resistance of pipes prepared from the polypropylene composition provided by the present invention can be further improved.

[0028] Preferably, the primary antioxidant is selected from at least two of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, and 1,3,5-(3,5-di-tert-butyl-4-hydroxybenzyl)-triazine-2,4,6-(1H,3H,5H)-trione.

[0029] Preferably, the primary antioxidant is selected from at least one of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; a combination of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione; and a combination of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,3,5-(3,5-di-tert-butyl-4-hydroxybenzyl)-triazine-2,4,6-(1H,3H,5H)-trione.

[0030] According to a particularly preferred embodiment, the primary antioxidant is one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, or one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, and the weight ratio of the two is 1:0.5-1.

[0031] Preferably, in the co-antioxidant, the phosphite antioxidant is selected from at least one of phosphite antioxidants with a melting point greater than 160°C. More preferably, in the co-antioxidant, the phosphite antioxidant is selected from at least one of tris(2,4-di-tert-butylphenyl) phosphite and (2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

[0032] Preferably, in the antioxidant, the thioester antioxidant is at least one of bis(octadecyl)thiodipropionate and dilauryl thiodipropionate.

[0033] Preferably, in this invention, the light stabilizer is a hindered amine light stabilizer.

[0034] Preferably, the hindered amine light stabilizer is at least one of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, and poly-{[6-(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl}[2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino]. The inventors have found that, in this preferred embodiment, the synergistic effect of the light stabilizer and the antioxidant results in pipe materials and pipes prepared from the polypropylene composition provided by the present invention exhibiting significantly superior physical properties and long-term hydrostatic properties.

[0035] Preferably, the acid absorbent is at least one of calcium stearate, zinc stearate, and sodium stearate.

[0036] Preferably, the content of the color masterbatch is 1-3 parts by weight. The inventors have found that pipes made from the polypropylene composition prepared using this preferred method have better thermal stability.

[0037] The present invention does not have any particular requirements on the type of color masterbatch, which can be any color masterbatch known to those skilled in the art.

[0038] As previously stated, a second aspect of the present invention provides a method for preparing pipe materials using the polypropylene composition described in the first aspect, the method comprising: mixing the components of the polypropylene composition; then heating and melting the mixture on a twin-screw extruder and extruding and granulating it to obtain the pipe material.

[0039] Preferably, in the mixing step of the method, the mixing temperature is 10-20°C.

[0040] It should be noted that the present invention does not have specific requirements for the mixing time, as long as uniform mixing can be achieved.

[0041] Preferably, the main screw speed of the twin-screw extruder in this method is 200-250 r / min, and the feeding speed is 8-15 r / min.

[0042] Preferably, according to the logistics direction, the twin-screw extruder in this method contains at least 6 sections.

[0043] More preferably, according to the logistics direction, the six sections of the twin-screw extruder in this method are, in sequence: melting, shearing, dispersion, compression, venting, and plasticizing.

[0044] Preferably, according to the logistics direction, the temperatures of each section in the twin-screw extruder are selected sequentially from: 170-210℃, 180-230℃, 190-230℃, 200-230℃, 210-230℃, and 190-220℃.

[0045] Preferably, the vacuum degree of each section in this method is independently 0-0.03 MPa. In this invention, the vacuum degree refers to the absolute value of the difference between absolute pressure and atmospheric pressure.

[0046] It should be noted that in the melting, shearing, dispersing, compressing, venting, and plasticizing steps, the present invention does not have special requirements for parameters such as melting time, shearing speed, dispersion effect, compression density, venting rate, and plasticizing time; all parameters can be performed in accordance with conventional operations known to those skilled in the art.

[0047] It should be further noted that the present invention does not have specific requirements for the average particle size of the obtained pipe material; conventional particle sizes known in the art can be used.

[0048] According to a particularly preferred embodiment, the operating conditions of the method include: the main screw speed of the twin-screw extruder is 200-250 r / min, the feeding speed is 8-15 r / min, the method includes six sections, wherein the temperatures of each section are 170-210℃, 180-230℃, 190-230℃, 200-230℃, 210-230℃, and 190-220℃, respectively, and the vacuum degree of each section is 0-0.03 MPa. The following description of the invention provides a specific set of operating conditions, which should not be construed as limiting the invention.

[0049] It should be noted that the method for preparing the ternary random copolymer is not specifically limited in this invention. It can be a continuous polymerization process or a batch polymerization process. The catalytic system for polymerization can be a Ziegler-Natta catalyst system or a metallocene catalyst system. For example, the ternary random copolymer of this invention can be obtained by slurry polymerization, bulk polymerization or gas-phase polymerization process.

[0050] As previously described, a third aspect of the present invention provides a tubular material prepared by the method described in the second aspect.

[0051] As previously stated, a fourth aspect of the present invention provides an application of the pipe material described in the third aspect in the field of pressure pipes.

[0052] Compared with the prior art, the pipe material prepared by the polypropylene composition provided by the present invention has excellent rigidity and toughness balance, excellent long-term thermal stability under hydrostatic pressure, and good low-temperature toughness.

[0053] In a preferred embodiment, the pipe material prepared from the polypropylene composition provided by the present invention has the following advantages: its notched impact strength at 0°C is ≥15 KJ / m. 2 The pipe exhibits excellent long-term thermal stability under hydrostatic pressure. Under the same pressure rating, using this composition to prepare pipes and fittings can save more than 20% of raw materials compared to ordinary polypropylene pipes, significantly reducing the production cost of pipes.

[0054] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, the raw materials used are all commercially available products.

[0055] The preparation methods of the ternary random copolymers A1-A8 and the binary random copolymers A9 and A10 in the following examples are as follows:

[0056] A total of 5000g of propylene, ethylene, and 1-hexene monomers were added to a 10-liter stainless steel high-pressure reactor equipped with a mechanical stirrer and temperature control device. The reactor was evacuated at 60°C to remove air and water vapor, and then purged with nitrogen gas. After repeating this process 2-3 times, 0.05-0.1g of Cp2ZrMe2 (dimethylzirconia) / MAO (methylaluminoxane) composite catalyst was added. The mixture was stirred for 1 hour, and 1000-1600mg of hydrogen gas was injected. The temperature was raised to 60-80°C, and the reaction was carried out for 1-2 hours. Stirring was stopped, the temperature was lowered, the pressure was released, and the products A1-A10 in Table 1 were obtained.

[0057] Among them, products A1-A10 with different ratios of ethylene monomer and 1-hexene monomer are obtained by controlling the ratio of propylene, ethylene monomer and 1-hexene monomer.

[0058] Table 1

[0059]

[0060] Note 1: In addition to the components listed, the remainder of the A1-A10 random copolymer consists of propylene structural units.

[0061] The names and sources of the raw materials used in the preparation examples and comparative examples are shown in Table 2.

[0062] Table 2

[0063]

[0064] Acid absorbent:

[0065] Calcium stearate, sodium stearate, and zinc stearate were all purchased from Jiangsu Taihu New Materials Co., Ltd.

[0066] In the following examples, the performance was obtained through testing using the following methods:

[0067] (1) Melt mass flow rate (MFR) of ternary random copolymer: It was tested according to standard GB / T3682.1-2018. The test conditions were: temperature 230℃ and load 2.16kg.

[0068] (2) Content of each structural unit of the ternary random copolymer: determined by nuclear magnetic resonance method, all are molar contents;

[0069] (3) Melting temperature of ternary random copolymer: According to standard GB / T19466.3-2004, it was obtained by differential scanning gauging.

[0070] (4) Tensile yield stress: Tested according to standard GB / T1040.2-2006, test speed is 50mm / min;

[0071] (5) Notched impact strength of simply supported beam at 23℃ and notched impact strength of simply supported beam at 0℃: Tested according to standard GB / T1043.1-2008;

[0072] (6) Tensile modulus of elasticity: obtained according to standard GB / T1040.2-2006;

[0073] (7) Long-term thermal stability of pipe under hydrostatic pressure conditions: Tested according to standard GB / T18742-2017.

[0074] In the following examples, unless otherwise specified, each “serving” or each “part by weight” means 10g.

[0075] The nuclear magnetic resonance spectrometer model is: IM300 superconducting nuclear magnetic resonance spectrometer, manufactured by Bruker, Switzerland.

[0076] The differential scanning calorimeter model is: TA-9900 differential scanning calorimeter, manufactured by DuPont, USA.

[0077] Preparation Example 1

[0078] This preparation example illustrates the method for preparing the pipe material provided by the present invention.

[0079] The preparation method includes:

[0080] According to the dosage ratio shown in Table Z-1, the components used to prepare the pipe material are first mixed evenly (mixing temperature is 10℃) and then fed into a twin-screw extruder (model ZSK-30, purchased from WP Company, Germany). After melting, shearing, dispersion, compression, degassing, and plasticizing, the pipe material is obtained by extrusion through a die and granulation, which is designated as P1.

[0081] The settings for the twin-screw extruder are as follows: the main screw speed is 225 r / min, the feeding speed is 20 r / min, and the temperature of each section is controlled sequentially at 190℃, 210℃, 220℃, 230℃, 220℃ and 210℃ according to the material flow direction. The vacuum degree of each section is maintained at 0.02 MPa.

[0082] Table Z-1

[0083]

[0084] Preparation Example 2

[0085] The preparation method was similar to that in Example 1, except that the components and their amounts used to prepare the pipe material were different; otherwise, the preparation method was the same as in Example 1, as detailed in Table Z-2. The resulting pipe material was designated P2.

[0086] Table Z-2

[0087]

[0088] Preparation Example 3

[0089] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different; otherwise, the process was the same as in Example 1, as detailed in Table Z-3. The resulting pipe material was designated P3.

[0090] Table Z-3

[0091]

[0092] Preparation Example 4

[0093] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different; otherwise, the process was the same as in Example 1, as detailed in Table Z-4. The resulting pipe material was designated P4.

[0094] Table Z-4

[0095]

[0096]

[0097] Preparation Example 5

[0098] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different. Ternary random copolymer A5 was used instead of ternary random copolymer A1 in Example 1 (see Table Z-5 for details). All other aspects were the same as in Example 1. The resulting pipe material was designated P5.

[0099] Table Z-5

[0100]

[0101] Preparation Example 6

[0102] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different, and no color masterbatch was added. Everything else was the same as in Example 1, as detailed in Table Z-6. The resulting pipe material was designated P6.

[0103] Table Z-6

[0104]

[0105]

[0106] Preparation Example 7

[0107] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different, and no color masterbatch was added. Everything else was the same as in Example 1, as detailed in Table Z-7. The resulting pipe material was designated P7.

[0108] Table Z-7

[0109]

[0110] Preparation Example 8

[0111] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different, and no color masterbatch was added. Everything else was the same as in Example 1, as detailed in Table Z-8. The resulting pipe material was designated P8.

[0112] Table Z-8

[0113]

[0114] Comparative Example 1

[0115] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different; otherwise, the process was the same as in Example 1, as detailed in Table D-1. Ordinary polypropylene pipe material, designated DP1, was obtained.

[0116] Table D-1

[0117]

[0118] Comparative Example 2

[0119] The preparation method was followed as in Example 1, except that the components and their amounts used to prepare the pipe material were different, and no color masterbatch was added. Everything else was the same as in Example 1, as detailed in Table D-2. Ordinary polypropylene pipe material, designated DP2, was obtained.

[0120] Table D-2

[0121]

[0122] The pipe materials prepared in Examples 1-8 and Comparative Examples 1 and 2 were used to prepare pipes, and the appearance quality of the pipes met the technical requirements of GB / T18742-2017. The mechanical properties of the composition were then determined, and a long-term thermal stability test was conducted on the pipes under hydrostatic pressure. The test results are shown in Table C-1.

[0123] Table C-1

[0124]

[0125] Note 1: The tensile strength test speed is 50 mm / min;

[0126] Note 2: Impact strength refers to the impact performance of a notched spline simply supported beam.

[0127] Note 3: The pipe specifications are S3.2dn20×en2.8mm;

[0128] Note 4: The thermal stability test conditions are 110℃ and 2.6MPa ring stress. The test is considered passed if the failure time is greater than or equal to 8760h, otherwise it is considered a failure.

[0129] As can be seen from the results in Table C-1, the pipe material prepared by the polypropylene composition provided by the present invention has the following advantages: its notched impact strength at 0℃ is ≥15KJ / m. 2 The pipe exhibits excellent long-term thermal stability under hydrostatic pressure. At the same pressure rating, using this composition to manufacture pipes and fittings can save more than 20% of raw materials compared to ordinary polypropylene pipes, significantly reducing production costs.

[0130] Therefore, the pipes made from the pipe materials provided by this invention have good physical properties and excellent thermal stability, and have good application prospects in the field of pressure pipes.

[0131] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A polypropylene composition, characterized in that, The polypropylene composition contains a ternary random copolymer, an antioxidant, and a light stabilizer; furthermore, the polypropylene composition also contains a color masterbatch and / or an acid scavenger; relative to 100 parts by weight of the ternary random copolymer, the content of the antioxidant is 0.1-1.5 parts by weight, the content of the light stabilizer is 0.03-0.8 parts by weight, the content of the color masterbatch is 2-4 parts by weight, and the content of the acid scavenger is 0-0.1 parts by weight; the ternary random copolymer is a copolymer formed from propylene monomer, ethylene monomer, and 1-hexene monomer; The melt flow rate of the ternary random copolymer is 0.20-0.40 g / 10 min; The content of the structural units provided by the ethylene monomer in the ternary random copolymer is 5.5-7.0 mol%, and the content of the structural units provided by the 1-hexene monomer is 1.5-1.8 mol%. The antioxidant is selected from at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants; the light stabilizer is a hindered amine light stabilizer.

2. The polypropylene composition according to claim 1, wherein, The antioxidant is a combination of a primary antioxidant and a co-antioxidant in a weight ratio of 1:0.4-0.6; and The primary antioxidant is selected from at least two hindered phenolic antioxidants with a melting point of 100-260℃, and the co-antioxidant is a phosphite antioxidant or a thioester antioxidant.

3. The polypropylene composition according to claim 2, wherein, In the antioxidant, the phosphite antioxidant is selected from at least one of phosphite antioxidants with a melting point greater than 160°C.

4. The polypropylene composition according to claim 2, wherein, The phosphite antioxidant is selected from at least one of tris(2,4-di-tert-butylphenyl) phosphite and (2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

5. The polypropylene composition according to claim 2, wherein, In the antioxidant, the thioester antioxidant is at least one of bis(octadecyl)thiodipropionate and dilauryl thiodipropionate.

6. The polypropylene composition according to any one of claims 1-5, wherein, The hindered amine light stabilizer is at least one of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, and poly-{[6-(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl}[2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino].

7. The polypropylene composition according to any one of claims 1-5, wherein, The acid absorber is at least one of calcium stearate, zinc stearate, and sodium stearate.

8. A method for preparing pipe materials, characterized in that, The method applies each component of the polypropylene composition according to any one of claims 1-7, and includes: mixing each component of the polypropylene composition; then heating and melting the mixture on a twin-screw extruder and extruding and granulating it to obtain the pipe material.

9. The pipe material prepared by the method of claim 8.

10. The application of the pipe material according to claim 9 in the field of pressure pipes.

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